Environmental and genetic effects on some lifetime traits of Sahiwal cattle
2003
Javed, K. (University of Veterinary and Animal Sciences, Lahore (Pakistan)) | Afzal, M. | Ahmad, M. | Akhtar, M.
Data on 8948 performance records of 2532 Sahiwal cows kept at Livestock Experiment Station Jahangirabad (Khanewal) were used in the present investigation. The least squares means for lifetime milk yield, productive life, herd life and longevity were 9277.84 plus minus 206.97 kg, 1352.76 plus minus 25.48 days, 2418.89 plus minus 47.92 days and 3743.39 plus minus 45.30 days, respectively. Year of birth and age at first calving were significant (P less than 0.01) sources of variation for lifetime milk yield, productive life and herd life while longevity was influenced by year of birth only. The heritability estimates by univariate analysis were 0.042 plus minus 0.03 for lifetime milk yield, 0.004 plus minus 0.013 for herd life and 0.017 plus minus 0.024 for longevity. The low estimates of heritability indicated that the variation due to additive gene action was probably small and that the variation due to environmental factors was more important.
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