Data relevant to 398 Egyptian buffaloes raised at Mehallet Mousa
Experimental Station between 1972-1992 were utilized in this investigation to
construct several selection indexes which determine the most suitable combination
of age at first calving (AFC), first lactation total milk yield (TMY), first dry period
(DP)and first calving interval (CI) in order to realize the most genetic improvement in
TMY. Overall mean of AFC was 1167.12 days, of TMY was 1231.57 kgs, of DP was
315.50 days and of CI was 597.25 days. Heritability estimate of AFC was 0.38, of
TMY was 0.43, of DP was 0.32 and of CI was 0.20. Phenotypic correlations were
highly significant but mild except those between DP and each of TMY and CI were
moderately negative and high positive , respectively. Similarly were the genetic
correlations except that between DP and AFC which was moderately positive. The
genetiC correlation between TMY and each of DP and CI were high negative and very
high positive, respectively. The highest expected genetic improvement (ilG) for TMY (357.5 kgs) was
obtained from the second index (12) which incorporated TMY, DP and CI. Also it
recorded the highest correlation with the aggregate genotype (rrr = 1.00) and the
highest reiative efficiency compared with the basic index (RE %= 125). Whereas the
lowest correlation with the aggregate genotype (riT = 0.65) and the lowest relative
efficiency (RE%=81) were obtained from 16 which included TMY and DP.