Affiliation:
1. Department of Animal Sciences, University of Tabriz, Tabriz, Iran
2. Department of Animal Science, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Iran
Abstract
This study aims to evaluate the genetics of imported semen and assess the
genetic trend of production traits in Holstein cows during their first
lactation in Iran. The data was collected from 28 different herds in Isfahan
province between 2011 and 2020. Variance-covariance components were
estimated by the restricted maximum likelihood method and the single and
multi-trait animal model. The correlation between breeding values for bulls
reported in catalogs and estimated in this was calculated. The mean of the
least squares by countries shows that the daughters of Spanish bulls have
the highest average for milk production, and the daughters of German,
French, Spanish, and American bulls have the highest average percentage of
fat and protein and the amount of fat and protein, respectively. Estimated
heritability for milk production, fat, and protein percentage, and the
amount of fat and protein were 0.34?0.011, 0.48?0.021, 0.41?0.016,
0.40?0.090, and 0.39?0.010 respectively. The mean genetic trend of milk
production, fat percentage, protein percentage, fat content, and protein
content were 92, 0.010, 0.004, 1.73, and 2.52, respectively. The correlation
between the estimated and reported breeding value of bulls for milk
production trait, percentage of fat and protein, and the amount of fat and
protein was estimated at 0.48, 0.67, 0.69, 0.14, and 0.26, and all of the
estimated correlations are statistically significant at the level of 0.05.
Based on the results for the most critical production trait in Isfahan
herds, milk production, American bulls have the best performance and genetic
trend.
Publisher
National Library of Serbia
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