A study of some factors affecting reproductive traits in a small producer crossbred dairy cows in the Sudan

Abstract

Three hundred and one records of Friesian × Kenana crossbred dairy cows during 
the period 1992 – 2000, were analyzed to evaluate the effect of parity order, calving season 
and sex of new born calves on some reproductive traits, including: days open, number of 
services per conception, gestation length and calving interval. The results documented 
insignificant effects of the investigated parameters on the reproductive traits measured. 
Values of days open, number of services per conception (NSPC), gestation length and 
calving interval (CI) were 99.1 ± 40.5 days, 1.8 ± 1.2, 279.0 ± 8.1 days and 379.0 ± 41.38 
days, respectively. Male calves were found to spend in the uterus as gestation period 
significantly lower time than female calves (278.0 vs. 280 days). The heritability indices 
of these traits were estimated and they were 0.16 ± 0.03, 0.13 ± 0.02, 0.22 ± 0.02 and 0.11 
± 0.03, respectively, indicating that these traits could be improved substantially by sound 
management since the genetic impact is very low. Good management of crossbred cows 
under tropical conditions therefore can contribute greatly towards improving these traits to 
levels comparable with their exotic ancestors.