Factors affecting the response of Bali cattle (Bos sondaicus) calves to supplementation prior to weaning

摘要

Some factors that contribute to variation in the responses of Bali cattle calves to dry season supplementation before weaning were examined on-farm in 10 villages located in three districts in East Nusa Tenggara Province, Indonesia from June to December 2008. The altitudes of the three districts were 0–100, 400 and 800 m above sea level. A total of 199 Bali (Banteng, Bos sondaicus) calves were offered a concentrate supplement from 1 month after birth (or June for calves born before May) at a level of 2% liveweight. The supplement consisted of grass hay and concentrate (rice bran, corn meal, leucaena leaf and fish meal) containing 18.6% crude protein. The supplement was offered to calves in the morning while confined to calf pens when the dams were released for grazing. Calves were reunited with the cows during the night. The effects of districts, herd size and month of birth on mortality rate, liveweight gain (LWG) and growth in supplemented calves were examined. Mortality rate averaged 1.0% and was not affected by month of birth, herd size or districts. The month of calving varied from March to September, but was mostly concentrated during June and July (55%). Month of birth did not significantly affect (P > 0.05) LWG of the calves, but the heart girth of calves born early (May) did increase at a slower rate (P < 0.05) than calves born late (August) (10 mm/day versus 27 mm/day). LWG of supplemented calves was faster (P < 0.05) in herds of 10 or less cow-calf pairs (220 g/day) than in herds of more than 10 cow-calf pairs (160 g/day). Altitude affected LWG (P < 0.05) of supplemented calves; gains were 170, 210 and 280 g/day for the three districts with altitudes of 1–100, 400 and 800 m, respectively. Implications of the factors affecting response to supplementation are discussed.