RELATIONSHIP AMONG ESTIMATES OF SIRES BREEDING VALUE FOR PART AND 300-DAYS MILK-YIELD

Data on 426 daughters of 27 Sahiwal sires maintained during 1951-73 at the National Dairy Research Institute, Karnal, were used to evaluate sires for part and first lactation 300 days milk yields. Breeding valu es of sires for part and 300 days milk yields were estimated bl best l inear unbiased prediction (BLUP) procedure using a model containing ye ar of calving, season or calving and sire genetic group as fixed effec ts, sires within sire genetic group as random effect and age at first calving as covariable. Sire evaluation for 90 days, 150 days, 210 days and 300 days milk yield of daughters were closely related. Rank and p roduct moment correlations between sires breeding value for 150 days a nd 300 days yield were close to 1. The accuracy of estimates of breedi ng value or sires for 300 days milk yield was higher than accuracy of sire's breeding value for part yield. Additional number of daughters w ere required to have accuracy of breeding values based on 90 days or 1 50 days milk yield similar to accuracy of sire's breeding values for 3 00 days milk yield. Selection of sires based on 150 days milk yield of daughters with reasonable accuracy can be made to reduce the time req uired to take selection decision.