This study examined the effect of supplementing exogenous cellulase on nutrient and energy utilization. Twelve desexed Boer crossbred goats were used in a replicated 3×3 Latin square design with 23-d periods. Dietary treatments were basal diet (control, no cellulase), basal diet plus 2 g unitary cellulase/kg of total mixed ration dry matter (DM), and basal diet plus 2 g compound cellulase/kg of total mixed ration DM. Three stages of feeding trials were used corresponding to the three treatments, each comprised 23 d, with the first 14 d as the preliminary period and the following 9 d as formal trial period for metabolism trial. Total collection of feces and urine were conducted from the 4th d of the formal trial, and gas exchange measures were determined in indirect respiratory chambers in the last 3 d of the formal trial. Results showed that cellulase addition had no effect (p>0.05) on nutrient digestibility. Dietary supplementation of cellulase did not affect (p>0.05) N intake and retention in goats. Gross energy (GE) intake, fecal energy and urinary energy excretion, heat production were not affected (p>0.05) by the cellulase supplementation. Total methane emission (g/d), CH4 emission as a proportion of live weight or feed intake (DM, organic matter [OM], digestible DM or digestible OM), or CH4 energy output (CH4-E) as a proportion of energy intake (GE, digestible energy, or metabolizable energy), were similar (p>0.05) among treatments. There was a significant (p<0.001) relationship between CH4 and live weight (y = 0.645x+0.2, R(2) = 0.54), CH4 and DM intake (y = 16.7x+1.4, R(2) = 0.51), CH4 and OM intake (y = 18.8x+1.3, R(2) = 0.51) and CH4-E and GE intake. Results from this study revealed that dietary supplementation of cellulase may have no effect on nutrient digestibility, nitrogen retention, energy metabolism, and methane emission in goat.
Keywords: Cellulase; Digestibility; Energy; Goat; Methane; Nutrients.