COMPARISON BETWEEN SOME PRODUCTIVE AND REPRODUCTIVE TRAITS AND GENETIC PARAMETERS IN THE FIRST THREE LACTATIONS IN EGYPTIAN BUFFALOES.

Abstract

The objectives of the present study were to estimate mean, heritability, genetic and phenotypic correlations and genetic trend. Data of 1776 records of Egyptian buffaloes, kept at Mehallet Mousa farm, Ministry of Agriculture, during the period from 1972 to 2002 were used to estimate the genetic parameters for productive traits, total milk yield (TMY), 305-day milk yield (305-DMY), lactation period (LP) and dry period (DP) and the reproductive traits were calving interval (CI) and days open (DO). Data were analysed using the software package VCE-6 Groeneveld et al (2010). Averages of TMY, 305-DMY, LP, DP, CI and DO were recorded to be 1057, 1000 kg, 226, 372, 538 and 224 days, respectively. In the first lactation and the corresponding numbers in the second lactation were 1446, 1364 kg, 253, 288, 503 and 188 days but in the third lactation were 1586, 1523 kg, 253, 241, 477 and 160 days. The heritability values estimated for the productive traits in the first three parities were generally low and ranged between 0.03 to 0.19 and the values for reproductive traits were usually close to zero in the second lactation 0.001 and 0.0001, respectively. Genetic and phenotypic correlations in the first parity among all traits studied were positive except the genetic and phenotypic correlation between DP and (TMY, 305- DMY, LP) was negative. Genetic correlation between LP and, (TMY, 305-MY, CI and DO) and between DP and (TMY, 305-MY, CI) were negative in the second parity, also genetic correlation between DP and (TMY, 305-MY, LP) and between 305-MY and (CI, DO), and between TMY and CI were negative in the third parity. Annual genetic trend for milk traits in the first three lactations were negative for TMY, LP, 305-MY, CI and DO and ranged between -3.681 to -22.57 but it was positive for DP and ranged between 1.04 to 1.738.