Performance of Boran and Crossbred Cattle for Beef Production Under Ranch Conditions in Tanzania: 1.Gestation Length and Growth to 36 Months

Abstract

Records collected in a crossbreeding experiment involving Boran and nine groups of Boran x Bos taurus crossbred cattle in two ranches in central Tanzania were analysed. The traits studied were length of gestation (available on the crosses only) and live weight at various stages ji-om birth to three years of age. The records were analysed by means of Statistical Analysis System (SAS) for general linear models. Length of gestation varied significantly al/long groups of crosses (i.e. by breed of sire). The overall mean gestation length was 282.8 days. Most crossbred groups were heavier than pure Boran both atbirth and at subsequent ages. At three years of age the crosses, pooled over sire breeds, exceeded the Boran by about 10 percent. South Devon crosses were the heaviest at this age, followed by Charolais, Chianina, Brown Swiss, and SimTilental crosses. These crosses were 12 to 15 percent heavier than the pure Boran. Males (steers) were about 5 percent heavier than females. The findings are generally in line with results obtained in crossbreeding experiments elsewhere and suggest that bulls of the fast growing, late maturing continelltal breeds could be useful as terminal sires also under Tanzanian conditions. If bulls of a dual-purpose breed, e.g. Simmental, were used, female progeny might be sold for dairy purposes. However, no firm conclusions can be drawn until data on the effect of crossbreeding on other traits, like reproductive performance and viability, have been collected and analysed.

Keywords: Crossbreeding, Boran, Bos taurus, growth, beef, ranching

Tanzania J.Ag~ic.Sc. (2006) Vol.7 No.2, -67-76