PARTIAL SUBSTITUTION OF CONCENTRATE MIX WITH DRIED Leucaena leucocephala LEAF REDUCED in vitro METHANE PRODUCTION IN RAMS WITHOUT AFFECTING THE NUTRIENT INTAKE AND PERFORMANCE TRAITS

Abstract

Background. Through in vitro studies, dried Leucaena leucocephala leaf (DLL) was identified as potential candidate in mitigating enteric methane (CH4) emission. Nevertheless, its efficiency as suitable feed for sheep has not been determined in Ethiopia. Objective. To assess the suitability of replacing the concentrate mix (CM) with DLL on voluntary intake, growth performance in rams and in vitro CH4 production. Methodology. Thirty yearling rams were first stratified according to their initial body weight similarities and then individuals from each stratum were randomly assigned to five treatment diets with six rams each. The control diet contained CM with 346 g/head/d (T1), and treatment diets replacing the CM in the control diet with DLL at a rate of 5% (T2), 10% (T3), 15% (T4) and 20% (T5) with the corresponding CM to DLL mixture ratio of 346:0, 329:17, 311:35, 294:52 and 277:69 g/head/day. Grass hay was provided ad libitum to all rams. Data were collected on fed intake and body weight. Methane (CH4) production was determined along with 24h in vitro gas production (GP). Digestible organic matter (DOM) and Metabolizable energy (ME) were estimated from 24h GP. Results. The contents of ash, crude protein (CP), neutral detergent fiber (NDFom), acid detergent fiber (ADFom) and acid detergent lignin were higher in DLL than in the control diet while it contained the lowest EE value. The DLL had the highest Ca and K values as compared to the control diet. The feed intake, live weight and weight gain did not differ (P>0.05) among rams supplemented with various levels of DLL. The total intake of CP increased across treatment diets and was significantly higher for T3, T4 and T5 than T1 and T2 diets. None of the supplementation levels of L. leucocephala affected the total intake of DM, NDFom and ADFom. There was a linear reduction (p<0.05) of in vitro CH4 production as the levels of DLL in the diet were increased. It was lowest in T4 and T5 diets being significantly different from those of T1 and T2. The T5 diet showed the lowest values and differed (p<0.05) from those of T1, T2 and T3. The ME and DOM values were higher (p<0.05) in T1 and T2 diets than that of T4 and T5. No difference in ME and DOM values were observed between T1, T2 and T3 diets as well as among T4 and T5 diets. Implications. The current findings suggest that conventional CM could be replaced with DLL up to 20% as alternative protein source in ruminant nutrition in tropical and sub-tropical regions. Conclusion. The replacement of CM with DLL significantly reduced the in vitro CH4 production across treatment diets without affecting the voluntary intake and growth performance parameters in rams.