Non-genetic factors affecting longevity and lifetime production traits of Friesian dairy cattle in Egypt.

The present study was focused on evaluation of the most important non-genetic factors affecting longevity and lifetime production traits using multitrait linear animal model. A total of 2914 Friesian heifer records and their subsequent lactations until culled or died, cover the period from 1979 to 2013 were obtained from the history sheets of Friesian cows maintained at Sakha and El-Karada experimental stations. The effect of AFC on most of longevity and lifetime production traits was highly significant (P<0.001). The optimum AFC was 23-25 month for the maximum longevity and lifetime production traits. Summer season of first calving (July, August and September months) showed the lowest means of longevity and lifetime production traits, however spring season of first calving (April, May and Jun months) showed the highest means of the same traits. Longevity and lifetime production traits showed a decreasing trend with increasing SP1c. Longevity and lifetime production traits increased linearly (P<0.01) with increasing LP1c. Longevity and lifetime production traits increased linearly (P<0.001) with increasing lactation number completed.