Formulating diets based on whole cassava tuber (Manihot esculenta) and gliricidia (Gliricidia sepium) increased feed intake, liveweight gain and income over feed cost of Ongole and Bali bulls fed low quality forage in Central Sulawesi, Indonesia

Context Formulating rations with high energy and protein feeds such as cassava tuber and gliricidia, is an important strategy to increase liveweight gain (LWG) of bulls and improve profitability of smallholder farmers in Indonesia. Aims Two on-farm experiments were conducted to evaluate the effect of increasing the supplementation level of a mixture of cassava (Manihot esculenta) whole root tuber powder and fresh gliricidia (Gliricidia sepium) on feed intake and LWG of Ongole and Bali bulls given fresh corn stover and elephant grass, respectively. Methods Two experiments were conducted, each with five treatments: a basal diet of fresh corn stover (Experiment 1 for Ongole bulls) or elephant grass (Experiment 2 for Bali bulls) fed ad libitum or this diet supplemented with a combination of cassava tuber (whole root tuber including peel, sun-dried and ground) and fresh, chopped gliricidia (1:1) on estimated dry matter (DM) basis, at DM levels of 0.4, 0.8, 1,2 and 1.6% liveweight (LW)/day. Each experiment was run for 18 weeks, consisting of a two week adaptation and 16 week experimental period. Parameters measured included basal DM intake, supplement DM intake, total DM intake, total water intake, faecal pH, daily LWG, feed conversion ratio (FCR) and income over feed cost (IOFC). Key results Increasing supplement level linearly (P < 0.05) decreased basal diet intake, but linearly increased total DM intake and LWG (P < 0.05) in both breeds. Basal diet DM intake was reduced at the rate of 0.43 kg/kg of supplement DM consumed for both Ongole and Bali bulls. Water intake and faecal pH were not affected (P > 0.05) by increasing supplement intake. Inclusion of cassava tuber and gliricidia supplement up to 1.6% LW/day, increased total feed DM intake (up to 3.28 and 3.18% LW/day, for Ongole and Bali bulls, respectively) and LWG (maximum Ongole bulls 0.69 kg/day and Bali bulls 0.46 kg/day). Daily income over feed cost (IOFC) increased significantly (P < 0.05) in association with increased supplement intake in both Experiments 1 and 2. Using the derived model without supplementation, the value of IOFC was only IDR 7802/day and IDR 7687/day, for Experiments 1 and 2, respectively. The highest IOFC was achieved at a supplement intake of 1.6% LW/day with values of IDR 13949/day and IDR 12543/day for Experiments 1 and 2 respectively. Conclusions The addition of a cassava tuber and gliricidia mixture up to 1.6% LW/day increased LWG and profit for smallholders fattening bulls. Implications Formulating a ration with cassava tuber and gliricidia can be economically beneficial in cattle fattening systems in Indonesia.