Effect of sources of supplementary protein on intake, digestion and efficiency of energy utilization in buffaloes fed wheat straw based diets

Sixteen adult mate buffaloes (average body weight 443 14 kg) were equally distributed into four groups in an experiment to study the effect of supplementary protein sources on energy utilization efficiency in buffaloes fed a wheat straw-based diet. The animals in the control group were offered a basal diet composed of 700 g deoiled ground nut cake and ad libitum wheat straw. Animals of other groups were offered 1.8 kg of soyabean meal (SBM), linseed meal (LSM) or mustard cake (MC) along with the basal diet. Protein supplementation increased the digestibility of DM (p < 0.01), OM (p < 0.01) CP (p < 0.01) and CF (p < 0.05). Maximum CP digestibility was observed on SBM, followed by LSM and MC when compared to the control. Total DMI and DOMI was significantly (p < 0.01) higher in protein supplemented groups with no differences between treatment groups. Digestible crude protein (DCP) intake and N balance were significantly (p < 0.01) different between the groups; maximum response was obtained with SBM supplementation, followed by LSM and MC. Faecal energy was significantly (p < 0.01) lower in SBM and LSM groups in comparison to other groups. Methane production (% DEI) was significantly (p < 0.05) lower on the SBM treatment. Metabolizable energy (ME) intake increased significantly due to protein supplementation. Metabolizable energy intake (MEI) of animals in the MC group was less than LSM and SBM. Energy balance was increased significantly (p < 0.01) due to protein supplementation and within supplement variation was also significant with maximum balance in SBM followed by LSM and MC groups. Protein supplementation significantly (p < 0.05) increased the digestibility and metabolizability of energy from whole ration. Metabolizable energy (ME) content (Mcal/kg DM) of SBM, LSM and MC was 4.49, 3.56 and 2.56, respectively. It was concluded that protein supplementation of wheat straw increased intake, digestibility and metabolizability of energy and maximum response could be obtained when soybean meal was used as a supplement.