Impact of phytogenic feed additives on growth performance, nutrient digestion and methanogenesis in growing buffaloes

Abstract

Twenty growing buffalo calves were fed on a basal diet consisting of wheat straw and concentrate mixture in a randomised block design, to study the effect of feeding phytogenic feed additives on growth performance, nutrient utilisation and methanogenesis. The four groups were viz. control (no additive), Mix-1 (ajwain oil and lemon grass oil in 1 : 1 ratio @ 0.05% of dry matter intake), Mix-2 (garlic and soapnut in 2 : 1 ratio @ 2% of DMI) and Mix-3 (garlic, soapnut, harad and ajwain in 2 : 1 : 1 : 1 ratio @ 1% of DMI). The experimental feeding was continued for a period of 8 months. A metabolism trial was conducted after 130 days of feeding. Methane emission from animals was measured by open-circuit indirect respiration calorimeter. The feed conversion efficiency was higher by 9.5% in Mix-1, 7% in Mix-2 and 10.2% in Mix-3 group than in control. The digestibility of nutrients was similar except crude protein, which was improved (P < 0.05) in treatment groups. All buffalo calves were in positive nitrogen balance. Comparative faecal nitrogen decreased and urinary nitrogen increased in all the supplemented groups compared with in the control group. Methane emission (in terms of L/kg dry matter intake and L/kg digestible dry matter intake) was reduced by 13.3% and 17.8% in Mix-1, 10.9% and 13.5% in Mix-2 and 5.1% and 9.8% in Mix-3 groups as compared with control. When expressed in L/kg organic matter intake and L/kg digestible organic matter intake, methane production was reduced by 13.3% and 16.7% in Mix-1, 10.9% and 12.9% in Mix-2 and 5.1% and 8.4% in Mix-3 groups compared with the control group. These feed additives inhibited methane emission without adversely affecting feed utilisation by the animals. The faecal energy, urinary energy and methane energy losses were not affected (P > 0.05) due to feeding of these additives. Further, long-term feeding experiments should be conducted on a large number of animals to validate these effects before they can be recommended for use at a field level.