PSX-12 Effects of the dietary hempseed meal on feed intake, digestion, methane emission, and heat production in Boer does during late gestation.

Abstract Hempseed meal (HSM) is a byproduct of oil extraction from hemp seed. A study was conducted to evaluate the effects of the different levels of HSM on feed intake, digestion, methane emission, and heat production in Boer does during late gestation. A total of thirty-six Boer does were used, with 9 per diet and were stratified based on body weight (BW) and litter size. The dietary levels of HSM were 0, 10, 20, and 30% of dry matter (DM). The diets consisted of 50% mixed grass hay and 50% concentrate, and were formulated to provide 16% crude protein (DM basis). Dietary levels of rolled corn and soybean meal were decreased as the level of HSM increased. Feeding of diets with HSM began at approximately 95 days of gestation. After 25 days of group feeding, with three does per treatment, the does were placed in metabolism crates for 9 days, consisting of 4 days for adaptation and 5 days for the collection period (days 125-130 of gestation). At end of the metabolic trial, an indirect calorimetry system was used for one day to measure oxygen consumption and emissions of carbon dioxide and methane, with measures used to determine heat production or energy expenditure. Data were analyzed using a mixed effects model of the Statistical Analysis System, with dietary HSM level as a class variable and testing of linear and quadratic effects of the level of HSM. Intake of DM changed linearly (P=0.01) and quadratically (P < 0.01) as the dietary level of HSM increased (1.84, 2.08, 2.82, and 2.13% BW for 0, 10, 20, and 30% HSM, respectively; SEM=0.141). Digestibility of DM decreased linearly (P< 0.01) as the level of HSM increased (68.4, 62.9, 60.1, and 53.4% for 0, 10, 20, and 30% HSM, respectively; SEM=1.321). Digestible DM intake differed among treatments (P=0.01) and only the quadratic effect was significant (P=0.01; 815, 851, 991, and 689 g/day for 0, 10, 20, and 30% HSM, respectively; SEM=62.6). Heart rate was not affected by HSM level (P >0.05; 107, 114, 112, and 115 beats/min for 0, 10, 20, and 30% HSM, respectively; SEM=4.0). Methane emission decreased linearly (P< 0.01) as the level of HSM increased (16.7, 15.1, 13.9, and 13.2 g/day for 0, 10, 20, and 30% HSM, respectively; SEM=1.165). Heat production was similar among dietary levels of HSM (2.36, 2.56, 2.51, and 2.45 MJ/kg BW0.75 for 0, 10, 20, and 30% HSM, respectively; SEM=0.096). In conclusion, there is potential for inclusion of HSM in diets of meat goats during late gestation at moderate levels, such as up to 20%.