Enzyme supplementation to increase value of soybean hulls fed to finishing swin

Soybean hulls are a by-product of soybean processing, and are widely available throughout the United States. The high concentration of nonstarch polysaccharides in soybean hulls limit the pig's ability to digest this feedstuff and thus decreases its value to pork producers. Current feeding recommendations for finishing pigs suggest limiting inclusion of soybean hulls in late finishing pig diets to 10%. Exogenous enzymes with protease and carbohydrase activity are commercially available for use in pig production and the addition of these enzymes to diets containing soybean hulls may enhance the utilization of otherwise wasted nutrient components. Three feeding trials were performed with the objective to examine the individual and combined effects of feeding soybean hulls and exogenous enzymes to grower-finisher pigs. In each trial, grower pigs (initial body weight 73 +/- 3 kg) were allotted to pens of 10 or 12 pigs. Pens of pigs were randomly assigned to one of four dietary treatments in a 2 x 2 factorial design with two levels of soybean hull (0 or 20%) combined with two levels of exogenous carbohydrase and protease enzyme supplementation (0 or 1,000 ppm). Pigs were fed ad libitum until 75% exceeded a market weight of 115 kg at which time the trial was complete. Every 14 d, pigs, feed, and feeders were weighed to determine ADG, ADFI, and G:F. Data were analyzed with ANOVA using JMP 12.0 (SAS Inst. Inc. Cary, NC) using a pen of pigs as the experimental unit. Results were considered significant at P ≥ 0.05. Grower pigs fed 20% soybean hulls grew 12% slower (P = 0.05) than pigs fed control diets. Grower pigs supplemented with 1,000 ppm REAP enzyme diets gained (P = 0.03) weight 17% faster and required (P = 0.01) 18% less feed per unit of gain as compared to pigs fed diets not containing enzyme. For finishing pigs, growth rate, average daily feed intake and feed efficiency were not different (P ≥ 0.10) based on diet type or enzyme supplementation. Overall, pigs of all trials showed 7% decreased growth rate (P = 0.01) and were 5% less efficient (P = 0.04) when fed diets containing 20% soybean hulls. However, pigs supplemented with enzyme grew 7% faster (P = 0.03) than those that were not given exogenous enzymes. There was no soybean hull enzyme interaction (P ≥ 0.10).