摘要 : The present study focuses on the influences of culling reasons on lifetime milk, fat and protein yield and efficiency, length of life and productive life as well as lactational survival in 524,190 German Brown cows born between 19... 展开 The present study focuses on the influences of culling reasons on lifetime milk, fat and protein yield and efficiency, length of life and productive life as well as lactational survival in 524,190 German Brown cows born between 1990 and 2001. All cows under analyses had completed lifetime records, first calving dates and dates when leaving the herd. Mixed linear models including sire and herd as random effects were employed for data analysis. The main reason for culling was infertility accounting for 25% of all culling reasons. The next ranking culling reasons were other reasons, high age, claw and leg disorders and udder diseases. Within the first three lactation numbers culling because of sales for breeding, low production, poor milkability and infertility were more common than in the other lactation numbers. Least squares (LS) means for survival rates by culling reasons were lowest for infertility in each lactation number. LS-means for length of life and productive life were 5.20 and 2.51 years when cows left the herd due to infertility. Cows culled due to infertility showed the lowest LS-means for lifetime milk, fat and protein yield with 14,864 kg milk, 615 kg fat and 526 kg protein, respectively. The largest effect on the frequency of culling due to infertility exerted the relative herd production level. Cows within one standard deviation of the relative herd production level differed by 12.9% for the LS-means of survival rates, while the differences for culling rates due to claw and leg disorders as well as udder diseases were at 2.4% and 2.6%, respectively. Cows with a high intra-herd production level showed higher LS-means for length of life and productive life when they left the herd due to mastitis or claw and leg problems but lower LS-means when the disposal reason was infertility. A high absolute herd production level correlated with high LS-means for culling rates because of infertility, claw and leg disorders, udder diseases and other reasons. The higher the Brown-Swiss proportion, the less frequent was culling due to infertility and udder diseases while culling due to claw and leg lesions increased. Analysis of the interactions among relative herd production level and disposal reasons indicated for disposals due to udder diseases the largest range in LS-means with 4.33 years for length of life and productive life, followed by claw and leg disorders with 4.24 years. The differences of LS-means for the interactions among herd production level and disposal reasons were for udder diseases at 1.52 years, claw and leg disorders at 1.48 years, other reasons at 1.43 years and infertility at 1.14 years. 收起