Weight gain and enteric methane production of cattle fed on tropical grasses

Context Planted grasses are becoming an increasingly important feed resource for tropical smallholder ruminant production; yet, limited research has been conducted to quantify productivity or enteric methane (CH4) production of animals consuming these grasses. Aim An experiment was assess yields and nutritional attributes the following three grasses: Cenchrus purpureus var. Kakamega 1 (Napier), Chloris gayana Boma (Rhodes) Urochloa brizantha Xaeres (Brachiaria), CH4 cattle fed on them. Methods Yearling Boran steers (n:18; initial liveweight 216 ± 5.8 kg (mean s.e.m.) were allocated one grasses, in a completely randomised design ad libitum two feeding periods, each period lasting 70 days. Intake, (LW), apparent total-tract digestibility assessed. The used grown site biomass monitored over 2-year period. Animal growth also simulated final weight 350 kg, amount size land required produce, days reach weight, estimated. Key results Mean voluntary dry-matter intake (DMI) ADG higher (P < 0.05) Period 2 than 1, but did not differ among treatments > within Methane yield (MY; g/DMI kg) similar (26.7–28.5, P = 0.26) Napier had conversion factor [Ym; (MJ)/gross energy (MJ)] Rhodes Brachiaria (0.0987 vs 0.0873 0.0903 respectively; 0.013). Our modelling indicated that took at least 30 more target LW, larger area produced other diets. Conclusion Even though animal performance MY differ, Ym currently estimated by Intergovernmental Panel Climate Change. Implication supported rate, implying growing higher-yielding such as offers opportunity optimise tropics. However, suitable practices protein supplementation need be explored enhance reduce production.