Effects of an ensiled mixture based on orange pulp on the intake and performance of fattening male lambs

Forty Afshari male lambs (body weight = 28 kg +/- 2.2 kg) were used to assess the effects of ensiled mixture based on orange pulp (EMOP) on intake, average daily gain, nitrogen (N) balance, digestibility, estimated microbial N synthesis (EMNS), rumen variables, blood metabolites, total antioxidant capacity (TAC), and in vitro methane (CH4) emission. The EMOP contained (per kg dry matter; DM) 320 g fresh orange pulp, 300 g wheat straw, 110 g beet pulp, 82 g corn flour, 82 g corn gluten, 82 g rice bran, 20 g urea, 2 g ammonium sulfate, and 2 g vitamin -mineral premix. This homogenous mixture was packed into 40-L plastic containers and ensiled for 90 days. The experimental diets contained different levels (0, 180, 360, or 540 g/kg DM) of EMOP, which were individually assigned to four groups of fattening lambs (10 replicates) in a randomized trial. Lambs were fed with the diets twice daily for 74 days (10-d adaptation and 64-d recording period). Animal performance, rumen fermentation, EMNS, N balance, and blood metabolites were determined and data were analyzed using the MIXED procedure in SAS. Increasing the dietary level of EMOP improved the digestibilities of organic matter and ash -free neutral detergent fiber, and feed efficiency (FE) (L, P = 0.04). The EMOP inclusion in the diet decreased rumen ammoniaN concentration (L, P = 0.04), total protozoa count (L, P = 0.03), in vitro CH4 emission (L, P < 0.001), and blood urea -N concentration (L, P = 0.02), but increased total ruminal volatile fatty acids content (P = 0.03), cellulolytic bacteria population (L, P = 0.01), the amount of EMNS (L, P = 0.02), N retention (L, P = 0.01), and blood TAC level (L, P = 0.01). Overall, feeding EMOP, up to 540 g/kg of diet DM, improved FE, nutrient digestibility, rumen fermentation, and general health of Afshari lambs. Ensiling fresh orange pulp in combination with dry feeds can be a valuable way to preserve this by-product as a feedstuff, particularly in the arid and semi -arid areas, which may reduce the ration cost of lamb -meat production, without negative effects on fattening performance.