Genetic analyses of scrotal circumference size and growth in Rambouillet lambs
Article Abstract:
Testicular weight of a Rambouillet ram is effectively approximated by scrotal circumference (SC). If this trait is a basis for selective breeding, it is important to realize its heritability and other factors affecting testis growth. Data from 541 Rambouillet ram lambs were collected over six years, and models incorporating the different factors affecting testicular and SC growth were constructed to determine the degree of their influence. It was shown that testicular growth from day 90 to day 180 had the greatest heritability and was not influenced by live weight and type of birth.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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Estimation of genetic parameters
Article Abstract:
A flock of Rambouillet sheep was studied for the heritabilities and genetic correlations for and between ovulation rate, scrotal circumference and litter size. Results show that the same set of genes regulate litter size and ovulation rate. There is a corresponding increase increase in litter size together with ovulation rate which is evident in 180-day body weight of litter. There is no sufficient data to correlate scrotal circumference to litter size and ovulation rate.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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Expected responses from alternative selection criteria
Article Abstract:
An experimental flock of Rambouillet sheep was used to compare predicted responses to direct, indirect and combined selection for litter size using genetic parameters. Results show that selection decisions can be improved when data concerning relatives and correlated traits are used instead of litter size record alone. There is a 155% improvement per generation of lambs when selection involves both sexes of lambs, litter size and ovulation rate.
Publication Name: Journal of Animal Science
Subject: Zoology and wildlife conservation
ISSN: 0021-8812
Year: 1992
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