Journal articles on the topic 'Lamb survival'
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Brien, F. D., M. L. Hebart, D. H. Smith, J. E. Hocking Edwards, J. C. Greeff, K. W. Hart, G. Refshauge, et al. "Opportunities for genetic improvement of lamb survival." Animal Production Science 50, no. 12 (2010): 1017. http://dx.doi.org/10.1071/an10121.
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Data on lamb survival and associated traits involving records from 15 192 lambs, 6308 dams and 284 sires from the Sheep CRC’s Information Nucleus were studied. Lamb survival to 3 days of age and to weaning was 85 and 80%, respectively, and heritability (±s.e.) was 0.014 ± 0.010 and 0.010 ± 0.010, respectively. Of the 14 traits recorded at birth, time taken for the lamb to bleat, rectal temperature and crown–rump length had the highest genetic correlations with lamb survival to weaning (–0.43 ± 0.32, 0.56 ± 0.33 and –0.38 ± 0.36, respectively). Under selection for a multi-trait objective including net reproduction rate (but not lamb survival), survival was predicted to decline genetically by 0.25 lambs weaned per 100 lambs born.year, although this was reversed to a gain of 0.20 lambs weaned per 100 lambs born.year by including the trait in the breeding objective and using 50 half-sib and 50 progeny records per selection candidate. Accuracy of selection for lamb survival was improved to 0.735 with a selection index of lamb survival to weaning, lamb ease, birth coat score, time taken to bleat, rectal temperature and crown–rump length, with the addition of 50 half-sibs and 50 progeny records per candidate. Our results suggest that unless actively incorporated into breeding objectives, lamb survival may genetically decline; however, gains are possible with direct selection using half-sib and progeny records. The addition of indirect selection criteria for lamb survival can further improve accuracy, up to 93.4%, but requires further investigation.
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Morel, P. C. H., S. T. Morris, and P. R. Kenyon. "Effect of birthweight on survival in triplet-born lambs." Australian Journal of Experimental Agriculture 48, no. 7 (2008): 984. http://dx.doi.org/10.1071/ea07401.
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Lambing percentage is the main contributor to higher profit on New Zealand sheep farms and has increased from 98% in 1960 to 124% in 2006. As ewe litter size increases so does the proportion of triplet-born lambs and consequently preweaning mortality rate. The purpose of this study was to investigate the effect of birthweight (BWT) on survival in triplet-born lambs within and among litters. Data from a total of 594 triplet crossbreed lambs born to mixed-age ewes was analysed. For the statistical analysis, the lambs were allocated according to their BWT, and within the litter were then allocated to three BWT groups (light, medium and heavy). The following parameters were calculated: total litter BWT (TBWT), percentage of TBWT for each lamb (PBWT = BWT/TBWT), coefficient of variation for BWT within litter and lamb average daily gain from birth to weaning. The mortality rate for the light, medium and heavy lambs was 56, 40 and 28%, respectively, and consequently the lightest lamb in a litter was 3.2 times more likely to die than the heaviest lamb. In the light lamb group, as BWT increased mortality decreased (P = 0.006), for medium lambs BWT did not influence mortality (P = 0.88) and in the heavy group there was a trend of increased BWT associated with increased mortality (P = 0.10). The negative relationship between lamb mortality and PBWT was identical in the three BWT groups (P < 0.0001). The effect of BWT on lamb mortality became non-significant when PBWT was fitted in the same model. This means that, in triplet-born lambs, mortality is not influenced by the BWT of the lamb itself, but by the BWT of its littermates. It can be calculated that a 4-kg lamb has a 24% chance of surviving in a litter of 16 kg, a 60% chance in a litter of 12 kg and an 87% chance of surviving in a litter of 8 kg. It is concluded that reducing the variation in BWT within a litter, or specifically managing the lightest lamb at birth, will increase the competitive ability for survival of each lamb and, therefore, decrease overall mortality and further improve farm profitability.
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Parkes, K. "Improving lamb survival." Animal Welfare 14, no. 2 (May 2005): 166. http://dx.doi.org/10.1017/s0962728600029250.
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Lockwood, A., J. Trompf, L. Kubeil, A. Thompson, G. Refshauge, G. Kearney, and S. Hancock. "Decreasing the mob size but not stocking rate of ewes at lambing increases the survival of twin lambs born on farms across southern Australia." Animal Production Science 60, no. 16 (2020): 1949. http://dx.doi.org/10.1071/an19632.
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Context Data collected from producers in south-eastern Australia found that the survival of twin-born lambs decreased by 3.5% for each extra 100 ewes in the mob at lambing. Increasing stocking rate by 1 ewe/ha decreased lamb survival by a further 0.7%. These survey findings suggest that lamb survival could be improved by optimising the allocation of ewes to mobs and paddocks at lambing. Aim The present paper reports two experiments. Experiment 1 tested the hypotheses that (1) the survival of twin-born lambs would be greater when ewes lamb in smaller mobs and at lower stocking rates, and (2) the effects of mob size and stocking rate would be greater in Merinos than in non-Merino breeds. Experiment 2 tested the hypothesis that the survival of twin-born Merino lambs would be greater at lower mob sizes when ewes lambed at stocking rates <4 ewes/ha. Methods Experiment 1 investigated a 2 × 2 factorial combination of mob size (high or low) and stocking rate (high or low) on the survival of twin-born Merino and non-Merino lambs at 70 on-farm research sites across southern Australia. Experiment 2 investigated the effect of high or low mob size on the survival of twin-born Merino lambs when ewes lambed at stocking rates of <4 twin ewes/ha at 15 on-farm research sites. In both experiments, adult twin-bearing ewes were randomly allocated into a treatment and lambing paddock on Day 140 from the start of joining at each farm. Lamb survival in each mob was calculated based on lamb losses between pregnancy scanning and lamb marking. Key results In both experiments, the effect of mob size on lamb survival was found to be linear, with survival of twin-born lambs decreasing by between 1.9% and 2.5% per additional 100 ewes in the mob at lambing, regardless of breed (P < 0.001). In Experiment 1, there was no effect of stocking rate or mob size by stocking rate on lamb survival. Conclusions The present research demonstrated that reducing mob size but not stocking rate will improve the survival of twin-born lambs to marking for extensive enterprises in Australia where ewes lamb at stocking rates of up to 12 ewes/ha. Implications These findings will contribute to guidelines for optimising ewe nutrition and resource allocation to improve lamb survival.
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Johns, C., J. Johns, and D. R. Stevens. "Increasing lamb survival and lamb weaning weight through feeding high fecundity crossbred sheep." NZGA: Research and Practice Series 16 (January 1, 2016): 323–28. http://dx.doi.org/10.33584/rps.16.2016.3244.
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The monitoring of a high fecundity ewe flock in the Te Anau basin demonstrates the process of improved feeding to improve lamb survival and growth to weaning. Feed budgeting was changed from traditional to tailored feed requirements based on measured ewe liveweight with wastage of 15% factored in. Feed allocation was changed from monthly to weekly increases during late pregnancy, and set stocking was delayed until the planned start of lambing. This increased late pregnancy feed allocation from 99 kg DM/ewe to 128 and 144 kg DM/ewe for twin and triplet bearing ewes, respectively. Ewe body condition score was maintained at between 3 and 3.5, with condition score loss between scanning and lambing being reduced to zero. Lamb survival and lamb liveweight gain to weaning increased in both twin and triplet bearing ewes. Pregnancy scanning increased from 200 to 222 lambs per 100 ewes, between 2007 and 2012, while lambing percentage (lambs weaned/ ewe mated) rose from 132% to 165%, with more ewes rearing lambs and rearing multiples. Lamb wastage declined from 37% in 2007 and 2008, to 25% in 2011 and 2012, though scanning percentage rose by 20%. Lamb weights increased from 27.5 to 36 kg/lamb at 100 days of age. The increase in the liveweight of lambs and ewes at weaning reduced the calculated feed requirements over summer and autumn, potentially releasing 70 to 110 kg DM/ewe to provide feed to meet the extra winter feed requirements. Keywords: ewe body condition score, feed allocation, lamb survival, lamb weaning weight
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Fogarty, NM, and DG Hall. "Performance of crossbred progeny of Trangie Fertility Merino and Booroola Merino rams and Poll Dorset ewes. 3. Reproduction, liveweight and wool production of adult ewes." Australian Journal of Experimental Agriculture 35, no. 8 (1995): 1083. http://dx.doi.org/10.1071/ea9951083.
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Reproduction, liveweight and wool production are reported for 4 cohorts of 377 Trangie Fertility x Dorset (TD) and 261 Booroola x Dorset (BD) ewes over 6 years. The BD ewes were 3-4 kg lighter (P<0.001) and had a higher ovulation rate prior to joining in February-March (2.37 � 0.03 v. 1.65 � 0.03) than TD ewes. This resulted in a higher litter size (2.07 � 0.03 v. 1.66 � 0.04) and number of lambs born per ewe joined (1.92 � 0.04 v. 1.56 � 0.04) for the BD ewes. Lamb survival was lower from BD than TD ewes (0.71 � 0.02 v. 0.85 � 0.02), so that the 2 ewe strains weaned the same number of lambs. The growth rate of lambs was lower from the BD ewes and overall they weaned 3.8 kg less (P<0.001) weight of lamb than TD ewes. Chill (index of environmental conditions at lambing), litter size and average birth weight of lambs in the litter (linear and quadratic) affected (P<0.001) lamb survival. At moderate levels of chill there was little difference in survival of single and twin lambs from BD and TD dams when birth weight was 4-5 kg, but survival declined more rapidly for progeny of BD ewes at lower birth weight. Under severe lambing conditions survival was depressed more for lambs born from BD ewes than TD ewes. Almost all ewes expressed oestrus over the 3, 6-week periods, December-January, January-February and March (joining). There was significant variation (P<0.001) in incidence of oestrus due to year and age (linear and non-linear), but not liveweight at joining, and there was little difference between ewe strains. Similarly, for post-lambing oestrus (to fit 8-monthly joining) and post-lambing anoestrous interval, there was little difference between strains, but year and age were highly significant (P<0.001). BD ewes had a lower (P<0.001) greasy fleece weight (3.76 v. 3.86 kg), than TD ewes. BD ewes were classified as either carriers (F+) or non-carriers (++) of the FecB gene, which was significant (P<0.001) for ovulation rate (+1.14 ovulations), litter size (+0.8 lambs), lamb survival (-18%), lambs born per ewe joined (+0.64 lambs) and total weight of lamb born per ewe joined (0.5 kg, P<0.01). The effect of the FecB gene was non-significant for lamb survival when litter size and lamb birth weight (P<0.001) were included in the model. Repeatability estimates based on over 3 records per ewe were about 0.2 for lambs born, weight of lamb born, lambs weaned and weight of lamb weaned per ewe joined. Component traits ranged from 0.27 for litter size to 0.10 for lamb survival, with fertility intermediate (0.15). Greasy fleece weight (0.72) and ovulation rate (0.41) had high repeatabilities with post-lambing anoestrous interval being low (0.11). Repeatability for ovulation rate was reduced to 0.34 when F+ ewes were excluded.
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Jordan, DJ, and DG Mayer. "Effects of udder damage and nutritional plane on milk yield, lamb survival and lamb growth of Merinos." Australian Journal of Experimental Agriculture 29, no. 3 (1989): 315. http://dx.doi.org/10.1071/ea9890315.
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A pen study investigated the effects of udder damage and 3 levels of nutrition (110, 90 and 70% of maintenance requirements) during the pre- and post-natal period on the performance of Merino ewes and lambs. Udder damage (only 1 functional teat) significantly reduced (P< 0.05) estimated daily milk yield of ewes (1 139 v. 963 mL/day), growth rate (180.5 v. 143.7 g/ day) and liveweight of lambs (10.1 v. 8.8 kg) at 4-6 weeks of age. Lamb survival was significantly reduced only in the 70% of maintenance treatment (82.2 v. 64.8%). Nutrition level significantly (P< 0.05) affected ewe and lamb performance. Estimated daily ewe milk yield (1146, 1070 and 938 mL/day), ewe liveweight (40.4, 39.2 and 37.1 kg) at lamb marking, and lamb growth rate (178.1, 169.5 and 138.8 g/day) and liveweight (10.2, 9.6 and 8.6 kg) at 4-6 weeks were significantly higher for ewes fed on 110 and 90% of their requirements than for ewes fed at 70% of their requirements respectively. Lamb survival (89.9%) from ewes fed at 110% of requirements was significantly higher than lamb survival (75.3 and 73.5%) from ewes fed at 90 and 70% of requirements respectively. There was no significant interaction between the level of nutrition and udder damage in any parameter of ewe or lamb performance. Birth weight (3.0 v. 3.8 kg) and survival (49.3 v. 84.2%) were significantly (P<0.01) lower in twins than in single birth lambs. Growth rate of single lambs and single survivors of twins reared as single lambs were similar (167 and 160 g/day respectively); both of these groups grew more rapidly (P< 0.01) than lambs reared as twins (91 g/day). Lamb growth rate was positively correlated with ewe milk yield (r=0.75; P<0.01), ewe weight (r = 0.37; P< 0.01) and lamb birth weight (r = 0.24; P< 0.05). Lamb birth weight and ewe milk yield were also significantly and positively correlated with ewe weight. Male lambs were significantly heavier at birth and grew significantly faster than female lambs.
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O'Connor, C. E., and A. B. Lawrence. "Relationship between lamb vigour and ewe behaviour at parturition." Animal Science 54, no. 3 (June 1992): 361–66. http://dx.doi.org/10.1017/s000335610002081x.
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AbstractMaternal behaviour and lamb vigour are both considered major variables affecting lamb survival, but there are few data to describe their relative importance. To investigate the relationship between lamb vigour and maternal behaviour this study compared the behaviour of pure Scottish Blackface lambs with Mule (Bluefaced Leicester ♀. × Scottish Blackface ♂) lambs, all born indoors. Anecdotal accounts suggested a significant reduction in lamb vigour in Mule lambs, a matter also of significant practical importance given the current incease in Mule numbers. Observations on the grooming behaviour of 32 single or twin-bearing ewes, and on the general activity and udder-seeking behaviour of their lambs were made at parturition. In this study, neither ewe grooming behaviour nor general lamb activity were directly related to lamb sucking success. It was shown that, although Mule lambs had high birth weights and stood as quickly as Blackface lambs, they showed significantly fewer sucking attempts (P < 0·01) and took longer to suck successfully (28 min for Blackface v. 55 min for Mules). The inability of Mule lambs to suck successfully was due to their failure to show proper udder-directed behaviour. These results indicate the importance of considering the behaviour of both ewes and lambs as it would seem that it is not ‘poor’ maternal behaviour but inappropriate lamb behaviour that is a limiting factor in lamb survival in the Mule breed.
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GOWANE, G. R., C. P. SWARNKAR, H. K. NARULA, and A. CHOPRA. "Better odds of lamb survival in sheep at dry arid tropical region of India." Indian Journal of Animal Sciences 90, no. 4 (September 1, 2020): 628–35. http://dx.doi.org/10.56093/ijans.v90i4.104222.
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Lamb survival till first 28 days of life is critical as it increases the chances of economic gain in flock. Objective of the current study was to assess the incidence of neonatal mortality in lambs born in arid region of India and genetic and non-genetic factors affecting it. The present study was conducted using the data on 4,137 Magra and 4,595 Marwari sheep over 17 years (1999 to 2016). Incidence of neonatal mortality was very low in Magra (1.04%) and Marwari (2.48%) sheep, respectively in semi-intensive management system. Year and seasonal variation was observed for neonatal losses. Males had lower odds of survival as compared to females. Odds of survival were low if the lambs were born to dams of low body weight and in their first parity. It was observed that the lamb survival can be improved if due care of the lambs born with low birth weight (<2 kg) is taken. The heritability estimate was moderate in Magra sheep (0.17), indicating further scope for genetic improvement for lamb survival through selection. However, for Marwari sheep, the total heritability was 0.02, thus limiting the scope for selection. Arid region favoured the lamb survival. Hardiness of the Magra and Marwari sheep, their high lamb survival along with standard production potential is indicative of the good genetics of these sheep along with better management practices adopted at arid regional campus, thus reflecting better sheep welfare practices.
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Hall, DG, NM Fogarty, and AR Gilmour. "Performance of crossbred progeny of Trangie Fertility Merino and Booroola Merino rams and Poll Dorset ewes. 1. Lamb birth weight, survival and growth." Australian Journal of Experimental Agriculture 35, no. 8 (1995): 1069. http://dx.doi.org/10.1071/ea9951069.
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Merino rams of the Trangie Fertility and Booroola strains were joined to Poll Dorset ewes in single sire mating groups over 3 years. Forty sires produced a total of 1250 lambs in 885 litters from 451 ewes. Lamb birth weight averaged 4.1 kg, 80.8% of lambs survived to 3 days of age and growth rates to weaning (mean 93 days) averaged 289 g/day. Lambs with Trangie Fertility sires grew 15 g/day faster and were 1.3 kg heavier at weaning than those lambs with Booroola sires (P<0.001). There were no effects of sire strain on birth weight or lamb survival. Birth weight increased with dam liveweight in mid-pregnancy (P<0.001), and weaning weight and growth rate increased with dam liveweight at joining (P<0.001). Survival of lambs was predominantly a function of birth weight. Lambs weighing 4 kg at birth from primiparous dams had survival rates of 76% compared with 88% for lambs from multiparous dams (P<0.01). No lamb under 2.0 or over 6.3 kg survived, and 48% of deaths occurred within 1 day of birth. Dystocia, particularly of heavy, single-born lambs, caused 53% of observed lamb deaths. For the traits birth weight, lamb survival, weaning weight and growth rate, the direct heritabilities were 0.24 � 0.10, 0.05 � 0.05, 0.19 � 0.10 and 0.12 � 0.08 respectively; the corresponding maternal heritabilities were 0.08 � 0.05, 0.05 � 0.04, 0.05 � 0.05 and 0.07 � 0.05 respectively; and the common environmental effects among litter mates (c2) were 0.57 � 0.08, 0.47 � 0.08, 0.15 � 0.08 and 0.13 � 0.08 respectively.
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El Fadili, M., C. Michaux, J. Detilleux, and P. L. Leroy. "Comparison of five crossbreeding types involving Timahdit, D’man and improved terminal sire breeds of sheep: ewe reproduction, lamb survival and growth performance." Animal Science 71, no. 3 (December 2000): 435–41. http://dx.doi.org/10.1017/s1357729800055351.
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AbstractA crossbreeding experiment involving Timahdit (T), D'man (D) and improved sire breeds (M) was conducted to compare lamb production in five crossbreeding types: D ✕ D, T ✕ T, D ✕ T (DT), M ✕ T, and M ✕ DT lambs. Reproductive and production traits were analysed in 1187 litters, 1586 lambs born and 1346 lambs weaned, progeny of 605 ewes. Effects of crossbreeding type, year of birth, sex of lamb, age of dam, and type of birth were significant on the majority of traits studied. The D ✕ D and M ✕ DT crossbreeding system showed the highest litter sizes at lambing and at weaning with respective values in D ✕ D (2·17, 1·34) and M ✕ DT (1·72, 1·39). Ewes bearing the M ✕ DT cross lambs showed the highest (P < 0·05) litter weight at weaning (28·28 kg) followed by those with M ✕ T (23·14 kg), and D ✕ D (22·53 kg) lambs. M ✕ DT and M ✕ T lambs were heavier and grew faster than the other lambs. On the other hand, lamb survival rates and growth traits were the lowest in D ✕ D but those in T ✕ T and D ✕ T genetic types of lamb were intermediate. Results showed that D as a dam breed had a favourable effect on litter size (P < 0·01) but unfavourable effect on lamb survival and birth weight. The reproductive performance of DT crossbred ewes, due to their high prolificacy and lamb survival, associated with the favourable effect of an improved terminal sire (M) for growth traits, indicated that the three breed cross (M ✕ DT) could enhance lamb production in Morocco.
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Hall, DG, AR Gilmour, and NM Fogarty. "Variation in reproduction and production of Poll Dorset ewes." Australian Journal of Agricultural Research 45, no. 2 (1994): 415. http://dx.doi.org/10.1071/ar9940415.
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Poll Dorset ewes were joined to Booroola Merino (n = 22) or Trangie Fertility Merino (n = 26) rams in single sire joinings during late summer/autumn of 1978, 1979, 1980 and 1981. Rams were changed each year and there were 1678 individual ewe joinings. A maximum of 527 ewes were used in any one year, and they represented 14 studs and varied in age, reproductive history and liveweight. The traits, litter size, maternal lamb survival, lambs weaned per ewe lambing and weight of lamb weaned per ewe lambing (kg at 100 days) were analysed for the effect of year, stud, age, lambs born and ewe liveweight. Litter size averaged 1-37, maternal lamb survival 0.70, and number of lambs weaned per ewe was 0.94. There were large variations in the reproductive traits due to year and stud and lesser effects due to age. Each extra kilogram of ewe liveweight at joining increased litter size by 0.012 and weight of lamb weaned by 0.39 kg, but had no significant effect on maternal lamb survival or number of lambs weaned. Multiple-bearing ewes weaned 0.72 more lambs and 16 - 2 kg more lamb weight than single-bearing ewes. Lamb survival was similar for singleand multiple-bearing ewes. Greasy fleece weight averaged 2.2 kg ewe-' and single bearing ewes produced 0.19 kg/ewe more than multiple-bearing ewes. Dystocia caused 53% and starvation/mismothering/exposure caused 23% of lamb deaths; the proportion of deaths due to starvation/mismothering/exposure increased with increasing ewe joining liveweight. The large variation between studs in reproductive performance partly reflected genetic differences between Poll Dorset flocks which could be exploited. Estimates of heritabilities ranged from 0.06 to 0.14 � 0.10 for the reproductive traits and were 0.10 � 0.12 for ewe liveweight and 0.16 � 0.20 for greasy fleece weight. However much of the between stud variation may also have arisen from early environmental effects. Estimates of repeatability ranged from 0.06 to 0.l5 � 0 05 for reproduction traits and were 0.44 � 0.06 for ewe liveweight at joining and 0.56 � 0.08 for greasy fleece weight.
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McLeod, Lynette J., Glen R. Saunders, Steven R. McLeod, Michelle Dawson, and Remy van de Ven. "The potential for participatory landscape management to reduce the impact of the red fox (Vulpes vulpes) on lamb production." Wildlife Research 37, no. 8 (2010): 695. http://dx.doi.org/10.1071/wr10082.
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ContextRed fox (Vulpes vulpes) predation has an impact on populations of many species throughout its range worldwide, and as such, the red fox is the target of control programs. AimsWe investigated the potential for participatory landscape management to reduce the impact of fox predation on a major prey species, lambs. MethodsThe present study monitored fox-management programs already operating across 4.5 million hectares of regional New South Wales to compare the impact of varying (frequency and spatial coverage) control effort on lamb survival. Key resultsThe frequency and timing of fox control was correlated with lamb survival. Lamb survival was higher in areas where fox baiting was carried out twice a year, in autumn and late winter/spring. Spatial coverage of the control program was also positively correlated with lamb survival. Properties that had near neighbours (up to 2.5 km away) participating in group fox-control programs had higher survival of lambs than properties that did not. ConclusionsThese results support the development of a high level of group participation in fox-control programs that considers both spatial extent and frequency of baiting programs. They also support a movement away from the reactionary, short-term practice of baiting small areas to protect vulnerable prey. ImplicationsCoordinated group-baiting programs are likely to deliver improved lamb survival and should be promoted in areas where ongoing control programs for foxes are necessary.
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Dwyer, C. M., A. B. Lawrence, and S. C. Bishop. "The effects of selection for lean tissue content on maternal and neonatal lamb behaviours in Scottish Blackface sheep." Animal Science 72, no. 3 (June 2001): 555–71. http://dx.doi.org/10.1017/s1357729800052097.
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AbstractBritish hill sheep are required to give birth to and rear their lambs under harsh extensive conditions. The aim of this study was to investigate whether genetic selection for increased (LEAN) or decreased (FAT) carcass lean content in the Scottish Blackface breed over 7 years had affected the ability of ewes to rear lambs by altering the expression of maternal and neonatal lamb behaviours. The behaviour of 61 ewes (32 LEAN and 29 FAT) and their 119 lambs were recorded at parturition and over the first 8 weeks of life. Overall there were very few effects of selection on the behaviour of the ewes. LEAN ewes were significantly faster than FAT ewes to start grooming their lambs after birth and FAT ewes tended to withdraw more frequently from their lambs than LEAN ewes. There was, however, a highly significant effect of selection line on lamb behaviour. LEAN lambs were significantly quicker than FAT lambs to perform all righting movements (median latency to stand (mins): LEAN = 11·7, FAT = 23·4, P < 0·01), were more likely both to suck (percentage that sucked: LEAN = 81·0%, FAT = 57·1%, P < 0·05), and to play within the first 2 h of birth. The higher rate of sucking in LEAN lambs persisted over the first 3 days after birth (percent observations where lambs were sucking: LEAN = 7·8 (s.e. 0·8), FAT = 5·1 (s.e. 0·6), P < 0·05), when LEAN lambs were also significantly closer to their mothers than FAT lambs. Thereafter, there were no significant effects of ewe or lamb line on behaviours recorded up to 8 weeks after birth. Overall lamb mortality to 8 weeks was 19·3% and was not significantly affected by lamb line. However, lambs that were slow to perform early behaviours had a reduced survival to 8 weeks of age. These data suggest that, although ewe maternal behaviour has not been significantly affected by selection for lean growth, the activity of the neonatal lamb has been affected. Lamb activity was related to lamb survival, even in our indoor lambing conditions. It is likely that the speed with which newborn lambs stand and suck will be even more important for survival under extensive conditions.
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Hall, DG, LR Piper, AR Egan, and BM Bindon. "Lamb and milk production from Booroola ewes supplemented in late pregnancy." Australian Journal of Experimental Agriculture 32, no. 5 (1992): 587. http://dx.doi.org/10.1071/ea9920587.
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Booroola ewes in moderate body condition on pasture, were either not supplemented, or supplemented prior to parturition with lupin grain for 9 days in a preliminary experiment, or with lupin or oat grain for 17 days in the main experiment. Measurements included lamb birth weight and survival and, in the main experiment only, ewe milk production and lamb immunoglobulin concentrations. With 9 days of lupin grain supplementation, lamb survival to weaning increased by about 12% (P<0.05), size of litter weaned increased from 1.26 to 1.52 (P<0.01) and lamb birth weight increased by about 0.2 kg (P<0.01). In the main experiment, supplementation with lupins resulted in 95% survival to day 9 of twin-born lambs, compared with 68% for lambs from control and oat-fed ewes (P<0.05). Extra lamb losses, due to starvation in the unsupplemented group, were matched by losses due to dystocia in the fed groups. Lamb birth weights, and ewe milk production and composition, were similar across treatments. During the feeding treatment period, only the lupin supplemented ewes maintained their fat score while the other ewes lost 0.5 of a fat score (P<0.01). Fewer (P<0.1) multiple-born lambs from lupin supplemented ewes had low serum immunoglobulin scores, indicating that the lupin supplement may have affected production or intake of colostrum.
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Fogarty, N. M., D. L. Hopkins, and R. van de Ven. "Lamb production from diverse genotypes. 1. Lamb growth and survival and ewe performance." Animal Science 70, no. 1 (February 2000): 135–45. http://dx.doi.org/10.1017/s1357729800051675.
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AbstractGrowth and survival of 3673 female and cryptorchid lambs representing the range of types (second cross, first cross and Merino) produced in the Australian lamb industry are reported. The lambs were sired by a selection of Poll Dorset (D; no. = 7), Texel (T; no. = 10), Border Leicester (BL; no. = 12) and Merino (M; no. = 12) rams and born to Border Leicester × Merino (BLM) and Merino (M) dams, which resulted in six lamb genotypes (D×BLM, T×BLM, D×M, T×M, BL×M and M×M). The second cross lambs (D×BLM, T×BLM) were heavier at birth, weaning and post-weaning and had higher growth rates, than first cross lambs (D×M, T×M, BL×M), which were higher than M×M lambs (P< 0·01). For post-weaning weight (cryptorchids at 156 days) second cross lambs were 4·2 (s.e. 0·3) kg heavier than comparable sired first cross lambs, with the BL×M 2·6 (s.e. 0·5) kg lighter than other first cross types and the MxM a further 4·2 (s.e. 0·6) kg lighter. The average advantage of D over T crosses was 1·0 kg for post-weaning weight, with greater variation amongst individual sires.Lamb survival to weaning was 76% and it was affected by birth weight and birth type (P< 0·01). Sire breed had no significant effect on lamb survival, whereas lambs from BLM ewes had higher survival than those from M ewes (P< 0·01).Overall the proportion of ewes lambing was 84% with a mean litter size of 1·77. There was no difference infertility between AI (thawed frozen semen and laparoscopic insemination) and natural (single sire) mating, although the M were higher than the BLM ewes (P< 0·01). Gestation length was 2·3 days shorter (P< 0·01) for BLM than M ewes and there was no difference between D and T sire breeds. There was little effect of birth type on gestation length but it increased with birth weight within birth type categories. Between year repeatability of gestation length for ewes was 0·33 (s.e. 0·05).
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Clarke, Lynne, David Pam Yakubu, and Michael E. Symonds. "Influence of maternal bodyweight on size, conformation and survival of newborn lambs." Reproduction, Fertility and Development 9, no. 5 (1997): 509. http://dx.doi.org/10.1071/r97016.
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Although body condition score was not significantly different between light (<55 kg, n = 6) and heavy (≥60 kg, n = 70 ewes at mating, it declined between Day 30 and Day 90 of gestation in light but not heavy ewes, and remained lower up to term. All ewes bore twins, delivered near term (Days 144–146) by Caesarean section. One lamb was immediately placed into a warm (30°C; WD) and its twin into a cool (15°C; CD) ambient temperature, and tissues were sampled at 0·5 h or 6 h. All CD lambs born to light ewes exhibited hypothermia and/or respiratory failure and did not survive longer than 30 min; these symptoms were not observed in their WD twins or any lamb born to heavy ewes. Total lamb birth weight, placental weight and fetal cotyledonary weight were lower with light than with heavy ewes. Lambs born to light ewes had less perirenal adipose tissue and smaller liver, heart, kidneys, brain, adrenals and thyroid, although their heart, brain and pancreas represented a larger proportion of total bodyweight; pancreas weight was similar to that in lambs born to heavy ewes. Hence, maternal bodyweight critically influences placental weight and lamb size and survival after birth.
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Brougham, Billie-Jaye, Alice C. Weaver, Alyce M. F. Swinbourne, Bobbie E. Lewis Baida, Jennifer M. Kelly, Simon K. Walker, David O. Kleemann, and William H. E. J. van Wettere. "Maternal Supplementation with Dietary Betaine during Gestation to Improve Twin Lamb Survival." Animals 10, no. 10 (September 26, 2020): 1749. http://dx.doi.org/10.3390/ani10101749.
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Betaine increases the synthesis of creatine, an energy-rich amino acid that increases adenosine triphosphate (ATP) and has neuroprotective properties which may improve post-natal lamb survival. This study determined whether maternal betaine supplementation during gestation would improve body weight, thermoregulation, time to stand and suck, colostrum intake and survival to weaning of twin lambs. Twin-bearing Merino ewes received dietary betaine at either 0 g/day (Control, CTL), 2 g/day from ram introduction to parturition (Early betaine, EB) or 4 g/day from Day 80 of gestation to parturition (Late betaine, LB). Ewes were housed individually during parturition and measures were collected at 4, 24 and 72 h and Day 7 post-partum, and at marking (53.2 ± 0.2 days of age) and weaning (99.3 ± 0.2 days of age). The EB treatment resulted in heavier lambs at weaning compared with CTL and LB lambs (p < 0.05). Time to stand and suck from birth was longer in EB lambs (p < 0.05), whereas, the interval from birth to first suck was shorter for LB lambs (p < 0.05). Lamb survival rate was the highest for LB lambs at 72 h and Day 7 (p < 0.05), and lowest for EB lambs on Day 7 (p < 0.05). These data indicated that betaine supplementation at 4 g/day during the second half of pregnancy improved twin lamb survival to Day 7 and shortened the interval from birth to first suck; whereas feeding ewes 2 g/day of betaine for the duration of pregnancy increased twin lamb body weight at weaning, but increased both the time to attain behavioural milestones and mortalities before Day 7.
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Bickell, S. L., R. Nowak, P. Poindron, D. Ferguson, and D. Blache. "Maternal behaviour at parturition in outdoor conditions differs only moderately between single-bearing ewes selected for their calm or nervous temperament." Animal Production Science 50, no. 7 (2010): 675. http://dx.doi.org/10.1071/an09118.
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Maternal and lamb behaviours play a major role in lamb survival and there is evidence that selection for calm temperament may help improve lamb survival by improving maternal behaviour. However, the apparent better maternal behaviour of calm ewes might be due partly to their lower reactivity to the presence of the human observer rather than to better maternal behaviour per se. The extent to which the selection for temperament influenced the behaviour of the ewe and lamb after parturition with minimal human disturbance was investigated in the present work. Single-bearing multiparous and primiparous ewes were observed to determine any interactions of temperament with maternal experience on ewe and lamb behaviours. Postpartum ewe-lamb interactions under outdoor lambing conditions were captured by continuous video recordings by a remote controlled recording device for up to 2 h postpartum. Calm ewes licked their lambs more and tended to stay longer on the birth site. Nervous lambs stood up earlier and were quicker to start performing exploratory behaviour. However, duration of suckling during the observation period did not differ between the calm and nervous lambs. There were no effects of maternal experience on the behaviour of the lamb and there were no interactions between temperament and maternal experience on the behaviour of the ewe or lamb. Our study indicates that temperament does influence the early postpartum behaviour of ewes and lambs under extensive field conditions.
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Riggio, V., S. C. Bishop, and R. Finocchiaro. "Genetic analysis of early lamb survival in extensively reared lambs." Italian Journal of Animal Science 4, sup2 (January 2005): 73–75. http://dx.doi.org/10.4081/ijas.2005.2s.73.
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Hinch, GN, JJ Lynch, JV Nolan, RA Leng, BM Bindon, and LR Piper. "Supplementation of high fecundity Border Leicester x Merino ewes with a high protein feed: its effect on lamb survival." Australian Journal of Experimental Agriculture 36, no. 2 (1996): 129. http://dx.doi.org/10.1071/ea9960129.
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Two hundred and fifty Border Leicester x Merino ewes (40% heterozygous for the Booroola Fec B gene) were used in an experiment, replicated over 2 years, to examine the effects of cottonseed meal-based supplementation on lamb survival, birth, marking and weaning weight, as well as, liveweight and fleece characteristics of ewes. From 50 to 100 days of pregnancy, half of the ewes were supplemented with 80 g/head.day. The supplemented group was then split according to litter size and, until 30 days after lambing, were offered pellets at 80, 160 and 220 g/head .day, respectively, for ewes bearing single, twin and triplet (or more) lambs. Over the 2 years, ewes averaged 2.11 lambs per parturition and supplementation significantly increased lamb survival to weaning (73 v. 58%) with no interaction with litter size. Although supplementation had a positive effect on birth weight of all but twins, the effects of supplementation on survival were independent of birth weight effects. Significant effects of year, sire breed and litter size on lamb survival and birth weight were also noted. No effects of supplementation were apparent on lamb growth while ewe age, sire breed, sex and rearing rank all significantly influenced growth rates. Ewe weights, fleece weights and staple strength were significantly influenced by year, ewe age and litter size but not by supplementation. These findings indicate the benefits to lamb survival of providing a 'bypass' protein supplement to high fecundity flocks even when ewes are grazing good quality pastures.
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Moraes, Andreia Barros de, Cesar Henrique Espírito Candal Poli, Vivian Fischer, Neuza Maria Fajardo, Marta Farias Aita, and Gabriela Caillava da Porciuncula. "Ewe maternal behavior score to estimate lamb survival and performance during lactation." Acta Scientiarum. Animal Sciences 38, no. 3 (August 8, 2016): 327. http://dx.doi.org/10.4025/actascianimsci.v38i3.29923.
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Mortality of perinatal lambs and low weight at weaning cause huge liabilities to farmers. Current study describes maternal-filial behavior and evaluates the use of maternal behavior score (MBS) to estimate the behavior of ewes and lambs soon after birth, and correlate it with lamb mortality and performance during lactation. Thirty-seven Corriedale ewes were used in a completely randomized design. MBS was assessed up to 24 hours after birth, taking into consideration the distance of the ewe from the lamb at the approach of a person. Maternal behavior, placental weight, weight gain of the lambs until weaning and their survival rate were also evaluated until two hours after lambing. More than 90% of the ewes had adequate maternal behavior, with parental care, even though ewes were very sensitive to the presence of people. There was no significant correlation between MBS and maternal behavior, lamb mortality rate and live weight gain. Under these conditions, MBS was not a useful tool to estimate maternal behavior and performance of lambs.
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Schreurs, N. M., P. R. Kenyon, F. J. Mulvaney, P. C. H. Morel, D. M. West, and S. T. Morris. "Response of additional ewe lamb liveweight during gestation on birth and weaning weight of offspring and liveweight of the ewe lamb at weaning." Animal Production Science 50, no. 6 (2010): 528. http://dx.doi.org/10.1071/an09185.
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Increasing the liveweight of ewe lambs during gestation may have positive effects on lamb birthweight and weaning weight and also on ewe lamb liveweight at weaning. Specific times during the gestation period of the ewe lamb may be more responsive to improved nutrition and increases in liveweight. The objective of this work was to use a meta-analytic approach to investigate the effects of ewe lamb liveweight at mating and during pregnancy on lamb birth and weaning weights, and the ewe lamb’s liveweight at weaning. Increasing ewe lamb liveweight in early gestation and in particular before mating gave the greatest increases in the birth and weaning weight of the lambs, and also of the ewe lamb’s liveweight at weaning compared with increasing liveweight in the second and third trimester of gestation. This indicates that management practices for ewe lambs that generate higher liveweight at mating are likely to result in increased lamb survival, higher weaning percentages, greater lamb weaning weights and create rising 2-year-old ewes with better liveweight for mating in the subsequent season. Compared with ewe lambs that gave birth and reared singletons to weaning, those ewe lambs that gave birth to twins and reared twins had greater increases in lamb birthweights, lamb weaning weights and ewe lamb weights at weaning for each extra kilogram of ewe lamb liveweight during gestation. For ewe lambs, especially those that birth and rear twins, management options that increase the pre-mating weights will have the greatest response in lamb birthweight, weaning weight and liveweight of the ewe lamb itself at weaning.
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HEANEY, D. P., and J. N. B. SHRESTHA. "EFFECTS OF SOYFLOUR IN MILK REPLACER ON THE PERFORMANCE OF ARTIFICIALLY REARED LAMBS." Canadian Journal of Animal Science 67, no. 3 (September 1, 1987): 757–63. http://dx.doi.org/10.4141/cjas87-078.
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Two artificial rearing experiments were conducted to evaluate both preweaning and postweaning performance of artificially reared lambs, ad libitum fed a milk replacer having one-third of the milk protein replaced by soyflour protein (S) compared with those fed MR with all the protein provided by milk products (M). From weaning at 21 d of age to 91 d of age all the lambs were fed the same high-concentrate diet. In the first experiment there were no significant differences in lamb weights, daily gains, postweaning feed conversion or lamb survival. In the second experiment there were lower (P < 0.05) postweaning daily gains, lower (P < 0.05) 91-d weights and higher (P < 0.05) postweaning feed conversion (2.69 vs. 2.52 kg feed kg−1 gain) for S lambs compared with M lambs, although there were no significant differences due to MR treatment for weaning weights, preweaning daily gains or lamb survival. In both experiments the S lambs consumed slightly more MR than M lambs. Using prices prevailing at the time of the study the lower ingredient cost of the soyflour resulted in a saving in MR cost of $1.45 per lamb weaned. In the second experiment, the lower MR cost would have been partially offset by the approximately 1 kg extra liveweight per lamb at 91 d of age. It was concluded that soyflour could contribute one-third of the total protein in MR for ad libitum fed, artificially reared lambs with little, if any, reduction in lamb performance. However, savings in feed costs resulting from the cheaper ingredient cost might be partially offset by lower postweaning lamb gains. Key words: Lambs, artificial rearing, milk replacer, soy protein
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Holst, PJ. "Supplementary feeding of oat grain or lucerne hay to crossbred ewes at lambing." Australian Journal of Experimental Agriculture 27, no. 2 (1987): 211. http://dx.doi.org/10.1071/ea9870211.
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Border Leicester x Merino ewes (body condition score 2.6-3.0) grazing short pastures were given feed supplements during lambing, to examine effects on lamb survival. Supplementary feeding of poor quality lucerne hay, good quality lucerne hay or oaten grain, each given ad libitum, began 3 days prior to the start of the 4-week lambing period and continued to the end of lambing. One third of the ewes had twins. Lamb marking percentage for the unsupplemented treatment was 108.5% compared with 109.9, 118.1 and 111.7% for the poor quality lucerne hay, good quality lucerne hay and oaten grain treatments respectively. Of twin-bearing ewes given good quality hay, 60% reared both lambs, compared with 48-49% of those given poor quality hap or grain (n.s.) and 36% of those not supplemented (P < 0.05). Supplements did not improve the survival rate of single lambs. Overall survival (combining birth types) of lambs was also significantly improved by a supplement of good quality hay. The observed differences in twin survival were associated with differences in ewe grazing behaviour. These results support recommendations that supplementary feeding of twin-bearing ewes approaching lambing with a body condition score of 2.6-3.0 will improve lamb survival and weaning weights.
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Hass, Christine C. "Bighorn lamb mortality: predation, inbreeding, and population effects." Canadian Journal of Zoology 67, no. 3 (March 1, 1989): 699–705. http://dx.doi.org/10.1139/z89-101.
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Survival of lambs in the population of bighorn sheep (Ovis canadensis) on the National Bison Range, Montana, was less than 25% during 1983 and 1984. Sixty-seven percent of lamb mortality occurred within 3 days of birth; ewe behaviour and recovered remains indicated that coyotes likely accounted for most of the mortality. Herd history, calculated inbreeding coefficients, and the observation of several small, weak lambs implied that inbreeding depression, while probably not a major factor in lamb mortality, may have predisposed some lambs to predation. Lamb production was high (88–96%); in spite of high mortality, population numbers were stable.
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Kenyon, P. R., D. K. Revell, and S. T. Morris. "Mid-pregnancy shearing can increase birthweight and survival to weaning of multiple-born lambs under commercial conditions." Australian Journal of Experimental Agriculture 46, no. 7 (2006): 821. http://dx.doi.org/10.1071/ea05329.
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In several field studies, mid-pregnancy shearing has increased lamb birthweight, which may be associated with an increase in lamb survival. However, animal numbers have been too low in these studies to accurately examine any effects on survival rates to weaning. This study was designed to investigate the effect of mid-pregnancy shearing on the birthweight of multiple-born lambs and their survival rates to weaning under commercial farming conditions at 2 different sites. At Riverside, 657 twin- and 47 triplet-bearing ewes were either shorn at mid-pregnancy (n = 347) or left unshorn (n = 357). Similarly, at Tuapaka, 532 twin-, and 60 triplet-bearing ewes were either shorn at mid-pregnancy (n = 291) or left unshorn (n = 301). Mid-pregnancy shearing significantly (P<0.05) increased the birthweights of lambs at each site (by 0.44 and 0.13 kg at Riverside and Tuapaka, respectively). Mid-pregnancy shearing significantly (P<0.05) increased lamb weaning weights (by 1.07 kg) and survival rates to weaning (by 5.5%) at Riverside, but not at Tuapaka. These findings show that mid-pregnancy shearing under commercial farming conditions can increase the birthweight of multiple-born lambs and, when the birthweight response is large enough to reduce the numbers of otherwise lightweight lambs, it is associated with an increase in survival rates to weaning.
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Plush, K. J., F. D. Brien, M. L. Hebart, and P. I. Hynd. "Thermogenesis and physiological maturity in neonatal lambs: a unifying concept in lamb survival." Animal Production Science 56, no. 4 (2016): 736. http://dx.doi.org/10.1071/an15099.
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Lamb mortality represents reproductive wastage and an animal welfare concern. While lambs are thought to be at a thermogenic advantage following birth in comparison to other species, death from exposure can still be a major contributor to lamb mortality, largely because of the inclement conditions often prevailing at lambing. For this reason, thermogenesis has been studied extensively in neonatal lambs. Heat is produced in the neonatal lamb by shivering and non-shivering thermogenesis. The latter is heat generated by metabolism of brown adipose tissue (BAT) found largely in the thorax and peri-renal areas of the newborn lamb. Brown adipose tissue differs from normal adipose tissue in that it contains densely packed mitochondria, a high cytochrome c content and a vast vascular network. Heat is generated in BAT by uncoupling of the proton conductance mechanism from ATP production, resulting in heat production instead of stored energy. The ability of lambs to resist cooling differs among individuals and this is likely to be due to both genetic and phenotypic factors. The heritability of cold resistance is moderate-to-high and polymorphic gene markers associated with energy homeostasis and cold-related mortality have been identified. Additionally, several aspects of the phenotype of the lamb have been associated with cold resistance. Most relate to properties of the coat, skin and bodyweight, the latter being particularly important, presumably through effects on surface area to volume ratios and subsequent heat loss. The ability of the neonate to achieve the transition from intra- to extra-uterine life has been termed physiological maturity and is associated with the ability to activate appropriate neuro-endocrinological and behavioural changes that are consistent with homeostasis of energy metabolism. Ways to alter physiological maturity of the lamb, such as nutrition, pharmacology and genetic selection, have been identified, and while these show promising results with regards to thermoregulation, a key limitation of their application has been the lack of a repeatable, representative model of neonatal cold stress. An estimation of the non-shivering component potential of a lamb’s ability to thermoregulate can be derived from norepinephrine challenges, but more useful models of real-world cold stress are climate chambers or controlled water bath tests. Further use of repeatable test models such as these with appropriate neuroendocrine and metabolic metrics will identify key components and markers of physiological maturity associated with lamb thermogenesis and survival.
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Nel, C. L., A. A. Swan, K. Dzama, A. J. Scholtz, and S. W. P. Cloete. "Genetic parameters and trends for lamb survival following long-term divergent selection for number of lambs weaned in the Elsenburg Merino flock." Animal Production Science 61, no. 18 (2021): 1965. http://dx.doi.org/10.1071/an21198.
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Context Mortality of new-born lambs is well known to have important implications for both animal production and welfare. Improving survival rates by genetic selection is very desirable, but the low heritability of survival traits challenges the prospect of useful genetic gain. Aim This study aimed to derive genetic and environmental parameters for lamb survival in the Elsenburg Merino resource flock. It also investigated correlations to possible indicator traits birthweight and birth coat score and reported genetic progress in breeding values for lamb survival following 33 years of divergent selection. Methods The flock was divergently selected for number of lambs weaned and was separated by the High (positive) and Low (negative) selection groups. The pedigree file identified 8138 lambs as the progeny of 273 sires and 2062 dams. The study considered total survival from birth to weaning (Tsv) that was also partitioned into perinatal survival to 3 days of age, and the remaining period. Variance components were derived by linear mixed models by using the ASREML® program. Genetic trends were derived by predicting mean breeding values for selection groups within each year and evaluated by fitting linear and broken-stick regression models. Results Predicted Tsv of H-line lambs (0.81 ± 0.01) was higher (P < 0.01) than that of L-line lambs (0.68 ± 0.01). Heritability was significant but low for survival traits (0.03–0.07), moderate for birthweight (0.16) and high for birth coat score (0.54). Genetic trends of the H-line trended divergently (P < 0.01) to the L-line for survival traits, but a changepoint (P < 0.01) in trend suggested that the H-line reached a selection plateau following 19–22 years of selection. Preceding this period, the rate of genetic change equalled ~1% of the mean for Tsv. Conclusions Despite the low heritability of survival, the genetic trends reported in this study contradicted the premise that genetic selection is not a worthwhile method to reduce incidences of lamb mortality. Implications It is recommended that lamb survival phenotypes should be recorded and incorporated into indices individually where possible, but composite traits are a viable alternative.
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Nel, C. L., A. A. Swan, K. Dzama, A. J. Scholtz, and S. W. P. Cloete. "Genetic parameters and trends for lamb survival following long-term divergent selection for number of lambs weaned in the Elsenburg Merino flock." Animal Production Science 61, no. 18 (2021): 1965. http://dx.doi.org/10.1071/an21198.
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Context Mortality of new-born lambs is well known to have important implications for both animal production and welfare. Improving survival rates by genetic selection is very desirable, but the low heritability of survival traits challenges the prospect of useful genetic gain. Aim This study aimed to derive genetic and environmental parameters for lamb survival in the Elsenburg Merino resource flock. It also investigated correlations to possible indicator traits birthweight and birth coat score and reported genetic progress in breeding values for lamb survival following 33 years of divergent selection. Methods The flock was divergently selected for number of lambs weaned and was separated by the High (positive) and Low (negative) selection groups. The pedigree file identified 8138 lambs as the progeny of 273 sires and 2062 dams. The study considered total survival from birth to weaning (Tsv) that was also partitioned into perinatal survival to 3 days of age, and the remaining period. Variance components were derived by linear mixed models by using the ASREML® program. Genetic trends were derived by predicting mean breeding values for selection groups within each year and evaluated by fitting linear and broken-stick regression models. Results Predicted Tsv of H-line lambs (0.81 ± 0.01) was higher (P < 0.01) than that of L-line lambs (0.68 ± 0.01). Heritability was significant but low for survival traits (0.03–0.07), moderate for birthweight (0.16) and high for birth coat score (0.54). Genetic trends of the H-line trended divergently (P < 0.01) to the L-line for survival traits, but a changepoint (P < 0.01) in trend suggested that the H-line reached a selection plateau following 19–22 years of selection. Preceding this period, the rate of genetic change equalled ~1% of the mean for Tsv. Conclusions Despite the low heritability of survival, the genetic trends reported in this study contradicted the premise that genetic selection is not a worthwhile method to reduce incidences of lamb mortality. Implications It is recommended that lamb survival phenotypes should be recorded and incorporated into indices individually where possible, but composite traits are a viable alternative.
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Alexander, G., D. Stevens, LR Bradley, and SA Barwick. "Maternal behaviour in Border Leicester, Glen Vale (Border Leicester derived) and Merino sheep." Australian Journal of Experimental Agriculture 30, no. 1 (1990): 27. http://dx.doi.org/10.1071/ea9900027.
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Ewe and lamb behaviour in traditional Border Leicesters, Glen Vale Border Leicesters of the NSW Agriculture and Fisheries, Glen Vale x Border Leicester crosses and medium-fine-wool Merinos, all running in paddocks of 3-4.5 ha, were compared in spring 1983 at Glen Innes, N.S.W. Twenty-eight aspects of behaviour with a known or reputed influence on lamb survival, especially of multiples, were examined in undisturbed and contrived situations. The Glen Vales and their crosses were superior to the Border Leicesters and Merinos in behaviour and lamb survival, particularly behaviour concerned with the ability of ewes to keep their lambs together. The study indicates that contrived twin-care tests could form the basis of a selection program to improve maternal care and survival of multiples.
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Brown, D. J., R. M. Jones, and G. N. Hinch. "Genetic parameters for lamb autopsy traits." Animal Production Science 54, no. 6 (2014): 736. http://dx.doi.org/10.1071/an13227.
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Heritabilities and genetic correlations were estimated between individual and composite autopsy traits for lambs autopsied in the Australian Sheep Cooperative Research Centre information nucleus flocks between 2008 and 2011 (n = 3224). Correlations were also estimated between autopsy categories and the production parameters Yearling greasy-fleece weight and Yearling weight, and the potential survival indicator traits: Lamb ease, Thorax circumference and Crown–rump length. All autopsy trait heritability estimates were low (range 0.01–0.04). For all traits, a higher proportion of the variance was partitioned into the maternal permanent environment than the direct effects (range 0.01–0.12), suggesting that selection based on lamb autopsy results would impart little advantage over the lamb survival trait itself in improving lamb survival. Genetic correlations between Lamb ease and all autopsy traits were positive, indicating that birth trauma is related to all causes of lamb deaths and that Lamb ease may be a useful selection criterion in seedstock flocks to reduce overall mortality. There were also positive genetic correlations between Thorax circumference after adjusting for birthweight and two classes of dystocia, as well as a positive correlation between Thorax circumference and incidences of Starvation mismothering, implying that Thorax circumference may be a useful indirect field measurement to reduce death from these causes. Of concern were the antagonistic genetic correlations estimated between Yearling greasy-fleece weight and a composite trait of All Dystocia classes plus Starvation mismothering (0.27 ± 0.15), implying that selection for increased fleece weight could be having a detrimental effect on overall lamb survival.
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Schmoelzl, Sabine, and Fran Cowley. "The case for pre-parturient selenium and iodine supplementation of ewes for improving lamb survival." Animal Production Science 56, no. 8 (2016): 1263. http://dx.doi.org/10.1071/an15362.
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Lamb survival is an issue of high relevance to the Australian sheep industry, as lamb-survival rates have direct bearing on overall reproductive performance of the sheep, and also constitute a main concern from an animal welfare perspective (Mellor and Stafford 2004). Both genetic and management factors play an important role in this complex issue (Hinch and Brien 2014). Ewe nutrition is of particular relevance as the intrauterine growth conditions prepare the lamb for the crucial transition to life outside the uterus. Effects of body condition of the ewe during various stages of the pregnancy have been investigated in detail, yet much less is known about the critical role of micronutrient provision to the ewe. Although several risk factors for selenium (Se) and iodine (I) subclinical deficiencies exist for sheep on pasture in Australia, determining micronutrient status in sheep or pasture is not straightforward. Several studies have separately found effects of Se and I supplementation on lamb survival. Studies investigating the interaction of Se and I supplementation have been few but results have demonstrated an interaction between Se and I. With increased twinning rates as a result of increased selection of numbers of lambs weaned, nutritional demands during pregnancy across flocks are increasing, and effects of micronutrients on lamb health and survival have greater impact. New opportunities in nutritional research are encouraging new studies into the effects of Se and I supplementation on lamb survival.
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Paganoni, B. L., M. B. Ferguson, G. A. Kearney, and A. N. Thompson. "Increasing weight gain during pregnancy results in similar increases in lamb birthweights and weaning weights in Merino and non-Merino ewes regardless of sire type." Animal Production Science 54, no. 6 (2014): 727. http://dx.doi.org/10.1071/an13263.
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Birthweight is the single largest determinant of survival in lambs and can be predicted from ewe liveweight at conception and liveweight changes during pregnancy. These prediction equations are known for Merino ewes, but it is unknown if they are applicable to non-Merino breeds. We tested the hypothesis that increasing conception weights of ewes will increase the birthweights, survival to weaning and weaning weights of their lambs, irrespective of ewe or sire breed, but that non-Merino lamb birthweights would be less responsive than Merino lamb birthweights, to changes in ewe liveweights during pregnancy. Ewe liveweight, lamb birth and weaning weight records from Merino sires mated to Merino ewes (MM), Border Leicester Merino (Maternal) sires mated to Merino ewes, Poll Dorset or Suffolk (Terminal) sires mated to Merino ewes (TM), and Terminal sires mated to Border Leicester Merino ewes (TMAT) were analysed from the 2007 to 2011 lambings of eight information nucleus flocks. Lamb birthweights increased by 0.032 ± 0.0012 kg from MM ewes and 0.024 ± 0.0026 kg from TMAT ewes with every 1-kg increase in conception weight (P < 0.001). Irrespective of breed, for every 1-kg increase in liveweight change during early and late pregnancy, lamb birthweights increased by 0.021 ± 0.0019 kg and 0.034 ± 0.0019 kg and weaning weights by 0.26 ± 0.013 kg and 0.09 ± 0.011 kg, respectively (P < 0.001). Survival to weaning of single, twin and triplet lambs was highest for lambs from TMAT ewes (89.3% ± 1.25, 84.6% ± 1.49 and 73.4% ± 2.35) and lowest for TM ewes (80.2% ± 1.89, 72.8% ± 2.09 and 57.4% ± 2.98; P < 0.001). Coefficients relating ewe liveweight change during pregnancy to lamb birthweights are similar for Merino and Maternal ewes, however conception weights of Maternal ewes are significantly heavier than Merino ewes when run together, and lamb birthweights from Maternal ewes are less responsive to ewe conception weights. The coefficients reported in this paper will enable development of optimum management guidelines for single-, twin- and triple-bearing Maternal ewes.
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Brash, LD, NM Fogarty, and AR Gilmour. "Reproductive performance and genetic parameters for Australian Dorset Sheep." Australian Journal of Agricultural Research 45, no. 2 (1994): 427. http://dx.doi.org/10.1071/ar9940427.
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Reproductive performance of ewes in a large Dorset stud flock is reported. The data included 2488 ewes with 10016 joining records over 25 years. Average performance for reproductive traits were: fertility 92%, litter size 1.31, neonatal lamb survival 91%, lamb survival to weaning 85%, with overall lambs born 1.20 and lambs weaned 1.02 per ewe joined. Differences between breeds (Poll Dorset and Dorset Horn), season of birth (spring and autumn) and season of joining (spring and autumn) were significant for most reproduction traits. Linear and quadratic regressions for age of ewe at joining were highly significant for all traits (P < 0.001) with maximum performance between three and six years of age. Estimates of heritability for ewe reproductive traits were: 0.062 � 0-02 for number of lambs born and 0.04 � 0.01 for number of lambs weaned per ewe joined, and component traits, 0.02 �0 -01 for fertility, 0 08 � 0 -02 for litter size and 0.00 � 0.01 for lamb survival. Estimates of repeatability were less than 0.14 for all the reproduction traits, which resulted in substantially higher predicted heritabilities when repeated records were used. Heritability estimates for average ewe lifetime performance, with approximately four records, were 0.08 � 0 06 for lambs born, 0.12 � 0.05 for lambs weaned, 0.08 � 0.04 for fertility, 0.l9 � 0 -04 for litter size and zero for lamb survival. The genetic correlations between litter size and lambs born and weaned were close to unity, whereas those for fertility were lower and declined from lambs born (0.6l � 0.22) to lambs weaned (0-45 � 0.30). The estimated heritability for ewe longevity, defined as the number of years the ewe remained in the breeding flock, was 0.00 � 0.03. The potential for genetic improvement in reproductive rate is discussed in relation to other reports in the literature and in the context of the roles of the Dorset breed in the Australian lamb industry. Increased reproductive rate in Dorset flocks impacts on stud profitability and the rate of genetic improvement from selection for other traits such as liveweight. The parameter estimates derived will be used in compiling breed-specific parameter sets for genetic evaluation in LAMBPLAN.
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Gootwine, E., A. Bor, R. Braw-Tal, and A. Zenou. "Reproductive performance and milk production of the improved Awassi breed as compared with its crosses with the Booroola Merino." Animal Science 60, no. 1 (February 1995): 109–15. http://dx.doi.org/10.1017/s1357729800008201.
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AbstractOvulation rate, embryo survival, lamb production, lamb survival and milk production of Awassi and BooroolaAwassi crossbred ewes, kept indoors, were compared. Awassi were non-carriers while Booroola × Awassi (F1) and about half of 3/4 Awassi-1/4 Booroola (BQ) ewes were heterozygous at the FecB gene. Mean ovulation rate increased by 1·5 to 1·6 corpora lutea per ewe ovulating and prolificacy by 0·7 lambs born per ewe lambing in Fj and BC1 (B+) ewes as compared with Awassi. Embryo survival rates in BC1 ewes with two, three and four ovulations were 0·83, 0·68 and 0·71, respectively. Lamb survival rates at 1 day of age were 0·93, 0·90 and 0·77 and average birth weight was 4·9, 4·0 and 3·0 kg for lambs born as singles, twins and triplets, respectively. Average milk production of the Awassi was 506 I per ewe per lactation. F1 and BC1 ewes produced respectively, proportionately 0·48 and 0·63 of the Awassi milk production and there was no significant difference in milk production between BC1,(B+) and BC1(++) ewes. The relatively low milk production of the Booroola Awassi crosses suggests that heterosis and recombination effects on milk production were negative. It is concluded that incorporation of the B allele per se can increase lamb production in the Awassi without affecting its milk production.
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Odevci, B. B., E. Emsen, and M. N. Aydin. "Machine learning algorithms for lamb survival." Computers and Electronics in Agriculture 182 (March 2021): 105995. http://dx.doi.org/10.1016/j.compag.2021.105995.
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Hutchison, Dayna, Bronwyn E. Clarke, Serina Hancock, Andrew N. Thompson, Elise Bowen, and Caroline Jacobson. "Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes." Animals 12, no. 4 (February 18, 2022): 513. http://dx.doi.org/10.3390/ani12040513.
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Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared to multiparous ewes was 58% (74 vs. 132%; p < 0.001), and this was attributable to a 50% difference in reproductive rate (109 vs. 159%; p < 0.001) and 16% difference in lamb survival to marking (67 vs. 83%; p < 0.001). The difference in marking rate for maiden Merino two-tooth ewes lambing at approximately 2 years-of-age compared to mature multiparous ewes was 22% (80 vs. 102%; p < 0.001) and this was attributable to a 24% difference in reproductive rate (108 vs. 132%; p < 0.001) and 3% difference for lamb survival (75 vs. 78%; p < 0.05). Positive correlations for reproduction traits (reproductive rate, lamb survival and marking rate) between maidens and multiparous ewes were observed for maiden Merino two-tooth ewes (p < 0.001), but these correlations were weak or non-existent for non-Merino ewe lambs. Strategies to improve both reproductive rate and lamb survival can address the poorer and more variable reproductive performance of maiden ewes.
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Behrendt, R., J. E. Hocking Edwards, D. Gordon, M. Hyder, M. Kelly, F. Cameron, J. Byron, M. Raeside, G. Kearney, and A. N. Thompson. "Offering maternal composite ewes higher levels of nutrition from mid-pregnancy to lambing results in predictable increases in birthweight, survival and weaning weight of their lambs." Animal Production Science 59, no. 10 (2019): 1906. http://dx.doi.org/10.1071/an18505.
Full textAbstract:
Management of nutrition during pregnancy for maternal composite ewes has the potential to improve lamb production and survival in prime lamb production systems but existing condition score (CS) guidelines developed for Merinos may not be appropriate for the optimum production of maternal ewes. To address this, three replicated experiments were conducted at two research sites in Victoria and one in Western Australia. Ewes (781–800 per site) were allocated to four CS treatments following pregnancy scanning (~Day 50) and differentially fed to reach approximate targets of CS 2.4, 2.8, 3.2 and 3.6 by lambing. Single and multiple bearing ewes grazed together, and nutritional treatments were applied until the end of lambing after which ewes and lambs were aggregated into management groups containing all treatments. At lambing, maternal ewe liveweight had a range between treatments of 13.7–19.1 kg (average 16.4 kg) and CS varied by 1.1–1.5 of a CS (average 1.24). Across site analysis indicated that lamb birthweight and weaning weight increased with application of higher CS treatments (P < 0.001). There was also an improvement in survival of multiple born lambs with increasing CS at lambing (P < 0.001). Birthweight was significantly related to survival (P < 0.001) at all sites with no significant effect of birth type on lamb survival. Changes in birthweight and weaning weight could be predicted from ewe joining liveweight, ewe liveweight change to Day 90 and ewe liveweight change Day 90 to lambing. The coefficients derived for each of these effects were similar to those found in previous experiments examining Merino and crossbred Border Leicester Merino ewes. The optimum CS targets for multiple bearing maternal composite ewes may be higher than the industry recommended target for Merino ewes based on advantages in lamb survival and weaning weight.
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Oldham, C. M., A. N. Thompson, M. B. Ferguson, D. J. Gordon, G. A. Kearney, and B. L. Paganoni. "The birthweight and survival of Merino lambs can be predicted from the profile of liveweight change of their mothers during pregnancy." Animal Production Science 51, no. 9 (2011): 776. http://dx.doi.org/10.1071/an10155.
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The single largest influence on the survival of lambs in the first few days of life is their birthweight. Fetal growth and birthweight are regulated by genotype of the fetus, maternal genotype, maternal nutrition and the external environment. In this paper we report the extent to which the changes in maternal liveweight during pregnancy and lactation (liveweight profile) of Merino ewes can be used to predict the birthweight and survival of their progeny to weaning. At two sites [Victoria (Vic.) ~700 ewes and Western Australia (WA) ~300 ewes] in each of 2 years, a similar experiment used adult Merino ewes to explore effects of nutrition from joining to Day 100 of pregnancy and from Day 100 of pregnancy to weaning. The average difference between extreme treatments at Day 100 of pregnancy were 7 kg in ewe liveweight and 0.7 of a condition score (CS) and at lambing 11.9 kg and 1.3 of a CS. This resulted in average birthweights of progeny from different treatments ranging from 4.0 to 5.4 kg and survival to weaning ranging from 68 to 92%. Across the four experiments between 68 and 85% of all lamb deaths to weaning occurred within 48 h of birth. Lambs born to ewes in CS 2 at Day 100 of pregnancy were lighter (P < 0.05) in both years at the Vic. site than those from ewes in CS 3 at Day 100 of pregnancy. Lambs born to the ewes grazing a feed on offer of 800 kg DM/ha during late pregnancy were also lighter than those from other levels of feed on offer between 1100 and 3000 kg DM/ha at the Vic. site in both years and at the WA site in 1 year (P < 0.001). Lambs from the 800 kg DM/ha treatment during late pregnancy at the Vic. site had a lower survival than other treatments, especially in the second year. There were no significant effects of treatments on lamb survival at the WA site; however, the results were in the same direction. The birthweight of individual lambs was significantly related to the liveweight profile of their mothers. Their liveweight at joining, change in liveweight to Day 100 of pregnancy and change in liveweight from Day 100 to lambing all contributed (P < 0.05) to the prediction of the birthweight of their lambs. The responses were consistent across experimental sites and years, lamb birth rank and sex, and confirmed that the effects of poor nutrition up until Day 100 of pregnancy could be completely overcome by improving nutrition during late pregnancy. At the Vic. site, survival to 48 h was most influenced by the birthweight of the lamb and survival was significantly higher in single- than twin-born lambs and female than male lambs after adjusting for differences in birthweight. A higher chill index during the 48 h after birth reduced survival of both single and twin lambs to a similar extent, but reduced survival of male lambs more than female lambs. There were no effects of birthweight or chill index on lamb survival at the WA site where most lambs weighed more than 4 kg at birth and climatic conditions during lambing were less extreme. Overall, these results supported our hypothesis that improving the nutrition of Merino ewes during pregnancy increases birthweight and this leads to improved survival of their progeny.
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Kenyon, P. R., R. G. Sherlock, S. T. Morris, and P. C. H. Morel. "The effect of mid- and late-pregnancy shearing of hoggets on lamb birthweight, weaning weight, survival rate, and wool follicle and fibre characteristics." Australian Journal of Agricultural Research 57, no. 8 (2006): 877. http://dx.doi.org/10.1071/ar05336.
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Pregnancy shearing of mature ewes has been shown to influence lamb birthweight and sometimes lamb survival to weaning and wool follicle characteristics. However, the effects of shearing hoggets in mid- or late-pregnancy under New Zealand’s pastoral conditions have not been examined. This study was designed to determine the effects of mid- and late-pregnancy shearing on lambs born to Romney hoggets. Single-bearing hoggets were either shorn at average day 79 of pregnancy (n = 74), at average day 119 (n = 80), or left unshorn (n = 76) while their twin-bearing counterparts were either shorn at average day 79 of pregnancy (n = 18) or left unshorn (n = 12). Mid-pregnancy shearing was found to increase the birthweights of singles (by 0.32 kg, P < 0.05) in comparison with unshorn ewes; however, this relationship was not observed in twins. Neither mid- nor late-pregnancy shearing affected lamb survival to weaning. Singles born to late-pregnancy shorn ewes had whiter wool (P < 0.05) in comparison with lambs born to unshorn dams. Dam treatment had no other effects on follicle or wool characteristics. The results of this study indicate that mid-pregnancy shearing of hoggets can be used as a technique to increase birthweight in single lambs but not twin-born lambs. Pregnancy shearing had no effect on lamb survival rates to weaning, whereas shearing in late-pregnancy had minor effects on wool colour that would be unlikely to affect wool value in Romneys. Shearing in mid-pregnancy had no effect on either progeny follicle or wool characteristics.
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Kopp, K. J., S. M. Robertson, and M. A. Friend. "Barley grain supplementation in late gestation to twin-bearing Merino ewes grazing high-biomass and high-quality pasture does not increase lamb survival." Animal Production Science 59, no. 3 (2019): 543. http://dx.doi.org/10.1071/an17378.
Full textAbstract:
Survival of lambs affects the profitability of Merino enterprises, with mortality from birth to marking the most prominent factor leading to poor reproductive performance. Survival of lambs following parturition is dependent on the ability to access colostrum and milk, which can be altered by the provision of barley grain to promote lactogenesis and colostrum production when feed availability is suboptimal. The present study evaluated whether the survival of lambs could be improved by supplementing ewes grazing abundant quality pasture with barley grain. Naturally joined Merino ewes (n = 240, 65.5 kg, body condition score (CS) 3) bearing twin fetuses grazing spring pastures (1712 kg DM/ha green, 12.3 MJ ME/kgDM, and 18.5% crude protein at the commencement of the experiment) were allocated to a supplemented or a control diet, with two replicates of each. Ewes were supplemented with 550 g/ewe.day barley grain (12.6 MJ ME/kgDM, 10% crude protein) for 20 days before and 2 weeks following the commencement of lambing (supplemented), or were unsupplemented (control). Ewes gained 0.5 CS and 10.6 kg liveweight from pre-lambing to lamb marking age in both treatments, indicating that their energy intake was high. The proportion of lambs surviving from birth to marking was 0.79 for control and supplemented treatments. Lamb survival was affected by the interaction (P = 0.039) between treatment and sex, with control female lambs having a significantly higher survival than control male lambs. Supplemented lambs reared as singles (17.1 ± 0.95 kg) had significantly (P < 0.05) heavier marking weights thanthe control lambs reared as singles (14.8 ± 1.1 kg), supplemented lambs reared as twins (14.7 ± 0.71 kg) and control lambs reared as twins (15.5 ± 0.70 kg). Lamb survival was not increased by provision of barley grain in the final weeks before lambing and the first 2 weeks of lambing when ewes were in good CS and grazed ample high-quality pastures.
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Robertson, S. M., M. A. Friend, J. C. Broster, and B. J. King. "Survival of twin lambs is increased with shrub belts." Animal Production Science 51, no. 10 (2011): 925. http://dx.doi.org/10.1071/an11006.
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Abstract Perinatal lamb mortality is a major source of reproductive loss, particularly for twins. A study was conducted to determine whether provision of shelter in the form of shrub belts (a ‘maternity ward’) could increase survival of twin lambs compared with hedgerows, and whether hedgerows improve survival of single lambs compared with unsheltered paddocks. Measurements were recorded for Merino × Poll Dorset cross twin lambs born in hedgerows (phalaris or hessian) or shrub belts and single lambs born in hedgerows or unsheltered paddocks over the years 2007–2009. Records for 382 single and 726 twin lambs were used. The survival of single lambs was not increased (P = 0.06) by hedgerow shelter. The survival of twin lambs in shrubs was 10% higher (P < 0.05) than that in hessian hedgerow shelter in 2008–2009 (0.77 cf. 0.70), associated with a reduction in deaths from starvation and/or mismothering and/or exposure. The hessian shelter was associated with an increased (P < 0.05) growth rate to weaning of single lambs, but the growth rates of twin lambs were lower (P < 0.05) in shrub than in hessian shelter. In 2010, a second study of 178 twin Merino × Poll Dorset cross lambs found that survival of lambs born alive was not improved by shrubs compared with unsheltered paddocks (0.80 versus 0.77; P > 0.05). It is concluded that shrub belts which forced twin-bearing ewes to lamb in a sheltered environment reduced perinatal mortality in one of three datasets, but was not repeated. The shrubs take time to establish, and the benefit will be small if weather is mild during lambing.
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Hinch, G. N., and F. Brien. "Lamb survival in Australian flocks: a review." Animal Production Science 54, no. 6 (2014): 656. http://dx.doi.org/10.1071/an13236.
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Lamb survival is known to be a key component of reproductive efficiency in sheep flocks. It has been the subject of a large number of studies over the decades and this review provides an update and insights into the latest understanding of the extent and variability of lamb losses across Australia. The pattern of causes of lamb losses, including dystocia, starvation/exposure, mismothering and predation, are examined. Likewise the importance of birthweight in contributing to such losses is discussed as are strategies for improving lamb survival. The strategies examined include improved ewe nutrition, shelter provision and selection for cold resistance and improved maternal behaviour.
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McCoard, Sue, Shen-Yan Hea, Catherine McKenzie, Kirsty Hammond, and Tim Smith. "Impact of change in body condition score in mid-late pregnancy in ewes fed a mixed diet on lamb survival and performance." Journal of New Zealand Grasslands 82 (October 28, 2020): 211–19. http://dx.doi.org/10.33584/jnzg.2020.82.442.
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The objective of this study was to evaluate the effect that body condition score of pregnant ewes fed on turnip and swede crops during mid-late gestation had on offspring survival and performance. Data were collected from 755 multiparous mixed-age ewes carrying 1–4 fetuses. Ewes grazed a turnip crop for 1 month prior to pregnancy scanning with supplementary ryegrass/clover baleage (~75 days gestation) followed by a swede crop with supplementary Lucerne baleage for 1 month following pregnancy scanning (to ~120 days gestation). Ewe body condition score (BCS) at mating, pregnancy scanning and pre-lambing, along with lamb survival and growth rates to weaning were recorded. Lamb survival from pregnancy scanning to tailing differed by litter size (P<0.001) with lower survival in litters with 3 or more lambs compared to singles and twins which did not differ. Improving BCS from pregnancy scanning to 120 days gestation had a positive effect on lamb survival irrespective of litter size and ewe age (P<0.001). Lamb survival in ewes ≥5 years of age, irrespective of litter size, was lower (P<0.001) compared to 2 or 3–4-year-old ewes, which in turn did not differ from each other. The key finding of the study was that loss in BCS from pregnancy scanning to 120 days gestation, negatively impacted on lamb survival, especially in ewes carrying 3 or more fetuses and in ewes >5 years of age irrespective of the number of fetuses carried. Furthermore, there was high variation in BCS change observed in both early and mid-pregnancy.
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Cloete, S. W. P., and A. J. Scholtz. "Lamb survival in relation to lambing and neonatal behaviour in medium wool Merino lines divergently selected for multiple rearing ability." Australian Journal of Experimental Agriculture 38, no. 8 (1998): 801. http://dx.doi.org/10.1071/ea98095.
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Summary. Two lines of Merino sheep were divergently selected from the same base population since 1986 on maternal ranking values for multiple rearing ability. In the high (H) line, ewe and ram progeny were preferably descended from ewes that reared >1 lamb per joining. In the low (L) line, replacements were the progeny of ewes that reared <1 lamb per joining. Data on lamb mortality, lambing and neonatal behaviour as well as lamb production were obtained from these lines over 5 years (1993–97). Lamb survival was improved (P<0.01) in the H line, mainly as a result of the improved survival of multiples. It was evident that the survival of lambs was not compromised by selection for ewe multiple rearing ability, despite the fact that higher mortality levels are expected with an increase in multiple birth rate. No line difference was found for the time lapse from birth to first standing for >10 s, but H line lambs were quicker (P<0.01) to progress from standing to suckling than L line contemporaries (28 v. 38 min respectively). This line difference remained after adjustment for better co-operation of H line ewes with the first suckling attempts of their progeny. Ewes in the H line tended (P = 0.18) to remain longer on or near their birth sites than L line contemporaries (403 v. 362 min respectively). They also tended to be less (P = 0.07) likely to desert their lambs than L line ewes (12/424 = 0.028 v. 14/230 = 0.061 respectively). After least-squares adjustment for their heavier (P<0.01) litter weight, H line ewes experienced shorter (P<0.05) births than their L line contemporaries (46 v. 57 min respectively). Fewer (P<0.05) H line lambs died during or shortly after parturition (respective proportions of 22/890 = 0.025 and 25/441 = 0.057), while maiden H line ewes were less (P<0.05) likely to be assisted at lambing than L line contemporaries (4/107 = 0.037 v. 8/61 = 0.131 respectively). With regard to overall lamb production, it was found that the number of lambs weaned per ewe present at lambing in the H line was improved (P<0.05) in all years relative to that observed in the L line, the differences ranging from 25% in 1993 to 47% in 1997. Lamb weaning weight was correspondingly improved (P<0.05) in H line lambs, the differences ranging from 8% in 1994 to 22% in 1996. Fairly high levels of production could thus be attained with predominantly pasture-fed ewes selected for multiple rearing ability.
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Ridler, Anne L., Kate J. Flay, Paul R. Kenyon, Hugh T. Blair, Rene A. Corner-Thomas, and Emma J. Pettigrew. "Factors Associated with Mortality of Lambs Born to Ewe Hoggets." Animals 12, no. 3 (January 28, 2022): 319. http://dx.doi.org/10.3390/ani12030319.
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The reproductive performance of ewe hoggets is poorer than that of mature-age ewes due to production of fewer lambs with poorer survival. Scant data are available on the risk factors for, and causes of, the mortality for lambs born to ewe hoggets, the impact of ewe deaths on lamb loss, and the causes of death for lambs born to ewe hoggets vs. mature-age ewes lambing in the same circumstances. In this study, 297 lambs born to 1142 ewe hoggets were necropsied along with 273 lambs born to 1050 mature-age ewes. Low lamb birthweight, multiple litter size, and increasing ewe hogget average daily gain from breeding to late pregnancy were risk factors for lamb mortality. The most common cause of mortality for lambs born to ewe hoggets was stillbirth and the risk factors for stillbirth were similar to those for lamb mortality generally. Approximately 11% of ewe hoggets’ lamb deaths were due to the death of the dam. Causes of mortality differed between lambs born to ewe hoggets vs. those born to mature-age ewes. Management practices to increase ewe hogget lambs’ birthweights (particularly those from multiple litters) and supervision of ewe hoggets at lambing time are recommended.
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Holst, PJ, DG Hall, and CJ Allan. "Ewe colostrum and subsequent lamb suckling behaviour." Australian Journal of Experimental Agriculture 36, no. 6 (1996): 637. http://dx.doi.org/10.1071/ea9960637.
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Behavioural and colostral data were obtained from 70 parous Border Leicester x Merino ewes (and their lambs) that lambed in 0.25 ha paddocks. Data collected included a colostral sample immediately postpartum, lamb weight and temperature, site of parturition and lamb sucking attempts to 48 h post-partum. Colostrum dry matter percentage was 56.5 for ewes with single lambs and 61.5 for ewes with twins (P<0.05). Colostrum colour and consistency score (1-7) of twin-bearing ewes was 5.5 compared with single-bearing ewes of 6.5 (nearer normal milk). Lamb sucking behaviour suggested the more viscous the colostrum, the more often the lamb attempts to suck (P<0.001) and for a longer period at each attempt (P<0.05). This effect diminished over time so that by 24-48 h there was no difference in behaviour expressed as duration x number of sucking bouts, when normal milk would be expected. Twin lambs had significantly more sucking bouts than single lambs up to 4 h post partum. The consequences of these observations would be more serious for twin lamb survival and may explain why some individual twin lambs often die from starvation.
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Gronqvist, G. V., R. E. Hickson, P. R. Kenyon, S. T. Morris, K. J. Stafford, and R. A. Corner-Thomas. "Behaviour of twin- and triplet-born lambs and their dam 3 to 18 hours after birth is not a useful predictor of lamb survival to weaning." Asian-Australasian Journal of Animal Sciences 33, no. 11 (November 1, 2020): 1848–57. http://dx.doi.org/10.5713/ajas.19.0479.
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Objective: An experiment was designed to determine if behaviour traits expressed by twinand triplet-bearing lambs and their dams at 3 to 18 hours of age (after the immediate ewelamb bonding had occurred) were associated with lamb survival to weaning.Methods: The behaviour of twin and triplet lambs and their dams was assessed in the paddock at 3 to 18 hours after birth. Observations were made of the number of high- and low-pitched bleats, time to stand, make contact with dam, suck from dam and follow dam were recorded for each lamb. The maternal behaviour score of each dam was assessed. A random sub-sample of lambs were assessed during a maternal-recognition test at 12 or 24 hours of age. Traits included time spent standing, sitting, walking, time taken to reach the ewes and time spent with the ewes as well as the number of high- and low-pitched bleats emitted by the lamb.Results: In the paddock, for each additional second required for twin-born lambs to follow their dam, lambs were 1.004 (95% confidence interval [CI] 1.000 to 1.008) times more likely to survive to weaning (p<0.05). The opposite relationship, however, was seen in triplet lambs. For each additional second required for triplet-born lambs to follow their dam, lambs were 0.996 (95% CI 0.993 to 0.999) times as likely to survive to weaning (p<0.05). During the maternal recognition test, twin-born lambs were 0.989 (95% CI 0.979 to 1.000) times as likely to survive to weaning for every additional second they took to reach the contact zone (p<0.05). Similarly, triplet-born lambs were 0.994 (95% CI 0.989 to 0.999) as likely to survive for every additional second they took to reach their dam (p<0.05).Conclusion: All ewe behaviours and the majority of lamb paddock and test behaviours were not associated with the survival of twin- or triplet-born lambs and, therefore, are of little use as indicators of lamb survival to weaning.
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Thomas, D. L., Y. M. Berger, and B. C. McKusick. "East Friesian germplasm: Effects on milk production, lamb growth, and lamb survival." Journal of Animal Science 77, E-Suppl (2000): 1. http://dx.doi.org/10.2527/jas2000.77e-suppl1g.
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