Food intake, eating rate, weight gains, metabolic rate and efficiency of feed utilization in Bos taurus and Bos indicus crossbred cattle

Abstract

SUMMARYFood intake, eating rate, weight change and fasting metabolic rate were measured on 12 animals of each of the following breed-types: Hereford × Shorthorn (HS), Brahman × HS (BX) and Africander × HS (AX). Measurements were made on ad libitum and fixed levels of lucerne and ad libitum and fixed levels of low-quality tropical pasture hay (approx. 1·2% N) during feeding periods of about 100 days' duration.The BX and AX were heavier and either gained more weight or lost less weight than the HS on all diets. At feeding levels close to maintenance, which included the ad libitum pasture hay diet, adjustment for differences in either live weight or intake did not alter the unadjusted ranking of the breeds. On ad libitum lucerne, however, adjustment for either weight or intake showed higher gain in the HS than in the BX. The voluntary food intake per kg live weight was consistently and significantly highest for the HS and lowest for the BX. Rates of eating were not significantly different for the different breed-types but they were higher for high-quality lucerne and for the lower level of feeding. Fasting metabolic rate per kg live weight was highest for the HS and lowest for the BX; the difference between the breeds varied with the previous dietary treatment. The ratio of voluntary food intake to fasting metabolism was practically constant between breeds and animals within breeds, though different between diets.Correlations for animals within breeds and years between the various parameters within diets and between diets are presented.