Estimation of genetic parameters of weekly test-day milk yields and first lactation 305-day milk yield in Murrah buffaloes

Aim: The aim was to estimate genetic parameters of weekly test-day (TD) milk yields and first lactation 305-day milk yield (FL305DY) in Murrah buffaloes. Materials and Methods: The data on 39059 weekly test-day milk yield (WTDY) records during first lactation of 961 Murrah buffaloes calved from 1977 to 2012 and sired by 101 bulls maintained in an organized farm at National Dairy Research Institute, Karnal was analyzed to study the effect of genetic and non-genetic factors. Least squares maximum likelihood program was used to estimate genetic and non-genetic parameters affecting WTDY and FL305DY. Heritability was estimated using paternal half-sib correlation method. The genetic and phenotypic correlations among WTDY and 305day milk yield was calculated from the analysis of variance and covariance among sire groups. Results: The least squares means for FL305DY was found to be 1853.49±15.88 Kg. The least squares means of overall WTDY ranged from 2.44±0.07 kg (TD-43) to 7.95±0.06 kg (TD-8). Effect of period, season and age at first calving groups was found to be highly significant (p<0.01), significant (p<0.05) and non-significant on FL305DY, respectively. The h2 estimate of FL305DY was 0.25±0.09. The estimates of phenotypic and genetic correlations between 305-day milk yield and different WTDY ranged from 0.52 to 0.84 and from 0.19 to 0.98, respectively. Conclusions: Our study showed that the effect of period of calving was highly significant (p<0.01) on FL305DY as well as all the WTDY. The estimates of phenotypic and genetic correlations were generally higher in the middle segment of lactation suggesting that these TD yields could be used as the selection criteria for early evaluation and selection of animals.