The effect of diet and frequency of watering on the performance of growing cattle given food at maintenance

An 18-week experiment investigated the effects of type of diet and frequency of watering on the performance of growing cattle given food at maintenance (metabolizable energy (ME) allowance (MJ) = 8.3 + 0.091 M where M = live weight of the animal). Three diets with 20:80 (low, L), 50:50 (medium, M) and 80:20 (high, H) roughage to concentrate ratios (10.2, 7.8 and 5.4 MJME per kg dry matter) were used in combination with free access to water for 2.5 h once daily or once every 3rd day. A completely randomized-block design with a 3 (diets) X 2 (watering frequencies) factorial arrangement of treatments was used. Five animals were allocated per treatment (average weight 245 (s.d. 21.6) kg). Dry-matter intake increased as the roughage content of the diet increased (P < 0.05) but was not affected by the watering regime (P > 0.05). Total water intake was found to be positively correlated with dry-matter intake and increased with dietary roughage level. Animals watered daily drank more (P < 0.05) water (12.6 v. 10.0 kg/day) than those watered every 3rd day. The apparent digestibility of the diets decreased as the amount of roughage increased (diet L734 g/kg, M471 g/kg and H433 g/kg). Similar apparent digestibilities were observed under the two watering frequencies (546 g/kg and 547 g/kg). Type of diet significantly (P < 0.05) affected the final weights of the steers. Animals given diet H were proportionately 0.07 heavier than those offered diet L corresponding to total weight changes of -0.8 and +18.4 kg respectively. Carcass weight, backfat thickness and eye muscle area were not affected by the treatments. The chemical composition of the 9 to 11th rib joint was only affected by diet H which gave less fat (P < 0.05). Water, fat, protein and ash content averaged 607, 118, 190 and 84 g/kg respectively.