Research Journal of Dairy Sciences 2 (1): 5-8, 2008 ISSN: 1993-5277 © Medwell Journals, 2008 Corresponding Author: H.E. Mohamed, Department of Animal Science, Faculty of Health, Agriculture and Natural Sciences, Tshwane University of Technology, Pretoria 5 Effect of Season of Calving and Parity on Some Productive Traits in Pure and Crossbred Cattle in Sudan E.O. Amasaib, A.M. Abu Nikhaila, A.N.M.A. Fadel Elseed and H.E. Mohamed 1 2 1 3 Department of Animal Nutrition, Department of Dairy Production, 1 2 Faculty of Animal Production, University of Khartoum, Sudan Department of Animal Science, Faculty of Health, Agriculture and Natural Sciences, 3 Tshwane University of Technology, Pretoria Abstract: This study was conducted to compare some productive traits (overall milk yield; 100 days milk yield; lactation length) and the effect of season of calving and parity number on imported versus locally bred and cross bred (50, 56.5 and 62.5%) in 2 different farms in Khartoum, Sudan. The results indicated a highly significant effect of breed in terms of 100 days milk yield; however, season of calving and parity showed insignificant effect in both farms examined. The lactation length impact on 100 days milk yield is significant at p<0.01 between purebred and cross ones. Key words: Season, calving, parity, cattle, Sudan INTRODUCTION The Holstein-Friesian is the most widely used exotic The demand for animal products is increasing in the tropics and there is an urgent need for research to discover how to increase production in such areas. In arid countries the low level of productivity of indigenous breeds of cattle along with the increasing demand for milk and its products in urban areas have necessitated the importation of exotic European breeds, particularly the Holstein-Friesian, for use directly in milk production or to upgrade the indigenous breeds. Little attention has been given to the physiological problems that exotic breeds might have in order to withstand the harsh environmental conditions. Various reports indicated low production levels of milk for the Sudanese breed cattle (Osman and Elamin, 1971; Bayoumi and Danasoury, 1963). The mean 305-day milk yield (kg) in Holstein Friesian was 7980±54.2 (Wicks et al., 2006). Significant effects of parity were observed on the same parameters. Breed was also found to have a significant effect on some of the parameters. However, there was no significant interaction between breed and parity. The differences between breeds and between parities are typical of the values reported in the literature (Nielsen et al., 2003). Breed was found to have significant effects on both the peak yield. The effects of parity on the coefficients of the lactation curve were found to be independent of the breed of cow in question (Hansen et al., 2006). dairy breed in all farming sectors of many tropical countries including Sudan. The breed is popular for its potentially high milk producing ability and has attractive capabilities for a country where milk supply is not yet able to meet the demands of the growing population. Management systems vary greatly from low input, low milk output to intensive zero grazing based on irrigated pasture production (Peeler and Omore, 1997). Information on the productive herd-life of these animals in the Sudan environment is scarce, the objectives of this study were to evaluate the effect of seasons of calving and parity on selected productive traits in Holstein-Friesian crossbred in Sudan environment under 2 different managemental systems (Butana farm versus University of Khartoum farm). MATERIALS AND METHODS Farms and feeding: Butana farm is located in Tieba Elhasanab, 30 km south of Khartoum. This farm was established in 1989 by the importation of 500 Holstein- Friesian at different stage of pregnancy form the Netherlands. Khartoum University farm is located in Khartoum North, Shambat. This farm was established in 1940 by purchasing of local breeds and adopted in 1972 breeding program with Holstein-Friesian. It maintains the level of foreign blood ranging from 25-62.5%.