Lamb production from diverse genotypes. 1. Lamb growth and survival and ewe performance

2000 ◽  
Vol 70 (1) ◽  
pp. 135-145 ◽  
Author(s):  
N. M. Fogarty ◽  
D. L. Hopkins ◽  
R. van de Ven
Keyword(s):  
Birth Weight ◽  
Gestation Length ◽  
Weaning Weight ◽  
Growth And Survival ◽  
Frozen Semen ◽  
Lamb Survival ◽  
Lamb Growth ◽  
Sire Breed ◽  
Selection Of ◽  
Birth Type

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).

Genetic evaluation of crossbred lamb production. 1. Breed and fixed effects for birth and weaning weight of first-cross lambs, gestation length, and reproduction of base ewes

2005 ◽  
Vol 56 (5) ◽  
pp. 443 ◽  
Author(s):  
N. M. Fogarty ◽  
V. M. Ingham ◽  
A. R. Gilmour ◽  
L. J. Cummins ◽  
G. M. Gaunt ◽  
...  
Keyword(s):  
Litter Size ◽  
Fixed Effects ◽  
Mixed Model ◽  
Genetic Evaluation ◽  
Gestation Length ◽  
Production Traits ◽  
Weaning Weight ◽  
Frozen Semen ◽  
Lamb Survival ◽  
Sire Breed

This is the first paper in a series that reports on a national maternal sire central progeny test program (MCPT) to evaluate the genetic variation for economically important production traits in first- and second-cross progeny of maternal and dual purpose (meat and wool) sires and the scope for genetic improvement. The MCPT program also provides direct linkages between breeds that will contribute information for across-breed genetic evaluation. Crossbred progeny by 91 sires from more than 7 maternal breeds (including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester) at 3 sites over 3 years with 3 link sires in common at each site and year were evaluated in this study. National estimated breeding values for the sires that were entered by industry breeders indicated that there was some selection for weight, but not other traits and the sires were generally representative of the maternal genetics available to the industry. There were 8377 base Merino and Corriedale ewes artificially inseminated with thawed-frozen semen from the 91 sires and 8193 crossbred lambs born and 6117 lambs weaned. Mixed model analyses of birth and weaning weight, lamb survival, and gestation length as well as fertility, litter size, and lamb weaning rate of the base ewes are reported. Sire breed was significant for birth weight (with a range of 4.0–4.4 kg at an average litter size of 1.8) and weaning weight (19.6–22.5 kg), as well as lamb survival (70–79%) and gestation length (147.1–150.3 days). Birth/rearing type was significant for all traits. Males were significantly heavier than females at birth and weaning, although there was no sex difference for lamb survival or gestation length when birthweight was included in the model. Pregnancy rate from the artificially inseminated base ewes varied from 40 to 84% at the 3 locations in the various years. Sire breed was significant for the number of lambs weaned per ewe lambing, but not for fetal number or litter size born. There were also significant differences in performance due to the source of the base ewes at each site.

Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: genetic analyses of pre-weaning performance of first-cross calves

1980 ◽  
Vol 31 (2) ◽  
pp. 417 ◽  
Author(s):  
R Barlow ◽  
GH O'Neill
Keyword(s):  
Birth Weight ◽  
Genetic Correlations ◽  
Environmental Variation ◽  
Direct Selection ◽  
Gestation Length ◽  
Strongly Correlated ◽  
Weaning Weight ◽  
Selection For ◽  
Sire Breed ◽  
Size At Birth

First-cross calves of Simmental (S), Friesian (F), and Brahman (B) sires were compared with straight-bred calves of Hereford (H) sires over 5 years at Grafton, N.S.W. There was a total of 775 calves sired by 205 bulls with complete records of performance from conception to weaning. Analyses were conducted to determine sire breed and sire breed x environment effects, and to provide paternal half-sib estimates of heritabilities and genetic and phenotypic correlations. Various models were used to ascertain the sensitivity of genetic parameters to the removal of different sources of variation. Among females, S x H were heaviest at birth, while among males, B x H were heaviest. The regression coefficient of birth weight on gestation length was significantly greater for B x H calves than for other crosses. All crosses grew significantly faster to weaning and were significantly heavier at weaning than H x H calves. However, there were a number of significant interactions between sire breed and environmental variables for measures of pre-weaning growth. S x H and F x H calves appeared most sensitive to environmental variation, while B x H appeared least sensitive. The significance of this is discussed. Estimates of heritability for most traits were high. Values derived by using simple models were: gestation length, 0.68; birth weight, 0.56; average daily gain (ADG) to weaning, 0.47; weaning weight, 0.54; eyelid pigmentation, 0.50. Heritabilities of birth weight and ADG during the early pre-weaning period appeared most sensitive to the amount of environmental variation removed in the model. Gestation length was positively correlated with size at birth but negatively correlated with growth to weaning. There were large positive genetic correlations among various measures of size at birth, and among various measures of growth to weaning. When compared with ADG to weaning, weaning weight was more strongly correlated with birth weight, but less strongly correlated with gestation length. The results also indicated that selection for gain over a fixed time period, immediately prior to weaning, would be as efficient as direct selection for total ADG to weaning.

Supplementation of high fecundity Border Leicester x Merino ewes with a high protein feed: its effect on lamb survival

1996 ◽  
Vol 36 (2) ◽  
pp. 129 ◽  
Author(s):  
GN Hinch ◽  
JJ Lynch ◽  
JV Nolan ◽  
RA Leng ◽  
BM Bindon ◽  
...  
Keyword(s):  
Birth Weight ◽  
Litter Size ◽  
Protein Supplement ◽  
High Fecundity ◽  
Lamb Survival ◽  
Staple Strength ◽  
Protein Feed ◽  
Lamb Growth ◽  
Positive Effect ◽  
Sire Breed

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.

scholarly journals Farklı Yaşlarda Sütten Kesimin Prolifik ve Terminal Irk Melez Kuzuların Büyüme Özellikleri ve Yaşama Güçleri Üzerine Etkisi

2020 ◽  
Vol 8 (11) ◽  
pp. 2255-2260
Author(s):  
Müzeyyen Kutluca Korkmaz ◽  
Ebru Emsen
Keyword(s):  
Weight Gain ◽  
Birth Weight ◽  
Growth Performance ◽  
Live Weight ◽  
Weaning Weight ◽  
Growth And Survival ◽  
Sex Effect ◽  
Different Ages ◽  
Weaning Age ◽  
Birth Type

In this study, we compared the growth and survival characteristics of Romanov × Morkaraman (F1 Rom), Romanov × F1 Romanov (G1 Rom) and Charollais × F1 Romanov (Charom) crossbreed lambs weaning weight at different ages. After birth, from three genotypes lambs were weaned at two different ages of 50 and 75 days and growth performance after weaning was examined at 120 days of age. The effect of three different genotypes and birth type on birth weight was very important, and sex effect was insignificant. In weaning weight, only the effect of birth type was found to be significant. Lamb birth and weaning weights were in Charom, F1 Rom, G1 Rom lambs, 3.38-15.28; 3.98-15.04; 3.21-15.55 kg, respectively. The type of birth showed variation in the birth weight of the lamb and the decrease in lamb birth weights (Single: 4.19 kg: Twin: 3.42 kg; Triplet: 3.15 kg and Quadrature: 2.88 kg) was observed as the number of offspring increased. The effect of the birth type on weaning weights was similar in single and triplet. Single-born lambs have higher weaning weights than those of twins and quadruplets. Average daily live weight gain (ADG) from weaning in single lambs, 247.37 g were found higher than twin (190.67 g), triplets (201.44 g) and quadruplets (178.57 g). The effect of weaning age was insignificant on weaning weights. The first month weight after weaning, effect of the genotype of the lamb, the birth type and the sex were insignificant; but effect of weaning age was significant weaning weights and first month after weaning weights the ADG. The late weaned lambs had higher next first month live weight (18.62-17.89 kg) and ADG (179.45-81.32 g). The live weights of the lambs on the 120 days were similar and none of the factors investigated were found to be effective.

scholarly journals KAJIAN PERFORMA BOBOT PRASAPIH DOMBA GARUT DI UPTD-BPPTDK MARGAWATI GARUT (Study on the Performance of Preweaning Weight of Garut Sheep at UPTD-BPPTDK Margawati Garut)

2020 ◽  
Vol 8 (1) ◽  
pp. 15-21
Author(s):  
Ayu Kamila Haya ◽  
Asep Anang ◽  
Denie Heriyadi
Keyword(s):  
Birth Weight ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Duncan Multiple Range Test ◽  
High Demand ◽  
Weaning Weight ◽  
Factors Affecting ◽  
Range Test ◽  
Selection Of ◽  
Birth Type

The development of local genetic resources is important to meet the need of high demand of lamb meat in Indonesia, especially in West Java, through the selection of superior breeds of Garut sheep. The selection has to be initiated by studying the Garut sheep performances to determine the environmental factors affecting the preweaning performances of the sheep and involving those factors in the analysis of genetic parameters. The study was held on the Unit Pelayanan Teknis Dasar Balai Pengembangan Perbibitan Ternak Domba dan Kambing (UPTD-BPPTDK) Margawati Garut from August 21st to September 18th, 2019. The purpose of this experiment was to study the effect of sex and litter size on preweaning weight, i.e birth weight, weight on 30, 60, 90 days, and weaning weight (100 days). The traits were analyzed on 6.349 heads, 3.214 rams, and 3.135 ewes, from 2012 to 2019 using the General Linear Model (GLM) and Duncan multiple range test of SAS 9.0 software. The fixed effects used in the analysis were the sex and the birth type. The results showed that the performance of Garut Sheep based on the preweaning weight was affected significantly (P<0.05) by the sex, with the average of birth weight, 30, 60, 90 days weight and weaning weight (100 days) were 2.46 kg, 5.64 kg, 7.73 kg, 9.92 kg, 10.97 kg (rams) and 2.33 kg, 5.42 kg, 7.34 kg, 9.36 kg, and 10.28 kg (ewes). The pre-weaning weight was also significantly affected (P<0.05) by the birth type, in which  the average of birth weight, 30, 60, 90 days weight and weaning weight (100 days) were 2.96 kg, 6.49 kg, 8.98 kg, 11.29 kg, 12.52 kg (single), 2.25 kg, 5.09 kg, 6.78 kg, 8.71 kg, 9.52 kg (twin), 1.79 kg, 4.62 kg, 6.24 kg, 8.09 kg, 8.92 kg (triplet), 1.54 kg, 4.53 kg, 5.89 kg, 7.15 kg, 8.03 kg (quadruplet), and 1.51 kg, 3.84 kg, 5.23 kg, 6.58 kg, 7.15 kg (quintuplet). Based on the results, preweaning weight must be corrected by the sex and the birth type before the genetic parameters are analyzed to avoid bias of selection results.

Comparative farrowing to weaning performance in Meishan and Large White pigs and their crosses

1995 ◽  
Vol 60 (2) ◽  
pp. 269-280 ◽  
Author(s):  
G. J. Lee ◽  
C. S. Haley
Keyword(s):  
Birth Weight ◽  
Standard Deviation ◽  
Litter Size ◽  
Large White ◽  
Weaning Weight ◽  
Growth And Survival ◽  
Probability Of Survival ◽  
Litter Weight ◽  
Litter Traits ◽  
Breed Differences

AbstractGrowth and survival from birth to weaning were monitored during three generations of crossbreeding between British Large White (LW) and Chinese Meishan (MS) pigs. The design allowed comparisons between sow genotypes ranging from zero to all MS genes, which were mated toLWor MS boars, to produce progeny with proportions of 0·0 to 0·5 or 0·5 to 1·0 MS genes, respectively. Crossbreeding parameters of both maternal and direct piglet performance were estimated for the first two parities using restricted maximum likelihood (REML) methods for litter traits (litter weight at birth, litter mean and within litter standard deviation of piglet weight at birth, proportion surviving to weaning, litter size and weight at weaning and litter mean piglet weight at weaning) and for traits of the piglet (birth weight, probability of survival and weaning weight). For litter traits, the estimated contribution of the additive maternal effect to the breed differences (MS-LW) was significant for litter mean piglet birth weight (–0·46 (s.e. 0·04) kg), survival to weaning (0·15 (s.e. 0·02)), litter size at weaning (1·6 (s.e. 0·16) piglets), litter weaning weight (–11·2 (s.e. 3·8) kg) and litter mean piglet weaning weight (2·54 (s.e. 0·24) kg). Adding litter size and litter mean piglet birth weight to the model removed the additive maternal contribution to the breed differences in survival, and litter size and reduced that for litter mean piglet weaning weight. The contribution of the direct additive effect to the breed difference (MS-LW) was significant for the within litter standard deviation in birth weight (0·018 (s.e. 0·006)), survival to weaning (0·12 (s.e. 0·02)) and litter size (1·12 (s.e. 0·64)) and weight (11·6 (s.e. 4·0) kg) at weaning, but not for piglet weight at birth or weaning. Fitting litter size and litter mean birth weight had comparatively little impact on the direct additive effects. There were significant maternal heterosis effects for litter weight at birth and litter size and weight at weaning, the estimated deviation of the F1 from the midpoint of the two purebreds 3·22 (s.e. 0·55) kg, 2·20 (s.e. 0·47) piglets, and 20·1 (s.e. 3·3) kg respectively, but none for survival or piglet weights. There were direct heterosis effects for litter weight and litter mean piglet weights, the estimated deviation of the Fjfrom the mid point of the two purebreds being 1·16 (s.e. 0·41) kg and 0·14 (s.e. 0·02) kg, for survival to weaning (0·04 (s.e. 0·02)) and for litter weight (11·2 (s.e. 2·5) kg) and litter mean piglet weight (0·96 (s.e. 0·17) kg) at weaning. Fitting litter size and litter mean piglet birth weight removed or reduced both maternal and direct heterosis effects. Individual piglet analyses gave similar results to analyses of the equivalent sow trait. It was concluded that in litters born to MS cows, the lower piglet survival and lower weaning weights were related to the larger litter sizes and lower piglet birth weights. For their birth weight, however, MS piglets have a greater ability to survive and thrive. The large direct and maternal heterosis effects observed for litter and mean piglet weight at weaning werepartly associated with the heavier birth weight of the crossbred piglet.

The effect of nutrition in mid pregnancy and ewe liveweight change on birth weight and management for lamb survival in highly fecund ewes

1992 ◽  
Vol 32 (1) ◽  
pp. 1 ◽  
Author(s):  
NM Fogarty ◽  
DG Hall ◽  
PJ Holst
Keyword(s):  
Birth Weight ◽  
Treatment Period ◽  
Litter Size ◽  
Late Pregnancy ◽  
Weather Conditions ◽  
Gestation Length ◽  
Nutritional Treatment ◽  
Lamb Survival ◽  
Staple Strength ◽  
Fleece Weight

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

Influence of shearing regime and grass silage quality on the performance of pregnant ewes

1990 ◽  
Vol 51 (3) ◽  
pp. 573-582 ◽  
Author(s):  
Heather J. Black ◽  
D. M. B. Chestnut
Keyword(s):  
Birth Weight ◽  
Weight Change ◽  
Live Weight ◽  
Milk Composition ◽  
Gestation Length ◽  
The Mean ◽  
Silage Quality ◽  
Carry Over ◽  
Lamb Growth ◽  
Carry Over Effect

ABSTRACTThe performance of housed ewes, shorn at various stages during pregnancy and offered silages ad libitum made from grass harvested at two contrasting stages of growth, was studied. The mean increase in silage dry matter (DM) intake due to shearing (0·11 kg/day; P > 0·05) was small in comparison with that resulting from offered earlier-cut silage (0·27 kg/day; P < 0·001). The mean increase in twin lamb birth weight from ewes shorn at least 6 weeks before lambing was almost 1 kg per lamb (P < 0·01) with no significant effect on ewe live-weight change. Greatest increase in lamb birth weight (1·11 kg; P < 0·01) was produced by shearing several times during pregnancy, with least response (0·23 kg; P < 0·05) from shearing once only, 4 weeks before lambing. The effect of silage quality on lamb birth weight was not significant, despite the large difference in DM intake of the two silages. This difference in intake was reflected by ewe live-weight change over pregnancy with those ewes offered early-cut silage gaining 5·57 kg while those offered late-cut silage lost 4·53 kg (P < 0·001). There was a marked fall in respiration rate and rectal temperature after each shearing and, compared with shorn ewes, unshorn ewes had a mean gestation length which was 2·04 days shorter (P < 0·01). In terms of lamb growth rates, ewe milk yields and milk composition, the performance on all treatments after turn-out to pasture was satisfactory and no significant carry-over effect of treatments applied during pregnancy were observed during the first 5 weeks of lactation.

MASS SELECTION FOR POST-WEANING GROWTH IN SWINE. V. CORRELATED RESPONSE OF REPRODUCTIVE TRAITS AND PRE-WEANING GROWTH

1976 ◽  
Vol 56 (4) ◽  
pp. 791-801
Author(s):  
I. GARNETT ◽  
G. W. RAHNEFELD
Keyword(s):  
Birth Weight ◽  
Average Daily Gain ◽  
Reproductive Traits ◽  
Correlated Response ◽  
Mass Selection ◽  
Gestation Length ◽  
Control Line ◽  
Weaning Weight ◽  
Selection For ◽  
Daily Gain

Female reproductive performance and pre-weaning survival and growth were examined in a population of swine over 11 generations of selection for post-weaning average daily gain (ADG). Three separate breeding groups were used: (1) a Lacombe (L) line selected each generation for ADG, (2) a Yorkshire control (Y) line, and (3) a crossbred Lacombe × Yorkshire group (LY) generated each generation from the L and Y lines. Breeding group differences were evident for litter size, perinatal mortality, pre-weaning mortality, gestation length, birth weight, pre-weaning average daily gain (PreADG) and weaning weight. Selection did not affect number born, number born alive, number weaned or birth weight. When the values for the L line were expressed as a deviation from the control, pre-weaning mortality showed an increase. The increase appeared to be due to a decrease in the control rather than an increase in the L line. Gestation length showed a negative response to selection. As in the case of pre-weaning mortality, the response appeared to be a reflection of the instability of the control line. Genetic gains in PreADG of 0.004 kg/day/generation were realized in both the L line and LY group. Correspondingly, responses of 0.18 and 0.19 kg/generation were realized for weaning weight in the L line and LY group.

The comparative productivity of five ewe breeds. 1. Lamb growth and survival

1980 ◽  
Vol 20 (104) ◽  
pp. 272 ◽  
Author(s):  
KD Atkins
Keyword(s):  
Growth Rate ◽  
Birth Weight ◽  
Survival Rate ◽  
Agricultural Research ◽  
Research Station ◽  
Dual Purpose ◽  
Growth And Survival ◽  
Body Weights ◽  
Formed Part ◽  
Lamb Growth

An experiment was conducted at Temora Agricultural Research Station to compare birth weights, growth rates to weaning, and survival of lambs from five breeds. These data formed part of a larger study comparing the productivity of these breeds as possible dual-purpose ewe breeds. The breeds were a Border Leicester X Merino fixed halfbred (BLM), Corriedale, Polwarth, and a South Australian strong wool (S.A. Merino) and a medium wool Peppin strain of Merino. The descending order of ranking of the breeds on birth weight and growth rate to weaning was BLM, Corriedale, S.A. Merino, Polwarth and Peppin Merino. A significant breed x year interaction in pre-weaning growth rate was recorded, since the absolute differences between breeds increased as the overall mean growth rate increased. Breed means for the survival rate of single-born lambs ranged from 80.7 to 86.4 lambs weaned per 100 lambs born and they were not significantly different from each other. The mean survival rate of multipleborn lambs from the S.A. Merino and Polwarth breeds were 65.0 and 69.5 respectively, and these were significantly lower than the survival rate of multiples from the other breeds (76.8 to 80.4). Within breeds, birth weight was found to be positively related to survival at low birth weights but negatively related to survival at high body weights

Sign in / Sign up

Export Citation Format

Share Document