LAUSR

Abstract The objective of this experiment was to study the effects of substituting alfalfa with orange leaves on energy, nitrogen and carbon balance, methane emission, and milk performance in dairy goats. Ten Murciano-Granadina dairy goats in mid lactation (43.5 ± 3.59 kg of body weight [BW]) were selected in a crossover design experiment, where each goat received two treatments in 2 periods. One group of five goats was fed a mixed ration with 450 g of pelleted alfalfa and 550 g of pelleted concentrate/kg of dry matter (ALF diet), and the other diet replaced alfalfa with orange leaves (ORG diet). Inclusion of ORG than ALF diet reduced (P = 0.041) dry matter intake. The metabolizable energy intake was identical between treatments (901 kJ/kg of BW0.75, on average) and, the efficiency of metabolizable energy for milk production was 0.73. Retention of energy was lower (P = 0.001) in ORG diet than ALF diet. Carbon and nitrogen intake (P = 0.022 and P = 0.004, respectively) was greater for diet ALF than ORG, with no differences in milk carbon and nitrogen. The ORG diet reduced (P = 0.037) milk fat 3 g/kg, and CH4 (P = 0.001) 6 g/d. One of the milk fatty acids positively correlated with CH4 production was C16:0; it was greater (P