Artículos de revistas: "Ewes Nutrition"

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Kenyon, P. R., S. J. Pain, P. G. Hutton, C. M. C. Jenkinson, S. T. Morris, S. W. Peterson y H. T. Blair. "Effects of twin-bearing ewe nutritional treatments on ewe and lamb performance to weaning". Animal Production Science 51, n.º 5 (2011): 406. http://dx.doi.org/10.1071/an10184.

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Nutrition of the ewe at various stages of pregnancy is known to affect ewe and offspring performance. However, little is known regarding the potential interactions among differing maternal nutrition regimens in early and mid–late pregnancy. The objective of the present study was to examine the effects and potential interactions of three pastoral nutritional treatments from Day 21 of pregnancy (P21) to P50 (Sub-maintenanceP21–50 (total liveweight change achieved, SMP21-50, –0.15 ± 0.02 kg/day) v. MaintenanceP21–50 (MP21-50,–0.02 ± 0.02 kg/day) v. Ad libitumP21–50 (AdP21-50,0.15 ± 0.02 kg/day) and two pastoral nutritional treatments from P50 to P139 [MaintenanceP50–139 (designed to match change in conceptus mass, total liveweight change achieved, 0.19 ± 0.01 kg/day) v. Ad libitumP50–139 (0.26 ± 0.01 kg/day)] on 382 twin-bearing ewes and their offspring until 91 days after the mid-point of lambing (L91). Ewe liveweight and condition scores in pregnancy and lactation, and lamb liveweights, indices of colostrum uptake and survival were recorded. There were no interactions between nutritional periods for lamb liveweight, apparent colostrum intake and survival, and ewe liveweight, condition score and total weight of lamb per ewe at the end of the study. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on either ewe liveweight or body condition score. Ewe nutritional treatment during P21–50 had no effect on lamb birthweight. Lambs born to AdP50–139 ewes were lighter (P < 0.05) than those born to MP50–139 ewes (5.32 ± 0.04 v. 5.48 ± 0.04 kg, respectively). Ewe nutritional treatment during P21–50 or P50–139 had no (P > 0.05) effect on indices of colostrum uptake in lambs at 24–36 h of age. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on lamb liveweight, survival or total weight of lamb per ewe. In conclusion, although considerable differences in ewe liveweight were observed during pregnancy, the nutritional treatments had no effect on the production parameters measured at the end of the study. These results indicate, first, that farmers can use early pregnancy as a period to control ewe nutrition when ewes are offered at least pregnancy maintenance levels of nutrition in the mid–late pregnancy period and, second, that there is no advantage from offering twin-bearing ewes a level of nutrition above their pregnancy maintenance requirements in mid–late pregnancy.

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Young, J. M., R. Behrendt, M. Curnow, C. M. Oldham y A. N. Thompson. "Economic value of pregnancy scanning and optimum nutritional management of dry, single- and twin-bearing Merino ewes". Animal Production Science 56, n.º 4 (2016): 669. http://dx.doi.org/10.1071/an15202.

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The nutritional requirements of twin-bearing ewes are ~25% greater than those of ewes with single fetuses during late pregnancy and nearly twice those of non-pregnant ewes. Underfeeding ewes, resulting in liveweight loss during late pregnancy, can have adverse effects on the production and survival of both the lamb and the ewe, and improving twin-lamb survival is critical to improving the overall reproductive performance of the National Merino flock. Scanning for pregnancy status and litter size allows for more precise management of the nutrition of the ewe flock according to the different nutritional needs of dry, single- and twin-bearing ewes. In the present paper, we tested the hypothesis that it is profitable to identify pregnancy status and litter size, and the optimum nutrition profiles are different for dry, single- and twin-bearing ewes. We tested this by examining a range of nutrition strategies for flocks where only the dry ewes were identified, or for flocks where the single- and twin-bearing ewes were identified. A MIDAS model set up for the Hamilton region in south-western Victoria was used for this analysis as it represents the whole flock and it includes a powerful feed-budgeting module that optimises animal and pasture management across the whole farm. The survival and production of the single- and twin-born progeny was adjusted on the basis of the liveweight profile of the single- and twin-bearing ewes. Our hypothesis was supported and profitability was increased by approximately AU$4630/farm or AU$0.80/ewe, by scanning ewes for pregnancy status and litter size, and the optimum liveweight profiles were different for dry, single- and twin-bearing ewes. The majority of the increase in profit was due to identifying litter size and being able to differentially manage the single- and twin-bearing ewes. When ewes are scanned for pregnancy status and litter size, the most profitable combination of profiles involves all ewes losing 4 kg in early pregnancy and single-bearing ewes regaining the 4 kg to lamb at their standard reference weight, twin-bearing ewes gaining 8 kg to lamb above their standard reference weight and dry ewes losing a further 4 kg to be 8 kg lighter than their standard reference weight at lambing time.

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Thompson, A. N., M. B. Ferguson, D. J. Gordon, G. A. Kearney, C. M. Oldham y B. L. Paganoni. "Improving the nutrition of Merino ewes during pregnancy increases the fleece weight and reduces the fibre diameter of their progeny's wool during their lifetime and these effects can be predicted from the ewe's liveweight profile". Animal Production Science 51, n.º 9 (2011): 794. http://dx.doi.org/10.1071/an10161.

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Nutrition of ewes during pregnancy can have permanent impacts on the production potential of their progeny. The hypothesis tested in the experiments reported in this paper was that improving the nutrition of Merino ewes during pregnancy and lactation increases the fleece weight and reduces the fibre diameter of their progeny’s wool during their lifetime. In addition, that these effects on the progeny’s wool production can be predicted from the ewe’s liveweight profile. At sites in Victoria and Western Australia in each of 2 years, a wide range in the liveweight and condition score profiles of Merino ewes was generated by varying the amount of supplements fed from joining to Day 100 of pregnancy and the amount of feed on offer grazed from Day 100 to weaning. The site in Victoria was based on perennial pastures and included both single- and twin-bearing ewes whereas the site in Western Australia was based on annual pastures and included single-bearing ewes only. The production and characteristics of wool from the progeny were measured until 51 months of age at the site in Victoria and 33 months of age at the site in Western Australia. The nutritional treatments and the resulting changes in ewe liveweight had significant impacts on the fleece weight and to a lesser extent the fibre diameter of wool produced by their progeny, but there were no consistent effects on other characteristics of progeny fleece wool. The fleece weight of the progeny was related to the liveweight change during pregnancy of their mothers (P < 0.05) and the relationships were similar for the two experiments at each site. At the site in Victoria, a loss of 10 kg in ewe liveweight between joining and Day 100 of pregnancy reduced fleece weight by ~0.2 kg at each shearing until 51 months of age whereas gaining 10 kg from Day 100 of pregnancy to lambing had the opposite effect. The effect of changes in ewe liveweight during late pregnancy on the fleece weight of their progeny at each shearing was of similar magnitude at the site in Western Australia. When evident, the effect of the ewe liveweight profile on the fibre diameter of progeny wool was opposite to the effect on clean fleece weight and the effect of poor nutrition in early to mid pregnancy could be completely overcome by improving nutrition during late pregnancy. Twin-born and reared progeny produced ~0.3 kg less clean wool at each shearing (P < 0.001) that was 0.3-μm broader (P < 0.001) than that from single-born progeny at the site in Victoria. However, the effects of varying ewe nutrition and ewe liveweight change during pregnancy on fleece weight and fibre diameter of progeny wool were similar (P > 0.05) for both single- and twin-born or reared progeny. Overall, these results supported our hypothesis and it is clear that the nutritional management of Merino ewes during pregnancy is important for optimal wool production from their progeny during their lifetime.

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Kenyon, P. R., R. A. Corner-Thomas, S. W. Peterson, S. J. Pain y H. T. Blair. "Pregnancy nutrition does not influence lamb liveweight in developmentally programmed ewes". Animal Production Science 54, n.º 9 (2014): 1465. http://dx.doi.org/10.1071/an14217.

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In sheep, maternal nutrition can affect the offspring’s milk production at its first lactation and the grand-offspring’s liveweight to weaning. However, this apparent developmental programming effect on milk production and grand-offspring liveweight has not persisted. Therefore, the aim of the present study was to determine if nutrition of the programmed ewe in mid- to late pregnancy affected this response. Developmentally programmed ewes (G1) that had been born from dams (G0) offered submaintenance, maintenance or ad libitum feeding levels from Day 21 to Day 50 of pregnancy and then either pregnancy maintenance or ad libitum to Day 140 were used for this study. These ewes were offered one of two pastoral-based pregnancy nutritional treatments (controlled vs unrestricted) from Day 76 of pregnancy until lambing. Pre- and post-herbage masses of the unrestricted treatment (2181 ± 47.6 and 1431 ± 24.6 kg DM/ha, respectively), were greater (P < 0.05) than the controlled treatment (1164 ± 31.6 and 819 ± 16.0 kg DM/ha, respectively). At Day 71 of pregnancy, there were no differences (P > 0.05) in G1 liveweight (70.2 ± 0.8 vs 70.3 ± 0.8 kg for controlled and unrestricted feeding, respectively), or body condition scores (2.5 ± 0.06 vs 2.5 ± 0.05) between pregnancy nutritional treatments. In late pregnancy, unrestricted G1 ewes were heavier (P < 0.05, 97.4 ± 1.0 vs 86.8 ± 1.0 kg) and had greater (P < 0.05) body condition scores (3.4 ± 0.06 vs 2.5 ± 0.06) and back-fat depths (8.0 ± 0.3 vs 5.9 ± 0.03 mm) than controlled nutritional treatment ewes. There were no interactions (P > 0.05) between grand-dam feeding levels and ewe nutritional treatment on lamb (G2) liveweights at birth or in lactation. This indicates that under the conditions of the present study, nutrition of the G1 ewe did not affect the expression of the developmental programming effect. Further studies might be warranted to determine the causes of this inconsistency in grand-offspring liveweight. Nutrition of the G1 ewe had a minor effect (P < 0.05) on G2 lamb birthweight and liveweight in early lactation but not (P > 0.05) in late lactation or on lamb survival. These findings indicate there is no little to no benefit to the lamb until weaning from offering ewes pre- and post-grazing masses above ~1200 and 800 kg DM/ha, respectively, in mid- to late pregnancy.

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Jenkinson, C. M. C., A. K. Earl, P. R. Kenyon y H. T. Blair. "Effects of maternal nutrition during pregnancy on fetal growth and maternal constraint in sheep". Animal Production Science 52, n.º 7 (2012): 524. http://dx.doi.org/10.1071/an11245.

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This study set out to determine the stage of gestation at which maternal constraint on fetal growth occurs and whether pregnancy nutritional level could alleviate that constraint. One-hundred and thirty-eight Cheviot (C) and 114 Suffolk (S) ewes were split into two groups and bred with either 12 S or 12 C rams to generate four ewe/fetal groups CC (C dam and C sire), CSinC (crossbred fetus in C ewe), CSinS, and SS. At Day 21 of pregnancy (P21), half of the ewes in each of the four groups were randomly allocated to either a maintenance (M) or ad libitum (A) nutritional treatment, under pastoral grazing conditions. At P100, a subgroup of singleton-bearing ewes including ewes from all four groups (n = 55 in total) were euthanised (Study 1). Maternal, placental and fetal weights and sizes were recorded. The remaining ewes were fed to appetite from P140 and were allowed to lamb (n = 114 in total, Study 2) and lamb liveweights were recorded within 12 h of birth and at average days 30 and 100 (L30, L100) of lactation. In both studies, M ewes were lighter (P < 0.05) than A ewes, and CC and CSinC ewes were lighter (P < 0.05) than CSinS and SS ewes. In Study 1, maternal nutritional treatment had no effect (P > 0.05) on fetal bodyweight although fetuses from A ewes had heavier (P < 0.05) livers, spleens and thyroids than fetuses from M ewes. CC and CSinC fetuses were lighter (P < 0.01) than both CSinS and SS fetuses. In Study 2, lambs born to M ewes were lighter (P < 0.05) at birth and at L100 than lambs born to A ewes. CC lambs were lighter (P < 0.01) than CSinC, CSinS and SS lambs at birth. At L30 and L100, CC lambs were lighter (P < 0.05) than CSinC lambs, which, in turn, were lighter (P < 0.05) than both CSinS and SS lambs, which did not differ (P > 0.05). Combined, these studies indicate that maternal nutrition may have little impact on singleton-offspring development until late gestation while, in contrast, dam size affected fetal size by the end of the second trimester. These data suggest that the C ewe constrains the growth of the crossbred fetus well before a ‘physical’ constraint would be expected.

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Parr, R. A., A. H. Williams, I. P. Campbell, G. F. Witcombe y A. M. Roberts. "Low nutrition of ewes in early pregnancy and the residual effect on the offspring". Journal of Agricultural Science 106, n.º 1 (febrero de 1986): 81–87. http://dx.doi.org/10.1017/s0021859600061773.

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SUMMARYMature Merino ewes (n = 500) were allotted at random to embryo removal (day 35; day 0 = day of oestrus detection), foetal removal (day 90) or lambing groups. These groups were further randomly divided into four single-sire mating groups. From day 1 until day 35 ewes were individually penned and fed either 50 or 150% of a maintenance ration (0·5 M or 1·5 M respectively). At day 35 single embryos were removed from anaesthetized ewes in the embryo removal group and all other ewes were endoscoped to confirm pregnancy. These ewes were then returned to pasture. Plasma samples were taken from all ewes on days 2, 4, 16, 23, 30 and 35 for analysis of glucose concentration. At day 90, ewes allotted to the foetal removal group were anaesthetized and plasma samples were obtained from the ewe's jugular vein and the umbilical arteryand vein. Ewes were then hysterectomized and the foetus was weighed and measured. Functional cotyledons were dissected from the uterus and chorio-allantois and all tissues were weighed. The remaining ewes (lambing group) were supervised at lambing and lambs were identified, weighed and measured.Live-weight changes from weaning and wool production and quality were measured in ewe and ram lambs at their first shearing (11 months of age). Ovulation rates in the first two oestrous seasons of the ewes and wool production at their second shearing (2 years of age) were also measured.During the 35-day treatment period, mean live-weight changes of ewes were –4·9 and + 1·8 kg in the 0·5 M and 1·5 M groups respectively. Pregnancy rates were similar in both groups but embryos from 0·5 M ewes weighed less than those from 1·5 M ewes (1·7 ± 0·04 ν. 1·9 ± 0·05 g; P < 0·005). Foetuses taken at 90 days from 0·5 M ewes were smaller than those from 1·5 M ewes but these differences reached significance (P < 0·025) only in the measurement of chin–crown length (8·0 ± 0·09 ν. 7·6 ± 0·11 cm). Correlations between foetal weight and total cotyledon weight, chorio-allantoic weight and empty uterine weight were all significant. Plasma glucose concentrations of ewes in the 0·5 M group were significantly (P < 0·001) reduced by day 9. Differences between the two nutrition groups in maternal and umbilical plasma glucose concentrations at day 90 were not significant, though foetuses from 0·5 M and 1·5 M ewes removed a mean of 30 and 11% respectively of available glucose from the umbilical vein. Differences in live weight between 1·5 M and 0·5 M animals at weaning and in the post-weaning period were not significant (P > 0·05). Wool production and woolquality were similar for both groups. Spontaneous ovulation rates measured on four occasions during the postpubertal oestrous season and on three occasions the following year were not significant (P > 0·05). Treatment with pregnant mare's serum gonadotrophin (PMSG) increased ovulation rates in the ewes of both groups; however, the differences failed to reach significance (P > 0·05); mean (± S.e.) ovulations per ewe were 4·8 ± 0·61 ν. 4·6 ± 0·60 for 1·5 M and 0·5 M group ewes respectively.

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Kenyon, P. R., R. E. Hickson, P. G. Hutton, S. T. Morris, K. J. Stafford y D. M. West. "Effect of twin-bearing ewe body condition score and late pregnancy nutrition on lamb performance". Animal Production Science 52, n.º 7 (2012): 483. http://dx.doi.org/10.1071/an12085.

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This study aimed to investigate the effects of ewe body condition score and nutrition on twin-bearing ewes and their offspring. At maximum Day 112 of pregnancy (range 96–112 days), 185 twin-bearing ewes were allocated to either a ‘Medium’ or ‘ad libitum’ (Adlib) feeding treatment for the following 25 days (P112–P136). Each feeding treatment included ewes of body condition score: 2.0 (CS2.0, Medium n = 32, Adlib n = 28), CS2.5 (Medium n = 31, Adlib n = 33) or CS3.0 (Medium n = 30, Adlib n = 31). After P136 ewes were offered Adlib feeding conditions. Medium treatment ewes were lighter (P < 0.05) than Adlib ewes at P136 and P142 and displayed lower (P < 0.05) body condition score at P136 and back-fat depths at P142. CS2.0 ewes had lower (P < 0.05) liveweights and body condition score at P112, P136 and P142 than CS2.5 ewes, which in turn had lower (P < 0.05) liveweight and body condition scores than CS3.0 ewes. Ewe feeding treatment had no effect (P > 0.05) on lamb liveweight or apparent colostrum intake. Ewe body condition score had no effect (P > 0.05) on lamb birthweight or apparent colostrum intake. Lambs born to CS2.0 ewes had greater (P < 0.05) survival than lambs born to CS2.5 ewes. At the end of the study lambs born to CS2.0 ewes were lighter (P < 0.05) than those born to CS2.5 and CS3.0 ewes although, there was (P > 0.05) no effect of condition score on total litter liveweight. In conclusion, these results suggest twin-bearing ewes of body condition 2.0–3.0 can be offered restricted feeding levels to at least Day 136 of pregnancy with few implications for their lambs.

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Gunn, R. G., A. J. F. Russel y E. Barthram. "A note on the effect of nutrition during mid pregnancy on lamb production of primiparous ewes in high body condition at mating". Animal Science 43, n.º 1 (agosto de 1986): 175–77. http://dx.doi.org/10.1017/s000335610001847x.

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Mid-Pregnancy nutrition has been shown to have both positive and negative effects on lamb birth weight in primiparous Scottish Blackface ewes. The direction of the effect depends on the level of body condition at mating, being negative in ewes in high body condition (Russel, Foot, White and Davies, 1981). In the same study, it was argued that the effect in younger ewes could be due to their greater sensitivity to both under- and over-nutrition during the earlier to mid stages of their first pregnancy than is evident in older ewes. Russel et al. (1981) also suggested that the level of mid-pregnancy nutrition is likely to have effects on other aspects of production such as embryonic loss, foetal mortality and even ewe mortality.

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Corner, R. A., P. R. Kenyon, K. J. Stafford, D. M. West, N. Lopez-Villalobos, S. T. Morris y M. H. Oliver. "Effect of nutrition from mid to late pregnancy on the performance of twin- and triplet-bearing ewes and their lambs". Australian Journal of Experimental Agriculture 48, n.º 5 (2008): 666. http://dx.doi.org/10.1071/ea07033.

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This experiment was conducted to determine the effect of two different feeding levels on ewes during mid and late pregnancy on lamb birthweight and growth to weaning. Twin- and triplet-bearing Romney ewes (n = 80 and 56, respectively) were allocated to one of two feeding regimes and provided pastures with an average sward height of less than 2 cm (~700 kg dry matter/ha) or greater than 4 cm (~1300 kg dry matter/ha). Ewes were allocated to these feeding regimes during mid pregnancy (day 70–107 of pregnancy; P70–P107) and were reallocated in late pregnancy (P108–P147). This resulted in four sward height treatments: 2–2, 2–4, 4–2 and 4–4. During mid pregnancy, ewes provided with >4-cm-high swards had liveweight gains of 262–290 g/day compared with 12–31 g/day for ewes provided with <2-cm-high swards. In late pregnancy, ewe liveweight gains were influenced by the ewes’ previous nutritional treatment. Ewes in the 2–4 treatment had higher daily gains (538 g/day) than 4–4 ewes (343 g/day). In addition, 4–2 ewes gained 90 g/day compared with 247 g/day for 2–2 ewes. Throughout pregnancy, triplet-bearing ewes were heavier (P < 0.05) than twin-bearing ewes, but during lactation ewe weights were similar. On P130, ewes provided with <2-cm-high swards (4–2 and 2–2) had greater β-hydroxybutyrate (P < 0.05) and lower glucose (P < 0.05) plasma concentrations than ewes provided with >4-cm-high swards (2–4 and 4–4). On P139, however, ewes provided with 4–4 swards had higher plasma non-esterified fatty acid and β-hydroxybutyrate concentrations than ewes in all other treatments. Lambs born to ewes in the 4–4 treatment had the greatest birthweights (P < 0.05), whereas lambs born to 2–2 ewes had the lowest birthweights. The birthweight of lambs born to 2–4 ewes was similar to that of lambs born to ewes provided with 4–2 and 4–4 swards. At weaning, ewe weights were similar between ewe nutritional treatments and ewes bearing twin or triplet fetuses. These findings suggest that when pasture growth is inadequate to provide pasture sward heights of 4 cm throughout pregnancy, restricted intake in mid-pregnancy may be partially compensated by providing additional pasture in late pregnancy.

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Behrendt, R., J. E. Hocking Edwards, D. Gordon, M. Hyder, M. Kelly, F. Cameron, J. Byron, M. Raeside, G. Kearney y A. N. Thompson. "Offering maternal composite ewes higher levels of nutrition from mid-pregnancy to lambing results in predictable increases in birthweight, survival and weaning weight of their lambs". Animal Production Science 59, n.º 10 (2019): 1906. http://dx.doi.org/10.1071/an18505.

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Management of nutrition during pregnancy for maternal composite ewes has the potential to improve lamb production and survival in prime lamb production systems but existing condition score (CS) guidelines developed for Merinos may not be appropriate for the optimum production of maternal ewes. To address this, three replicated experiments were conducted at two research sites in Victoria and one in Western Australia. Ewes (781–800 per site) were allocated to four CS treatments following pregnancy scanning (~Day 50) and differentially fed to reach approximate targets of CS 2.4, 2.8, 3.2 and 3.6 by lambing. Single and multiple bearing ewes grazed together, and nutritional treatments were applied until the end of lambing after which ewes and lambs were aggregated into management groups containing all treatments. At lambing, maternal ewe liveweight had a range between treatments of 13.7–19.1 kg (average 16.4 kg) and CS varied by 1.1–1.5 of a CS (average 1.24). Across site analysis indicated that lamb birthweight and weaning weight increased with application of higher CS treatments (P < 0.001). There was also an improvement in survival of multiple born lambs with increasing CS at lambing (P < 0.001). Birthweight was significantly related to survival (P < 0.001) at all sites with no significant effect of birth type on lamb survival. Changes in birthweight and weaning weight could be predicted from ewe joining liveweight, ewe liveweight change to Day 90 and ewe liveweight change Day 90 to lambing. The coefficients derived for each of these effects were similar to those found in previous experiments examining Merino and crossbred Border Leicester Merino ewes. The optimum CS targets for multiple bearing maternal composite ewes may be higher than the industry recommended target for Merino ewes based on advantages in lamb survival and weaning weight.

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Fogarty, NM, DG Hall y PJ Holst. "The effect of nutrition in mid pregnancy and ewe liveweight change on birth weight and management for lamb survival in highly fecund ewes". Australian Journal of Experimental Agriculture 32, n.º 1 (1992): 1. http://dx.doi.org/10.1071/ea9920001.

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The effect of moderate undernutrition in mid pregnancy on lamb birth weight and survival of single- and multiple-bearing ewes is reported. A total of 1220 ewes of 3 crossbred types with different fecundity, Booroola Merino x Dorset (BD), Trangie Fertility Merino x Dorset (TD) and Border Leicester x Merino (BLM), were examined over 2 years. The treatments were low (L) and high (H) nutrition at pasture for 4 weeks from about day 75 of pregnancy. Ewe liveweight of the L group at the end of the treatments was 5 kg lower in 1984 and 8 kg lower in 1985 (P<0.01) than the H group. The differences were smaller by late pregnancy and post-lambing. The L treatment increased (P<0.01) birth weight by 0.16 kg in 1984 but had little effect in 1985. Litter size had the greatest effect on birth weight (P<0.01). Ewe crossbred type and lamb sex effects were also significant (P<0.01), although they tended to be reduced for higher order births. Nutritional treatment had no effect on gestation length. Ewe liveweight at joining and weight gains before and after the treatment period significantly affected birth weight and accounted for the large difference in birth weight between years (0.7 kg). Ewe weight gain during the treatment period in mid pregnancy had no significant effect on lamb birth weight. Nutritional treatment in mid pregnancy had no effect on lamb survival. Litter size significantly affected lamb survival, although inclusion of birth weight in the model reduced the effect. Weather conditions, as measured by chill index, significantly (P<0.01) affected lamb survival in 1984 but accounted for less variation in 1985 (P<0.05). Lamb survival for ewes was ranked BLM > TD > BD. Maximum survival was achieved at birth weights of 4-5 kg from BD and TD ewes and 5-6 kg from BLM ewes. The L treatment reduced (P<0.01) ewe greasy fleece weight by 0.15 kg but did not affect staple strength. Plasma glucose concentration at the end of treatment was lower (P<0.01) for L ewes, but there was no difference between L and H ewes in late pregnancy. Glucose declined with increasing fetal number. Plasma B-hydroxybutyrate concentration was lower for the H group than for L, and also for BLM than TD and BD ewes (P<0.01).

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Edwards, J. E. Hocking, K. J. Copping y A. N. Thompson. "Managing the nutrition of twin-bearing ewes during pregnancy using Lifetimewool recommendations increases production of twin lambs". Animal Production Science 51, n.º 9 (2011): 813. http://dx.doi.org/10.1071/an09158.

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The effect on ewe and lamb production by differential management of single- and twin-bearing Merino ewes during pregnancy and lactation was examined. The hypothesis that the survival and productivity of single- and twin-born progeny is not affected by differential management of single- and twin-bearing ewes was tested. To test this hypothesis, two ewe flocks were monitored on a commercial property in the south-east of South Australia. The body condition score of one flock of ewes was managed according to Lifetimewool recommendations for southern Australian (Lifetimewool flock; n = 464). Lifetimewool recommendations are that body condition score should be 3.0 at mating and then allowed to decline to an average of 2.7, which is maintained until lambing. Twin- and single-bearing ewes were managed as separate mobs after pregnancy scanning to meet their energy requirements. The second flock was managed similarly to the commercial ewe flock and was representative of ewe management practices in the region (normal-practice flock; n = 464). At lambing, the condition score of the Lifetimewool flock was 0.7 condition scores units greater than the normal-practice flock. Ewe clean fleece weight and fibre diameter were greater in the Lifetimewool flock and their lambs had higher survival rates to weaning. Over three shearings, progeny from Lifetimewool ewe flocks produced more clean wool (P < 0.0001) but there was no consistent effect on fibre diameter, staple length or staple strength. Twin-born lambs from ewes managed to Lifetimewool guidelines had a similar liveweight and produced similar quantity and quality of wool to single-born lambs managed to Lifetimewool guidelines, but still suffered higher rates of mortality to weaning. This suggests that it is possible to manage ewes pregnant with twins to ensure that their surviving progeny perform at a level similar to single-born progeny managed under similar targets.

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Behrendt, R., A. J. van Burgel, A. Bailey, P. Barber, M. Curnow, D. J. Gordon, J. E. Hocking Edwards, C. M. Oldham y A. N. Thompson. "On-farm paddock-scale comparisons across southern Australia confirm that increasing the nutrition of Merino ewes improves their production and the lifetime performance of their progeny". Animal Production Science 51, n.º 9 (2011): 805. http://dx.doi.org/10.1071/an10183.

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Experiments conducted by Lifetimewool at plot-scale have shown that differences in the maternal liveweight during pregnancy and lactation (liveweight profiles) of individual Merino ewes influences their wool production and reproductive rate as well as the birthweight, survival, weaning weight and lifetime wool production of their lambs in a predictable manner. This study determined whether these impacts of nutrition of the ewe on ewe and progeny performance are measurable on commercial properties across southern Australia at a paddock-scale where ewes were aggregated into flocks with a greater spread of the date of conception and where the liveweight profile of the flocks were managed based on random samples of 100 ewes and liveweight was uncorrected for fleece weight or conceptus. Eighteen paddock-scale experiments at 15 sites were conducted in cooperation with wool producers across Victoria, Western Australia, New South Wales, South Australia, and Tasmania. Each co-operator joined up to 1000 mixed aged adult Merino ewes. The flock was scanned using ultrasound at Day 50 from the start of joining to identify those ewes that conceived during the first 21 days of joining. These ewes were then split at random into two treatments and fed to achieve a target difference in liveweight of 10 kg or ~1 condition score/fat score at lambing. The production of ewes during their year of pregnancy and following their next joining was measured as was the performance of their progeny up to their third shearing. Only the 13 paddock-scale experiments that achieved a difference in liveweight profile at lambing of at least 4 kg were included in the final analysis. In these 13 experiments, increasing the nutrition of Merino ewes during pregnancy clearly increased the clean fleece weight and fibre diameter in ewes and the survival and lifetime wool production of their lambs. In most cases the size of the effect was not significantly different to that predicted by the relationship derived using individual liveweight profiles in the plot-scale experiments. This confirms that managing average ewe liveweight or condition score/fat score profile through better nutrition will lead to predictable increases in the performance of ewes and their progeny performance under commercial conditions and validates the use of the plot-scale relationships in economic analyses.

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14

Kenyon, P. R., S. T. Morris, K. J. Stafford y D. M. West. "Effect of ewe body condition and nutrition in late pregnancy on the performance of triplet-bearing ewes and their progeny". Animal Production Science 51, n.º 6 (2011): 557. http://dx.doi.org/10.1071/an10192.

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The aim of the present study was to determine the production response of triplet-bearing ewes and their lambs to two differing feeding treatments in mid to late pregnancy and to determine the effect of ewe body condition. Ninety-two days after the start of their breeding period (P92) triplet-bearing ewes, were allocated to either a Medium (n = 72) or ad libitum (‘Adlib’, n = 72) feeding treatment until P113, followed by both groups being merged and offered ad libitum feeding conditions until lambing. The Medium feeding treatment was designed to ensure pre- and postgrazing herbage masses were below 1200 and 1000 kg DM/ha, respectively. Each feeding treatment included ewes from the following body condition score groups: 2.0 or less (CS ≤2.0), 2.5 (CS2.5) or 3.0 or greater (CS ≥3.0). At P113, Medium ewes were lighter (P < 0.05) and had lower (P < 0.05) body condition scores than Adlib ewes (72.4 ± 0.80 vs 75.2 ± 0.85 kg and 2.8 ± 0.06 vs 3.3 ± 0.06, respectively). However, at P141 liveweight no longer differed (P > 0.05, 86.2 ± 0.94 vs 86.6 ± 0.99 kg, respectively), although a small difference in condition score remained (P < 0.05, 3.0 ± 0.07 vs 3.3 ± 0.08, respectively). Ewe feeding treatment had no effect (P > 0.05) on lamb liveweight or survival or ewe liveweight and body condition during lactation. Ewe body condition score group had no effect (P > 0.05) on lamb birthweight. Lambs born to CS2.5 group ewes were heavier 70 days after the midpoint of lambing (L70) than those born to CS ≤2.0 group ewes (20.9 ± 0.41 vs 19.6 ± 0.36 kg, respectively), although they displayed lower survival to L70 (56.0 vs 69.5%). Liveweight at L70 and survival of lambs born to CS ≥3.0 group ewes (20.0 ± 0.39 kg and 61.7%) did not differ (P > 0.05) from those born to either CS ≤2.0 or CS2.5 group ewes. In conclusion, these results suggest triplet-bearing ewes can be maintained under restricted feeding conditions until at least Day 113 of pregnancy without negatively affecting ewe or lamb performance when they are subsequently offered unrestricted feeding for the remainder of pregnancy and during lactation. Under these grazing conditions the body condition of triplet-bearing ewes had little to no effect on their subsequent performance or that of their lambs.

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15

Annett, R. W. y A. F. Carson. "Effects of plane of nutrition during the first month of pregnancy on conception rate, foetal development and lamb output of mature and adolescent ewes". Animal Science 82, n.º 6 (diciembre de 2006): 947–54. http://dx.doi.org/10.1017/asc2006111.

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AbstractEmbryo transfer studies have demonstrated that high plane feeding in early pregnancy is detrimental to the successful establishment of pregnancy in adolescent but not mature ewes. To further examine this relationship with ewes that conceive naturally and to investigate its effects on foetal development, 102 Greyface and Texel×Greyface ewes (body condition score (BCS) 3·8) and 114 Texel×Greyface adolescent ewes (BCS 3·3) were allocated to one of three treatments following a synchronized mating. From day 1 to 31 of pregnancy, animals were offered grass nuts (10·2 MJ metabolizable energy (ME) per kg dry matter (DM); 163 g crude protein per kg DM) at one of three levels to supply approximately 2·0 (H); 1·0 (M) and 0·6 (L) of their predicted ME requirements for maintenance. Increasing the post-mating plane of nutrition resulted in significant increases in ewe live weight (P<0·001) and BCS (P<0·001) during the treatment period. When diets were standardized for all animals during mid pregnancy (days 31 to 105), L ewes gained more live weight (P<0·05) and BCS (P<0·001) than H ewes. Early pregnancy nutrition had no effect on the conception rate of mature ewes; however adolescent ewes on the H and M treatments had lower conception rates (P<0·05) than those offered the L diet (0·59, 0·61 and 0·82 respectively). As a result, L adolescent ewes tended to have a higher mean total lamb birth weight per ewe mated (P=0·09) although lamb output at weaning was not influenced by plane of nutrition. Lambs born from adolescent mothers had lower lamb birth weights (P<0·001) and a shorter mean head length, crown-rump length and thoracic girth (P<0·001). Foetuses from H ewes had longer hind legs than those from L ewes on day 83 of gestation (P<0·05) and at term (P<0·05). The results of this study suggest that allowing adolescent but not mature ewes to lose live weight and body condition can increase the proportion of productive ewes following a natural service.

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16

Pain, S. J., D. S. van der Linden, P. R. Kenyon y H. T. Blair. "Does dam pre-breeding nutrition and/or birth rank affect the glucose and fat metabolism of 18-month-old female offspring?" Animal Production Science 52, n.º 7 (2012): 546. http://dx.doi.org/10.1071/an11294.

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Twin- and triplet-born lambs are smaller and lighter at birth than singletons and remain so until at least 1 year of age. However, there is little evidence in the literature to demonstrate if these smaller/lighter twin- and triplet-born lambs are metabolically different to singletons later in life. Additionally, many studies have demonstrated that dam nutrition during the periconceptual period can program the fetus in utero, influencing development, growth and performance later in life. However, little is known regarding the impact of differing levels of maternal nutrition before the periconceptual period, during the period of preantral follicle development. This study aimed to determine if dam pre-breeding nutrition (High versus Maintenance, 113–71 days pre-breeding) and birth rank (single versus twin versus triplet) affected the metabolic responses of ewes at 18 months of age, to an intravenous glucose (0.17 g/kg liveweight) (GTT) and insulin (0.15 IU/kg liveweight) (ITT) tolerance test. Dam pre-breeding nutrition had no effect (P > 0.05) on glucose and insulin responses to GTT, or glucose and cortisol responses to ITT. However, before both GTT and ITT, ewes born to High-fed dams had greater (P < 0.05) β-hydroxybutyrate (β-HBA) baselines than those born to Maintenance-fed dams, and also had greater (P < 0.05) maximum β-HBA change in response to both GTT and ITT. Birth rank tended (P = 0.06) to affect maximum glucose concentration change in response to glucose administration, with twin-born ewes having a greater increase in glucose compared with both singletons (P = 0.06) and triplet-born (P < 0.05) ewes in response to a glucose challenge. Insulin area under the curve 0–120 min after glucose administration of twin-born ewes was lower (P = 0.05) than both single- and triplet-born ewes. Prior to ITT, baseline β-HBA concentrations of single-born ewes were lower (P < 0.05) than triplet-born ewes. Single-born ewes had a reduced (P < 0.05) decrease in β-HBA change compared with twin- and triplet-born ewes in response to ITT. In summary, this study showed little difference in glucose and insulin metabolism of single-, twin- and triplet-born lambs at 18 months of age. However, the level of dam nutrition 113–71 days pre-breeding appears to have lasting effects on β-HBA metabolism in ewe progeny. The next step is to determine if these metabolic differences result in any measurable animal performance differences, as this would have implications for feeding regimes of ewes before mating and selection of appropriate ewe progeny for use as replacement animals.

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17

Dawson, L. E. R., A. F. Carson, D. J. Kilpatrick y A. S. Laidlaw. "Effect of herbage allowance and concentrate food level offered to ewes in late pregnancy on ewe and lamb performance". Animal Science 81, n.º 3 (diciembre de 2005): 413–21. http://dx.doi.org/10.1079/asc41950413.

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AbstractTwo experiments were undertaken to investigate the effect of herbage allowance and concentrate food level offered to twin-bearing ewes in the last 6 weeks of pregnancy on ewe and lamb performance. In each study, 96 twin-bearing Greyface (Border Leicester × Scottish Blackface), Rouge × Greyface and Texel × Greyface ewes were used. In experiment 1, the ewes were allocated to eight treatments consisting of two herbage allowances (1·3 and 2·6 kg herbage dry matter per ewe per day) and four concentrate food levels ranging from zero to 1000 g per day. In experiment 2, ewes were offered four herbage allowances (1·3, 1·75, 2·2 and 2·6 kg herbage dry matter per ewe per day) and zero or 500 g concentrates per day. In experiment 1, herbage allowance and concentrate food level had no significant effect on lamb birth weight, lamb mortality or lamb performance up to weaning. Herbage dry matter intake decreased linearly with increasing concentrate food level with a substitution rate of 18 g of herbage dry matter per 100 g concentrate food level. In experiment 2, lamb birth weight increased with increasing herbage allowance (P< 0·01) and with increasing concentrate food level (P< 0·01). However, lamb performance to weaning was unaffected by late pregnancy nutrition. The satisfactory levels of performance obtained with ewes offered grass-only diets in late pregnancy indicates that grazed grass is a high nutritive value food for twin-bearing ewes in late pregnancy.

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18

Kassem, R., J. B. Owen y I. Fadel. "A note on the characteristics of oestrus and ovulation in Awassi ewes". Animal Science 50, n.º 1 (febrero de 1990): 198–201. http://dx.doi.org/10.1017/s000335610000461x.

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The length of the oestrous cycle observed in 20 ewe lambs and 424 ewes of the Awassi breed gave mean values of 16·4 (s.d. 1·31) days for ewe lambs and 17·4 (s.d. 1·84) days for ewes. Plane of nutrition did not affect cycle length in ewe lambs and age of ewe (from 2 to 5 years) did not affect oestrous cycle length in ewes (P > 0·05). Of 40 ewes treated with progesterone intravaginal sponges 33 (83%) showed oestrus and 28 (70%) ovulated at the first (synchronized) and 31 (78%) and 30 (75%) at the repeat oestrus. Mean duration of oestrus was 40·0 (s.d. 16·37) h (range 8 to 72) for the first and 34·7 (s.d. 11·19) h (range 16 to 54) for the repeat oestrus. Ovulation rate, measured in the same ewes, gave mean values of 1·18 (s.d. 0·460) for the first and 1·223 (s.d. 0·440) for the repeat oestrus.

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19

Jordan, DJ y DG Mayer. "Effects of udder damage and nutritional plane on milk yield, lamb survival and lamb growth of Merinos". Australian Journal of Experimental Agriculture 29, n.º 3 (1989): 315. http://dx.doi.org/10.1071/ea9890315.

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A pen study investigated the effects of udder damage and 3 levels of nutrition (110, 90 and 70% of maintenance requirements) during the pre- and post-natal period on the performance of Merino ewes and lambs. Udder damage (only 1 functional teat) significantly reduced (P< 0.05) estimated daily milk yield of ewes (1 139 v. 963 mL/day), growth rate (180.5 v. 143.7 g/ day) and liveweight of lambs (10.1 v. 8.8 kg) at 4-6 weeks of age. Lamb survival was significantly reduced only in the 70% of maintenance treatment (82.2 v. 64.8%). Nutrition level significantly (P< 0.05) affected ewe and lamb performance. Estimated daily ewe milk yield (1146, 1070 and 938 mL/day), ewe liveweight (40.4, 39.2 and 37.1 kg) at lamb marking, and lamb growth rate (178.1, 169.5 and 138.8 g/day) and liveweight (10.2, 9.6 and 8.6 kg) at 4-6 weeks were significantly higher for ewes fed on 110 and 90% of their requirements than for ewes fed at 70% of their requirements respectively. Lamb survival (89.9%) from ewes fed at 110% of requirements was significantly higher than lamb survival (75.3 and 73.5%) from ewes fed at 90 and 70% of requirements respectively. There was no significant interaction between the level of nutrition and udder damage in any parameter of ewe or lamb performance. Birth weight (3.0 v. 3.8 kg) and survival (49.3 v. 84.2%) were significantly (P<0.01) lower in twins than in single birth lambs. Growth rate of single lambs and single survivors of twins reared as single lambs were similar (167 and 160 g/day respectively); both of these groups grew more rapidly (P< 0.01) than lambs reared as twins (91 g/day). Lamb growth rate was positively correlated with ewe milk yield (r=0.75; P<0.01), ewe weight (r = 0.37; P< 0.01) and lamb birth weight (r = 0.24; P< 0.05). Lamb birth weight and ewe milk yield were also significantly and positively correlated with ewe weight. Male lambs were significantly heavier at birth and grew significantly faster than female lambs.

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20

Holst, PJ, ID Killeen y BR Cullis. "Nutrition of the pregnant ewe and its effect on gestation length, lamb birth weight and lamb survival". Australian Journal of Agricultural Research 37, n.º 6 (1986): 647. http://dx.doi.org/10.1071/ar9860647.

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The nutrition of grazing, pregnant crossbred ewes was managed so that from 6-15 and from 15-20 weeks of pregnancy, ewes were offered either high (H) or low (L) quality and quantity of nutrition as provided by pasture. At one week prior to parturition, the ewes in each of the four treatment groups (HH, HL, LH, LL) were then placed onto good pasture for lambing. Differential nutrition during pregnancy significantly affected gestation length of the ewes, with HH ewes having the shortest gestation. By day 148, 1.6 times more HH ewes had lambed compared with the LL group ewes. Significant differences were observed in lamb birth weight5 with nutrition in the last trimester (15-20 weeks) having a greater influence on birth weight. This was particularly so for twins. There was no significant difference in the survival of the single lambs, but for twin lambs survival was lowest with the LL ewes. These results show the consequences of maintaining or altering nutrition of single- and twin-bearing ewes during pregnancy. Birth weight of twin-born lambs was most responsive. Apart from lambs of the LL group ewes, the weaning weights of surviving lambs were largely unaffected by prenatal nutrition to one week prepartum.

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21

Dwyer, Cathy M., Alistair B. Lawrence, Stephen C. Bishop y Mitch Lewis. "Ewe–lamb bonding behaviours at birth are affected by maternal undernutrition in pregnancy". British Journal of Nutrition 89, n.º 1 (enero de 2003): 123–36. http://dx.doi.org/10.1079/bjn2002743.

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Maternal undernutrition in pregnancy results in low birth-weights and impaired postnatal survival in sheep. Largely anecdotal evidence suggests that the expression of appropriate maternal and neonate behaviours may also be disrupted by undernutrition. In the present study, we investigated the effect of a moderate (35 %) reduction in ewe nutritional intake in pregnancy on the expression of ewe–lamb bonding behaviours in primiparous Scottish Blackface ewes. Low-intake (L) ewes had significantly higher plasma progesterone than high-intake (H) ewes from mid-gestation onwards (e.g. plasma progesterone at 20 weeks (n/l): H 15·72, L 22·38, SED 1·80, P<0·001), AND A LOWER OESTRADIOL: PROGESTERONE VALUE THAN H EWES AT DELIVERY (H 0·46, L 0·35, sed 0·05, P<0·05). Lamb birth-weight was reduced in the L lambs compared with H lambs (mean body weight (kg): H 3·31, L 3·00, sed 0·14, P<0·05), but the incidence of malpresentation at delivery was greater in L lambs. L ewes spent significantly less time licking their lambs than H ewes after delivery (time grooming in 2 h after birth (%): H 56·12, L 48·17, sed 2·639, P<0·01) and were more aggressive towards the lambs. Lamb behaviours were not directly affected by maternal nutritional treatment, but lamb birth-weight had a significant effect on neonatal developmental progress. Low-birth-weight lambs were slower than heavier lambs to stand and sucked less frequently. In tests of maternal attachment to the lamb, H ewes received higher scores than L ewes at both 24 h after birth (ewes receiving high scores (%): H 41·3, L 21·4, P<0·05) and at 3 d postnatal. We conclude that even a moderate level of undernutrition impairs the attachment between ewes and lambs by affecting maternal behaviours expressed at birth. In addition, the results suggest that levels of nutrition resulting in a decrease in birth weight will affect neonatal lamb behavioural progress.

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22

Keady, T. W. J. y J. P. Hanrahan. "Effects of altering the plane of nutrition during the rearing phase and pregnancy of 2-tooth ewes, of two genotypes, on ewe and subsequent lamb performance". Proceedings of the British Society of Animal Science 2009 (abril de 2009): 70. http://dx.doi.org/10.1017/s1752756200029094.

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Ewe replacements are a major cost in sheep production. This cost is influenced by replacement rate and rearing expense which is a function of plane of nutrition offered during the first winter, subsequent grazing season prior to joining at 18 months of age and during pregnancy prior to lambing as 2-tooth ewes. There is a paucity of data on the impact of plane of nutrition between 6 months of age and first lambing as 2-tooth ewes on body size and subsequent productivity. The weight of lamb carcass produced per ewe, which is influenced by litter size, lamb survival and growth rate, is the main factor affecting output per ewe. Plane of nutrition at different stages during the rearing phase, genetic potential for prolificacy and their potential interactions may be important. The aim of the current study was to evaluate effects of plane of nutrition during the first winter, subsequent grazing season and during first pregnancy, and potential interactions, on ewe body size and productivity and subsequent lamb performance using two breed types with contrasting prolificacy potential.

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23

Demmers, K. J., B. Smaill, G. H. Davis, K. G. Dodds y J. L. Juengel. "Heterozygous Inverdale ewes show increased ovulation rate sensitivity to pre-mating nutrition". Reproduction, Fertility and Development 23, n.º 7 (2011): 866. http://dx.doi.org/10.1071/rd10344.

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This study aimed to determine whether ewes heterozygous (I+) for the Inverdale mutation of the bone morphogenetic protein-15 (BMP15) gene with high natural ovulation rate (OR) show similar sensitivity to nutritional manipulation as non-carriers (++). Increasing pre-mating nutrition results in OR increases in sheep, but whether this effect occurs in ewes with naturally high OR is unknown. Over 2 years, I+ or ++ ewes were given high (ad libitum) or control (maintenance) pasture allowances for 6 weeks prior to mating at a synchronised oestrus, with OR measured 8 days later. The high group increased in weight compared with controls (+5.84 kg; P < 0.01), accompanied by increased OR (+19%; P < 0.01). As well as having higher OR (+45%; P < 0.01), I+ ewes responded to increased feed with a larger proportional increase in OR (+27%; P < 0.01) compared with the response in ++ ewes (+11%; P < 0.05), suggesting an interaction between BMP15 levels and nutritional signals in the follicle to control OR. Although litter size increases only tended to significance (+12%; P = 0.06), extra feed resulted in over 50% of I+ ewes giving birth to more than three lambs, compared with 20–31% of I+ ewes on maintenance rations. This information can guide feed management of prolific Inverdale ewes prior to breeding.

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24

Robertson, S. M., B. J. King, M. B. Allworth, J. Rummery y M. A. Friend. "The effect of peri-conceptual grazing of live pasture on fetal numbers in unsynchronised ewes". Animal Production Science 54, n.º 8 (2014): 1008. http://dx.doi.org/10.1071/an13086.

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Methods of increasing the number of lambs born per ewe that avoid the use of pharmaceutical methods of oestrus synchronisation but which require a short period of increased nutrition are desirable. Four separate experiments evaluated whether peri-conceptual grazing of lucerne, compared with senescent herbage or other live herbage, increased fetal numbers in unsynchronised ewes. Merino ewes that grazed lucerne pasture for 7 days before joining and for the first 7 days of a 5–6-week joining produced up to 21 extra (P < 0.05) fetuses per 100 ewes joined, compared with ewes grazing cereal stubble with minimal live herbage (Experiment 2). In Experiments 1, 3 and 4, Merino or First Cross ewes grazing either cereal stubbles or phalaris pasture with as little as 200 kg DM/ha of live herbage produced a similar (P > 0.05) number of fetuses per ewe joined as those grazing on lucerne, either because this quantity of live feed was sufficient to increase fetal numbers, or because, for Experiment 3, First Cross ewes may not have responded at the commencement of the breeding season. It is concluded that grazing live pasture for 7 days before joining and for the first 7 days of joining during the breeding season can substantially increase fetal numbers in unsynchronised ewes compared with ewes grazing stubbles containing no live herbage. The response appears to occur on a range of plant species, and a small quantity of live herbage can elicit a response. Grazing lucerne in the peri-conceptual period did not increase (P > 0.05) the proportion of non-pregnant ewes. Further studies are required to determine how early in the breeding season ewes with a distinct breeding season will respond to nutritional manipulation.

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van der Linden, D. S., P. R. Kenyon, C. M. C. Jenkinson, S. W. Peterson y H. T. Blair. "Carry-over effects of ewe nutrition and birth rank during the previous pregnancy on the milking performance during the subsequent lactation of Romney ewes". Animal Production Science 51, n.º 2 (2011): 102. http://dx.doi.org/10.1071/an10088.

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This study investigated whether selection for ewe size and nutrition during the previous pregnancy would affect the lactational performance of the ewe and liveweight gain of her lamb(s) in the subsequent year. A subgroup of singleton-bearing Romney ewes were milked once a week, for 7 consecutive weeks. Singleton-bearing ‘light’ ewes that gave birth to twins in the previous year had reduced milk yields from Day 21 of lactation (L21) onwards in the present year compared with those that gave birth to singletons in the previous year. Lambs born to light ewes had reduced liveweight gain from birth to L21 compared with those born to ‘heavy’ ewes. Singleton-bearing ewes in the present year that were fed maintenance and gave birth to twins in the previous year, produced less milk from L21 onwards compared with those that were maintenance-fed and singleton-bearing in the previous year. Singleton lambs born to milked ewes that were fed maintenance and gave birth to twins in the previous year, had lower liveweight gain from birth to L21 in the present year compared with lambs born to ewes fed maintenance and gave birth to singletons in the previous year. In the entire population, lambs born to ewes fed maintenance and that gave birth to twins in the previous year were lighter at L21 than lambs born to ewes fed ad libitum and bearing twins in the previous year. This indicates that if nutrition is suboptimal, or the ewes are lighter in the previous year, those that were twin-bearing are more likely to rear lighter lambs in the present year. Therefore, farmers need to take these points into consideration when devising feeding plans for the present year.

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26

Gunn, R. G., D. A. Sim y E. A. Hunter. "Effects of nutrition in utero and in early life on the subsequent lifetime reproductive performance of Scottish Blackface ewes in two management systems". Animal Science 60, n.º 2 (abril de 1995): 223–30. http://dx.doi.org/10.1017/s1357729800008389.

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AbstractOver 3 years, a flock of Scottish Blackface ewes was managed so that one-third of the ewes received a high level of nutrition during the last 100 days of pregnancy (P), one-third received a high level of nutrition during the first 100 days of lactation (L) and one-third received a low level of nutrition as derived from a hill grazing over the same two periods (C). From these ewes, 496 ewe lambs were retained at weaning (19 to 22 weeks of age), balanced for treatment, year and birth type. At 6 months of age half of the lambs, similarly balanced, were transferred to an upland grazing system (U) for three breeding years. The other half was retained on the same hill grazing as their mothers for the same period (H). At the end of the study, all ewes were fed to reduce the range in body condition at a synchronized mating and ovulation rates were determined at slaughter.Differences in live weight of ewes due to treatment between groups P, L and C had disappeared by 18 months. There were no pre-mating differences between treatments in live weight or body condition score except that ewes in group P had higher live weights than those in group C at condition scores greater than 2·75. There was little effect of grazing system on the differences between treatments in live weight or body condition score at 30 and 42 months but H ewes were heavier and fatter at 18 months of age. Ewe mortality was consistently less in group L than in groups P and C and on system H than on system U, although the differences were not statistically significant. Group L had fewer barren ewes than groups P and C, and barrenness was significantly greater in the U than the H system. Group C had proportionally more single than multiple births than either groups P or L.At the end of the study there were no differences between the treatments in the proportion of ewes successfully mated at the final mating nor in their ovulation rates in relation to pre-mating body condition.It is concluded that nutrition during either the lactation period or late pregnancy period can influence subsequent lifetime reproductive performance and that this was expressed through an effect on embryo or foetal loss since there were neither residual differences apparent in live weight or condition score nor in ovulation rate potential.

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27

Dove, H., M. Freer y J. Z. Foot. "The nutrition of grazing ewes during pregnancy and lactation: relationships between herbage, supplement and milk intakes, and ewe and lamb liveweight and body composition". Animal Production Science 58, n.º 7 (2018): 1253. http://dx.doi.org/10.1071/an16541.

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This paper reports results from a study of ewes in pregnancy and lactation, during which times they grazed at a high versus medium stocking rate and either received or did not receive a pelleted supplement. We measured ewe liveweight, condition score and body composition; intakes by ewes of pasture and supplementary feed; milk production by ewes, and; birthweight, milk intake, liveweight gain and body composition of single and twin lambs. Ewes grazing at the medium stocking rate consumed more pasture in late pregnancy and the intake of supplement significantly reduced pasture intake. Nevertheless, total intakes of organic matter or digestible organic matter were unaffected by supplementation and were significantly higher at the medium stocking rate. Effects of stocking rate on intake persisted into early and mid-lactation, but supplement intake did not affect pasture intake in lactation. Pasture intakes in pregnancy were not markedly different between twin-bearing and single-bearing ewes, nor were pasture intakes in lactation affected by the number of lambs suckled. Ewes suckling twins produced much more milk. There were significant effects of birth type, ewe stocking rate and supplementation on lamb milk intake and liveweight gain. The data were reanalysed by regression, to explore the effects of actual herbage masses and ewe intakes, and the possible effects of non-treatment terms such as ewe age, condition score and dentition score at allocation. These analyses confirmed the above effects of treatment, but also demonstrated that ewes in better condition at the start of the experiment ate less pasture in both pregnancy and lactation, and produced significantly less milk. Ewe organic matter intakes in pregnancy were not related to dentition score at allocation, but in early and mid-lactation were reduced by ~170 g organic matter/day and 280–380 g organic matter/day, respectively, per unit increase in dentition score. There was no significant effect of ewe dentition score on lamb milk intake, but there was a significant penalty of ~19 g lamb liveweight gain/unit increase in ewe dentition score at allocation. Future studies of this kind thus need to include estimates of the condition score and dentition score of ewes when they commence the experiment.

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Orji, B. I. y J. Steinbach. "PUBERAL DEVELOPMENT IN THE NIGERIAN DWARF SHEEP". Nigerian Journal of Animal Production 7, n.º 1 (14 de enero de 2021): 63–69. http://dx.doi.org/10.51791/njap.v7i1.2075.

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THE Incidence of the first behavioural oestrus (puberty) in 28 ewe lambs was investigated to determine the effect of the plane of nutrition on it. The ewes were randomly alloted and reared on two planes of nutrition: one exclusively on roughage (grazing and bay) the second roughage supplemented with concentrate at the rate of 454g a day from weaning to puberty. The ewe lambs were checked for standing heat with two vasectomised rams twice daily - mornings and evenings. The age and body weight at puberty and the average daily gain from weaning to puberty In unsupplemented ewes were 339.5 ± 7.8 days, 14.6 ± 0.9kg and 29.4 ± 4.7g respectively. The corresponding figures for the supplemented ewes were 262.0 ± 16.2 days, 16.2 ± 0.7kg and 73.0 ± 6.6g. The ewe lambs born as singles attained puberty at a younger age but lambs fed supplemented concentrate ration had a significantly higher growth rate and attained puberty at a significantly younger age and higher body weight than ewe lambs fed on roughage only. The durations of early postpuberal oestrus and oestrous cycle were 41.03 ± 2.94 hours and 18.00 ± 0.63 days respectively.

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Tillquist, Nicole M., Amanda S. Reiter, Mia Y. Kawaida, Brandon I. Smith, Sarah A. Reed, Steven A. Zinn y Kristen E. Govoni. "PSIII-24 Poor gestational nutrition impacts sheep offspring growth but not feed efficiency". Journal of Animal Science 99, Supplement_3 (8 de octubre de 2021): 311. http://dx.doi.org/10.1093/jas/skab235.571.

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Abstract The objective was to determine the effects of poor maternal nutrition during gestation on growth and feed efficiency of offspring. We hypothesized that body weights (BW) would decrease and residual feed intake (RFI) would increase (reduced feed efficiency) in offspring of restricted- and over-fed ewes. Forty-six multiparous Dorset ewes pregnant with twins were fed 100%, 60% or 140% of NRC requirements from d 30 of gestation until parturition. Offspring are referred to as CON (n = 10 ewes; 12 rams), RES (n = 13 ewes; 21 rams), and OVER (n = 16 ewes; 13 rams), respectively. Lamb BW were measured weekly from birth to d 28 and biweekly until d 252 of age. Starting at d 167±13.6, daily intake of a complete pelleted feed was recorded using a Super SmartFeed (C-lock Inc., Rapid City, SD) over a 77 d- feeding period. Average BW were taken two days before, at mid-point, and two days after the feeding trial period and RFI was calculated for each animal. Rams were euthanized at d 284±12 and body morphometrics, loin eye area (LEA), back fat thickness, and organ weights were collected. From birth to d 252, ram lambs were 5.4 kg heavier (P < 0.001) than ewe lambs. Control ewe lambs were 4.3 kg heavier than RES and OVER (P < 0.05) from birth to 9 months and CON rams were 4.7 kg heavier (P < 0.01) than RES. Rams (-0.17) were more efficient than ewes (0.23; P < 0.01); however, no dietary treatment difference was observed (P ≥ 0.57). No differences in muscle mass, LEA, and adipose deposition were observed (P ≥ 0.41). These data indicate that poor maternal diet during gestation impacts offspring growth but not RFI. Further investigation is warranted to determine if differences in BW are a result of metabolic alterations impacted by poor maternal nutrition during gestation.

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30

Freitas-de-Melo, A., R. Ungerfeld, A. Orihuela, M. J. Hötzel y R. Pérez-Clariget. "Early mother–young relationship and feeding behaviour of lambs are unaffected by low pasture allowance until the beginning of the last third of gestation in single-bearing ewes". Animal Production Science 58, n.º 5 (2018): 930. http://dx.doi.org/10.1071/an16157.

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Nutrition during gestation influences ewes’ bodyweight (BW), the bond with their lamb, milk yield and lamb development, and thus feeding behaviour of lambs during postnatal rearing. The aim of this study was to determine if the level of native pasture allowance from before conception until the beginning of the last third of gestation of single-bearing ewes influences the ewe–lamb relationship at birth and the feeding behaviour of lambs during postnatal rearing. A second aim was to determine whether the nutritional treatments affect ewes’ milk yield and their lambs’ bodyweight. Eleven multiparous Corriedale ewes grazed a high pasture allowance [10–12 kg of dry matter (DM)/100 kg of BW/day; HPA treatment], and another 11 grazed a low pasture allowance (5–8 kg of DM/100 kg of BW/day; LPA treatment) for 145 days beginning 40 days before conception. After the end of this treatment all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine until 3 days before birth. Ewes’ BW was recorded monthly before and during gestation. Latency from parturition until the ewe licked her lamb, latency for lamb to stand up and suckle were recorded, and Maternal Behaviour Score was determined 12–24 h after birth. All the variables recorded during postpartum were determined approximately every 30 days. Grazing, ruminating and suckling events of the lambs were recorded from Day 23 until 142 days of age. Milk yield was determined from 32 until 140 days after lambing. Lambs’ BW was recorded from birth until 140 days of age. On Day 41 the BW change tended to be greater in HPA ewes than in LPA ewes, and on Days 79 and 105 it was greater in HPA ewes than LPA ewes (P = 0.006 and P = 0.005 respectively). Treatments did not affect the behaviours at birth of ewes and lambs, milk yield, ruminating and suckling events of lambs, ewes’ and lambs’ BW. The lambs from HPA ewes tended to present a greater frequency of grazing than the LPA lambs. Different levels of native pasture allowances from before conception until the last third of gestation in single-bearing ewes, followed by an increase in nutrient supply, did not affect ewe–lamb behaviours at birth, milk yield, lambs’ growth, and their feeding behaviours during rearing.

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31

Hart, K. W., A. Chadwick, F. Sebe, P. Poindron, R. Nowak y D. Blache. "Colostrum quality of ewes of calm temperament is not responsible for low lamb mortality". Australian Journal of Experimental Agriculture 46, n.º 7 (2006): 827. http://dx.doi.org/10.1071/ea05348.

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Perinatal lamb mortality is a serious issue for the sheep industries. Starvation is implicated in many of these lamb deaths. Ewes with a calm temperament lose significantly fewer lambs than ewes with nervous temperament, particularly in the critical first 3 days after birth. Colostrum provides essential nutrition to neonatal lambs. This research set out to determine whether ewe temperament affects the quantity and quality of colostrum that ewes produce. Calm temperament was found to have an influence on the viscosity of colostrum 6 h after birth. High variability in all aspects of colostrum production were found in the study and may be a limiting factor in lamb survival in certain circumstances. There is little evidence, however, to suggest a strong association with ewe temperament and is therefore unlikely to explain the lower lamb mortality that is reported to occur among calm ewes.

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32

Sarvinda, Diahanvika Tri, Sigit Bintara, I. Gede Suparta Budisatria, Kustantinah Kustantinah y Endang Baliarti. "The Effect of Flushing Premating with Spirulina Platensis Supplementation on Ewes Postpartum Estrus". Buletin Peternakan 46, n.º 1 (27 de febrero de 2022): 31. http://dx.doi.org/10.21059/buletinpeternak.v46i1.67523.

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Lactating ewes require high nutrients for basic life requirements and milk production. If not fulfilled, it can have an impact on Negative Energy Balance (NEB) that reduces body weight, Body Condition Score (BCS), and extend the appearance of Postpartum Estrus (PPE). Premating flushing feed is an effort to improve ewe nutrients by adding high nutrition for preparation before mating so that after lambing and suckling, the ewe immediately estrus. This research aimed to evaluate the performance of ewes through premating flushing feeding. The research was conducted at Mendo Galak Farm, Sleman, Yogyakarta. Twenty ewes 2-3 years old with BCS 2-3 divided into two groups; the group with flushing treatment consisted of dried water spinach (Ipomoea reptans poir), concentrate feed with Spirulina sp. (14,92% crude protein, 60,28% total digestible nutrients), and the control group (PS) without Spirulina sp. (crude protein 11,82%, total digestible nutrients 53,20%). Flushing feed was given after a month postpartum as much as 3% dry matter of body weight. The recorded parameter was daily feed consumption, monthly body weight, BCS, and postpartum estrus. The data obtained were tested by an independent T-test with Statistical Product and Service Solution (SPPS ver. 22). The results showed the consumption and digestibility of CP, TDN, and ewe's ADG had a significant difference (P<0.05). Postpartum estrus (PPE) of flushed ewes had no significant difference (P>0.05), 73.90±11.55 vs. 77.60±14.65 days, respectively. The conclusion was that flushing premating treatment with the addition of Spirulina platensis increased the nutrient intake and digestibility of CP, TDN, and ADG but had not shortened on postpartum estrus of lactating ewes.

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33

Blumer, S. E., G. E. Gardner, M. B. Ferguson y A. N. Thompson. "Whole-body fatness is a good predictor of phenotypic feed and liveweight efficiency in adult Merino ewes fed a poor-quality diet". Animal Production Science 56, n.º 4 (2016): 789. http://dx.doi.org/10.1071/an15217.

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Weight loss due to poor nutrition in adult ewes over summer–autumn is economically expensive due to immediate costs such as feed and labour but also due to ongoing costs to reproductive success and ewe health. We predicted that adult Merino ewes with a higher proportion of fat would be more efficient, both through lower intake and reduced weight loss. Four-year-old Merino ewes (n = 64) were held in single pens and fed a chaff-based diet either ad libitum, with the aim of achieving liveweight maintenance, or a restricted amount to achieve liveweight loss of 100 g/day. Liveweight change and feed intake were measured, and residual liveweight change and residual feed intake were used to indicate efficiency. There was a difference of 2 MJ of metabolisable energy per day between the most efficient and least efficient ewes for residual feed intake, and a difference of 90 g per day between the most efficient and least efficient ewes for residual liveweight change. There was a significant association between blood plasma concentrations of leptin and both liveweight and feed efficiency, so that ewes with high concentrations of leptin had a lower daily intake, and/or lost less weight than did those with low concentrations of leptin. Managing adult Merino ewes to maximise fat-tissue accretion during spring via genetics and/or nutritional management could be a useful strategy to reduce feed requirements during summer–autumn because the ewes will be more efficient and have larger fat reserves to lose before achieving a lower critical limit.

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34

Cunningham, Kirsty, Andrew Van Burgel, Khama R. Kelman, Claire M. Macleay, Beth L. Paganoni y Andrew N. Thompson. "Interactions between Ewes and Rams during Mating Can Be Used to Predict Lambing Dates Accurately, but Not Sire". Animals 12, n.º 13 (1 de julio de 2022): 1707. http://dx.doi.org/10.3390/ani12131707.

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Ewes often lamb over extended periods so the level of nutrition during pregnancy and lambing may be suboptimal for ewes that conceived later during mating. Predicting lambing dates would allow cohorts of ewes with similar gestational ages to be managed more precisely to achieve targets for ewe nutrition, feed on offer, mob sizes and access to shelter to improve lamb survival. The interactions between ewes and rams during mating have been used to predict the time of oestrus and lambing dates successfully, but this has not been tested at a commercial scale. In this study, proximity sensors were used to measure interactions between inexperienced Merino ewes (n = 317) and experienced rams (n = 9) during a 27-day mating period under commercial production conditions. When the gestation length was assumed to be 150 days, 91% of lambing dates were predicted within ±6 days of the actual birth date of lambs and 84% of lambing dates were predicted within ±3 days. The use of proximity sensors during mating was an effective means of predicting lambing dates, and there was no significant difference in accuracy for single bearing verses multiple bearing ewes. However, DNA parentage data showed the ram corresponding with the maximum daily interactions ratio was the sire for only 16% of all progeny, suggesting they could not be used to indicate the sire of the progeny.

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35

Edwards, L. J., J. R. McFarlane, K. G. Kauter y I. C. McMillen. "Impact of periconceptional nutrition on maternal and fetal leptin and fetal adiposity in singleton and twin pregnancies". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, n.º 1 (enero de 2005): R39—R45. http://dx.doi.org/10.1152/ajpregu.00127.2004.

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It has been proposed that maternal nutrient restriction may alter the functional development of the adipocyte and the synthesis and secretion of the adipocyte-derived hormone, leptin, before birth. We have investigated the effects of restricted periconceptional undernutrition and/or restricted gestational nutrition on fetal plasma leptin concentrations and fetal adiposity in late gestation. There was no effect of either restricted periconceptional or gestational nutrition on maternal or fetal plasma leptin concentrations in singleton or twin pregnancies during late gestation. In ewes carrying twins, but not singletons, maternal plasma leptin concentrations in late gestation were directly related to the change in ewe weight that occurred during the 60 days before mating [maternal leptin = 0.9 (change in ewe weight) + 7.8; r = 0.6, P < 0.05]. In twin, but not singleton, pregnancies, there was also a significant relationship between maternal and fetal leptin concentrations (maternal leptin = 0.5 fetal leptin + 4.2, r = 0.63, P < 0.005). The relative mass of perirenal fat was also significantly increased in twin fetal sheep in the control-restricted group (6.0 ± 0.5) compared with the other nutritional groups (control-control: 4.1 ± 0.4; restricted-restricted: 4.4 ± 0.4; restricted-control: 4.3 ± 0.3). In conclusion, the impact of maternal undernutrition on maternal plasma leptin concentrations during late gestation is dependent on fetal number. Furthermore, we have found that there is an increased fetal adiposity in the twins of ewes that experienced restricted nutrition throughout gestation, and this may be important in the programming of postnatal adiposity.

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36

Wallace, JM, RP Aitken y MA Cheyne. "Effect of post-ovulation nutritional status in ewes on early conceptus survival and growth in vivo and luteotrophic protein secretion in vitro". Reproduction, Fertility and Development 6, n.º 2 (1994): 253. http://dx.doi.org/10.1071/rd9940253.

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Overfeeding during early pregnancy in ewes compromises pregnancy establishment and/or embryo survival. To determine whether high feed intakes after ovulation alter the secretory dialogue between the conceptus and the endometrium, 24 embryos (8-16-cell) from ewes fed maintenance rations were synchronously transferred in singleton on Day 3 of the cycle (oestrus, Day 0) into the uterus of ewes receiving a high or low plane of nutrition from Day 0 (n = 12 ewes per group). Embryo survival and conceptus growth were assessed on Day 16. At this time, pregnancy was maintained in 11 of 12 recipient ewes per group and conceptus mass was not influenced by nutritional plane (637 +/- 48 v. 583 +/- 72 mg for high and low groups respectively). Conceptus and endometrial tissues were cultured separately for a further 24 h in vitro in the presence of [3H]leucine. There was no quantitative difference between nutritional treatments in the incorporation of radiolabel into proteins synthesized and secreted by the conceptus or endometrium. Secretion of ovine trophoblast protein-1 was also similar in both groups. Peripheral progesterone concentrations were significantly (P < 0.05) lower throughout the luteal phase in recipient ewes on high v. low intakes after ovulation. This effect was independent of ovulation rate which was 3.1 +/- 0.40 and 2.6 +/- 0.25 corpora lutea for high and low groups respectively. A high plane of nutrition after ovulation did not influence embryo survival and development in vivo or luteotrophic protein secretion in vitro despite a reduction in peripheral progesterone concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

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37

Kidane, Alemayehu, Jos Houdijk, Spiridoula Athanasiadou, Bert Tolkamp y Ilias Kyriazakis. "Nutritional sensitivity of periparturient resistance to nematode parasites in two breeds of sheep with different nutrient demands". British Journal of Nutrition 104, n.º 10 (9 de agosto de 2010): 1477–86. http://dx.doi.org/10.1017/s0007114510002503.

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The periparturient relaxation of immunity (PPRI) to parasites in mammals is sensitive to both metabolisable protein (MP) supply and animal genotype (different reproductive outputs). We tested the hypothesis that the sensitivity of PPRI to MP scarcity would not differ between different levels of reproductive output when nutrient intake is adjusted for associated differences in MP demand; this hypothesis assumes that PPRI has a nutritional basis only. Scottish Blackface (BF) and the more productive Mule (MU) ewes were infected with the abomasal parasite Teladorsagia circumcincta, and from day− 21 to day32 (day0 is parturition), they were fed restrictedly at either 0·8 (low protein (LP)) or 1·3 (high protein (HP)) times their breed-specific estimated MP requirement (n 18 for each breed–feeding treatment combination). During late pregnancy, LP feeding reduced ewe body weight gain in both breeds, tended to increase faecal egg count (FEC), but it did not affect plasma pepsinogen. During lactation, LP feeding reduced litter growth rate and ewe plasma urea and plasma albumin concentrations compared with HP feeding in both breeds. However, breed and feeding treatment interacted for ewe FEC, worm egg excretion and plasma pepsinogen, which were higher for the LP-MU ewes compared with the HP-MU and BF ewes. The lower degree of PPRI of the BF ewes during lactation compared with the MU ewes at a similar degree of MP scarcity suggests that the effect of reproductive output on nutritional sensitivity of PPRI cannot be explained by associated differences in nutrient demand only.

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38

Kelly, RW, I. Macleod, P. Hynd y J. Greeff. "Nutrition during fetal life alters annual wool production and quality in young Merino sheep". Australian Journal of Experimental Agriculture 36, n.º 3 (1996): 259. http://dx.doi.org/10.1071/ea9960259.

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The effect of maintenance v, submaintenance diets of pregnant ewes in 1991 and 1992 on establishment of the wool follicle population in their progeny, and its effect on the progeny's wool production (quantity, quality and variation across the body of the animal) to 1.4 years of age was examined. The experimental protocol used cloned animals created by bisecting embryos at day 6 of pregnancy. Each clone was placed in a ewe, which was subsequently fed from about day 50 to 140 of pregnancy at maintenance or submaintenance. Ewes on maintenance nutrition maintained liveweight throughout pregnancy, while submaintenance ewes were 12.1 kg lighter (P<0.001) 10 days before lambing. In 1991, a total of 74 lambs were born, including 17 sets of surviving clones. In 1992, 102 lambs were born, including 18 sets of surviving clones. Only data for the 35 sets of genetically identical 'twin' progeny and their dams are reported. Birth weights of lambs born to ewes fed at the submaintenance rate were 0.5 kg lighter (P<0.01) than their 'twins' born to ewes fed at maintenance. Midside secondary:primary (Sf: Pf) ratios for mature wool follicles were less (P<0.01) at birth, lamb and hogget shearing (1.4, 1.5 and 2.1 units respectively) for the progeny born to ewes fed at submaintenance. Progeny from ewes on the submaintenance treatment produced less clean wool, 0.1 kg to 0.4 years of age (P<0.01) and 0.14 kg between 0.4 and 1.4 years of age (P = 0.10), than their maintenance counterparts. Hogget wool was 0.1 pm broader (P<0.05), with a 0.5% units lower coefficient of variation of fibre diameter (P<0.01), and a position of break closer to the staple tip (P<0.001) for progeny of submaintenance ewes than their maintenance counterparts. There were no significant differences in yield, staple length, staple strength and percentage of fibres greater than 30 pm in diameter. Differences in mean fibre diameter arose between 1 and 1.4 years of age, coinciding with the period that the animals were grazing high quality pasture. Effects of maternal undernutrition on mean fibre diameter and Sf: Pf follicle ratios of progeny were most pronounced on the hind leg (P<0.01), and not significant on the front leg. However, variations in other wool quality traits across the body of the hoggets, expressed as a percentage of the midside value, were not significantly affected by maternal undernutrition. Clearly when evaluating management strategies for the pregnant ewe, the effect on lifetime production and quality of wool of their progeny needs to be considered. Merino hoggets that produce an extra 0.14 kg clean wool that is 0.1 pm finer will compensate for some extra management and feeding of their dams during pregnancy to prevent weight loss. If these effects continue throughout the life of the animal, then it will increase the cost effectiveness of feeding to maintain maternal weight over pregnancy.

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39

Clarke, Lynne, Michael J. Bryant, Michael A. Lomax y Michael E. Symonds. "Maternal manipulation of brown adipose tissue and liver development in the ovine fetus during late gestation". British Journal of Nutrition 77, n.º 6 (junio de 1997): 871–83. http://dx.doi.org/10.1079/bjn19970086.

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AbstractWe examined the effect of maternal chronic cold exposure, induced by winter-shearing ewes 4 weeks before their predicted lambing date, on brown adipose tissue (BAT) and liver development in lambs. Fetuses were sampled from under-fed (60% of energy requirements for maintenance and pregnancy of an unshorn ewe) shorn or unshorn ewes at 126,140 and 145 d of gestation. Lambs were sampled from ewes within 2 h of birth. Throughout gestation fetal body, BAT and liver weights were similar in shorn and unshorn groups. The level of GDP binding to mitochondrial uncoupling protein remained low throughout gestation, but increased dramatically after birth. Lambs born to shorn ewes possesd more mitochondrial protein and exhibited a significantly higher total thermogenic activity in BAT. Type I iodothyronine 5 deiodinas(EC 3.8.1.4) activity in BAT peaked at birth, as did hepatic iodothyronine Sdeiodinase activity and was significantly greater in lambs born to under-fed shorn ewes, which exhibited a higher plasma triiodothyronine concentration. Chronic maternal adaptations to prolonged cold exposure appear to enable pregnant ewes to compensate for the negative effects of under-feeding on fetal growth and development

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40

Piaggio, L., H. Deschenaux, F. Baldi, S. Fierro, G. Quintans y G. Banchero. "Plane of nutrition of Corriedale ewe lambs from foetal life to the onset of breeding affects weight at service and reproductive outcome". Animal Production Science 55, n.º 8 (2015): 1011. http://dx.doi.org/10.1071/an13260.

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The objective of this study was to identify periods in the life (foetal and postnatal) of Corriedale ewe lambs where different nutrition levels can affect bodyweight at breeding and pregnancy rate in their first year of life. The effect of three different phases of nutrition on the growth and pregnancy rate (n = 133) of Corriedale ewe lambs of 7 months of age were evaluated. Phase 1 included the last phase of gestation of their mothers (30 last days of gestation, Day –30; partum = Day 0) until marking (Day 24). Phase 2 was between marking and weaning (Day 114) and phase 3 between weaning to the onset of breeding (Day 207). For phase 1, 350 adult ewes had access to improved pastures (phase 1, H) or native pastures (phase 1, L). After lambing, all ewes and their lambs were offered native pastures. After marking only ewes bearing females lambs were kept. In phase 2, 67 lambs born to H and 66 lambs born to L ewes were sorted in two new treatments: access to native pastures supplemented with ~1% of their bodyweight with soybean meal (phase 2, H) or access to native pastures alone (phase 2, L). In phase 3, each of the lambs of the four treatments applied during phase 2 were sorted in two new treatments: access to improved pastures (phase 3, H) or native pastures supplemented with 0.7% of liveweight with soybean meal (phase 3, L). Breeding period lasted 41 days and pregnancy diagnosis was performed 86 days after the onset of breeding. The pregnancy rate varied from 0% to 47%. Phase 3 of nutrition was the only phase that affected pregnancy rate (28% vs. 10% for female lambs offered H and L plane of nutrition respectively; P = 0.005). A discriminative analysis demonstrated that the liveweight at breeding was the only variable that affected the success of pregnancy in ewe lambs (P = 0.0025). Moreover, the ewe lambs that were heavier at the onset of breeding (more than 35 kg or in average 38 kg) were the most successful to get pregnant (35% of pregnancy for lambs over 35 kg and 13% for lambs under 35 kg, P = 0.0044). In conclusion, under the conditions of this experiment, the most important parameters to explain successful pregnancy of ewe lambs were the growth rate after weaning, and the liveweight at the onset of breeding.

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41

Abecia, J. A., F. Forcada y L. Zarazaga. "A note on the effect of level of nutrition after weaning on the resumption of reproductive activity by ewes of two Spanish breeds lambing in spring". Animal Science 56, n.º 2 (abril de 1993): 273–76. http://dx.doi.org/10.1017/s000335610002136x.

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Two experiments were carried out from April to September 1990 at Zaragoza, Spain. Fifty-three Rasa Aragonesa (RA) ewes, weaned in April, were studied in experiment 1, whilst 33 Salz (Sz) ewes, weaned in June, were studied in experiment 2. From weaning onwards, the animals were allocated to two groups receiving two planes of nutrition: high (H) and low (L). Mean time between weaning and the first detected oestrus was 113 (s.e. 2·7) and 52 (s.e. 3·0) days for RA and Sz ewes, without any significant effect of the plane of nutrition. Ewes of the H group showed a constantly higher ovulation rate than those of the L group with a significant effect of the plane of nutrition in the second fortnight of August (P < 0·05) and of September (P < 0·001) in RA ewes (1·68 v. 1·29 and 1·89 v. 1·38 corpora lutea for H and L groups, respectively) and in September (P < 0·01) in Sz ewes (2·53 v. 2·00 corpora lutea for H and L groups).In conclusion, a slightly higher plane of nutrition after weaning in these sheep breeds, lambing in spring, cannot advance either the reproductive resumption or increase the ovulation rate of the first cycle. The high plane of nutrition after weaning exerts a significant effect on the ovulation rate in the medium term, in the early breeding season.

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42

Ashworth, C. J., C. M. Dwyer, K. McIlvaney, M. Werkman y J. A. Rooke. "Breed differences in fetal and placental development and feto-maternal amino acid status following nutrient restriction during early and mid pregnancy in Scottish Blackface and Suffolk sheep". Reproduction, Fertility and Development 23, n.º 8 (2011): 1024. http://dx.doi.org/10.1071/rd10290.

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This study assessed the effect of feeding 0.75 energy requirements between Days 1 and 90 of pregnancy on placental development and feto-placental amino acid status on Day 125 of pregnancy in Scottish Blackface and Suffolk ewes carrying a single fetus. Such moderate nutrient restriction did not affect placental size, placentome number or the distribution of placentome types. Although fetal weight was unaffected by maternal nutrition, fetuses carried by nutrient restricted mothers had relatively lighter brains and gastrocnemius muscles. Suffolk fetuses were heavier and longer with a greater abdominal circumference, relatively lighter brains, hearts and kidneys, but heavier spleens, livers and gastrocnemius muscles than Blackface fetuses. Total placentome weight was greater in Suffolk than Blackface ewes. Ewe breed had a greater effect on amino acid concentrations than nutrition. Ratios of maternal to fetal amino acid concentrations were greater in Suffolk ewes than Blackface ewes, particularly for some essential amino acids. The heavier liver and muscles in Suffolk fetuses may suggest increased amino acid transport across the Suffolk placenta in the absence of breed differences in gross placental efficiency. These data provide evidence of differences in nutrient handling and partitioning between the maternal body and the fetus in the two breeds studied.

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43

Pocar, P., L. F. Pisani, S. Antonini, V. Tosetti, T. A. L. Brevini, F. Gandolfi y S. M. Rhind. "278 GENE EXPRESSION PROFILE OF OVINE OOCYTES AND CUMULUS CELLS WITH REFERENCE TO PREMATING NUTRITION". Reproduction, Fertility and Development 19, n.º 1 (2007): 254. http://dx.doi.org/10.1071/rdv19n1ab278.

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Previous studies on sheep have demonstrated effects of maternal nutrition on fetal development with effects being observed on reproductive function (Rae et al. 2002 Anim. Reprod. Sci. 72, 63–71), blood pressure (Gopalakrishnan et al. 2004 Am. J. Physiol. Regul. Integr. Comp. Physiol. 287, R12–R20), and behavior (Erhard et al. 2004 Behav. Brain Res. 151, 25–35) in the adult offspring. It is known that gene expression in developing oocytes and very early embryos is influenced by their environment and some of the effects of nutrition on reproductive and other systems are likely to be expressed through such early changes (Hyttel 2000 Anim. Reprod. Sci. 60–61, 49–60). Effects of nutrition on oocyte function (i.e. before ovulation and fertilization) and resultant embryo quality have been observed (Gonzalez-Bulnes et al. 2004 Reprod. Fertil. Dev. 16, 421–435), but effects on oocyte gene expression have not been investigated. The aim of the present study was to investigate the effects of premating nutrition on the expression of selected genes in sheep cumulus cells and oocytes. For this purpose, 16 cast age ewes of proven fertility were used. At the time of manipulation and study, all ewes had a condition score of approximately 2.5. During the 2 weeks before slaughter, ewes of one group were fed a ration providing 0.5-live weight (n = 10) maintenance requirements and the other group 1.5-live weight (n = 6) maintenence requirements. This treatment ensured that all animals had similar numbers of potentially ovulatory follicles but different patterns of ovarian follicle maturation and, accordingly, different numbers of follicles and oocytes undergoing the final stages of maturation. The ewes's reproductive cycles were synchronized using intravaginal pessaries inserted 2 weeks before slaughter. At slaughter, ovaries were recovered and oocytes and associated cumulus cells were aspirated from all follicles >2 mm in diameter. For each ovary, oocytes derived from follicles with a diameter <4 mm and >4 mm were pooled separately, and stored for further analysis. Associated cumulus masses were collected and stored singly for subsequent investigations. As expected from previous observations, the number of visible follicles, the ratio of small-to-large antral follicles, and the total numbers of oocytes per ewe were similar for control and underfed ewes. Furthermore, the expression levels of the markers for oocyte growth, GDF-9, BMP-15, and c-kit, were investigated. Data were analyzed by ANOVA followed by Duncan test. Results showed no major differences between groups, independent of follicle diameter. These data suggest that the nutritional status of donor ewes did not significantly affect the expression profiles of these genes. However, further analyses on a greater panel of genes is required to rule out premating nutrition effects on oocyte gene expression. Furthermore, effects on the cumulus cell gene expression profile remain to be investigated. This work was supported by the University of Milan, FIRST 2006; Scottish Executive Environment and Rural Affairs Department.

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44

Waterhouse, A., D. N. Logue y L. C. Roger. "The effects of increased prolificacy on lamb and ewe mortality in an intensive hill sheep system". BSAP Occasional Publication 15 (1992): 176–78. http://dx.doi.org/10.1017/s0263967x00004237.

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Increased prolificacy is often believed to increase the incidence of both lamb and ewe mortality especially in harsher environments. Fecundin® (Coopers Pittman Moore) is a vaccine which leads to immunization against androstenedione and a resulting increase in prolificacy (Rhind, 1987). The use of this drug gives a method of manipulating prolificacy without confounding any effects with improved nutrition, the most usual means of modifying reproductive success.A programme was commenced in 1985 in which half the ewes in a flock of Scottish Blackface ewes was vaccinated with Fecundin (F), the remainder left unvaccinated (N). In subsequent years ewes were maintained on the same treatment. The data presented here are an analysis of a single age group of ewes completing a full lifetime on each treatment. Eighty-five ewes were allocated at random to each treatment. These were vaccinated in autumn 1985, given a booster vaccination 4 weeks pre-ram joining in 1986, 1987 and 1988 and sold as ‘cast for age’ after lamb weaning in 1989. With the exception of injection with Fecundin, at all times management was independent of treatment.

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45

Wilkinson, S. C. y D. M. B. Chestnutt. "Effect of level of food intake in mid and late pregnancy on the performance of breeding ewes". Animal Science 47, n.º 3 (diciembre de 1988): 411–19. http://dx.doi.org/10.1017/s000335610000355x.

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ABSTRACTIn three experiments pregnant ewes (mean weight 72·5 kg) were subjected to different planes of nutrition on grass silage-based diets during mid pregnancy and, in factorial designed trials with ad libitum silage or ad libitum silage + concentrates in late pregnancy. The high plane of mid-pregnancy nutrition resulted in an average gain of 11·5 kg between weeks 7 and 14 of pregnancy while the low plane gave an average loss of 3·5 kg during this period. These differences did not affect lamb birth weight but ewes on the high plane were 7·2 kg heavier after lambing than those on the low plane. The effect of plane of nutrition during mid pregnancy on silage intake during late pregnancy was variable but there was some evidence of a greater reduction in intake during the last few weeks of pregnancy following the high plane of mid-pregnancy nutrition. The higher plane of nutrition in late pregnancy resulted in higher ewe live weights as well as higher lamb birth weights and highest lamb birth weights occurred following restriction in mid pregnancy and a high plane of nutrition in late pregnancy.Plasma 3-hydroxybutyrate levels were variable but there was little evidence of an effect of mid-pregnancy nutrition although levels appeared to be increased by the low plane of nutrition in late pregnancy.

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46

Pillai, S. M., A. K. Jones, M. L. Hoffman, K. K. McFadden, S. A. Reed, S. A. Zinn y K. E. Govoni. "Fetal and organ development at gestational days 45, 90, 135 and at birth of lambs exposed to under- or over-nutrition during gestation1,2,3". Translational Animal Science 1, n.º 1 (1 de enero de 2017): 16–25. http://dx.doi.org/10.2527/tas2016.0002.

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Abstract To determine the effects of poor maternal nutrition on offspring body and organ growth during gestation, pregnant Western White-faced ewes (n = 82) were randomly assigned into a 3 × 4 factorial treatment structure at d 30.2 ± 0.2 of gestation (n = 5 to 7 ewes per treatment). Ewes were individually fed 100% (control), 60% (restricted) or 140% (over) of NRC requirements for TDN. Ewes were euthanized at d 45, 90 or 135 of gestation or underwent parturition (birth) and tissues were collected from the offspring (n = 10 to 15 offspring per treatment). Offspring from control, restricted and overfed ewes are referred to as CON, RES and OVER, respectively. Ewe data were analyzed as a completely randomized design and offspring data were analyzed as a split-plot design using PROC MIXED. Ewe BW did not differ at d 30 (P ≥ 0.43), however restricted ewes weighed less than overfed and overfed were heavier than controls at d 45, and restricted weighed less and overfed were heavier than controls at d 90 and 135 and birth (P ≤ 0.05). Ewe BCS was similar at d 30, 45 and 90 (P ≤ 0.07), however restricted ewes scored lower than control at d 135 and birth (P ≤ 0.05) and over ewes scored higher than control at d 135 (P ≤ 0.05) but not at birth (P = 0.06). A maternal diet by day of gestation interaction indicated that at birth the body weight (BW) of RES offspring was less than CON and OVER (P ≤ 0.04) and heart girth of RES was smaller than CON and OVER (P ≤ 0.004). There was no interaction of maternal diet and day of gestation on crown-rump, fetal, or nose occipital length, or orbit or umbilical diam. (P ≥ 0.31). A main effect of maternal diet indicated that the RES crown-rump length was shorter than CON and OVER (P ≤ 0.05). An interaction was observed for liver, kidney and renal fat (P ≤ 0.02). At d 45 the liver of RES offspring was larger than CON and OVER (P ≤ 0.002), but no differences observed at d 90, 135 or birth (P ≥ 0.07). At d 45, the kidneys of OVER offspring were larger than CON and RES (P ≤ 0.04), but no differences observed at d 90, 135 or birth (P ≥ 0.60). At d 135, OVER had more perirenal fat than CON and RES (P ≤ 0.03), and at birth RES had more perirenal fat than CON and OVER (P ≤ 0.04). There was no interaction observed for offspring heart weight, length or width, kidney length, adrenal gland weight, loin eye area or rib width (P ≥ 0.09). In conclusion, poor maternal nutrition differentially alters offspring body size and organ growth depending on the stage of gestation.

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47

Treacher, T. T., F. Bahhady, H. Hreitani y A. Termanini. "A comparison of the performance of Turkish and Syrian strains of Awassi ewes at two levels of nutrition". Proceedings of the British Society of Animal Production (1972) 1994 (marzo de 1994): 202. http://dx.doi.org/10.1017/s030822960002746x.

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Although milk is an important product of sheep systems using the Awassi breed in the Near East, typically giving 25% of the gross income, there is little information on the yields of Awassi ewes at defined levels of nutrition. The Awassi is the dominant breed of sheep in the Near East. It is the only breed in Jordan, Lebanon and Syria, which have a total sheep population of 16.9 million. In Iraq about 50% of the 7.8 million sheep are Awassis. There are also approximately 1 million Awassi sheep in Turkey, mainly in the south along the border with Syria. Turkish Awassi ewes have been selected for milk yield for many years at the Ceylanpinar State Farm.In 1991, ICARDA purchased 40 ewes, aged 2 years, from the Ceylanpinar flock. In 1992, these ewes and 40 ewes selected at random from 2 year old ewes in the flock at ICARDA's Tel Hadya station at Aleppo, in northern Syria, were compared, using two levels of nutrition in lactation. The ewes in the ICARDA flock are typical of well managed flocks in northern Syria.

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48

Quirk, MF y BW Norton. "The relationship between the cobalt nutrition of ewes and the vitamin B12 status of ewes and their lambs". Australian Journal of Agricultural Research 38, n.º 6 (1987): 1071. http://dx.doi.org/10.1071/ar9871071.

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An experiment was undertaken at Mt Cotton, south-east Queensland, to investigate the relationship between the cobalt nutrition of ewes and the occurrence of vitamin B12 deficiency in ewes and their lambs. Ewes received either no supplementary cobalt (C), 0.03 mg cobalt day-1 (LC), 0.06 mg cobalt day-1 (HC) or a cobalt bullet and grinder (CB). LC and HC ewes received their supplement as a weekly drench. Supplementation commenced prior to joining, and ewes subsequently grazed pangola grass pastures containing between 0.05 and 0.11 mg kg-1 cobalt.Cobalt supplementation of ewes increased their liveweight, reproductive and lactation performance. The milk production of ewes was influenced by the level of supplementation, with C, LC, HC and CB ewes producing 31.1, 41.5, 47.7 and 50.31. of milk respectively during the first 4 weeks of lactation. The lower productivity of C ewes was associated with concentrations of vitamin B12 in serum of less than 200 pg ml-1 and with the presence of detectable concentrations of methylmalonic acid (>80 8moles l-1) and formiminoglutamic acid (>30 8moles l-1) in their urine.The growth of lambs was influenced by the cobalt nutrition of their dams; the mean liveweight gain from birth to weaning (14 weeks of age) for lambs from C, LC, HC and CB ewes was 95, 158, 194 and 231 g day-1. Vitamin B12 deficiency was evident in lambs reared by C ewes from 4 weeks of age, but lambs from LC and HC ewes did not become deficient until 8 and 12 weeks of age respectively. Lambs from CB ewes remained free of signs of deficiency prior to weaning. Urinary formiminoglutamic acid concentration was a more reliable indicator of vitamin B12 status in young lambs than urinary methylmalonic acid concentration. The concentrations of vitamin B12 in the serum of lambs were low in all groups (< 150 pg ml-1) and were generally unaffected by the cobalt nutrition of their dams.A dietary cobalt intake of about 0.15 mg day-1 appeared to be necessary for optimal milk production from ewes. However, this level of dietary cobalt was inadequate for provision of sufficient quantities of maternal vitamin B12 to meet the requirements of lambs in the later stages of lactation.

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49

Filo, S., A. V. Goodchild y T. T. Treacher. "Effects of Body Condition and Level of Nutrition Before Mating on Fertility of Awassi Ewes". Proceedings of the British Society of Animal Production (1972) 1994 (marzo de 1994): 222. http://dx.doi.org/10.1017/s0308229600027665.

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Surveys of flocks in the Near East have shown that lambing percentages of Awassi ewes are rarely above 85% and often as low as 65%. This is a major cause of the low output of sheep systems in the region. The low fertility results from a combination of poor nutrition, poor management, disease and possibly the effects of high temperatures at mating, which generally occurs in mid-summer.Studies by Kassem et al (1989) and Thomson and Bahhady (1988) indicated that the reproductive performance of Awassi ewes is affected by body condition at mating. Neither of these studies was specifically designed to investigate the effects of weight or body condition and level of nutrition before mating on reproduction in Awassi ewes. The experiment reported here is the second in a series specifically designed to investigate the effects of body condition at mating, and level of nutrition before and after mating, on the fertility of Awassi ewes.

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50

Bass, Casie S., Dale A. Redmer, Samantha L. Kaminski y Anna T. Grazul-Bilska. "Luteal function during the estrous cycle in arginine-treated ewes fed different planes of nutrition". Reproduction 153, n.º 3 (marzo de 2017): 253–65. http://dx.doi.org/10.1530/rep-16-0526.

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Functions of corpus luteum (CL) are influenced by numerous factors including hormones, growth and angiogenic factors, nutritional plane and dietary supplements such as arginine (Arg), a semi-essential amino acid and precursor for proteins, polyamines and nitric oxide (NO). The aim of this study was to determine if Arg supplementation to ewes fed different planes of nutrition influences: (1) progesterone (P4) concentrations in serum and luteal tissue, (2) luteal vascularity, cell proliferation, endothelial NO synthase (eNOS) and receptor (R) soluble guanylate cyclase β protein and mRNA expression and (3) luteal mRNA expression for selected angiogenic factors during the estrous cycle. Ewes (n = 111) were categorized by weight and randomly assigned to one of three nutritional planes: maintenance control (C), overfed (2× C) and underfed (0.6× C) beginning 60 days prior to onset of estrus. After estrus synchronization, ewes from each nutritional plane were assigned randomly to one of two treatments: Arg or saline. Serum and CL were collected at the early, mid and late luteal phases. The results demonstrated that: (1) nutritional plane affected ovulation rates, luteal vascularity, cell proliferation andNOS3,GUCY1B3, vascular endothelial growth factor (VEGF) andVEGFR2mRNA expression, (2) Arg affected luteal vascularity, cell proliferation andNOS3,GUCY1B3,VEGFandVEGFR2mRNA expression and (3) luteal vascularity, cell proliferation and the VEGF and NO systems depend on the stage of the estrous cycle. These data indicate that plane of nutrition and/or Arg supplementation can alter vascularization and expression of selected angiogenic factors in luteal tissue during the estrous cycle in sheep.

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