The Effects Of Nutrition, Age At First Calving And Breed On Some Reproductive Traits In Butana Dairy Farm.

The aim of this investigation was to study the effects of foreign blood percentage, age at first calving and plane of nutrition on some reproductive traits which involved calving interval and days open (service period) in two dairy herds, composed of imported Holstein- Friesian and cross-breed with 50% foreign blood. The reproductive traits under study were then compared between the two herds. The results indicated that the age at first calving has no significant effect (P<0.05) on calving interval and days open, despite that the length of calving interval was longer in the pure Holstein- Friesian cows (465.2) days compared to the cross-breed with 50%foreign blood (403.9) days. The results showed that the foreign blood percentage had a significant effect (P<0.05) on calving interval and days open of both imported herd and crossbreed. Also the results showed that the plane of nutrition has a significant effect (P