Effect of some of genetic and non-genetic parameters on lamb survival in Baluchi, Iranblack and Zandi breed sheep
Message:
Abstract:
Background
Lamb survival is a complex trait that is influenced by the maternal ability, management practices, and environmental variables at the time of birth and during the rearing period.
Objectives
In this study genetic and non-genetic parameters affected on lamb survival from birth to weaning were estimated for Baluchi, Iranblack and Zandi lambs.
Methods
Numbers of observation were 10793, 4826 and 6140 record of lamb survival from birth to weaning for Baluchi, Iranblack and Zandi breeds. Genetic parameters were estimated using restricted maximum likelihood (REML) procedure under 16 different models, inclusive animal, and sire and threshold models by ASReml software. In addition to an animal, sire and threshold models, using a logit link function, were used for analyses of lamb survival. The most appropriate model was determined based on Akaike’s Information Criterion (AIC) method.
Results
Mean of survival was 89.11, 84.44 and 87.37% for Baluchi, Iranblack and Zandi lambs, respectively. The most appropriate model for survival in Baluchi sheep including direct additive genetic effects and common litter effects, for Iranblack sheep including direct additive genetic effects, maternal additive genetic effects, maternal permanent environmental effects, common litter effects and covariance between direct and maternal additive genetic effects. However, the most appropriate model for survival of Zandi sheep only including direct additive genetic effects. The most appropriate model under sire models for Baluchi sheep including direct additive genetic effects and common litter effects, for Iranblack sheep including direct additive genetic effects, maternal permanent environmental effects and common litter effects. Also for Zandi sheep including direct additive genetic effects and maternal permanent environmental effects. Estimated direct heritability for survival with animal model was 0.08±0.01, 0.07±0.02 and 0.09±0.02 which after correction were changed to 0.22, 0.20 and 0.20 for Baluchi, Iranblack and Zandi sheep, respectively. Estimated direct heritability for survival with sire model was 0.06±0.02, 0.06±0.03 and 0.05±0.02 which after correction were changed to 0.17, 0.16 and 0.13 for Baluchi, Iranblack and Zandi sheep, respectively. In addition, the estimation of heritability for lamb survival from threshold model was 0.16±0.04, 0.22±0.07 and 0.17±0.06 for Baluchi, Iranblack and Zandi sheep, respectively.
Conclusions
The results showed that the corrected heritability obtained from animal model and sire model did not differ from the estimated heritability from the threshold model.
Language:
Persian
Published:
Journal of Animal Science Research, Volume:26 Issue: 1, 2016
Pages:
157 to 166
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