68
Effect of α-galactosidase and citric acid on nursery pig growth performance
Soybean meal contains nonstarch polysaccharides which lower the feed’s digestibility and can limit inclusion of soybean meal in nursery pig diets. Addition of exogenous enzymes, such as α-galactosidase, may increase nutrient digestibility of corn-soybean meal diets by hydrolyzing bonds between nonstarch polysaccharides that are not usually severed by endogenous enzymes. Addition of an acidifier, such as citric acid, may decrease diet pH thereby increasing α-galactosidase activity. In addition, citric acid may have direct effects on improving growth performance. The purpose of this study was to examine the effect of supplementing nursery diets with α-galactosidase, citric acid, or both. Weaned pigs (29±2 d, 8.5 ± 1.7 kg) were sorted into 20 pens (1.75 x 1.19 m, 6 pigs/pen) in an environmentally controlled nursery at the Illinois State University Farm, Lexington, IL. Pens were balanced for weight (51.5 ± 0.3 kg) and gender (3 barrows, 3 gilts). Corn-soybean meal diets, formulated to meet or exceed NRC requirements, were fed in-phase for 21 days. Dietary treatments were Control (corn-soybean meal), Enzyme (Control + 7.94 ppm α-galactosidase), Citric (control + 5% citric acid), and Dual (Control + 7.94 ppm α-galactosidase + 5% citric acid). Feed disappearance and pig BW were measured weekly to calculate pen ADFI, ADG, and G:F. Analysis of variance was performed using SAS (SAS Institute Inc., Cary, NC). Means were compared using Tukey’s HSD. Pen was the experimental unit, but results are presented on an individual pig basis. Pigs fed Citric or Dual diets were more efficient (P < 0.05) than pigs fed Enzyme. However, pigs fed Enzyme had significantly higher (P < 0.05) ADFI than pigs fed Citric and Dual diets (767.2 g/d vs. 616.7 g/d and 610.4 g/d), as well as, significantly higher (P < 0.05) ADG than pigs fed Control and Citric diets (520.0 g/d vs. 457.6 g/d and 453.7 g/d). Pigs fed enzyme gained weight faster than pigs fed Control or Citric diets, but were less efficient than pigs fed Citric or Dual diets. Improving ADG in nursery pigs is generally more beneficial than improving G:F. For improved weight gain, and feed intake, α-galactosidase supplementation of nursery diets should be considered. Inclusion of 5% citric acid does not improve efficacy of α-galactosidase in the aforementioned diets.
Keywords: α-galactosidase, citric acid, nursery pig