Abstract
The overall mean values estimated weights were 32.4 kg for body at birth 124.3 kg at weaning, 379.1 kg at first calving and 0.61 kg as pre-weaning daily gain. The average milk yield per lactation was 1171.2 kg. The lactation period was 269.8 days. The dry period was 194.5 days and calving interval was 464.3 days. Effects of year of calving were significant (P <0.01 or 0.05) on birth weight, weaning weight, pre-weaning daily gain. Effects of season of calving were significant (P <0.01 or 0.05) on birth weight, weaning weight and pre-weaning daily gain. Birth weight of heifers was affected significantly (P <0.01) by dam's weight at calving, while pre-weaning daily gain was affected significantly (P <0.01) by birth weight and weaning period. Effects of milking system (manual and mechanical) were significant (P <0.05) on lactation period and milk yield. The comparison between the data of the present study (1993 - 1995) and that obtained from a previous one (1983 - 1987) on the same farm, showed decline in all the studied traits. Stayability of Egyptian buffalo cow averages (survival rates) to 60, 72 and 84 months of age were 87, 60 and 44.0%, i.e. 13, 40 and 56% of the original buffalo cows left the farm prior to 60, 72 and 84 months of age, respectively. Averages of productive indexes estimated at the different ages were the highest at 60 and 72 months of age.
Regarding the udder traits, season of calving effects were highly significant (P <0.01) on teat length, teat diameter and distance between front teats. Parity effects on all udder traits were not significant. Lactation month affected significantly (P <0.01 or 0.05) all udder traits. Milking system (manual or mechanical) effects were significant (P <0.01 or 0.05) on milk yield and right and left front teat lengths. Partial regression coefficients of udder measurements on daily milk yield were significant (P <0.01 or 0.05). The phenotypic correlations between left and right teats, length and diameter of the four teats and distances between the teats, were mostly high and positive. Residual correlations were lower than phenotypic correlations between traits studied. Repeatability values of the traits related to teat length and distances between teats were moderate to high.