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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. Exogenous enzymes with protease and carbohydrase activity are commercially available and may improve utilization of soybean hulls by pigs. 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, pigs (initial body weight 73 ± 3 kg) were allotted to pens of 10 or 12 pigs. Pens were randomly assigned to one of four dietary treatments in a 2 × 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 in 2 phases (grower 70–90 kg and finisher 90–115 kg) until 75% of the pigs reached 115 kg. Every 14 d, pigs, feed, and feeders were weighed to determine ADG, ADFI, and G:F. Least square means were compared using JMP 12.1 (SAS Institute Inc.) The statistical model included soybean hull inclusion rate (0 or 20%), exogenous enzyme inclusion rate (0 or 1,000 ppm), and their interaction terms. The experimental unit for all analyses was pen. Differences were considered trends if P ≤ 0.10 and significant if P ≤ 0.05. There were no significant interactions between soybean hull inclusion rate and enzyme supplementation and so only main effects are presented. Grower pigs supplemented with 1,000 ppm enzyme grew more efficiently than unsupplemented grower pigs (G:F = 0.44 vs 0.38 g/g; P = 0.02). There was a trend (P = 0.06) for enzyme supplemented grower pigs to grow more rapidly than unsupplemented pigs (ADG = 1.00 vs 0.86 kg/d). There was also a trend (P = 0.06) for grower pigs fed 20% soybean hulls to grow less quickly that pigs fed 0% soybean hulls (ADG = 0.86 vs 0.99 kg/d). For finishing pigs, ADG, ADFI, and G:F were not impacted (P ≥ 0.10) by diet type or enzyme supplementation. Balanced diets containing 20% soybean hulls will support growth and performance in finishing pigs. Grower pigs may benefit from exogenous carbohydrase and protease enzyme supplementation when fed diets containing 20% soybean hulls.
Keywords: Carbohydrase, Non-starch polysaccharides, Protease, Soybean hulls