Abstract

Data was obtained from the dairy herd of the Arab Company for Agricultural Production and Processing (ACAPP) in a semi arid area 40 km south of Khartoum. The data used was of the first five lactations in 4784 records of 2998 cows covering the period from 1982 to 1998. Harvey’s computer program (1990) was used for data analysis. The analysis of variance showed that sires had a significant effect on age at first calving, Number of Services Per Conception (NSPC), breeding efficiency, calving interval and open period. Age at first calving was significantly (p<0.01) affected by year seasons of birth. The year-seasons of calving had a highly significant effect (p<0.01) on calving interval, open period and breeding efficiency. The effect of parity number on calving interval and breeding efficiencywassignificant, while it was not significant on open period and NSPC. The least squares means of age at first calving, calving interval, open period, NSPCand breeding efficiency were 28.98±0.35 months, 14.74±0.131 months, 131.7±2.08 days, 2.36±0.21 and 80.797±0.614% respectively. Heritabilites for age at first calving, calving interval, open period, NSPC and breeding efficiency were 0.092±0.021, 0.008±0.005, 0.004±0.005, 0.100±0.017 and 0.057±0.011 respectively. There were negative genetic correlations between breeding efficiency and both of age at first calving (-1.000±0.370) and NSPC (-0.956±0.121). There were also negative genetic correlations between calving interval and both of open period (-0.406±0.541) and NSPC (0.705±0.286). There were positive genetic correlations between breeding efficiency and both of calving interval (0.637±0.3080), and open period (0.706±0.551). Open period and NSPC (0.791±0.550). Reproductive performance of Holstein Friesian under dryland conditions was below what was expected. However, their performance was better than that of local types but not better than estimates reported for crossbreds.

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