Genetic parameters of production and type traits and longevity in Holstein population
1996
Kawahara, T. (Hokkaido Dairy Cattle Milk Recording Association, Sapporo (Japan)) | Suzuki, M. | Ikeuchi, Y.
Genetic parameters of production and type traits, and longevity in Hokkaido Holstein population were simultaneously estimated by using EM-type REML procedures with a multiple-traits sire model. The data set used for this study was formed from two subsets. First, the analysis of production and type traits were conducted using 74,748 cows with both first lactation records initiated in 1993 and completely terminated in May, 1993, and type information classified before 45 months of age and within 305 days following the first calving. Next, to investigate the relationships of longevity with production and type traits, the first data set was reviewed to obtain the second data set, records on 34,840 cows before June 1987 so that they had the opportunity to live at least 72 months by June 1993. Heritabilities ranged from 0.32 (protein yield) to 0.82 (SNF content) for production traits and from 0.05 (foot angle) to 0.37 (stature) for type traits. Heritabilities for longevity increased as age increased but were lower across ages, ranging from 0.07 (stayability) to 0.12 (production life) at 72 month. Genetic correlations among milk, fat, protein and SNF yield were high, ranging from 0.62 to 0.96. Genetic correlations of production traits with longevity tended to decrease slowly as age increased, but productive life measured to 72 months of age had high genetic correlations with yield traits, from 0.67 with milk and fat yield to 0.s69 with SNF. Most of traits for longevity had low negative genetic correlations with some traits associated with body size, and low and moderately positive genetic correlations with some udder traits, angularity and rump-angle
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