Evaluation of soy protein concentrates in nursery pig diets

¹ Department of Animal Sciences and Industry, Kansas State University, Manhattan, 66506-0201

^* To whom correspondence should be addressed. E-mail: jderouch{at}ksu.edu.

	Abstract

Four experiments were conducted using 730 weanling pigs to determine the effects of soy protein concentrate (SPC) in diets for weanling pigs. Experimental diets were fed from d 0 to 14 post-weaning and a common diet was fed from d 15 to 28 for Exp. 1, 2, and 3; experimental diets were fed from d 0 to 7 post weaning in Exp.4. In Exp.1, the 4 experimental diets included: 1) 0% soybean meal (SBM) diet containing animal protein sources; 2) 40% SBM diet; or 28.55% SPC (replaced 40% SBM on a total lysine basis) from 3) Source 1, or 4) Source 2. Pigs fed diets containing either animal protein or 40% SBM had greater ADG and ADFI (P < 0.05) than pigs fed either SPC source. In Exp. 2, the 5 experimental treatments included diets 2, 3, and 4 from Exp. 1, along with 14.28% SPC from each SPC source used in Exp. 1 (replaced of total lysine from 40% SBM diet). From d 0 to 14 and 0 to 28, there was a SPC source x level interaction for ADG (P < 0.01) and tendency for ADFI (P < 0.07). Replacing SBM with SPC from Source 1 did not affect pig performance. However, replacing SBM with SPC from Source 2 resulted in an improvement (quadratic, P < 0.05) in ADG for pigs fed the diet containing 14.3% SPC, but no benefit to replacing all the SBM with SPC. Replacing SBM with SPC from either source improved G:F (quadratic, P < 0.01), with the greatest G:F observed for pigs fed the diets with 14.3% SPC. Experiment 3 evaluated increasing levels of Source 2 SPC with treatments consisting of: 1) 0% (40% SBM); 2) 7.14%; 3) 14.28; 4) 21.42; and 5) 28.55% SPC. There was a tendency for increased ADG (quadratic, P < 0.06) and increased ADFI (quadratic, P < 0.04) as inclusion of SPC in the diet increased from 7.1 to 21.4%, and decreased when 28.6% SPC was fed. Gain:feed improved (linear, P < 0.01) as SPC level in the diet increased. Inclusion of approximately 14 to 21% SPC from Source 2 maximized pig performance. In Exp. 4, pigs were offered a choice of consuming the diets containing 40% SBM or 28.6% SPC from Source 2. Daily feed intake was greater (P < 0.0001) for the SBM diet (186 g/d) than for the SPC diet (5 g/d). Our results suggest that replacing a portion, but not all, of the high SBM diet with SPC from Source 2, but not from Source 1 improves pig performance. The poor intake of pigs fed high levels of SPC may indicate a palatability problem, thus limiting its inclusion in nursery pig diets.

Key Words: growth, ingredient, protein, soy protein concentrate, weanling pigs