SELECTION INDICES FOR FRIESIAN COWS USING TWO METHODS OF CALCULATING RELATIVE ECONOMIC VALUES FOR SOME IMPORTANT PRODUCTIVE AND REPRODUCTIVE TRAITS | ||||
| Journal of Agricultural Chemistry and Biotechnology | ||||
| Article 1, Volume 30, Issue 12, December 2005, Page 8037-8052 PDF (3.37 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jacb.2005.238847 | ||||
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| Author | ||||
M.N. EI-Arian 
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| Animal Production Department, Faculty of Agriculture, Mansoura University, Egypt | ||||
| Abstract | ||||
| A total of 598 first lactation records of Friesian cows progeny of 30 sires and 535 dams were used in this study. Analysis was carried out using Maximum Likelihood procedures with the model used including month and year of calving as fixed effects and sires as random effects. The estimates of phenotypic and genotypic variances and co variances of, 305 day milk yield, 305 day fat yield, 305 day protein yield, calving interval and age at first calving and their relative economic values derived by two methods were used for constructing selection indices, method 1 ,actual relative economic V alues (REV( 1) and method 2,relative weights(REV(2)). Heritability estimates were 0.3i, 0.12, 0.17, 0.19 and 0.44, respectively. Genetic correlations between milk traits were high, positive and significant (p < 0.01) ranging from 0.85 to 1.00 and their corresponding phenotypic correlations from 0.60 to 0.97. Twenty-six selection indices for each method of relative economic value derivation (REV) were constructed. The selection index 11A or 11s which in corporated 305 days milk yield, 305days protein yield,calving interval and age at first calving, was the best (had the highest accuracy (RIH ) and relative efficiency values) and were recommended, if the selection was exercised at the end of the first lactation. Rank correlation coefficient between the ranking of 598 Friesian cows !;ty the both methods of relative economic valus was 0.95 . thus ,the second method of relative economic values was recommended for ease of calculation. | ||||
| Keywords | ||||
| Selection Indices; Friesian cows; relative economic values; Genetic and phenotypic parameters; milk yield; fat yield; protein yield; calving interval and age at first calving | ||||
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