• Asian-Australasian Journal of Animal Sciences
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• v.13 no.3
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• pp.292-299
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• 2000

Forty-four Javanese thin-tail ewes were used to study the effect of superovulation prior to mating and of ration quality on lamb birth weight at parturition. Twenty-two ewes weaning at least one lamb were used to measure lamb preweaning growth. Prior to mating, the experimental ewes were injected twice with prostaglandin, with an 11 d interval between injections to synchronize the estrous cycle. At the last prostaglandin injection, 24 ewes were also injected with 700 IU of pregnant mare serum gonadotropin (PMSG) to stimulate superovulation and the remainder were injected with saline as control. During pregnancy and lactation, the experimental ewes were fed either on a low (12% CP and 65% TDN) or a high (15% CP and 75% TDN) quality ration. During lactation, the milk was collected twice a day and was refed to the lambs by bottle feeding immediately after collection. Superovulation or ration quality as a main factor did not significantly affect lamb birth weight. Litter size significantly affected lamb birth weight (p<0.05), and there was an interaction of superovulation and litter size. Nonsuperovulated ewes giving birth to multiple lambs had significantly lower average lamb birth weight (1.34 kg) as compared to those giving birth to a single lamb (1.97 kg) (p<0.05). However, superovulated ewes giving birth to multiple lambs had no significant difference in average lamb birth weight (1.68 kg) as compared to those giving birth to a single lamb (1.91 kg) (p>0.05). Superovulation of ewes prior to mating resulted in a significant improvement in lamb birth weight in the multiple litter size, without significant effect on average preweaning daily gain (p=0.07). Superovulation had a promising use in improving animal production through improvement of prenatal growth during pregnancy and milk production during lactation.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.3
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• pp.469-473
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• 1992

Data on the birth weight, 8 week body weight and ewe body weight of an unselected random mating Romney Marsh sheep flock are analyzed to study the influence of various environmental factors. The average birth weight of lambs was 5.06 kg. Sex of lamb, birth type and dam age contributed significant variation in lamb birth weight (p < 0.05). Males were significantly heavier than females (p < 0.05) and singles were significantly heavier than multiples (p < 0.05) at birth. Birth weight of lamb increased with the progress of dams' age. The overall average 8 week body weight of lambs was 20.84 kg. Effect of birth weight, sex, birth type and dam age was significant on 8 week body weight of lamb. Eight week body weight increased with the increase of lamb birth weight (b=1.285 kg). Ewes' body weight taken before tupping was affected by ewes' age, year of performance and their weight at birth. It was concluded that performance data on lamb birth weight, 8 week body weight and ewe body weight should be corrected for the above relevantly significant environmental factors in any genetic calculation in the United Kingdom Romney March sheep.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1669-1673
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• 2004

Milk yield, lamb birth weight and weaning weight responses to shearing during winter in sheep were investigated. A total of 46 Karayaka ewes were allocated into two treatment groups. Pregnant ewes in one group were shorn on day 100 of gestation (Shorn, n=24) and the remaining ewes were left unshorn to serve as controls (Unshorn, n=22). The ewes were maintained on pasture during the day and housed in the evenings. Lamb birth weight, weaning weight and ewes'' daily milk yield in fifteen dayintervals until weaning (75 days) were recorded. Shearing ewes on day 100 of pregnancy increased gestation length (p<0.01) compared to unshorn ewes (147.8${\pm}$0.45 vs. 145.9${\pm}$0.42 days). Birth weights of lambs from shorn ewes on day 100 of their pregnancy were higher (p<0.01) than those from unshorn ewes (3.7${\pm}$0.11 vs. 3.2${\pm}$0.07 kg). Shearing pregnant ewes increased (p<0.05) the lamb weaning weight at day 75 post-lambing (23.6${\pm}$1.10 vs. 19.5${\pm}$0.91). It also increased milk yield (p<0.05). Milk yields on day 75 of lactation were 302${\pm}$33 and 425${\pm}$25 g per day for unshorn and shorn ewes on day 100 of pregnancy, respectively. Lamb survival at weaning was higher (p<0.05) in lambs from shorn ewes compared to those from unshorn ewes. In conclusion, shearing pregnant ewes in winter months enhanced milk yield, lamb birth weight, lamb weaning weight and lamb survival. It is suggested that increasing both lamb birth weight and subsequent milk yield of dams by shearing ewes on day 100 of pregnancy during winter may improve postnatal lamb viability.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.3
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• pp.371-375
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• 2008

This study investigated the effects of maternal undernutrition during late pregnancy on lamb birth weight. 45 Mongolian ewes, synchronized for oestrus and then mated, were divided into four groups and offered 0.86 MJME/kgw-0.75d-1 (control group; CG : ad libitum access to feed), $0.44MJME/kgw^{-0.75}d^{-1}$ (Restricted Group 3; R3), $0.33MJME/kgw^{-0.75}d^{-1}$ (Restricted Group 2; R2) and $0.20MJME/kgw^{-0.75}d^{-1}$ (Restricted Group 1; R1) respectively during late pregnancy (90-150 days). During restriction, maternal net body weight loss, insulin and NEFA concentrations and lamb birth weight were measured. The results indicated that loss of maternal body weight in R3, R2 and R1 was 4.42, 7.23, 11.13 kg respectively, which was significantly (p<0.01) higher than that in CG (0.93 kg). Insulin concentrations of the ewes in R1, R2 and R3 were lower and were significantly different (p<0.05) between restricted groups and CG at 124 d of pregnancy. NEFA concentrations in all groups tended to decrease from 90d of gestation to parturition and in R1 were significantly (p<0.05) lower than in CG at 124 d of gestation. Lamb birth weight in R1 was significantly lower than in R2, R3 and CG (p<0.05). In conclusion, with decreasing supply of maternal nutrition, the retardation of fetal growth became worse. When the plane of nutrition was below $0.33MJME/kgw^{-0.75}d^{-1}$, significant effects of maternal undernutrition on lamb birth weight were observed.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.1
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• pp.29-35
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• 1995

A selection experiment with Romney Marsh sheep was used to evaluate correlated responses to selection. The selected flock was formed in 1979 by the Romney Group Breeders where selection was for prolificacy, defined as the number of live lambs born per ewe joined per year and a randomly selected control flock was established in 1982. Selection for prolificacy resulted in (i) increased ewe fertility, (ii) increased ewe ovulation rate, (iii) increased ewe litter size, (iv) decreased ewe body weight, (v) decreased lamb birth weight and (vi) decreased lamb 8-week weight. The rates of correlated responses per year respectively for ewe fertility, ewe ovulation rate, ewe litter size, ewe body weight, lamb birth weight and lamb 8-week weight were 0.033(0.002), 0.043(0.016), 0.019(0.005), -0.017(0.066), -0.055(0.025) and -0.150(0.057).

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.61-67
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• 1999

Data from 22837 lambings of Lohi and Kajli ewes from 1962 through 1994 were used to analyse productive and reproductive traits and wool production, Overall litter size at birth averaged 1.33 being 1.45 for Lohi and 1.21 for Kajli ewes. The corresponding values at weaning were 1.23, 1.32 and 1.14, respectively. Litter size was consistently lowest for one year old, with a substantial increase at two, three and four years of ewe age and marginal increase thereafter, Ewes lambing in spring weaned 0.08 more lambs per parturition than ewes lambed in Autumn (p<0,01). Lamb birth weights were affected by ewe breed (p<0.01) and increased with ewe age. Overall lamb weaning weight (120 d) of 17993 lambs was 20.3 kg. Weaning weight was affected by breed, sire, year of birth, sex, rearing rank and weaning age (p<0.01). The highest mean weaning weight was 21.9 kg for Lohi lambs followed by Kajli lambs (18.8 kg), Lambs from Kajli ewes were 9% heavier at birth but 14% lighter at weaning. Twin born lambs were 18% lighter at birth and 13% at weaning than single born lambs. Male lambs were 3% heavier at birth and 4.5% heavier at weaning than female lambs. Overall annual mean wool production was 2,64 kg, Kajli ewes were heavier at breeding than Lohi ewes (i.e. 46.2 vs 44.8 kg). Lohi ewes being 3% less body weight produced 38% more wool and 18% more litter weaning weight than Kajli ewes, When average weight of lamb weaned per ewe weaning lambs was adjusted for ewe average metabolic body size, Lohi ewes were most efficient (i.e. arbitrary assigned value of 100) compared to Kajli ewes achieving only 83% of Lohi level.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.4
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• pp.459-464
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• 2009

Data and pedigree information for Lori-Bakhtiari sheep used in this study were 6,239 records of lamb mortality from 246 sires and 1,721 dams, collected from 1989 through 2007 from a Lori-Bakhtiari flock at Shooli station in Shahrekord. The traits investigated were cumulative lamb mortality from birth up to 7 days, up to 14 days, up to 21 days, and up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 months of age. The models included fixed factors that had significant effects and random direct genetic, maternal genetic and maternal permanent environmental effects. Variance components were estimated using the restricted maximum likelihood procedure applying three animal models with and without maternal and common environmental effects. The overall mean of cumulative lamb mortality rate was 22.95% from birth to 1 year of age, while the overall mortality rate up to 3 and from 3 to 6 months of age was 6.14% and 12.76%, respectively. The mortality rate after 6 months of age declined as the lambs grew older. The age of dam had no important effect on lamb mortality. The type of birth was more important during the preweaning period than at later ages, and lamb mortality rate was higher in twins. The year of birth, month of birth and sex of lamb significantly (p${\leq}$0.01) affected the cumulative lamb mortality rate at all ages. The least square mean of mortality during the final one-third of the lambing period was higher than the first and middle onethird of the lambing period. Male lambs were found to be at a higher risk of mortality than females. Birth weight of the lamb had a highly significant (p${\leq}$0.01) effect on lamb mortality at all ages as a quadratic regression. Direct and maternal heritability estimates of lamb mortality ranged from 0.01 to 0.13 and 0.01 to 0.05, respectively. Direct heritability increased with age of lamb, while maternal effects (genetic and common environmental) were important in the preweaning period. These results indicate that lamb mortality can be reduced first through farm management practices and secondly by genetic selection. Both animal and maternal effects should be considered in breeding programmes for reducing lamb mortality at preweaning.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.828-833
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• 2002

Thirty mature pregnant ewes of the Phan Rang breed with an initial live weight of 30 to 45 kg were used to compare the effects of three different diets in late pregnancy on ewe and lamb performance. All diets contained 20% of whole sugar cane, 16% rice bran, 26% cassava root and 6% molasses urea block. The remaining 32% of dry matter consisted of Jackfruit (JF diet), 16% each of Jackfruit and Cassava foliage (JF+CS diet) or Jackfruit and Flemingia foliage (JF+FM diet). The diets were fed at 3.5% of actual BW of the individual animal. The foliages were offered at 120% of the amount decided in the diets of the requirements. The JF+CS diet resulted in significantly higher feed intake than the JF diet, and also a higher feed intake than the JF+FM diet, but this difference was not significant. The ewe weight changes during the last 8 weeks of pregnancy, or from start to 24 h after lambing, were significantly different. The highest weight gain was obtained from the ewes fed the JF+CS diet. Diets had no effect on weight changes of ewes during 3 weeks after lambing but a significant effect on the litter birth weight, with the JF+CS diet giving the highest litter birth weight. There was, however, no effect on the litter weight at 21 days or litter growth rate from birth to 21 days due to the experimental diets.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1690-1694
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• 2002

Genetic parameters were estimated for birth weight and weaning weight from three year (1991-1993) data totalling 1100 records of 25 rams to 205 ewes of Indigenous Sabi flock maintained at Grasslands Research Station in Zimbabwe. AIREML procedures were used fitting an Animal Model. The statistical model included the fixed effects of year of lambing, sex of lamb, birth type and the random effect of ewe. Weight of ewe when first joined with ram was included as a covariate. Direct heritability estimates of 0.27 and 0.38, and maternal heritability estimates of 0.24 and 0.09, were obtained for birth weight and weaning weight, respectively. The total heritability estimates were 0.69 and 0.77 for birth weight and weaning weight, respectively. Direct-aternal genetic correlations were high and positive. The corresponding genetic covariance estimates between direct and maternal effects were positive and low, 0.25 and 0.18 for birth weight and weaning weight, respectively. Responses to selection were 0.8 kg and 0.14 kg for birth weight and weaning weight, respectively. The estimated expected correlated response to selection for birth weight by directly selecting for weaning weight was 0.26. Direct heritabilities were moderate; as a result selection for any of these traits should be successful. Maternal heritabilities were low for weaning weight and should have less effect on selection response. Indirect selection can give lower response than direct selection.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.890-894
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• 2002

The accuracy of the gamma function to describe lactation curve of Yankasa ewes was investigated using milk production data obtained from 168 ewes with either complete or incomplete 84 day lactation records. Ewes were daily hand milked after over-night separation from lamb and thorough disinfection of the udder. The daily milk yield on the average was estimated from the weekly total yield. The effect of type of birth, parity, season of birth and lactation length on the components of lactation curve (a, b, c and s) were analysed by least-square procedures. All factors except parity significantly (p<0.01) influenced the curve parameters. The goodness of fit of the function did not differ between the two classes of varying duration of lactation; incomplete lactation however, showed a lower persistency and as expected lower level of production. Correlations ($r_p$) between lamb weight gain and milk yield using the weight records from lamb weighed at weekly intervals indicated a high and positive relationship in the early lactation that decreased in intensity as the lactation advanced.