Factors Limiting Liveweight Gain of Beef Cattle on Rangeland in Botswana

Abstract

Six range parameters measured monthly over an 11-month period on nine ranches distributed throughout the main ecological zones of Botswana were related to the monthly liveweight changes of growing cattle. Clipped and esophageal fistula samples provided estimates of crude protein content (CP) and dry matter digestibility (DM), while available DM and grazing index provided estimates of available herbage. Linear, quadratic, and multiple regressions all indicated that liveweight change was influenced primarily by the CP content of the herbage selected. The CP content of fistula samples accounted for 54% of the variation in liveweight gain, while digestibility of the same samples accounted for 32%. Quadratic regressions failed to account for any more variance than linear regressions. The inclusion of digestibility with CP content in a multiple linear regression failed to have any effect. The addition of grazing index to CP content increased the variance accounted for in both the fistula and clipped samples from 54% to 56% and 48% to 53%, respectively. It appears that under the natural range conditions of Botswana, crude protein is presently the major limiting factor, and initial research efforts must be directed towards increasing the CP content of the diet available to beef cattle.