Influence of soybean protein source on growth performance and nutrient digestibility of piglets from 21 to 57 days of age

The effects of including soy protein concentrate (SPC) and soybean meal (SBM) of different origins in the diet on growth performance and nutrient digestibility of weanling pigs were studied in 2 experiments. In both experiments, pigs received in phase I (21-49 d of age) one of five diets that differed in the soy protein source used. Two diets were based on SPC from USA or Brazil (BRA) origin and the other three diets were based on SBM from USA, BRA or Argentina (ARG) origin. In phase II (49 to 57 d of age), all pigs received a common maize-SBM diet. Pre-planned orthogonal comparisons (SPC vs. SBM; USA vs. BRA SPC; and USA vs. BRA vs. ARG SBM) were conducted to detect differences among soy treatments. In experiment 1, growth performance was similar for piglets fed diets containing SPC than for piglets fed diets containing SBM. In phase I (P = 0.067) and cumulatively (P = 0.082), post-weaning diarrhea (PWD) was lower in pigs fed SPC than in pigs fed SBM. The inclusion of USA meal in the diet improved ADG (P < 0.01) and G:F ratio (P < 0.01) compared with the inclusion of South American meals. The coefficient of total tract apparent digestibility (CTTAD) of crude protein was higher in pigs fed SPC (P < 0.05) than in pigs fed SBM. Nutrient digestibility was similar for both SPC diets but lower (P < 0.001) in pigs fed BRA SBM than in pigs fed USA or ARG SBM. In experiment 2, growth performance of the pigs was not affected by the soy product used, but in phase I (P = 0.062) and cumulatively (P = 0.083), PWD was lower in pigs fed SPC than in pigs fed SBM. Also, pigs fed the USA and BRA SBM had lower incidence (P < 0.05) of PWD than pigs fed the ARG SBM. No differences in the CTTAD were detected between diets based on SPC and diets based on SBM, or between SPC origins but nutrient digestibility tended to be higher (P < 0.10) for the USA than for the South American SBM. The data indicate that the chemical composition and nutritive value of commercial soy products varied between sources and among commercial batches of SBM, affecting growth, PWD and nutrient digestibility of the piglets.