339 An Evaluation of the Effects of Feeding an Exogenous Fibrolytic Enzyme Product on the Growth Performance and Apparent Nutrient Digestibility of Growing Bison Calves Fed in a Commercial Feed Yard

Abstract

Abstract While exogenous enzyme supplementation has been tested in ruminants as early as the 1960’s, industry adoption of such technologies has been slow. With high feed costs, technologies such as feed enzyme could potentially help producers to lower the production cost by improving feed efficiency. A 69-day growing experiment was conducted at a commercial feed yard in Western NE using bison calves [n = 228; initial body weight (BW) = 269 kg, SD = 41 kg] to determine the effects of supplementation of an exogenous fibrolytic enzyme from T. reesei on calf dry matter intake (DMI), growth performance and nutrient apparent digestibility. A completely randomized design was utilized with two treatments, control (CON) or enzyme (CX), and four pens, with calves assigned randomly to pen and pen assigned to TRT (48 to 66 calves per pen). Individual calf BW were obtained on day 0, day 35, and day 69. The DMI was measured daily by pen, with feed offered adjusted daily and fecal samples were composited and analyzed on pen-basis. Data were analyzed using JMP statistical software, with initial BW included as a covariate in the analyses. Average daily gain and DMI in calves fed the CX treatment was 7% greater (0.895 vs. 0.830 kg/d; P = 0.02), and 11% less (7.83 vs. 8.75 kg/d; P = 0.02) than in calves fed the CON treatment, respectively, resulting a 18% numeric improvement in feed efficiency for calves fed the CX treatment compared with calves fed the CON treatment. Apparent starch digestibility tended to improve (P = 0.07) by 15% in calves fed the CX treatment compared with calves fed the CON treatment, while apparent neutral detergent fiber (NDF) digestibility (as a percent of NDF) was numerically improved by 9% in calves fed the CX treatment compared with calves fed the CON treatment. Although the mode of action warrants further investigation, these data suggest that feeding an exogenous fibrolytic enzyme product may be beneficial for growing bison calves, likely in part because of greater apparent nutrient digestibility.