Akademik Veri Yönetim Sistemi
INDIAN JOURNAL OF ANIMAL SCIENCES, cilt.72, sa.10, ss.875-877, 2002 (SCI-Expanded)
This study was conducted to estimate breeding values of 750 Holstein cows for 305-day milk yield recorded between 1982-1997. Estimates of breeding values for 305-day milk yield were obtained for animals using 2 different models.. First lactation records were analysed in a model (Model 1) that included direct genetic effect as the only random factor. All lactation records were analysed in a model (Model 2) that was the same as Model 1 but permanent environmental effects associated with animals were also taken into account. While phenotypic trends of 305-day milk yield were positive for first and all lactations with increases of 73.4 kg and 77.5 kg per annum respectively, genetic trend for 305-day milk yield were close to zero for both age groups.