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1
Martin, Graeme B., Soedjiharti Tjondronegoro, Rachid Boukhliq, Margaret A. Blackberry, Jan R. Briegel, Dominique Blache, James A. Fisher e Norman R. Adams. "Determinants of the annual pattern of reproduction in mature male Merino and Suffolk sheep: modification of endogenous rhythms by photoperiod". Reproduction, Fertility and Development 11, n. 6 (1999): 355. http://dx.doi.org/10.1071/rd00005.
Testo completoAbstract (sommario):
In mediterranean environments, pastures are very poor during the autumn and consequently small ruminants, such as sheep, would have been losing body mass for many months so, during mating, gamete production would be depressed in both sexes. Effectively, the nutritive requirements for a photo-period-driven, annual reproductive cycle are out of phase with seasonal changes in food availability. The problem could be overcome through more flexible timing of reproduction, perhaps explaining variations in seasonality between breeds that originate from differing latitudes. To study these concepts and the mechanisms involved, the endogenous rhythms and responses to photoperiod were compared in rams of ‘mediterranean origin’ (Merino) and ‘temperate origin’ (Suffolk). Groups of 16 rams of each breed were given a constant food supply and subjected to 16 months of constant equinoctial photoperiod (12L : 12D) or simulated ‘mediterranean’ changes in daylength (from 14L : 10D to 14D : 10L). With nutritional and photoperiodic inputs held constant, Merino and Suffolk rams showed similar endogenous rhythms in reproductive activity. Under constant nutritional inputs and a mediterranean photoperiodic cycle, the endogenous rhythms were modified differently in the two breeds, with the Merinos starting and finishing their seasons about 2 months earlier than the Suffolks. These observations partially explain the patterns observed in rams kept under field conditions. It is now necessary to test whether the rhythms of reproduction in these breeds are also modified by changes in nutrition and social cues.
2
Santiago, L. Lomas, D. Blache, M. A. Blackberry, G. B. Martin e A. B. Mâncio. "309. Nutrition, insulin, leptin and puberty in Merino ram lambs". Reproduction, Fertility and Development 17, n. 9 (2005): 132. http://dx.doi.org/10.1071/srb05abs309.
Testo completoAbstract (sommario):
Merino sheep developed in Mediterranean regions so are well adapted to acute changes in food availability. However, restricted intake during pregnancy, especially in animals that are pregnant over the dry summer, could limit the positive effects of a winter rainy season on fetal development. In this study, we tested whether the level of nutrition during pregnancy and during pre-pubertal development affected blood concentrations of insulin and leptin, scrotal circumference and age of puberty in male Merino lambs fed with pasture. During dry weather, pregnant sheep were supplemented ad libitum with hay and lupin grain (Lupinus angustifolius) to compensate for decreases in pasture supply. Puberty was detected using a standardised behavioural test with oestrous ewes. Lambs were considered pubertal if they displayed mounting in two successive weekly tests. There were no differences in plasma concentrations of insulin or leptin. The values for both hormones simply displayed the same pattern, with a rise after feeding and a fall during non-feeding periods. There was no difference among treatments in either scrotal growth or age to puberty (Table 1). This might be because the dietary treatments, being administered by food restriction under field conditions, would not have the same effects as severe undernutrition that has been used in laboratory studies. Alternatively, Merino sheep may have a greater capacity to cope with mild nutritional stress.
3
Lv, Xuefeng, Lei Chen, Sangang He, Chenxi Liu, Bin Han, Zhilong Liu, Mayila Yusupu et al. "Effect of Nutritional Restriction on the Hair Follicles Development and Skin Transcriptome of Chinese Merino Sheep". Animals 10, n. 6 (19 giugno 2020): 1058. http://dx.doi.org/10.3390/ani10061058.
Testo completoAbstract (sommario):
The high concentration of secondary branched wool follicles is a distinctive feature of the Merino sheep. At present, the molecular control of the development and branching of secondary wool follicles (SF) remains elusive. To reveal the potential genes associated with the development of hair follicles, we investigated the characteristics of prenatal and postnatal development of wool follicles, and the transcriptional expression profile in fetuses/lambs from dams under either maternal maintenance or sub-maintenance (75% maintenance) nutrition. The density of SF and the ratio of SF to primary wool follicles (PF) were reduced (p < 0.05) in fetuses from day 105 to 135 of gestation under sub-maintenance nutrition. Differentially expressed genes were enriched in the binding, single-organism process, cellular process, cell and cell part Gene Ontology (GO) functional categories and metabolism, apoptosis, and ribosome pathways. Four candidate genes, SFRP4, PITX1, BAMBI, and KRT16, which were involved in secondary wool follicles branching and development, were identified. Our results indicate that nutritional intervention imposed on pregnant ewes by short-term sub-maintenance nutrition could provide a strategy for the study of wool follicle development. Overall insight into the global gene expression associated with SF development can be used to investigate the underlying mechanisms of SF branching in Merino sheep.
4
Hötzel, Maria J., Stephen W. Walkden-Brown, James S. Fisher e Graeme B. Martin. "Determinants of the annual pattern of reproduction in mature male Merino and Suffolk sheep: responses to a nutritional stimulus in the breeding and non-breeding seasons". Reproduction, Fertility and Development 15, n. 1 (2003): 1. http://dx.doi.org/10.1071/rd02024.
Testo completoAbstract (sommario):
This study was designed to test whether an acute improvement in diet would increase gonadotrophin secretion and testicular growth in strongly photoperiod-responsive Suffolk rams and weakly photoperiod-responsive Merino rams in both the breeding (February–March) and the non-breeding (July–August) seasons. Mature rams (n = 5 or 6) of these breeds were fed a maintenance diet (0.9 kg chaff + 100 g lupin grain) or the same diet supplemented with 1.5 kg lupin grain for 42 days in each season. Lupin grain is a rich source of both energy and protein. Testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured in plasma from blood sampled every 20 min for 24 h on Days −1, 12 and 35 relative to the change in feeding. In rams supplemented with lupins, body mass increased in both breeds in both seasons (P < 0.001). Scrotal circumference and LH pulse frequency increased with lupin supplementation in both seasons (P < 0.003) in Merinos, but only during the breeding season (P < 0.003) in Suffolks. Plasma FSH concentrations were affected by diet only during the breeding season, being elevated on Day 12 in lupin-supplemented rams of both breeds (P < 0.05). It was concluded that Merino rams exhibit reproductive responses to improved nutrition irrespective of time of the year, whereas Suffolk rams respond to nutrition only when the hypothalamic reproductive centres are not inhibited by photoperiod. Thus, Suffolks do respond to nutrition, just as Merinos do, but only when photoperiod allows. This difference between breeds appears to be a result of differences in the neuroendocrine pathways that control pulsatile gonadotrophin-releasing hormone secretion.
5
Warner, R. D., D. W. Pethick, P. L. Greenwood, E. N. Ponnampalam, R. G. Banks e D. L. Hopkins. "Unravelling the complex interactions between genetics, animal age and nutrition as they impact on tissue deposition, muscle characteristics and quality of Australian sheep meat". Australian Journal of Experimental Agriculture 47, n. 10 (2007): 1229. http://dx.doi.org/10.1071/ea07229.
Testo completoAbstract (sommario):
The combined effects of age and genetics and Poll Dorset sire and growth path were studied in two separate experiments (n = 595 and 627, respectively). In the first experiment, containing genotype crosses typically used in Australia (Merino, Poll Dorset, Border Leicester) and sires selected for growth or muscling, sheep were slaughtered at 4, 8, 14 and 22 months. The second experiment used Poll Dorset sires selected for high muscling, fat or growth with progeny having two levels of nutrition postweaning. Border Leicesters expressed higher levels of carcass fat percentage and intramuscular fat and produced the heaviest carcass. Merinos had the lowest subcutaneous fat depth and highest carcass lean percentage when compared at the same age. The progeny of Poll Dorset sires selected for high muscling (PDm) expressed a shift toward glycolytic fibres relative to those from Merino sires, and PDm sires produced progeny with reduced spine and limb length and higher carcass muscle : mineral ratios, suggesting skeletal stunting. Genotype meat quality differences were minimal except that PDm sire topsides were tougher and Merinos produced higher pH meat. With age (4–22 months), lambs became heavier and fatter, fibres shifted towards oxidative and away from glycolytic, muscle myoglobin increased, the meat became darker and redder and tenderness declined. Early weaning had no effect on the time to reach slaughter weight, provided nutrition was not restricted. The sire genetics influence on the carcass composition far outweighed the effect of nutrition postweaning. Lambs on a restricted diet tended to have less acceptable meat quality but this was not evident in lambs from sires selected for high fatness. Sensory tenderness was improved and intramuscular fat was higher in lamb progeny from sires selected for high fatness.
6
Wheeler, JL, HI Davies, DA Hedges e PJ Reis. "Effects of nutrition and paring on linear hoof growth in sheep". Australian Journal of Agricultural Research 41, n. 1 (1990): 197. http://dx.doi.org/10.1071/ar9900197.
Testo completoAbstract (sommario):
Paring increased the linear hoof growth on the forefeet of Merino wethers by an average of 4.1% (P < 0.05) with a tendency for paring to promote faster growth on the medial digits. Effects of feeding these sheep with 400, 600, or 1000 g pelleted ration day-1 were assessed in a 4 X 4 Latin square design with 28-day periods using four measures of response. An extra (fifth) period was used to determine residual effects. The proportion of residual (carryover) to direct effect was much smaller for hoof growth than for wool. Hoof growth was not related to wool production. In another experiment, hoof growth rate of sheep increased from 103 to 136 8m day-1 when the intake of digestible dry matter was increased from 400 to 600 g day-1 (P< 0.001), and from 115 to 125 8m day -1 (P> 0.05) when the intake of digestible nitrogen was increased from 12 to 25 g day-1. Hoof growth rates of Merino wethers grazing native or sown pasture were not significantly affected by injecting DL-methionine daily into the abomasum. Hoof growth is not an appropriate index of wool growth. It may provide an easily measured, rapidly responsive and cumulative measure of nutritional changes, but its use cannot be recommended until more information is available on the factors that affect it and their interaction with ambient temperature.
7
van Burgel, A. J., C. M. Oldham, R. Behrendt, M. Curnow, D. J. Gordon e A. N. Thompson. "The merit of condition score and fat score as alternatives to liveweight for managing the nutrition of ewes". Animal Production Science 51, n. 9 (2011): 834. http://dx.doi.org/10.1071/an09146.
Testo completoAbstract (sommario):
The liveweight profile of Merino ewes is related to the production and profitability of the sheep enterprise, but few producers measure liveweight to manage the nutrition of Merino ewes. In this paper we examine the relationship between changes in liveweight and condition score using data from the Lifetimewool project and compare condition score and fat score as alternative monitoring tools. Analyses of liveweight and condition score data from 15 flocks of Merino ewes representing a range of different genotypes and environments showed that the relationship between change in liveweight and condition score was on average 9.2 kg per unit change in condition score or 0.19 times the standard reference weight of the flock. In two experiments experienced operators were used to estimate the condition score and fat score in over 200 ewes and accredited ultrasound scanners measured the eye muscle and fat depth at the C site in the same ewes. All assessments were repeated several times in random order. Within 24 h of the assessments the sheep were slaughtered at local abattoirs where the tissue depth at the GR site was measured on the hot carcasses. Both condition score and fat score were highly repeatable though subject to operator bias. They were related to each other and to the objective measures of fat and eye muscle depth at the C site. However, 95% of sheep below condition score 2.5 had a tissue depth (muscle and fat) at the GR site ≤3 mm, by definition equal to fat score 1. As the condition score of ewes on commercial properties often fluctuates between scores 2 and 3, and small changes in condition score within this range can have large effects on welfare and profit, we conclude that condition score is the most appropriate alternative to liveweight for managing the nutritional profile of ewes.
8
Hatcher, S., J. Eppleston, R. P. Graham, J. McDonald, S. Schlunke, B. Watt e K. J. Thornberry. "Higher weaning weight improves postweaning growth and survival in young Merino sheep". Australian Journal of Experimental Agriculture 48, n. 7 (2008): 966. http://dx.doi.org/10.1071/ea07407.
Testo completoAbstract (sommario):
Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning weight was the most important factor in determining postweaning liveweight, growth rates and survival with the significant impact of weaning weight on liveweight persisting for up to 6 months after weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postweaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher weaning weights that will set their weaners up for strong postweaning growth with a decreased likelihood of mortality.
9
Adams, N. R., J. R. Briegel e A. J. M. Ritchie. "Wool and liveweight responses to nutrition by Merino sheep genetically selected for high or low staple strength". Australian Journal of Agricultural Research 48, n. 8 (1997): 1129. http://dx.doi.org/10.1071/a97025.
Testo completoAbstract (sommario):
The biological mechanisms underlying differences in wool staple strength were examined in 2 groups of Merino sheep that have been genetically selected for high or low staple strength, while holding fibre diameter constant. The sheep were fed below maintenance for 87 days, and then re-fed ad libitum for 63 days with a diet containing either 9% or 23% crude protein, in a cross-over design, after which they returned to the paddock until shearing. The fleeces of the 2 groups differed in staple strength (25·2 v.17·5 N/ktex, P < 0·001) but were similar in mean fibre diameter and clean fleece weight. However, the pattern of wool growth was different. When fed below maintenance, sheep from the sound group grew more wool than sheep from the tender group (P < 0·05), but lost more liveweight (P < 0·01). During re-feeding, the sound sheep grew less wool than the tender sheep (P < 0·05), but gained more liveweight. The mean fibre diameter at the point of break was similar in both groups. Immediately after re-feeding, the fibre diameter increased more rapidly in the tender group than in the sound (P < 0·001), but a similar difference was observed between the high and low protein diets, with no effect on staple strength. The sound sheep had a lower standard deviation of fibre diameter than the tender sheep (P < 0·001), both in the whole fleece and in 3-weekly midside patches. The data indicated that the variability of fibre diameter between fibres made a larger contribution than the variability along fibres to the difference between the groups in overall variability of fibre diameter. The sheep were then grazed together at pasture for a second year and again differed in staple strength. In addition, the sound sheep grew less wool on green spring pastures and had a lower clean fleece weight (P < 0·05). The differences in wool growth rates between sheep from the sound and tender lines depended more on whether pasture was green than on the amount of pasture available. We conclude that the difference in staple strength between the sound and tender groups was most closely associated with the variability between fibres in diameter, and was also affected by a difference in variation in diameter along the fibres. Staple strength was not affected by the amount of wool at the point of break, or by the rate of change in fibre diameter after feeding. The sheep in the sound group grew less wool than those in the tender group when on good nutrition.
10
Martin, Graeme B., Maria J. Hötzel, Dominique Blache, Stephen W. Walkden-Brown, Margaret A. Blackberry, Rachid Boukhliq, James S. Fisher e David W. Miller. "Determinants of the annual pattern of reproduction in mature male Merino and Suffolk sheep: modification of responses to photoperiod by an annual cycle in food supply". Reproduction, Fertility and Development 14, n. 3 (2002): 165. http://dx.doi.org/10.1071/rd02010.
Testo completoAbstract (sommario):
Rams of a 'Mediterranean breed' (Merino) and a 'temperate breed' (Suffolk) were compared to determine how much of the differences between their reproductive seasons is owing to variation in their responses to photoperiodic and nutritional cues. In a previous study, both nutritional and photoperiodic inputs were held constant, and it was found that the two breeds show similar endogenous rhythms and, when the animals are challenged with a Mediterranean photoperiodic cycle, these endogenous rhythms are similarly modified. The present study tested whether an annual cycle in the supply of forage might modify the patterns that are generated by the interaction between photoperiod and endogenous rhythms. Both breeds were subjected to a simulated `Mediterranean' annual cycle in photoperiod (10L : 14D to 14D : 10L) and provided with either constant food supply or a simulated `Mediterranean' annual cycle in food supply. In Merino rams, testicular growth responded to photoperiod, but nutrition dominated those responses. In Suffolk rams, changes in testicular size can be completely out of phase with changes in body mass because they are driven primarily by photoperiod, with only subtle responses to changes in diet. The cycle of testicular growth in the Suffolk was driven by changes in the secretion of gonadotrophins (follicle-stimulating hormone concentrations and luteinizing hormone pulse frequency). By contrast, in the Merino, the nutritionally driven seasonal cycle of testicular growth was associated primarily with changes in body mass and this relationship could not always be explained by changes in gonadotrophin secretion. Melatonin secretion was not affected by food supply. Thus, the `Mediterranean' and `temperate' genotypes have similar endogenous rhythms that are similarly modified by photoperiod but, with respect to seasonal changes in nutrition, they differ in both the nature of their reproductive response and the physiological mechanisms that mediate those responses.
11
Foldes, Andrew, e Colin A. Maxwell. "Effect of pinealectomy and plane of nutrition on wool growth in Merino sheep". Journal of Pineal Research 15, n. 1 (agosto 1993): 27–34. http://dx.doi.org/10.1111/j.1600-079x.1993.tb00506.x.
Testo completo
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Peterson, A. D., A. N. Thompson, A. C. Schlink e P. I. Hynd. "Follicle abnormalities and fibre shedding in Merino weaners fed different levels of nutrition". Australian Journal of Agricultural Research 49, n. 8 (1998): 1173. http://dx.doi.org/10.1071/a98011.
Testo completoAbstract (sommario):
A study was conducted to examine the relationship between fibre shedding and staple strength in Merino weaners genetically different in staple strength and fed different levels of nutrition. Fibre shedding at the point of break along the staple was estimated using 3 different techniques: (i) a subjective scoring system of wool follicle activity, based on their morphology in transverse skin sections; (ii) the number of fibres with club-ends after differential staining to identify remnants of the shed-follicle bulb; and (iii) changes in the number of fibres in the cross-section along individual staples. Irrespective of the technique used, the estimated proportion of shed fibres did not differ significantly between the sheep bred for sound and tender wool, but increased significantly (P < 0·05) in response to adverse nutritional conditions. Across all treatments, there was a significant (r2 = 0·63; P < 0·001) correlation between the proportion of shutdown follicles and the percentage decrease in the number of fibres in the staple cross-section, although the average difference between the techniques was 11·5%. Both techniques indicated that, on average, about 30% of the total follicle population became inactive and shed their fibre under the most adverse nutritional conditions, and that this was as high as 50–60% for some individual sheep. Neither of these techniques was closely correlated to the proportion of fibres with club-ends (r2 = 0·15 and 0·20, respectively; P < 0·01). The proportion of shutdown follicles and the percentage decrease in the number of fibres in the staple cross-section explained 54% and 52% of the variance in staple strength, respectively, compared with only 19% explained by the percentage of fibres with club-ends at the point of break. However, as fibre shedding failed to remove any variance in staple strength additional to that already attributed to along- and between-fibre changes in diameter, it is concluded that fibre shedding per se does not contribute significantly to nutritional-induced differences in staple strength.
13
Stephenson, RGA, GR Suter e CJ Howitt. "Wool growth responses to DL-methionine administration and factors affecting the value of supplementation". Australian Journal of Experimental Agriculture 31, n. 4 (1991): 471. http://dx.doi.org/10.1071/ea9910471.
Testo completoAbstract (sommario):
Wool growth responses to methionine administration were assessed using Peppin Merino wethers on various planes of nutrition. In experiment 1, sheep were fed 700 g/day of lucerne pellets to maintain liveweight. DL-methionine (5.8 g) administered subcutaneously resulted in 0.29 mg/cm2.day (36%) more wool (P<0.01) and a 2.5 �m (15.2%) increase in fibre diameter (P<0.05). In experiment 2, two levels (700 and 1400 g/day) of lucerne pellets were offered, with and without methionine administered subcutaneously (5.8 g). Main treatment analysis indicated a significant (P<0.01) effect of nutrition on wool growth and fibre diameter, with no effect of methionine, except for a reduction (P<0.05) in liveweight gain. Methionine administration was associated with a non-significant increase (39%) in wool growth for the 700 g diet and no change for the 1400 g diet. In experiment 3, two levels (1.75 and 2.5 g/day) of methionine were infused (4 h daily) when sheep were fed a submaintenance ration of Rhodes grass chaff, supplemented with nitrogen and sulfur. Significant (P<0.05) wool growth responses at both levels of methionine infusion were similar, with absolute (0.21 and 0.23 mg/cm2.day) and percentage (52 and 58%) increases for 1.75 and 2.5 g/day methionine treatments, respectively. Methionine administration only increased wool production at nutritional levels of liveweight maintenance or below when wool growth values for control treatments were 0.63,0.59 and 0.40 mg/cm2.day for experiments 1, 2 and 3. Fibre diameters of sheep in untreated groups were 16.4 and 18.8 pm for experiments 1 and 2. These wool growth and fibre diameter values are 25-40% below what might be expected for this strain of Merino. The values of positive correlations between wool growth and fibre diameter were increased with increased nutrition and the administration of methionine in experiment 2. This result and the nil response at high basal wool growth, together with the low potential net return on the cost of methionine, suggest that the use of methionine could be unprofitable.
14
Searle, T. W., N. McC Graham e J. B. Donnelly. "Change of skeletal dimensions during growth in sheep: the effect of nutrition". Journal of Agricultural Science 112, n. 3 (giugno 1989): 321–27. http://dx.doi.org/10.1017/s0021859600085774.
Testo completoAbstract (sommario):
SummaryMeasurements of skeletal size were made at 2–3-month intervals on 30 Border Leicester × Merino castrate male (wether) sheep between 2 and 27 months of age. Fifteen sheep were fed ad libitum on a high-quality diet and the other 15 half the average amount consumed by the first group, age for age. The ad libitum group grew faster and were larger in all body dimensions on each occasion, except for leg length at 27 months which showed no statistical difference between groups. When the groups were compared over the live-weight range common to both (16–44 kg) the unrationed animals were consistently wider at the shoulders but smaller in leg and chest dimensions.The relationship between each body component and age is described by a Mitscherlich equation and the relationship with live weight by a linear equation in which both variables are log transformed. Separate relationships were determined for each sheep and tested for differences within and between groups.
15
Paganoni, B. L., C. M. Oldham, M. B. Ferguson, A. N. Thompson, P. E. Vercoe e D. G. Gordon. "Ewe nutrition during pregnancy and birthweight of lambs has minimal impact on fat and eye muscle depth in Merino progeny". Animal Production Science 53, n. 6 (2013): 509. http://dx.doi.org/10.1071/an12266.
Testo completoAbstract (sommario):
The hypothesis tested in this experiment was that Merino lambs with lower birthweights, due to poor ewe nutrition during pregnancy, would have more fat and less muscle than Merino lambs with higher birthweights. At two sites (Victoria and Western Australia) in each of 2 years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Progeny had fat and muscle depth at the C-site measured at various ages from 8 to 28 months of age. Across the four experiments, there were differences of 0.5 kg in birthweights and 8 kg in weaning weights between extreme treatments. The effects on the depth of fat and muscle were very small with fat depth increasing by 0.1–0.2 mm (5–7%) and muscle depth increasing by 0.2–0.7 mm (1–3%) when birthweights decreased by 1 kg. The effects of birthweight on fat depth are consistent with our hypothesis whereas the effects of birthweight on muscle depth are in contrast to our hypothesis. Nevertheless, the impacts of birthweight on the depth of fat and muscle measured at the C-site of progeny from Merino ewes, is unlikely to be of any commercial significance within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
16
White, C. L., G. B. Martin, P. I. Hynd e R. E. Chapman. "The effect of zinc deficiency on wool growth and skin and wool follicle histology of male Merino lambs". British Journal of Nutrition 71, n. 3 (marzo 1994): 425–35. http://dx.doi.org/10.1079/bjn19940149.
Testo completoAbstract (sommario):
The aims of this work were to quantify the requirements of Zn for wool growth in growing male Merino lambs, and to describe the histological lesions of Zn deficiency in skin and wool follicles. Four groups of male Merino lambs (n 4) weighing 22 kg were fed ad lib. for 96 d on diets that contained 4 (basal diet), 10, 17 or 27 mg Zn/kg. Sheep in a fifth group were fed on the diet containing 27 mg Zn/kg, but were pair-fed to sheep on the 4 mg Zn/kg diet. Zn was added to the basal diet as ZnSO4 to give the respective treatment concentrations. Sheep fed on the diet containing 4 mg Zn/kg showed clinical signs of Zn deficiency and lower feed intakes and wool growth than sheep in the other groups. Their wool fibres were improperly keratinized and the wool follicles contained a higher proportion of apoptotic bodies than other groups. There was no evidence of parakeratosis and the rate of bulb-cell production was not affected. Sheep from other groups showed no clinical signs of Zn deficiency, and mean feed intakes and growth rates did not differ significantly between sheep fed on diets containing 10, 17 or 27 mg Zn/kg. However, wool growth was reduced in sheep fed on the diet containing 10 mg Zn/kg compared with those fed on diets containing 17 or 27 mg/kg. The mean concentration of Zn in the plasma at which wool growth was 90 % of maximum was 0.5 mg/l. The equivalent value for the diet was 12 mg/kg, with 95 % confidence intervals of 8 to 16 mg/kg. The results suggest that Zn deficiency reduces wool growth through a specific mechanism, perhaps involving impaired protein synthesis.
17
Thompson, A. N., e P. I. Hynd. "Wool growth and fibre diameter changes in young Merino sheep genetically different in staple strength and fed different levels of nutrition". Australian Journal of Agricultural Research 49, n. 5 (1998): 889. http://dx.doi.org/10.1071/a97129.
Testo completoAbstract (sommario):
The wool growth response to nutrition by Merino weaners (liveweight 33· 2±0·58 kg) bred for high or low staple strength (SS) and fed to produce changes in liveweight was examined. The hypothesis tested was that genetic differences in SS are associated with differences in along-fibre variation in diameter. Sheep fed to maintain liveweight produced wool at a more constant rate with smaller and less rapid changes in fibre diameter than that produced by sheep which lost and then gained liveweight (P < 0·001). There were significant (P < 0·05) but relatively small differences in wool growth rate and fibre diameter between the SS selection flocks, and wool from sheep selected for high SS had less (P < 0 ·001) variation in diameter between individual fibres than wool from sheep selected for low SS Minimum fibre diameter was most closely associated with SS, accounting for 66% (P < 0·001) of the total variance in SS generated by selective breeding and nutrition. An increase in minimum fibre diameter of 1µm was associated with an increase in SS of about 5 N/ktex. Minimum fibre diameter and the rate of change in fibre diameter to the point of break along the staple collectively accounted for 72% (P < 0·001) of the total variance in SS. Addition of a term for between-fibre variation in diameter measured at the point of break removed an additional 8% (P < 0·001) of the variance in SS. We conclude that the mechanisms responsible for nutritionally induced and genetic differences in SS are not the same. Nutrition influences SS by affecting along-fibre diameter changes, whereas genetic differences in SS, at least as far as they are represented by the flocks used here, are largely attributable to between-fibre variations in diameter. The independence of nutritional and genetic effects on SS means that they should be exploited concurrently to reduce the incidence of tender wool production.
18
Kelly, RW, I. Macleod, P. Hynd e J. Greeff. "Nutrition during fetal life alters annual wool production and quality in young Merino sheep". Australian Journal of Experimental Agriculture 36, n. 3 (1996): 259. http://dx.doi.org/10.1071/ea9960259.
Testo completoAbstract (sommario):
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.
19
Leury, BJ, PJ Murray e JB Rowe. "Effect of nutrition on the response in ovulation rate in Merino ewes following short-term lupin supplementation and insulin administration". Australian Journal of Agricultural Research 41, n. 4 (1990): 751. http://dx.doi.org/10.1071/ar9900751.
Testo completoAbstract (sommario):
In experiment 1, groups of Merino ewes, 4-6 years old, were given daily wheat chaff 500 g plus vitamin and mineral supplements, or wheat chaff 800 g and pelleted feed containing lucerne, lupin and barley 350 g plus mineral and vitamin supplements. Diets provided 0.5 and 1.2 times maintenance requirements. On each plane of nutrition, lupins 750 g were given or not given 10 days before oestrus. In experiment 2, the same planes of nutrition were used and sheep were injected daily with insulin 15 IU, or left untreated. Ovulation rate increased in response to lupin feeding at both planes of nutrition. Exogenous insulin, given as a daily single injection did not increase ovulation rate.
20
Marshall, T. "Effect of month of birth and first summer's nutrition on the productivity of Merino wethers". Australian Journal of Experimental Agriculture 25, n. 4 (1985): 777. http://dx.doi.org/10.1071/ea9850777.
Testo completoAbstract (sommario):
Liveweight and greasy wool production of Merino wethers born in either mid-May, late June or early September in each of 2 years and subjected to three nutritional regimes (high, normal and low) over their first summer were studied over 4 years. Differences in liveweight of up to 9.0 kg between treatments due to month of birth persisted for 48 months while liveweight differences of as much as 15 3 kg due to nutritional treatment lasted only 24-30 months. Similarly, differences in greasy wool production of up to 0.8 kg between times of birth lasted for the duration of the study but differences between first summer nutritional treatment, although as much as 1.1 kg at the first adult shearing, persisted for only 2 years. The results strongly indicate that, in the high rainfall Mediterranean environment of southern Western Australia, sheep born late in the season will be of lower liveweight and will produce less wool than sheep born early in the season.
21
Adams, N. R., J. R. Briegel e J. C. Greeff. "Responses of wool growth rate and body reserves to nutrition in Merino ewes: a potential biological link between production and fitness". Australian Journal of Agricultural Research 58, n. 9 (2007): 913. http://dx.doi.org/10.1071/ar06386.
Testo completoAbstract (sommario):
This study examined whether the low body-fat reserves in sheep with high estimated breeding values (EBVs) for clean fleece weight (CFW) reported previously are affected by nutritional history, and second whether the effect may be related to differences in the variation in fibre diameter (CVfd). Groups of 11 20-month-old Merino ewes with high and low EBVs for CFW and for CVfd were compared in a 2 × 2 design at low bodyweight, then fed ad libitum for 100 days and re-measured. The response of wool growth rate to feed supply (WRF) was estimated as the slope of the regression against time of clean wool mass collected from mid-side patches at intervals of 30–40 days throughout the experiment. High CFW sheep had greater feed intake relative to liveweight and liveweight gain (P = 0.02), but did not differ significantly in other characteristics from low CFW sheep. High CVfd sheep had lower plasma concentrations of insulin (P = 0.02), IGF-1 (P = 0.03), and albumin (P = 0.02) throughout the study, and had less fat when in poor body condition (P = 0.02). The WRF was greater in both the high CFW (P = 0.003) and the high CVfd (P = 0.004) genotypes. When studied in poor body condition, sheep with a high WRF had lower liveweight (P < 0.001), lower body condition score (P < 0.001), lower plasma albumin (P < 0.001), and higher plasma growth hormone (P = 0.02), but these relationships weakened or disappeared after ad libitum feeding. Sheep with high WRF also had lower plasma concentrations of insulin (P = 0.002) and IGF-1 (P = 0.008) throughout the study, which may have brought about the increased responsiveness of protein and energy metabolism to nutrition. The results indicate that genetic selection for wool characteristics can affect the responsiveness of wool growth rate to nutrient supply. Sheep that are highly responsive grow more wool when offered abundant feed, but may have lower body nutrient reserves when on limited feed.
22
Blumer, S. E., G. E. Gardner, M. B. Ferguson e A. N. Thompson. "Environmental and genetic factors influence the liveweight of adult Merino and Border Leicester × Merino ewes across multiple sites and years". Animal Production Science 56, n. 4 (2016): 775. http://dx.doi.org/10.1071/an14419.
Testo completoAbstract (sommario):
Variation in liveweight change in the ewe flock during periods of poor nutrition can affect farm profitability through the effects of liveweight loss on potential stocking rate, management interventions including supplementary feeding, and ewe and lamb survival and productivity. There is variation between individual animals in their ability to manage periods of poor nutrition, but the links between liveweight change and breeding values in the adult ewe flock have not been quantified. We analysed 5216 liveweight profiles for 2772 ewes managed over 3 years at eight sites across Australia, to define the relative effects of environment, reproductive performance and breeding values on liveweight change. The range in liveweight loss varied from 1.3 kg to 21.6 kg, and for liveweight gain from 0.4 kg to 28.1 kg. Site and year had the largest influence on liveweight change, which demonstrates that seasonal conditions and management were the most important factors influencing liveweight change. Liveweight loss was influenced by previous and current reproductive performance but these effects were small in comparison to the effects of site and year. There were mixed associations with sire breeding values for growth, fat and muscle depending on site. An increase in sire breeding values for fat by 1 mm was associated with a reduction in liveweight loss by up to 1.3 kg regardless of ewe breed, and this was more evident at sites where ewes lost a greater proportion of their liveweight. While management had the greatest effect on liveweight change, there appears to be scope to use breeding values to select sheep that will lose less weight during periods of poor nutrition in some environments.
23
Evavianto, Dwi Fiky, Dimas Puri Astuti Hadiyani e Waluyo Edi Susanto. "Pengaruh pemanfaatan ampas kedelai dan onggok terfermentasi rhizopus sp dalam konsentrat domba Merino terhadap pertambahan bobot badan dan konsumsi pakan". Jurnal Sains Peternakan 6, n. 2 (29 dicembre 2018): 34–41. http://dx.doi.org/10.21067/jsp.v6i2.2887.
Testo completoAbstract (sommario):
ABSTRACT
This study aims to determine the benefits of soybean husk and onggok fermented rhizopus sp in feed merino sheep concentrate of body weight gain and feed intake. Materials used in the study is as much as 12 merino sheep and the methods used by the randomized trial (RAK) using the PO as controls (100% concentrate); P1 (AOT concentrate 90% + 10%); P2 (AOT concentrate 80% + 20%); P3 (AOT Concentrate 70% + 30%). The results of the study with 30% of AOT gift giving weight increase of 25.3 g / tail significantly different (F count> F table) and feed consumption P0 :. 215, 27g / tail, P1 : 203, 13g / eco, P2: 219,24g / tail, P3: 190.72 not significantly different (F arithmetic <F table 0.05), it can be concluded that the AOT replace concentrate when substituted have the same content to concentrate on P0 , P1, P2, and P3. From the results of this study cuncluded that the addition soybean husk and onggok fermented rhizopus sp in feed merino sheep concentrate can increase body weight gain and low consumption level but have a good nutrition with the level of gift 30%.
ABSTRAK
Penelitian ini bertujuan untuk mengetahui manfaat dari kulit kedelai dan onggok fermentasi Rhizopus sp dalam pakan merino domba konsentrat dari bobot badan dan konsumsi pakan. Bahan yang digunakan dalam penelitian ini adalah sebanyak 12 domba dan metode yang digunakan oleh uji coba secara acak (RAK) dengan menggunakan PO sebagai kontrol (100% konsentrat); P1 (AOT berkonsentrasi 90% + 10%); P2 (AOT berkonsentrasi 80% + 20%); P3 (AOT Konsentrat 70% + 30%). Hasil penelitian dengan 30% dari hadiah AOT memberikan peningkatan berat 25,3 g / ekor yang berbeda secara signifikan (F hitung> F tabel) dan pakan P0 konsumsi:. 215, 27g / ekor, P1: 203, 13 g / eco, P2: 219,24g / ekor, P3: 190,72 tidak berbeda nyata (F hitung <F tabel 0,05), dapat disimpulkan bahwa AOT menggantikan konsentrat ketika diganti memiliki konten yang sama untuk berkonsentrasi pada P0, P1, P2, dan P3. Dari hasil penelitian ini diaimpilkan bahwa penambahan kulit kedelai dan onggok fermentasi Rhizopus sp dalam pakan konsentrat domba merino dapat meningkatkan bobot badan dan tingkat konsumsi yang rendah tetapi memiliki gizi yang baik dengan tingkat pemberian 30%.
24
DIXON, R. M., R. THOMAS e J. H. G. HOLMES. "Interactions between heat stress and nutrition in sheep fed roughage diets". Journal of Agricultural Science 132, n. 3 (maggio 1999): 351–59. http://dx.doi.org/10.1017/s0021859698006248.
Testo completoAbstract (sommario):
Intake, digestion and growth were examined in young Merino×Border Leicester wether sheep held for 44 days in either cool (13–15°C, thermal humidity index 56–58) or hot (32–40°C, 50–70% relative humidity, thermal humidity index minimum 83–84, maximum 83–88) environments. The sheep were offered diets of medium quality hay ad libitum alone (Con) or supplemented with either 22 g air-dry/kg metabolic liveweight (W0·75) of barley grain fortified with urea and sulphur (Bar/N) or 10 g air-dry/kg W0·75 of fishmeal (FM). Intake of the Con diet by the sheep in the cool environment was high at 79 g DM/kg W0·75 per day. Sheep in the hot environment had higher rectal temperatures and higher respiration rates (40·1°C v. 39·2°C, 196 v. 56 respirations/min respectively, P<0·01). The hot environment reduced (P<0·05) total dry matter (DM) intake, estimated metabolizable energy (ME) intake, liveweight (LW) gain and nitrogen (N) balance. The provision of supplements did not change total DM intake, but increased (P<0·05) organic matter digestibility, estimated ME intake, LW gain and N balance. Wool growth was increased much more by the FM than by the Bar/N supplement, indicating that the supply of absorbed amino acids was increased substantially by the FM supplement. Neither voluntary intake nor productivity were influenced by any interactions between the thermal environments and the balance of nutrients provided by the diets. In conclusion, in these young sheep consuming a high intake of a medium quality roughage diet, moderate heat stress reduced intake and growth but did not affect the relative responses of the sheep to supplements providing principally fermentable ME or a similar amount of fermentable ME and additional metabolizable protein.
25
Denney, GD. "Phenotypic variance of fibre diameter along wool staples and its relationship with other raw wool characters". Australian Journal of Experimental Agriculture 30, n. 4 (1990): 463. http://dx.doi.org/10.1071/ea9900463.
Testo completoAbstract (sommario):
The variance of fibre diameter along the staple was estimated in a flock of 198 two-year-old Merino sheep, whose management and nutrition were typical of grazing sheep in central-western New South Wales. In a subgroup of this flock, it was found that the estimated variance of fibre diameter along the staple was highly repeatable between duplicate staples sampled from the same sheep, and variation in fibre diameter along the mid-side sample was representative of that variation in the whole fleece. In the main flock, variance of fibre diameter along the staple varied from 0.74 to 6.98 �m2 between sheep, but there were no differences between castrated males and ewes. Differences were found between sire groups in their susceptibility to environmental change. Phenotypic correlation between variance of fibre diameter along the staple and staple strength was -0.30 (P<0.001), but correlations with other raw wool characteristics were not different from zero (P>0.05).
26
Langlands, JP, JE Bowles, GE Donald e AJ Smith. "Trace element nutrition of grazing ruminants. 2. Hepatic copper storage in young and adult sheep and cattle given varying quantities of oxidized copper particles and other copper supplements". Australian Journal of Agricultural Research 37, n. 2 (1986): 189. http://dx.doi.org/10.1071/ar9860189.
Testo completoAbstract (sommario):
Hepatic copper (Cu) storage was determined by biopsy after oxidized Cu wire was given to sucking lambs at 0-43 days of age, and to weaned Merino sheep and Hereford cattle varying in age. Cu-calcium edetate (Cu-EDTA) and soluble glass pellets were also evaluated as Cu supplements. A dose of 45 mg oxidized particles/kg liveweight was predicted to induce a mean maximum response of 84 and 179 mg Cu/kg DM in hepatic concentrations in weaned Merino sheep and Hereford cattle at 49 and 100 days from dosing respectively; these responses should not result in unacceptable hepatic concentrations in cattle, or in sheep of low Cu status, but the response is variable, and supplementation as a precautionary measure without prior indications of Cu insufficiency is not desirable. The particles were effective when given to lambs from birth, but did not increase hepatic Cu concentrations in lambs when ewes were dosed post partum. A dose of 1 g particles/lamb was as effective as a 2 g dose in increasing hepatic Cu concentration, and lambs given 2 g were lighter than those given 1 g; the dose increased hepatic Cu concentrations for at least 292 days. Cu-EDTA was given subcutaneously at the rate of 50 mg Cu for sheep and 150 mg Cu for cattle, and was as effective in increasing hepatic Cu concentration as 45 mg oxidized particle/kg liveweight; it did not produce the severe reactions frequently reported in the literature. The soluble glass pellet was less effective, but studies with a later prototype suggest that subsequent formulations may be more satisfactory.
27
Hynd, PI. "Effects of nutrition on wool follicle cell kinetics in sheep differing in efficiency of wool production". Australian Journal of Agricultural Research 40, n. 2 (1989): 409. http://dx.doi.org/10.1071/ar9890409.
Testo completoAbstract (sommario):
Wide phenotypic variation in fibre output per follicle was generated by selecting sheep (five South Australian strongwool Merinos, one finewool Merino and one Corriedale) on this basis, and by offering these sheep a low-protein diet for 9 weeks, followed by a high-protein diet for a further 8 weeks. Clean wool production was measured over the final 3 weeks of each period, while fibre diameter, the rate of length growth of fibres and a number of follicle characters were measured over the last 7 days of each period. The rate of division of follicle bulb cells and the total volume of the germinative region of the follicle was estimated by image-analysis of bulb sections in skin biopsy samples.With the change from the low-protein diet to the high-protein diet, the rate of clean fleece production was increased by 33% (P<0.002), reflecting an increase in fibre diameter (8%) and rate of length growth of fibres (26%); the volume of the germinative region of the average bulb increased 30% (P<0.012) and the rate of bulb cell division by 35% (P<0.004); cortical cell volume also did not change (923 8m3 v. 965 8m3; the average proportion of fibre cross-sectional area occupied by paracortical cells increased from 0.2 1 to 0.35 ( P < 0.01 0); the proportion of dividing cells entering the fibre cortex ranged from 0.25 to 0.42 (mean, 0.31) between sheep on the low-protein diet, and from 0.22 to 0.39 (mean, 0.32) when the animals were fed the high-protein ration; the effect of diet on cell distribution to fibre and inner root sheath was not significant (P<0.601).Phenotypic differences in fibre output were primarily related to differences in the rate of bulb cell division (r= 0.896, P < 0.001), but inclusion of a term for the proportion of bulb cells entering the fibre cortex, removed an additional, significant proportion of the variance. Cortical cell volume, on the other hand, was poorly related to fibre output.
28
Zhang, Song, Dominique Blache, Margaret A. Blackberry e Graeme B. Martin. "Dynamics of the responses in secretion of luteinising hormone, leptin and insulin following an acute increase in nutrition in mature male sheep". Reproduction, Fertility and Development 16, n. 8 (2004): 823. http://dx.doi.org/10.1071/rd04086.
Testo completoAbstract (sommario):
In Merino rams, an increase in the plane of nutrition increases the frequency of luteinising hormone (LH) pulses within a few days and this response is correlated with changes in the circulating concentrations of metabolic hormones. To analyse early dynamic aspects of these responses, we studied mature rams fed with diets that contained either low or high amounts of energy and protein. Jugular blood was sampled every 20 min for 96 h, including a control period of 24 h before the change of diet in the high-diet group. In the high-diet group, a significant increase in LH pulse frequency was first detected 6 h after the increase in nutrition on Day 1 and the frequency remained significantly elevated throughout the 72-h treatment period, except for a 12-h period on Day 2. Following the change of diet, insulin concentrations increased within 3 h and leptin concentrations increased within 7 h, after which time the concentrations of both hormones remained high. Dietary treatment did not affect the concentrations of thyroxine or insulin-like growth factor-I, but the high diet increased the concentrations of tri-iodothyronine. These observations are consistent with insulin and leptin playing a role in the early activation of the gonadotrophin-releasing hormone–LH axis by nutritional inputs.
29
Adams, N. R., S. M. Liu, J. R. Briegel e J. C. Greeff. "Protein metabolism in skin and muscle of sheep selected for or against staple strength". Australian Journal of Agricultural Research 51, n. 5 (2000): 541. http://dx.doi.org/10.1071/ar99143.
Testo completoAbstract (sommario):
Two experiments were carried out to determine the mechanisms underlying the reduced effect of nutritional status on wool growth rate in Merino sheep that have been selected for high staple strength (SS). In Expt 1, each group of 6 young sheep of SS+ and SS– genotypes were fed at 0.4 or 1.1 times maintenance, and in Expt 2, groups of 8 sheep of each genotype were fed at 1.1 and 1.8 times maintenance. In both experiments, rates of protein synthesis in skin, muscle, gut, rumen, and liver were determined using a flooding dose of labelled phenylalanine. Feed intake and the digestibility of feed were not affected by genotype. Neither dissection of the carcasses at slaughter, nor deuterated water analysis in Expt 1, detected any differences between the genotypes in body composition. The feeding level affected the total daily amount of protein synthesised in all the organs examined, and the fractional rate of protein synthesis was affected by feeding level in all organs except the liver. The fractional synthesis rate of protein was less responsive to feeding level in the SS+ sheep in both skin and muscle (P < 0.05), but not in the liver, jejunum, or rumen. Total protein synthesis in muscle, and the estimated rate of protein degradation, were also less responsive to feeding level in the SS+ sheep (P < 0.05). We conclude that sheep genetically selected for high or low SS have altered local mechanisms in both skin and muscle that control the way they respond to nutrition. These findings provide a mechanism by which selection for wool growth rate also affects body metabolism.
30
Morcombe, PW, e JG Allen. "Improving production from September-born Merino lambs with a lupin grain supplement and phomopsis-resistant lupin stubbles". Australian Journal of Experimental Agriculture 33, n. 6 (1993): 713. http://dx.doi.org/10.1071/ea9930713.
Testo completoAbstract (sommario):
As a means of providing nutrition on dry pasture in the wheatbelt of Western Australia, supplements of lupin grain were fed to late-born Merino lambs and their dams before weaning onto lupin stubble. Each ewe-lamb pair consumed an average 19.5 kg lupin grain over the 46 days before weaning. This produced an extra 3.6 kg (P<0.01) liveweight gain by these lambs compared with their unsupplemented cohorts at weaning. The growth of the weaned lambs grazing phomopsis-resistant lupin stubbles was primarily influenced by the amount of residual lupin grain available to each sheep and liver injury caused by ingestion of phomopsins. In the first 69 days of stubble grazing, sheep stocked at 10ha gained 7.3 kg while those stocked at 20ka gained 2.1 kg (P<0.001). In the first 13 months of life, lambs supplemented with lupin grain before weaning grew more (P<0.05) clean wool by 0.17 kg than the unsupplemented lambs. However, the value of this extra wool would not have covered the cost of the lupin grain eaten. Wool staples produced by sheep grazed at 10/ha on lupin stubble were stronger (P<0.001) than those produced by sheep grazed at 20ha (24.4 v. 17.7 N/ktex). The position of greatest weakness in the staple coincided with weight loss prior to removal from the stubble. Singleton lambs born in September and weaned onto a phomopsis-resistant lupin stubble reached liveweights consistent with survival over the summer and good productivity in their first year of life. The effects of lupinosis and reductions in wool staple strength may have been avoided by monitoring liveweight change and taking the sheep off the stubbles when they were near peak liveweight.
31
Blache, Dominique, Pietro Celi, Margaret A. Blackberry, Robyn A. Dynes e Graeme B. Martin. "Decrease in voluntary feed intake and pulsatile luteinizing hormone secretion after intracerebroventricular infusion of recombinant bovine leptin in mature male sheep". Reproduction, Fertility and Development 12, n. 8 (2000): 373. http://dx.doi.org/10.1071/rd00102.
Testo completoAbstract (sommario):
The aim of the present study was to determine whether leptin might play a role in the gonadotrophic response of mature merino rams to changes in the level of nutrition in rams fed ad libitum. Recombinant bovine leptin was infused intracerebroventricularly and voluntary food intake (VFI) and luteinizing hormone (LH) pulse frequency were measured. In Experiment 1, rams (n = 5) were infused for 24 h per day for 5 days with vehicle or with leptin (0.04, 0.4 and 4.0g h –1 ). All doses decreased both VFI and LH pulse frequency. In Experiment 2, rams were infused for 24 h per day for 5 days with vehicle (n = 10) or leptin (4 g h –1; n= 5); a sub-group of 5 controls was pair-fed to the leptin-infused group to control for effects of changes in feed intake. LH pulse frequency was reduced equally in both the leptin-infused and pair-fed groups. Leptin did not affect other systems controlled by the hypothalamic–pituitary axis. Thus, rather than stimulate LH secretion, intracerebral leptin specifically inhibits it by reducing food intake, so it is unlikely that effects of nutrition on the reproductive axis in mature rams involves leptin as a single blood-borne signal. A range of nutritional or metabolic inputs may be needed, and perhaps interconnections between neural centres that control appetite and reproduction.
32
Liu, S. M., T. L. Smith, D. G. Palmer, L. J. E. Karlsson, R. B. Besier e J. C. Greeff. "Biochemical differences in Merino sheep selected for resistance against gastro-intestinal nematodes and genetic and nutritional effects on faecal worm egg output". Animal Science 81, n. 1 (agosto 2005): 149–57. http://dx.doi.org/10.1079/asc50180149.
Testo completoAbstract (sommario):
AbstractThe faecal egg count (FEC) and total egg output is reduced in parasite-resistant sheep and breeding sheep for resistance should reduce infective larval contamination of pastures. This research compares lambs and rams from the parasite-resistant flock, Rylington Merinos, with unselected controls at the same level of larval challenge and the same level of food supply in an animal-house environment. The sheep were penned individually. The parasite resistant sheep excreted 0·85-fold less eggs than the control animals after infection with Trichostrongylus colubriformis and Ostertagia circumcincta for 12 or 18 weeks. During the infection period the parasite resistant lambs had higher plasma immunoglobulin concentration and higher ratio of globulin to albumin than the control animals. In the mature rams these genotype differences diminished. They also had lighter mass of the small intestine with a higher proportion of mucosa, but heavier mass of the large intestine. Parasite infection caused a depletion of blood glutathione in the lambs given food at maintenance or 1·5 × maintenance, and the parasite-resistant sheep (both lambs and rams) also had lower glutathione concentration. Maintaining good body nutrient reserve before the infection reduced the egg output in the early stage of the infection. Food intake had little effect on worm egg production in young sheep given food at maintenance or above. It is suggested that an improvement of nutrition, sulphur-containing amino acids in particular, is required to recover the loss of productive performance caused by the infection.
33
Li, L., S. M. Liu, V. H. Oddy e J. V. Nolan. "Protein synthesis rates in skin components and skeletal muscle of sheep selected for divergent clean fleece weight in response to below- and above-maintenance nutrition". Australian Journal of Agricultural Research 58, n. 11 (2007): 1031. http://dx.doi.org/10.1071/ar06373.
Testo completoAbstract (sommario):
Protein metabolism in skin and muscle was studied in Merino wethers selected for high (F+, n = 10) or low (F–, n = 10) estimated breeding values for clean fleece weight, but with similar estimated breeding values for liveweight and fibre diameter, raised to 20 months of age under the same conditions, and then offered two levels of nutrition (0.8 or 1.8 × maintenance) for 37 days. Over 37 days, F+ sheep had greater rate of wool production, liveweight gain, and had greater eye-muscle and fat depth than F– sheep (P < 0.05). Fractional synthesis rates of protein (%/day) in the epidermis, dermis, whole skin and muscle were affected by both feeding level (P < 0.05) and genotype (P < 0.05). The fractional synthesis rates of protein were greater (P < 0.05) in F+ sheep at both levels of intake. There was an interaction (P < 0.01) between genotype and feeding level for the protein fractional synthesis rate in muscle, where F+ sheep were more responsive to higher feed intake. Muscle of F– sheep responded to increased amino acid supply by reducing the rate of protein degradation without altering synthesis rate; whereas muscle of F+ sheep responded by increasing the rates of both protein synthesis and degradation. The overall muscle fractional synthesis rate (1.6%/day) was ~7-times lower than the skin fractional synthesis rate (10.8%/day) in these animals (P < 0.01). F+ sheep had a higher rate of protein synthesis in dermis and whole skin to support their higher wool protein accretion at both levels of feed intake. Muscle protein synthesis rate was greater in F+ sheep offered above-maintenance metabolisable energy (ME) intake than those given below-maintenance ME intake but was unaffected by ME intake in F– sheep. The results indicate that selection for wool growth not only affects production of wool and the wool follicle, but also affects the rate of protein turnover in components of the skin and skeletal muscle.
34
Atasoglu, Cengiz, Gotthold Gäbel e Jörg R. Aschenbach. "Apical sodium–glucose co-transport can be regulated by blood-borne glucose in the ruminal epithelium of sheep (Ovis aries, Merino breed)". British Journal of Nutrition 92, n. 5 (novembre 2004): 777–83. http://dx.doi.org/10.1079/bjn20041265.
Testo completoAbstract (sommario):
The intestinal Na-dependent D-glucose co-transporter (SGLT)-1 in sheep is under dietary regulation by luminal substrates. The aim of the present study was to find out whether the SGLT-1 in the forestomach of sheep is also regulated by sugars. Furthermore, the location of a possible glucosensor (luminalv.intracellularv.basolateral) was to be elucidated. Ruminal epithelia of sheep (Ovis aries, Merino breed) were pre-incubated in Ussing chambers with various substrates on the mucosal (i.e. luminal) or serosal (i.e. blood) side. This pre-incubation period was followed by a second pre-incubation period without the tested substrates (washout period). Thereafter, apical D-glucose uptake by ruminal epithelial cells was determined with 200 μmol D-[14C]glucose/l in the absence or co-presence of the SGLT-1 inhibitor, phlorizin. Pre-incubation with D-glucose on the mucosal side had no significant effect on apical D-glucose uptake (P>0.05). In contrast, pre-incubation with D-glucose, D-mannose, 3-O-methyl-D-glucose or sucrose on the serosal side significantly increased D-glucose uptake compared with mannitol-treated controls (P<0.05). Serosal pre-incubation with cellobiose or D-xylose had no effect. The stimulation of D-glucose uptake by serosal D-glucose pre-incubation was concentration dependent, with maximal stimulation at about 10 mmol/l. We conclude that the ruminal SGLT-1 can be up-regulated in a concentration-dependent manner by blood-borne D-glucose via an extracellular sugar-sensing mechanism.
35
Kilminster, Tanya F., e Johan C. Greeff. "A note on the reproductive performance of Damara, Dorper and Merino sheep under optimum management and nutrition for Merino ewes in the eastern wheatbelt of Western Australia". Tropical Animal Health and Production 43, n. 7 (2 luglio 2011): 1459–64. http://dx.doi.org/10.1007/s11250-011-9871-8.
Testo completo
36
Pethick, DW, e JB Rowe. "The effect of nutrition and exercise in carcass parameters and the level of glycogen in skeletal muscle of Merino sheep". Australian Journal of Agricultural Research 47, n. 4 (1996): 525. http://dx.doi.org/10.1071/ar9960525.
Testo completoAbstract (sommario):
This study investigated the effects in sheep of feed intake and exercise training on (i) the level of glycogen in muscle, and (ii) carcass quality traits including growth rate, carcass weight, fat score, and the ultimate pH of muscle. Merino wethers, 12-months-old and starting body weight 38 kg, were individually penned and housed indoors. The effects of nutrition and exercise were tested for 2 levels of activity (sedentary v. exercised) and 4 levels of feed intake (1, 1.3, 1.5, 2.2 x maintenance) with 8 sheep per group housed individually. Exercise training was for 1 h at 8-9 km/h (approx. 55-65 VO2max), 3 times per week from week 4 to 9 of the experiment. The diet was 20% cereal straw, 26% lupin grain, 53% barley grain, mineral and vitamin premix, and virginiamycin. Animals were slaughtered at an abattoir in week 10. Regular exercise reduced growth rate, carcass weight, and fat score, but did not affect intake. At the highest level of intake, carcass weight was reduced by 0.53 kg and fat depth over the 12th rib (GR fat depth) by 6.3 mm, suggesting that muscle yield was increased. At all sampling times, the level of glycogen in the m. semimembranosis (SM) and m. semitendinosis (ST) increased linearly with increasing feed intake. Regular exercise caused increased glycogen level in SM samples immediately post-slaughter and in the SM, ST, and m. longissimus dorsi (LD) 48 h post-slaughter. The ultimate pH of muscle was reduced as the level of feed intake increased for all muscle groups. Exercise caused a reduction in the ultimate pH of the ST with no change for the SM and LD. The results indicate that glycogen levels in muscle are highly responsive to nutrition and regular exercise. In addition, exercise caused a reduction in subcutaneous fat with no change in feed intake.
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Liu, S. M., G. Mata, H. O'Donoghue e D. G. Masters. "The influence of live weight, live-weight change and diet on protein synthesis in the skin and skeletal muscle in young Merino sheep". British Journal of Nutrition 79, n. 3 (marzo 1998): 267–74. http://dx.doi.org/10.1079/bjn19980044.
Testo completoAbstract (sommario):
Wool growth is derived directly from protein synthesis in the skin of sheep, and is affected by the nutritional status of the animals. The present experiment examined both protein synthesis in the skin and muscle and wool growth in Merino lambs differing in live weight, intake and dietary protein source. The experiment was a 23 factorial design: twenty-four 5-month-old lambs initially weighing 33 kg (heavy) or 25 kg (light) were fed on a hay-based diet with either lupin seed or rapeseed meal as the major protein sources to maintain live weight (M) for 56 d, or were fed at 0.6M for 28 d (period 1) followed by 28 d at 1.6M (period 2). Fractional protein synthesis rates (FSR, % per d) in the skin and the m. longissimus dorsi on days 4 and 24 of period 1 and day 4 of period 2 were measured by means of a flooding dose of l-[ring-d5]phenylalanine, and wool growth on a skin patch over period 1 was also measured. The FSR ranged from 13.2 to 20.2% per d in the skin, higher than reported for other breeds, and 1.53–3.07% per d in the muscle. Sheep on the low intake (0.6M) had significant reductions in FSR, protein content (g), protein synthesis (g/d) in the skin, and wool growth (g/d). The heavy lambs had similar FSR to the light lambs, but had a higher skin protein content and total protein synthesis per unit of skin area (100 cm2) and, therefore, grew more wool. The rapeseed-meal diet increased FSR and wool growth only in the light lambs over the short term. The protein deposited in wool over period 1 was 0.185 of the total protein synthesis in the skin, regardless of live weight, intake or diet, a result similar to other breeds. With the changes in dietary intake, protein synthesis in the skin and muscle responded differentially, with nutrient partitioning at sub-maintenance in favour of wool growth but at supra-maintenance, following a nutrient restriction, in favour of weight gain in young growing sheep.
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Thompson, A. N., M. B. Ferguson, A. J. D. Campbell, D. J. Gordon, G. A. Kearney, C. M. Oldham e B. L. Paganoni. "Improving the nutrition of Merino ewes during pregnancy and lactation increases weaning weight and survival of progeny but does not affect their mature size". Animal Production Science 51, n. 9 (2011): 784. http://dx.doi.org/10.1071/an09139.
Testo completoAbstract (sommario):
Lamb growth to weaning, and during the period immediately following weaning, influences post-weaning mortality and may affect mature size. The hypothesis tested in the experiments reported in this paper was that changes in the maternal liveweight of Merino ewes during pregnancy and lactation could predict the weight at weaning, post-weaning survival and mature size of their progeny. At two sites (Vic. and WA) in each of two years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Across the four experiments this resulted in progeny weights ranging from 13.8 to 28.3 kg just before weaning. Lamb growth was primarily related to the amount of feed on offer during lactation, but was also related to the liveweight change of the ewe during pregnancy. These relationships were consistent in both experiments at each site. Weaning weight was strongly associated with post-weaning survival at the Vic. site. Survival rates decreased significantly when weaning weights were below 20 kg. These results indicate that management of ewe and lamb nutrition to maximise growth of lambs before weaning and growing weaners at 30 g/day or more after weaning are important for optimal post-weaning survival. The findings also suggest that the mature size of offspring is unlikely to be adversely affected by pre-weaning nutrition within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
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Sawyer, Gregory, Dylan Russell Fox e Edward Narayan. "Pre- and post-partum variation in wool cortisol and wool micron in Australian Merino ewe sheep (Ovis aries)". PeerJ 9 (27 aprile 2021): e11288. http://dx.doi.org/10.7717/peerj.11288.
Testo completoAbstract (sommario):
An individual merino sheep’s output of wool production is influenced by synergistic interactions of sheep genetics, climate, farm management, and nutrition available to the whole flock. The price paid to the producer for this wool commodity is determined via numerous tested parameters and /or subjective appraisal of the raw greasy wool. This research investigated the level of variation in wool cortisol (a physiological stress biomarker) and wool micron (MIC) in Merino ewes (Ovis aries), pre-partum and post-lambing (lactation/lambs at foot), using maiden ewe (n = 38) managed in an outdoor paddock in a commercial farm. The key findings of this study are; (1) wool quality indicators showed a significant variation between pre- and post- parturition including significant reduction in MIC and (2) there was a negative correlation between wool cortisol levels and wool micron pre-parturition (rs = − 0.179, p < 0.05). This relationship between wool cortisol and wool micron was positive (rs = + 0.29, p < 0.05) during post-parturition suggesting that ewes with lambs at foot ended up with finer wool (reduction in fibre diameter) but they also maintained high levels of wool cortisol. Furthermore, the comfort factor, curvature, standard deviation and spin fineness of the wool were also significantly reduced post-parturition. The results of this study show that metabolic resources partitioning in ewe associated with pregnancy and lambing can result in a reduction in wool quality indices. The activity of the HPA-axis is attenuated during late gestation and parturition as a maternal adaptation; however, the results of our study show that wool cortisol remained similar between pre- and post- lambing. This result indicates that environmental stressors that may have been operating on farm (e.g., cold winter period) could influence on maternal physiological stress response however the exact level of influence of environment conditions on ewe stress levels and productivity traits (e.g., lambing success and wool quality) warrants further investigation. In conclusion, the use of top-knot wool sampling in combination with wool cortisol analysis provides researchers with a convenient method to quantify wool quality and physiological stress simultaneously under commercial sheep production.
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Paganoni, B. L., M. B. Ferguson, S. Fierro, C. Jones, G. A. Kearney, P. R. Kenyon, C. Macleay, C. Vinoles e A. N. Thompson. "Early reproductive losses are a major factor contributing to the poor reproductive performance of Merino ewe lambs mated at 8–10 months of age". Animal Production Science 54, n. 6 (2014): 762. http://dx.doi.org/10.1071/an13240.
Testo completoAbstract (sommario):
The reproductive performance of Merino ewe lambs is lower than that achieved by mature ewes and is highly variable. It is likely that embryo loss represents a major source of reproductive wastage in Merino ewe lambs, but to our knowledge no studies have attempted to determine when the major reproductive losses occur or identify predisposing factors that are likely to lead to high rates of pregnancy failures in ewe lambs. After characterising where reproductive losses occurred in Merino ewe lambs mated at 8–10 months of age, we tested the hypothesis that pregnancy failure in ewe lambs is influenced by nutrition and liveweight change around conception and the genetic potential for growth of the ewe lamb. Two-hundred and twenty-four Merino ewe lambs born from 10 sires with Australian Sheep Breeding Values were teased for 14 days using vasectomised rams, and then fed two different diets for 68 days during mating. All ewe lambs were weighed and the appearance of crayon marks on their rump was recorded most days. Blood samples for progesterone assay were collected on Days 5, 12 and 17 after the first record of a crayon mark. Ultrasonography using a trans-rectal probe was used to measure the number of corpora lutea present, as a proxy for ovulation rate, 9 days after the first record of a crayon mark during the mating period. A further trans-rectal ultrasonography was undertaken 30 days after marking from the entire ram to determine pregnancy status and count the number of embryos. Over the entire mating period 54% of ewe lambs were pregnant with 66 fetuses per 100 ewes mated. The average ovulation rate was 150% however up to 84% of this potential was lost by weaning and the major contributor to this apparent deficit was the loss that occurred during the first 17 days after mating. Pregnancy failure was not significantly related to nutrition or liveweight change during mating however, there were significant differences in pregnancy failure between different sire groups. Pregnancy failure was significantly less for ewe lambs from sires with higher breeding values for weight and fat at post-weaning age (8–10 months). Only 60% of ewe lambs had achieved puberty when rams were introduced and only 83% by 35 days after mating. In addition, almost half of the ewe lambs that were mated for the first time during the first 35 days after rams were introduced, but failed to get pregnant, then seemed to skip a cycle or did not cycle again before the end of the 68-day mating period. Liveweight at introduction of entire rams was positively related to fertility, ovulation rate and reproductive rate. This study confirms that selection of sires with higher breeding values for post-weaning weight and fat will increase the fertility and reproductive rate of Merino ewe lambs mated at 8–10 months. This response is due in part to enhancing the onset of puberty and increasing the proportion of ewe lambs cycling at the start of mating and reducing pregnancy failure.
41
White, Colin L., Linda M. Tabe, Hugh Dove, John Hamblin, Paul Young, Nathan Phillips, Romney Taylor, Suresh Gulati, John Ashes e T?J?V Higgins. "Increased efficiency of wool growth and live weight gain in Merino sheep fed transgenic lupin seed containing sunflower albumin". Journal of the Science of Food and Agriculture 81, n. 1 (2000): 147–54. http://dx.doi.org/10.1002/1097-0010(20010101)81:1<147::aid-jsfa751>3.0.co;2-e.
Testo completo
42
Williams, Yvette J., Suzanne M. Rea, Sam Popovski, Carolyn L. Pimm, Andrew J. Williams, Andrew F. Toovey, Lucy C. Skillman e André-Denis G. Wright. "Reponses of sheep to a vaccination of entodinial or mixed rumen protozoal antigens to reduce rumen protozoal numbers". British Journal of Nutrition 99, n. 1 (15 agosto 2007): 100–109. http://dx.doi.org/10.1017/s0007114507801553.
Testo completoAbstract (sommario):
Two rumen protozoa vaccine formulations containing either whole fixed Entodinium or mixed rumen protozoa cells were tested on Merino sheep with the aim of decreasing the number and/or activity of protozoa in the rumen. Negative control (no antigen) and positive control (Tetrahymena corlissi antigens) treatments were also included in the experiment. Blood and saliva were sampled to measure the specific immune response. Protozoal numbers in the rumen were monitored by microscopic counts. Vaccination with protozoal formulations resulted in the presence of specific IgG in plasma and saliva, but saliva titres were low. Titres after secondary vaccination were higher (P < 0·05) than after primary vaccination. There was a moderate (r2 0·556) relationship (P < 0·05) between plasma and saliva titres for the rumen protozoal vaccine formulations. Rumen protozoa were not decreased (P>0·05) by the vaccination and there was also no difference (P>0·05) between treatments in rumen fluid ammonia-N concentration or wool growth. In vitro studies investigated the binding ability of the antibodies and estimated the amount of antibody required to reduce cell numbers in the rumen. The studies showed that the antibodies did bind to and reduced protozoa numbers, but the amount of antibody generated by vaccination was not enough to produce results in an in vivo system. It is suggested that the vaccine could be improved if specific protozoal antigens are determined and isolated and that improved understanding of the actions of protozoa antibodies in rumen fluid and the relationships between levels of antibodies and numbers of protozoa in the rumen is needed.
43
Allen, J. D., e J. M. Gawthornet. "Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep". British Journal of Nutrition 58, n. 2 (settembre 1987): 265–76. http://dx.doi.org/10.1079/bjn19870094.
Testo completoAbstract (sommario):
1. Merino sheep fed on a diet of chopped wheaten hay, chopped lucerne (Medicago saliva) hay and oat grain were the source of rumen contents for the study. The diet contained (mg/kg dry weight) 3.3 copper, 0.24 molybdenum and 2.8 sulphur. The effects of adding between 5 and 25 mg Mo/kg as ammonium molybdate (AM) or tetrathiomolybdate (TTM) on the distribution and forms of Cu and Mo in rumen contents were investigated in vivo and in vitro.2. Approximately 88 % of the Cu and 94% of the Mo in rumen contents were associated with the solid phase. When AM or TTM was added to rumen contents in vivo or in vitro the proportion of these elements in the solid phase was increased at the expense of the fluid phase.3. The addition of AM and TTM to rumen contents also decreased the proportion of Cu that was soluble in trichloroacetic acid (50 g/l; TCA) and increased the proportion of Cu that was not extractable by sequential treatment with TCA and neutral detergent.4. Column chromatography of neutral-detergent extracts of rumen contents revealed that TTM treatment caused Cu to be strongly bound to proteins of high molecular weight.5. Addition of sulphide to rumen contents did not result in significant changes in the distribution of Cu between the fluid and solid phases, or in the solubility of Cu in TCA.6. It is postulated that constant removal of TTM from the fluid phase via reaction with proteins and other macromolecules in the solid phase results in greater formation of TTM in vivo than would be expected from solution chemistry. The molybdo-proteins so formed are strong chelators of Cu and may be the agents responsible for the decrease in Cu absorption in animals that consume diets containing high concentrations of Mo.
44
Gherardi, S. G., e J. L. Black. "Influence of post-rumen supply of nutrients on rumen digesta load and voluntary intake of a roughage by sheep". British Journal of Nutrition 62, n. 3 (novembre 1989): 589–99. http://dx.doi.org/10.1079/bjn19890060.
Testo completoAbstract (sommario):
The effect of post-rumen supply of nutrients on the rumen digesta load and voluntary consumption of roughage by Border Leicester × Merino ram lambs was investigated. A chopped wheaten hay was offered to the ram lambs (n 24), whose nutrient intake was altered by infusing into the abomasum a liquid supplement, containing reconstituted cow's milk, sodium caseinate, minerals and vitamins, for a period of at least 30 d. Either two or three lambs were allocated by live weight to each of ten rates of nutrient supplementation. The lambs were slaughtered at a target live weight of 31 kg. Voluntary intake of hay was estimated over the last 7 d of feeding. The amounts of digesta and organic matter (OM) in the rumen were measured by emptying after slaughter. The particle size distribution of the digesta was measured by wet sieving and the fractional outflow rate of particulate matter by reference to the marker lignin. Growth rate of the lambs increased linearly as total energy infused increased. The linear increase in growth rate indicated that roughage was not substituted for infused nutrients on a direct energy basis. OM intake from hay declined linearly as the amount of nutrients infused increased. The decline in intake was associated with a decline in both total digesta and the amount of rumen OM. Both the fractional digestion rate of OM and the fractional outflow rate of particulate matter from the rumen were unaffected by the amount of nutrients infused. The results indicated that the rumen digesta load of young sheep fed on a single roughage is directly related to their energy deficit, that is the difference between the capacity of the animals to use energy and the energy available to them for metabolism.
45
Ferro, M. M., L. O. Tedeschi e A. S. Atzori. "The comparison of the lactation and milk yield and composition of selected breeds of sheep and goats". Translational Animal Science 1, n. 4 (1 dicembre 2017): 498–506. http://dx.doi.org/10.2527/tas2017.0056.
Testo completoAbstract (sommario):
Abstract The objective of this study was to characterize the milk yield (MY) and milk composition of relevant sheep and goat breeds raised around the world to be used with nutrition models for diet formulation and nutrient balancing. A 2-step approach was used. First, a database developed by the Food and Agriculture Organization was used to identify relevant breeds (i.e., frequently raised) by comparing the occurrence of transboundary breed names across countries. We selected transboundary breeds that occurred more than 3 times and other relevant breeds obtained from the specialized literature that had milk production information (e.g., MY, days in milk, and milk fat, protein, and lactose). The majority of sheep breeds were classified as nondairy (76%) because they lacked milk production information. Karakul and Merino accounted for up to 2.4% of sheep breeds raised around the world, whereas the other individual breeds accounted for less than 1%. In contrast, nondairy breeds of goats accounted for 46.3% and of the remaining 53.7%, Saanen, Boer, Anglo-Nubian, Toggenburg, and Alpine accounted for 6.5, 5, 4.4, 4, and 3%, respectively, of the transboundary breeds. Second, a database compiled from published studies for the selected sheep (n = 65) and goats (n = 78) breeds were analyzed using a random coefficients model (studies and treatments within studies as random effects). For sheep breeds, the average and SD were 1.1 ± 0.3 kg/d for MY, 6.9 ± 1% for milk fat, 5.4 ± 0.4% for milk protein, 5 ± 0.3% for milk lactose, 17.7 ± 1.4% for milk total solids, and 1,073 ± 91 kcal/kg of milk energy. Lacaune had the greatest MY compared to Comisana and Tsigai (1.65 versus 0.83 and 0.62 kg/d; respectively, P < 0.05), but milk components were not different among breeds. For goats breeds, the average and SD across breeds were 1.7 ± 0.6 kg/d for MY, 4.2 ± 0.9% for milk fat, 3.3 ± 0.4% for milk protein, 4.4 ± 0.4% for milk lactose, 12.7 ± 1.1% for milk total solids, and 750 ± 75 kcal/kg of milk energy. Alpine had similar MY to Saanen (2.66 versus 2.55 kg/d, respectively; P > 0.05), but greater (P < 0.05) than other breeds. The Boer breed had the greatest milk fat, protein, lactose, and total solids than several other breeds, leading to the greatest milk energy content (907 kcal/kg). Because there are many factors that can alter MY and milk composition, averages provided in this study serve as guidelines, and nutritionists must obtain observed values when using nutrition models.
46
Rowe, J. B., J. V. Nolan, G. de Chaneet, E. Teleni e P. H. Holmes. "The effect of haemonchosis and blood loss into the abomasum on digestion in sheep". British Journal of Nutrition 59, n. 1 (gennaio 1988): 125–39. http://dx.doi.org/10.1079/bjn19880016.
Testo completoAbstract (sommario):
1. An experiment was conducted to determine the effect of the abomasal parasite, Haemonchus contortus, on the pattern of digestion and nutrient utilization in Merino sheep. There were three groups of sheep: infected with H. contortus (300 larvae/kg live weight) (n 5), sham-infected by transferring blood from the jugular vein to the abomasum, and uninfected (control) sheep (n 9) which were fed daily rations equal to amounts consumed by ‘paired’ animals in the two other treatment groups. A diet containing (g/kg): lucerne (Medicago sativa) chaff 490, oat chaff 480, ground limestone 10, urea 10, and sodium chloride 10, was given in equal amounts at 3-h intervals.2. Continuous intrarumen infusions (8 d) of chromium and ytterbium were made in order to measure the flow of digesta through the rumen, duodenum and ileum with 15NH4Cl included in the infusate for the final 3 d. The loss of blood into the gastrointestinal tract was measured using 51Cr-labelled erythrocytes and the rate of irreversible loss of plasma urea was measured with reference to a single intravenous injection of [14C]urea. Samples of rumen fluid were taken for analysis of volatile fatty acid (VFA) concentrations.3. The infected and sham-infected sheep developed severe anaemia during the period over which digestion and metabolism measurements were made (packed cell volume 0·118 (SE 0·0042) and 0.146 (SE 0·0073) respectively). The corresponding rates of blood loss into the gastrointestinal tracts were 253 (SE 23) and 145 (SE 17) ml/d.4. The proportions of VFA in rumen fluid were altered (P < 0·05) in the infected group with a decrease in the ratio, acetate: propionate (control 3·28, infected 2·58, standard error of difference (SED)(0·21). There was also an increase in rumen fluid outflow rate (P < 0·01) from 4·05 litres/d in the control group to 5.53 litres/d in the infected group (SED) 0·43). Water intake was higher (P < 0·05) in the infected than in the control animals (2·25 and 1·84 litres/d respectively; SED 0·14).5. There was a decrease (P < 0·05) in apparent digestion of organic matter in the forestomachs of infected sheep (0·32 compared with 0·39 in the control, SED 0·02). There was also a decrease (P < 0·05) in the apparent digestion of organic matter across the whole digestive tract (0·65 control, 0·61 infected, SED 0·013).6. There was a loss of 2·6 and 1·8 g blood nitrogen/d into the gastrointestinal tract of the infected and sham-infected sheep respectively. In the infected sheep approximately 50 % of this N was accounted for as additional ammonia leaving the abomasum compared with 20% in the sham-infected group. The additional non-ammonia-N (NAN) entering the duodenum of parasitized or sham-infected animals was reabsorbed before the ileum. There was no effect of infection or sham-infection on the synthesis or digestion of microbial NAN.7. There was a higher (P < 0·001) rate of plasma urea irreversible loss in the infected sheep (8·9 control, 12·2 infected, 10·9 sham-infected, SED (control v. treated) 0·87 g N/d). This was apparently due to increased absorption of ammonia and increased urea excretion and transfer to the gut.8. The results show that in sheep infected with H. contortus there was a considerable increase in the amount of additional endogenous N entering the duodenum. Although the extra N lost into the gastrointestinal tract was reabsorbed before the digesta reached the ileum the animals suffered a net loss of amino acids since part of the reabsorbed N was in the form of ammonia and reabsorbed NAN was apparently ineffectively utilized.
47
Strickland, V. J., G. L. Krebs e W. Potts. "Pumpkin kernel and garlic as alternative treatments for the control of Haemonchus contortus in sheep". Animal Production Science 49, n. 2 (2009): 139. http://dx.doi.org/10.1071/ea07378.
Testo completoAbstract (sommario):
Two alternative remedies for controlling Haemonchus contortus in sheep (pumpkin kernel and garlic) were investigated. The experiment involved 18 4-month-old Merino ram lambs with six lambs per treatment group. The lambs were initially drenched to render them worm free, and then infected with 4000 L3 H. contortus larvae, 2 weeks later. Four weeks after infection, faecal egg counts were performed and lambs were allocated into treatment groups and fed their respective diets (control, pumpkin kernel or garlic) for 2 weeks. The lambs were combined into a single group grazing pasture for the last week of the experiment. Faecal worm egg counts (WEC) were carried out weekly for 3 weeks following allocation to treatment diets. Clinical signs of infection observed included liveweight, body condition score and voluntary feed intake. The pumpkin kernel treatment resulted in a 65.5% decrease in the initial level of WEC, but this increased back to the initial level as soon as animals came off treatment. The garlic resulted in a 64.4% decrease in WEC from the initial level and this increased slightly (to 25.5% of the initial level and 43.5% lower than the control) when the animals came off treatment, suggesting that there was a residual effect of the garlic and/or that the garlic had an effect beyond decreasing the fecundity of the parasites. There was no significant difference (P > 0.05) between treatments in liveweight, body condition score or voluntary feed intake. Throughout the experiment voluntary feed intake and liveweight increased while body condition scores remained stable. We concluded that pumpkin kernel and garlic show potential for parasite control by affecting the fecundity of the parasites. Our results also indicate that with good nutrition lambs can cope with high parasite burdens and still be productive during the early stages of infection.
48
Carro, M. D., e M. J. Ranilla. "Influence of different concentrations of disodium fumarate on methane production and fermentation of concentrate feeds by rumen micro-organisms invitro". British Journal of Nutrition 90, n. 3 (settembre 2003): 617–23. http://dx.doi.org/10.1079/bjn2003935.
Testo completoAbstract (sommario):
Batch cultures of mixed rumen micro-organisms were used to study the effects of different concentrations of disodium fumarate on the fermentation of five concentrate feeds (maize, barley, wheat, sorghum and cassava meal). Rumen contents were collected from four Merino sheep fed lucerne hayad libitumand supplemented with 300 g concentrate/d. Disodium fumarate was added to the incubation bottles to achieve final concentrations of 0, 4, 7 and 10 mm-fumarate. In 17 h incubations, the final pH and total volatile fatty acid production increased (P<0·001) linearly for all substrates as fumarate concentration increased from 0 to 10 mm. Propionate and acetate production increased (P<0·05), while the value of the acetate:propionate ratio decreased (P<0·05) linearly with increasing doses of fumarate. In contrast,l-lactate and NH3-N concentrations in the cultures were not affected (P>0·05) by the addition of fumarate. For all substrates, fumarate treatment decreased (P<0·05) CH4production, the mean values of the decrease being 2·3, 3·8 and 4·8 % for concentrations of 4, 7 and 10 mm-fumarate respectively. Addition of fumarate did not affect (P>0·05) the total gas production. If the results of the present experiment are confirmedin vivo, fumarate could be used as a feed additive for ruminant animals fed high proportions of cereal grains, because it increased pH, acetate and propionate production and it decreased CH4production.
49
García-Martínez, R., M. J. Ranilla, M. L. Tejido e M. D. Carro. "Effects of disodium fumarate onin vitrorumen microbial growth, methane production and fermentation of diets differing in their forage:concentrate ratio". British Journal of Nutrition 94, n. 1 (luglio 2005): 71–77. http://dx.doi.org/10.1079/bjn20051455.
Testo completoAbstract (sommario):
The effects of disodium fumarate on microbial growth, CH4production and fermentation of three diets differing in their forage content (800, 500 and 200 g/kg DM) by rumen micro-organismsin vitrowere studied using batch cultures. Rumen contents were collected from four Merino sheep. Disodium fumarate was added to the incubation bottles to achieve final concentrations of 0, 4 and 8 mm-fumarate, and15N was used as a microbial marker. Gas production was measured at regular intervals from 0 to 120 h of incubation. Fumarate did not affect (P>0·05) any of the measured gas production parameters. In 17 h incubations, the final pH and the production of acetate and propionate were increased linearly (P<0·001) by the addition of fumarate. Fumarate tended to increase (P=0·076) the organic matter disappearance of the diets and to decrease (P=0·079) the amount of NH3-N in the cultures. Adding fumarate to batch cultures tended (P=0·099) to decrease CH4production, the mean values of the decrease being 5·4 %, 2·9 % and 3·8 % for the high-, medium- and low-forage diet, respectively. Fumarate tended to increase (P=0·082) rumen microbial growth for the high-forage diet, but no differences (P>0·05) were observed for the other two diets. These results indicate that the effects of fumarate on rumen fermentation depend on the nature of the incubated substrate, the high-forage diet showing the greatest response.
50
Entwistle, K. W., L. J. Cummins, M. A. Hillard, J. E. Kinder, T. O'Shea, L. R. Piper, J. Thimonier e J. F. Wilkins. "Bernard Michael Bindon — reproductive physiologist, animal scientist, research leader". Australian Journal of Experimental Agriculture 46, n. 2 (2006): i. http://dx.doi.org/10.1071/ea05222.
Testo completoAbstract (sommario):
This paper is a foreword to a series of papers commissioned on ‘the impact of science on the beef industry’, where the Beef CRC-related collaborative scientific work of Professor Bernard Michael Bindon will be reviewed. These papers will be presented in March 2006, as part of a ‘festschrift’ to recognise his wider contributions to the Australian livestock industries for over 40 years. Bindon’s career involved basic and applied research in many areas of reproductive physiology, genetics, immunology, nutrition, meat science and more recently genomics, in both sheep and cattle. Together with his collaborators, he made large contributions to animal science by improving the knowledge of mechanisms regulating reproductive functions and in elucidating the physiology and genetics of high fecundity livestock. His collaborative studies with many colleagues of the reproductive biology and genetics of the Booroola Merino were amongst the most extensive ever conducted on domestic livestock. He was instrumental in the development of immunological techniques to control ovulation rate and in examining the application of these and other techniques to increase beef cattle reproductive output. This paper tracks his investigations and achievements both within Australia and internationally. In the later stages of his career he was the major influence in attracting a large investment in Cooperative Research Centres for the Australian cattle industry, in which he directed a multi-disciplinary approach to investigate, develop and disseminate science and technology to improve commercial cattle productivity.