Influence of bull-sires, age at first calving and service period on productive traits of improved Black and White cattle population
1988
Panic, M. | Latinovic, D. (Poljoprivredni fakultet, Beograd (Yugoslavia))
Average milk production in lactation were 5.018 kg with, 3.63% and 181.1 kg milk fat, and 5.123 kg, 3.61% and 184.1 kg in the standard lactation (305 days). Bull-sires showed high significant influence on: duration of lactation, milk yield, fat content, fat yield and fat corrected milk in both, lactation and standard lactation. Least Square contents (c) for FCM yield were between -973 kg or 20.4% and 514 kg or 10.8%. Heritability coefficients in the standard lactation were 0.201 for milk yield, 0.218 for the fat content in milk, 0.198 for the fat yield and 0.200 for the FCM-MKM yield. Phenotypic and genetic correlations between milk production and milk fat content were -0.714 and -0.722 while between milk, fat and FCM yield very close to 1.000. Linear regression dependency was found between reproductive and productive traits. Namely, for every day of prolonged service period, milk fat yield was higher about 0.04 kg and FCM 1.03 kg. In relation to the age at first calving, the same phenotype increased by 0.07 kg and 1.86 kg.
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