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Effect of feeding grower-finisher pig diets containing 20% soybean hulls with or without enzyme supplementation
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 suggest limiting inclusion of soybean hulls in finishing pig diets to 10%. Exogenous enzymes with protease and carbohydrase activity are commercially available and the addition of these enzymes to pig diets containing soybean hulls may enable utilization of nonstarch polysaccharides. 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 × 2 factorial design with two levels of soybean hulls (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. Grower pigs (70–90 kg) 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 weight 17% faster (P = 0.03) and required 18% less feed per unit of gain as compared to pigs fed diets not containing enzyme (P-value = 0.01). For finishing pigs (90–120 kg), growth rate, average daily feed intake and feed efficiency were not different (P ≥ 0.10) based on diet type or enzyme supplementation. There was no soybean hull × enzyme interaction during the grower or finisher phases. Overall, grower-finisher pigs grew 7% slower (P = 0.01) and were 5% less efficient (P = 0.04) when fed diets containing 20% soybean hulls. Pigs supplemented with enzyme grew 7% faster (P = 0.03) than those that were not given exogenous enzymes but there was no soybean hull × enzyme interaction. Results indicate that 20% soybean hulls can be fed to finisher pigs weighing more than 90 kg without negatively impacting growth or performance.
Keywords: Carbohydrases , Non-starch polysaccharides, Protease, Soybean hulls