اثر حذف صفت طول عمر از تابع هدف انتخاب در گاوهاي هلشتاين ايران

The Effect of Culling Herd Life from Selection Goal in Iranian Holstein Cows

To test the effect of culling herd life from the breeding goal function, 4 different selection indices were established as: index 1: using Milk production (Milk), Fat percentage of milk (fat%) and Rear Udder Height (Ruh); index 2: using Milk , fat% and Fore teat placement (Ftp), index 3: using Milk, fat% and Fore udder attachment (Fua); and index 4: using Milk, fat%, Ruh, Ftp and Fua) under two different selection goals, one of which included Milk, fat% and herd life while the other one was excluded of herd life. Calculations were made in economic situations of year 1995 and 2000. Response to selection and selection accuracy resulted from the above mentioned indices and under two economic situations revealed that exclusion of herd life would result in a decrease in genetic gain in the breeding goal function except when excluded from index 4 and under 1995 conditions, although by excluding this trait the selection accuracy may even increase.