Comparison between different selection indices for some productive traits in Friesian cows

Abstract

Data pertaining to 3,977 records collected over a period of 29 years for Friesian cows were utilized for the present study. Records were analyzed for actual total milk yield (TMY), 305-day milk yield (305d-MY), lactation period (LP) and days open (DO) by VCE 6.0 software while, selection indices (SI) using one phenotypic standard deviation as REV1 and Lamont method as REV2. Estimates of direct heritability were low and ranged from 0.02 to 0.23 while, maternal heritability were low and ranged from 0.03 to 0.028. The correlation coefficients between all studied traits were highly significant and ranged between 0.82 to 0.93. The results indicated that reducing interval of days open (DO) could be brought about by improving the farm managerial aspects. The selection criteria of different indices proved that the index I1which incorporated TMY, 305d-MY, LP and DO was the best (RIH = 0.49) and (RE % = 100.00). This index could effectively anticipate in genetic improvement of all the traits of the study; I1 = 0.144 (TMY) + 0.503 (305day/MY) + 1. 619 (LP) + 1.150 (DO). The application of this index I1 led to a predictive genetic gain of TMY, 305d-MY, LP and DO by 359.4 kg, 279.5 kg, 15.3 days and 3.2 days, respectively. The correlation coefficient between I1 and the total economic value was 0.49 while, the heritability estimate of the index was 0.86. Conclusively, such an index can help the investor in the field of dairy cattle to select the best animals in early lactation and in subsequent generation’s traits as well; which leads to an increase in economic return.