Replacement value of tree legumes for concentrates in forage-based diets. II. Replacement value of Leucaena leucocephala and Gliricidia sepium for lactating goats☆

Abstract Laboratory, digestion and lactation trials investigated the replacement value of the tree legumes Gliricidia sepium and Leucaena leucocephala for a concentrate supplement in kinggrass ( Pennisetum purpureum ) based diets. In the lactation trial, 15 does in mid-lactation were allocated to three dietary treatments in a 3 × 3 Latin square design with five square replications. In the digestion trial, six intact yearling male goats were assigned to the same treatments in a replicated 3 × 3 Latin square design. Diets were based on kinggrass and supplemented with either a commercial concentrate feed, gliricidia or leucaena. In the control diet, 60% of the total dietary N was supplied by the concentrate. In the legume-supplemented diets, gliricidia or leucaena replaced approximately 50% of the N supplied by the concentrate. Dried banana fruit ( Musa×paradisiaca ) was used in the legume-supplemented diets to equal the energy content of the control diet. Diets contained approximately 2.2% N and 73% total digestible nutrients. Legumes were greater in total N concentration than kinggrass, with leucaena containing more N than gliricidia ( P P P P P P >0.10) across treatments. Fecal N production was greater ( P P P P P >0.10) for all treatments. For iso-energetic diets, up to 50% of the concentrate N may be replaced by the tropical tree legumes gliricidia and leucaena without a reduction in milk production.