Selective grazing by cattle on spatially and seasonally heterogeneous rangeland in Sahel

The selective use by cattle of range resources in the Sahel was assessed in terms of quantity and nutritional quality of the herbage grazed and diet s elected. Peak standing crop was 1951 kg ha(-1) dry matter (DM) with 47.9 kg nitrogen (N) ha(-1) and 7.4 kg phosphorus (P) ha(-1). Esophageally fistula ted cattle diets were consistently (p < 0.05) higher in N, P and organic ma tter digestibility (OMD) than the herbage grazed. Cattle consumed 48% of th e mean annual herbage production. The results indicate grazing ruminants se lect a higher quality diet from Sahelian rangelands than can be predicted o n the basis of pasture evaluation alone. Therefore, the foraging behaviour of the animals needs to be considered in the evaluation of Sahelian rangela nds for animal production. (C) 1999 Academic Press.