Growth, carcass traits, and plasma amino acid concentrations of gilts fed low-protein diets supplemented with amino acids including histidine, isoleucine, and valine

Abstract

Three experiments were conducted to determine the fifth-limiting amino acid for growing pigs in an 11% CP, corn-soybean meal diet. In each experiment, 36 gilts (initial weight 19.5, 21.9, and 21.0 kg, respectively) were penned individually and fed one of six diets in a randomized block design for 35 d. Diets containing 16, 12, and 11% CP were fed in each experiment. All 12 and 11% CP diets were supplemented with lysine, tryptophan, threonine, and methionine to provide the same total concentrations as those in the 16% CP diet. In Exp. 1, the 11% CP diet was supplemented with isoleucine, valine, or isoleucine + valine to concentrations equal to those in the 16% CP diet. In Exp. 2, the 11% CP diet was supplemented with histidine, histidine + valine, or histidine + isoleucine + valine. In Exp. 3, the 11% CP diet was supplemented with valine, histidine + valine, or isoleucine + valine. Gilts were allowed free access to feed and water. In all experiments, ADG and feed efficiency (G/F) were reduced (P < or = 0.07) as dietary protein was reduced. Supplementation of isoleucine alone further reduced (P < 0.05) ADG, ADFI, G/F, and fat-free lean gain. In contrast, supplementation of valine alone resulted in numerical increases in ADG and ADFI in two experiments, although the differences were not significant (P > 0.05). Supplementation with histidine and valine together resulted in growth performance equal to or greater than that of pigs fed the 12% CP diet, but less than that of pigs fed the 16% CP diet. Supplementation of isoleucine and valine together resulted in better growth performance (P < 0.05) than supplementation of either amino acid alone. In two experiments (Exp. 1 and 3), supplementation of the 11% CP diet with isoleucine and valine together resulted in ADG that were not significantly different (P > 0.05) from those of pigs fed the 16% CP diet. Supplementation of all three amino acids (Exp. 2) did not improve performance over supplementations with histidine and valine. Plasma urea concentrations were reduced (P < 0.05) as dietary protein was lowered from 16 to 12%. Additions of crystalline amino acids did not affect plasma urea levels. Plasma amino acid concentrations reflected the dietary additions of crystalline amino acids, but did not assist in the identification of the sequence of limiting amino acids. These data suggest that valine is the fifth-limiting amino acid and that either histidine or isoleucine is the sixth-limiting amino acid in an 11% CP diet.

Requirement of standardized ileal digestible valine to lysine ratio for 8- to 14-kg pigs

“…In typical European diets, Val will often be the third to fifth limiting AA in diets for piglets (Figueroa et al, 2003;Mavromichalis et al, 1998;Nørgaard and Fernández, 2009). It has been reported that Val may be involved in appetite regulation acting as a signal of a non-dispensable AA deficiency (Gloaguen et al, 2011).…”

Response of piglets to the valine content in diet in combination with the supply of other branched-chain amino acids

“…When low-protein diets are formulated to contain crystalline amino acids, it is likely that several amino acids are co-limiting for performance. It is generally assumed that Val is the fifth-limiting amino acids in corn-soyabean meal-based diets in growing pigs (Figueroa et al, 2003). Barea et al (2009b) estimated the Val requirement expressed on a standardized ileal digestible (SID) basis and relative to Lys to be at least 70% using performance as a response criterion.…”

Effects of low-protein diets supplemented with indispensable amino acids on growth performance, intestinal morphology and immunological parameters in 13 to 35 kg pigs

“…Besides, reducing dietary CP level from 20.00% to 13.90% resulted in higher plasma concentrations of lysine, methionine and alanine, this response is in agreement with previous reports that the higher protein degradation of pigs occurred in pigs fed low-CP diet, thus increased the plasma concentration of some free AA . On the other hand, the higher plasma concentrations of lysine and methionine may be related to the higher supplementation of industrial lysine and methionine in low-CP diet (Figueroa et al, 2003). The lower plasma concentration of arginine may reflect the lower dietary provision of arginine in pigs fed low-CP diet.…”