Protein supplementation of grazing cattle in the semi-arid zone of Cameroon.

The effects of cottonseed meal (CSM) supplementation on forage dry matter intake (FDMI), forage dry matter digestibility (FDMD) and average daily gain (ADG) of steers on pasture in the semi-arid zone of northern Cameroon were evaluated during 120 d in the dry season and the residual effects during 120 d in the rainy season. Thirty steers (229 kg and 2.6 years) were randomly assigned to a complete block design of 3 treatments (0, 0.5 and 1.0 kg of CSM as a protein supplement per steer per day). After feeding CSM to individual steers in the mornings, all were allowed to free graze a pasture of Andropogon spp. Every month, 2 steers per treatment were put into digestion crates and ad lib fed hand-clipped forage of similar botanical composition as that grazed by the remaining steers. Cottonseed meal supplementation increased crude protein absorbed (CPA), rumen turn over rate (RTO) and ADG. Forage intake was increased only with 0.5 kg CSM. Forage dry matter and cell wall (NDF and ADF) digestibility tended to be decreased with 1.0 kg of CSM compared with 0.5 kg or no supplement. Cottonseed meal supplementation during the dry season increased FDMI and RTO, but had no effect on cell wall digestibility, FDMD, CPA and ADG during the rainy season. Data from this study suggest that 0.5 kg of CSM can increase FDMI, RTO, and ADG of cattle during the dry season and that improvement can be maintained throughout the subsequent rainy season.