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Asian Journal of Animal Sciences
  Year: 2013 | Volume: 7 | Issue: 1 | Page No.: 22-29
DOI: 10.3923/ajas.2013.22.29
 
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Use of Random Regressions for Estimating Heritability of Body Scores in Adapted Saudi Holstein Cows

F.S. Al-Hur

Abstract:
The objective of this study was to estimate the heritability and variance component of Body Condition Score (BCS) of adapted Holstein Friesian in the Kingdom of Saudi Arabia (KSA). The analysis of test day records for dairy cattle and covariance functions of random regression analysis allowed a continuous change of variances and co-variances of BCS on different lactation parts, cow ages and levels of daily milk production. Quadratic Legendre polynomials were used to estimate (co)variances of random effects. A model for analyzing test day records containing both the fixed and random regression coefficients was applied for genetic evaluation of first three lactations. Data was 45,349 BCS observations from calvings between 1989 and 1998 from four different dairy herds in KSA. Each evaluated animal received at least two measurements for BCS representing the random regression coefficients. Three genetic measures of BCS such as cow age, days in milk and the levels of daily milk production were compared. Overall means of BCS across early, mid and late part of production live were 2.8±0.10, 3.3±0.05 and 2.9±0.04, respectively. Based on the random regression solutions, the estimated heritability ranged from 0.19-0.53 for various parts of lactation and 0.02-0.48 across different cow age for BCS. The highest estimate of heritability of BCS based on random regression function of daily milk yield was 0.37 at 10 kg day-1. The corresponding lowest estimate of heritability was 0.26 at 35 kg day-1. The study showed a potential of using random regressions for estimating heritability in adapted animals under different environments.
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How to cite this article:

F.S. Al-Hur , 2013. Use of Random Regressions for Estimating Heritability of Body Scores in Adapted Saudi Holstein Cows. Asian Journal of Animal Sciences, 7: 22-29.

DOI: 10.3923/ajas.2013.22.29

URL: https://scialert.net/abstract/?doi=ajas.2013.22.29

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