Optimal combination of age at first calving and breeding efficiency for maximum life time milk production in dairy cattle.

摘要: 1050 records on age at first calving (AFC), 3700 records on breeding efficiency (BE) and 1050 records on lifetime milk yield (LMY) were collected for 1050 cows maintained at the Harighata Farm in West Bengal between 1966 and 1986. The cows represented 6 breed types: nondescript (ND), Hariana (HP), HP × ND, Holstein (HL) × ND, HL × HP and Jersey (JR) × HP, and were progeny of 66 sires. For the maximum LMY, the AFC-BE combinations were 1370 days and 82.27%, 1317 days and 96.16%, 1293 days and 98.34%, 892 days and 90.91%, 884 days and 97.96%, and 856 days for the 6 breed types respectively, compared with the observed breed averages of 1420 days and 67.41%, 1368 days and 80.08% 1332 days and 97.63%, 933 days and 79.41%, 953 days and 82.41%, and 920 days and 95.05%.