Genetic and phenotypic evaluation for reproductive performance of Egyptian buffaloes

Abstract

ABSTRACTAn analysis of cow reproductive traits was carried out on 2057 lactation records of Egyptian buffaloes. A total of 651 daughters (paternal half-sisters) of 82 sires were available for the analysis. Reproductive traits analysed were age at first, second and third calving (AC), number of services per conception (NSC), gestation length (GL) and calving interval (CI). Year of calving affected most reproductive traits (P< 0·001) while no important differences were detected among months of calving. Means of NSC, GL and CI decreased linearly (P< 0·01) as parity advanced. Age of cow at calving exerted a pronounced effect (P< 0·001) on NSC and CI. There was no systematic change in the estimates of heritability and sire components of variance for reproductive measures over the first three lactations. Heritability estimates for NSC and GL in the different parities were generally low, ranging between 0·04 and 0·18, while moderate estimates for AC and CI were obtained. Phenotypic correlations between reproductive traits were positive and relatively moderate or low. For most traits, positive and relatively high or moderate estimates of genetic correlations were observed. Mating bull was found to be an important source of variation for reproductive performance of Egyptian buffaloes. The highly significant effect of mating bull on reproductive traits could be considered as evidence for the importance of evaluating bull semen quality before the mating of cows