LIFETIME PRODUCTIVE TRAITS OF HOLSTEIN FRIESIAN CATTLE RAISED IN EGYPT

Abstract

A study on age at first calving , longevity traits and lifetime milk production traits was carried out in a commercial Holstein Friesian herd raised in El-Salhia, Esmaillia Governorate . That herd belongs to the General Cooparative for Developing the Animal Weath and Products.

Longevity traits were represented by age at last calving , length of productive life , length of herd life and number of lactations completed by the cow before its disposal . Lifetime milk production traits studied were lifetime 305-day milk yield , lifetime total milk yield , lifetime days in milk , milk yield per day of lifetime days in milk , milk yield per day of productive life and milk yield per day of herd life. Data dealt with were taken on 5662 normal lactations given by

I 029 cows sired by 139 bulls during nine consecutive years ( 1984 -

1992 ) . These data were analyzed using the least-squares maximum likelihood computer program of Harvey ( 1990).