Authors : B.E. Abdel-Aziz , T.E. Ali and F.A. Ahmed
Abstract: One thousand one hundred and four primiparous Butana, Kenana and ? Friesian x ? Kenana cross-bred heifers born during the years 1953 to 1986 at three Research Centre in North Sudan (Atabara) and Central Sudan (Nisheishiba and Um-Banein) were studied for age at First Calving (AFC). Also 4230 calving interval (CI) records covering the years from 1957 to 1986 were studied. The overall means of age at first calving of Butana, Kenana and ? Friesian x ? Kenana crosses were 43.20?0.11 (SE), 53.60? 0.13 and 42.30?0.34 months, respectively. The breed effect between the AFC of Kenana and their crosses to Friesian was found highly significant (p<0.001). The heifers? own season of birth had no major effect. But their own year of birth was found highly significant (p<0.001) source of variation upon age at first calving. Kenana breed located at Nisheishiba was found significantly (p<0.01) younger at first calving (52.70 months) when compared to those at Um- Banein (55.00 months). On the other hand, the result on calving interval revealed overall means of Butana, Kenana and ? Friesian x ? Kenana- crosses as 12.60?0.06, 15.20? 0.04 and 14.80?0.12 month, respectively. Unlike AFC, the effect of breed on CI was not found a major one in comparing Kenana and their crosses. But the effects of season and year of calving were found to have major sources of variation upon calving interval. The effect of herd location on CI was not found significant for the Kenana breed at Nisheishiba (15.30 months) and Um-Banein (15.20 months) centres. The longest mean CI was found to occur between the first and second parities in all genotypes studied except for Butana where the sixth CI had the highest mean. This effect of parity was found highly significant. Sex of calf affected neither age at first calving nor calving interval.
B.E. Abdel-Aziz , T.E. Ali and F.A. Ahmed , 2005. A Study of Some Factors Affecting the Age at First Calving and the Calving Interval of Different Sudan Zebu Breeds . Journal of Animal and Veterinary Advances, 4: 668-675.