Effects of Replacing Soy Protein Concentrate with Fermented Soy Protein in Starter Diet on Growth Performance and Ileal Amino Acid Digestibility in Weaned Pigs

Abstract

: For Exp. 1, 120 ((YorkshirexLandrace)xDuroc) weaned pigs (7.96±0.01 kg average initial BW, 21 days weaning) were used in a 28 d-growth assay to determine the effects of replacing soy protein concentrate (SPC) with fermented soy protein (FSP) in a starter diet (d 0 to 7) on the growth performance, apparent fecal amino acid digestibility and subsequent performance in weaned pigs. Dietary treatments included: i) FSP0 (basal diet; whey-skim milk powder-SPC based diet); ii) FSP5 (replacing SPC with 5% FSP); iii) FSP10 (replacing SPC with 10% FSP). Pigs were fed the phase I diet for 7 days, and then each group was fed a common commercial diet for 21 days to determine the effect of previous diet on subsequent performance. Average daily gain (ADG) from d 5 to 7 (linear effect, p = 0.01) and d 7 to 14 (linear effect, p 0.05). Average daily feed intake (ADFI) was higher in pigs fed with the 5% FSP diet than those fed with the other diets at d 0 to 2 post-weaning (quadratic effect, p = 0.05). Also, for the entire period of phase I (d 0 to 7), pigs consumed more 5% FSP diet compared to other treatments (quadratic effect, p = 0.03). Gain/feed (G/F) was not affected by dietary SPC or FSP in phase I and subsequent periods, but G/F from d 5 to 7 after weaning was improved linearly (p = 0.04) as dietary FSP level increased. Pigs fed with 10% FSP also improved G/F compared with those fed only SPC (p 0.05). Among essential amino acids, apparent digestibility of ileal arginine (Arg), lysine (Lys), methionine (Met) and phenylalanine (Phe) were improved as the FSP level increased (linear effect, p<0.1). Also, apparent ileal total essential, non-essential and total amino acid digestibilities were increased linearly (p<0.1). In conclusion, replacing SPC with fermented soy protein appeared beneficial in growth performance, N and amino acid digestibility during the early 7 days after weaning, and an equivalent effect showed on growth performance in subsequent period of 7 to 28 days after weaning.