Milk production and reproductive performance of Sahiwal cattle in semi-arid Kenya ED Ilatsia 1 , TK Muasya 1 , WB Muhuyi 2 and AK Kahi 3 * 1 Animal Genetic Resources Group, National Animal Husbandry Research Centre, Kenya Agricultural Research Institute, Naivasha, Kenya. 2 National Beef Research Centre, Kenya Agricultural Research Institute, Nakuru, Kenya. 3 Animal Breeding and Genetics Group, Department of Animal Sciences, Egerton University, PO Box 536, Egerton 20115, Kenya. *To whom correspondence should be addressed (a.kahi@incip.org) Abstract The aim of this study was to evaluate milk production and reproductive perform- ance of Sahiwal cattle in semi-arid Kenya. Milk production traits considered were lactation milk yield, lactation length and test-day milk yield, while reproductive traits included age at first calving, calving interval and number of services per conception. Various fixed effects affected performance of milk production and reproductive traits to varying significance levels. The mean estimates for milk production traits were 1368 kg, 282 days and 4.9 kg for lactation milk yield, lactation length and test-day milk yield, respectively. For reproductive traits, mean estimates were 468 days, 2.2 and 1345 days for calving interval, number of services per conception and age at first calving, respectively. There was a decline in lactation milk yield and lactation length, and an increase in calving interval and age at first calving over the years. Satisfactory management and appropriate genetic improvement strategies would result in improved performance. Implications of the results for genetic improvement of the breed in Kenya are discussed. Copyright © 2007 John Wiley & Sons, Ltd Key words: Sahiwal cattle, Kenya, milk production, reproduction Introduction Sahiwal cattle have been prioritised for development through genetic improvement and proper management for use in tropical and subtropical regions (FAO 1992). Utilisation of the Sahiwal in various pure-breeding and cross-breeding programmes will continue to be important in these regions. Therefore, breeding strategies are necessary to increase and sustain the productivity of this breed (Trail and Gregory 1981; Islam and Bhuiyan 1997; Muhuyi 1997; Ilatsia et al. 2007a). One of the initial steps in this direction is to obtain unbi- ased performance evaluations of economically important traits. In Kenya, mean performance estimates have been obtained for milk production and reproductive traits of Sahiwal cattle (e.g. Kimenye 1978; Mwandotto 1985; Rege et al. 1992; Muhuyi 1997). In those studies, short lactations were discarded in the analysis. In tropical cattle breeds, large variations exist Tropical Science Trop. Sci. 2007, 47(3), 120–127 Published online 9 October 2007 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/ts.205