摘要 : The performance records of 1081 crossbred daughters of 65 sires maintained at Instructional Dairy Farm of GB P U A T, Pantnagar during 1966 - 2005 were used to estimate genetic parameters of first lactation and life time traits. T... 展开 The performance records of 1081 crossbred daughters of 65 sires maintained at Instructional Dairy Farm of GB P U A T, Pantnagar during 1966 - 2005 were used to estimate genetic parameters of first lactation and life time traits. The least squares means for age at first calving (AFC), first lactation milk yield (FLMY), first lactation period (FLP), first dry period (FDP), first service period (FSP), first calving interval (FCI), life time milk yield (LTMY) and life time lactation length (LTLL) were estimated as 1176.44±26.86 days, 2656.34±139.19 kg, 319.81± 13.04 days, 121.24±14.09 days, 441.04± 26.40 days, 259.50± 15.40 days, 9654.28± 496.71 kg and 1094.87± 48.86 days respectively.The heritability estimates forthese traits were 0.11±0.03, 0.20±0.03, 0.25±0.04, 0.25±0.04, 0.44±0.04, 0.09±0.02, 0.10±0.03 and 0.12±0.03 respectively. The genetic and phenotypic correlations among all first lactation life time performance traits ranged form very low(-0.01+0.18AFCwithFLMY ) to very high(0.99+0.02 FLP with FCI). FLMY had positive genetic and phenotypic correlations with LTMY. These results suggested that selection on the basis of FLMY would enhance correlated response in life time performance traits. 收起