Improving calf survival and performance by supplementation in Bali cattle I. G. N. Jelantik A , M. L. Mullik A , C. Leo-Penu A , J. Jeremias A and R. Copland B,C A University of Nusa Cendana, Kupang, Indonesia. B School of Animal Science, The University of Queensland, Gatton, Qld 4343, Australia. C Corresponding author. Email: R.Copland@uq.edu.au Abstract. An on-farm experiment was conducted in several villages in the district of Kupang, East Nusa Tenggara Province (NTT), Indonesia from June to October 2007. The experiment investigated the efficacy of a supplementation strategy to improve calf survival and performance during the dry season. A total of 258 Bali (Banteng, Bos javanicus) cow--calf pairs were used in the experiment. Calves from the 190 cow--calf pairs in the treatment groups were allocated grass hay þ concentrate supplementation as follows: 1% (n = 98), 2% (n = 56) and 3% (n = 42) of calf bodyweight. There were 62 cow--calf pairs in the unsupplemented control group. The supplement consisted of grass hay and concentrate (rice bran, cornmeal, leucaena leaf and fish meal) containing 18% crude protein. The supplement was introduced to calves in the morning while confined to calf pens when the dams were grazing. Calves were reunited with the cows during the night. Parameters measured were calf mortality, calf and cow daily gain, and milk production. Supplementation tended to reduce calf mortality (P = 0.094) from 6.4% in control to 0% in calves receiving 2% and 3% supplement. Levels of supplementation significantly (P < 0.001) improved calf daily weight gain. Bodyweight changes and milk production of cows were unaffected by calf supplementation. It can be concluded that supplementation at 2% calf bodyweight reduces calf mortality and improves calf weight gain. Additional keywords: strategic supplementation, Bali calves, rice bran, liveweight, body measurements. Introduction High calf mortality may be the most important factor responsible for the low productivity of Bali cattle (Bos javanicus) from the West Nusa Tenggara (NTT) Province of Indonesia. Previous research indicates that the average calf mortality was 36% but in some villages calf losses could be more than 50% (Wirdahayati 1994; Fattah 1998; Jelantik 2001). In addition, the growth rate of the surviving calves is low with a significant impact on their productivity in later life (stunting). Thus, improving calf survival and growth may increase overall cattle productivity in the province of NTT. The most likely factor causing the high calf mortality rate in Bali cattle calves during the dry period is poor nutrition, especially of the cows. Previous research indicates that supplementation of calves during the dry season reduces calf mortality and increase calf performance. Research by Jelantik (2004) under experimental conditions has demonstrated the success of such an approach. This experiment aims to investigate the efficacy of strategic nutrient supplementation during both the dry and rainy seasons at the farmer level to improve calf and older animal performance and reduce calf mortality. The possibility of improving calf yield by providing supplements directly to the calves was assessed in a wider scope involving farmers in several villages. Materials and methods The experiment was conducted between June and October 2007. In total, 258 Bali calf--cow pairs were allocated from several villages in the district of Kupang, West Timor Indonesia. Most of the calves used in this experiment were born between June and August 2007. The animals were grazed on the available native pastures nearby the village for 8 h each day (0800--1600 hours). The calves were placed into three groups and randomly allotted to receive no supplementation (control) or supplementation at 1%, 2% and 3% of calf’s bodyweight daily on dry matter basis. The supplement consisted of 10% grass, 35% cornmeal, 26% rice bran, 15% dried leucaena leaf meal, and 14% fish meal. The calf supplement contained 18.6% crude protein. The nutrient content of feeds used as the supplement is presented in Table 1. The supplement was offered to the calves once a day in the morning in calf pens, where they were confined during the day while the dams were grazing on the natural pastures. Calves and cows spent the night together. Variables and measurements The calves were weighed every 2 weeks and their weight gains and losses were recorded. Body measurements were recorded at the time of weighing. Bali cows were weighed every month and scored for body condition using a 1--5 scoring system. Cow parity and age was recorded at the CSIRO PUBLISHING Australian Journal of Experimental Agriculture, 2008, 48, 954--956 www.publish.csiro.au/journals/ajea Ó CSIRO 2008 10.1071/EA08038 0816-1089/08/070954