Impact of increasing standardized ileal digestible valine: lysine in diets containing 30% dried distiller grains with solubles on growing pig performance

Abstract

A total of 2,430 pigs (DNA 600 x Topigs Norsvin 70, initially 39.4 kg) were used in a 28-d trial to determine the standardized ileal digestible (SID) Val:Lys requirement for pigs fed diets containing 30% DDGS. Treatments included 5 diets containing 30% DDGS with SID Val:Lys ratios of 60, 65, 70, 75, and 80%, plus a corn soybean meal (SBM) diet, for a total of 6 dietary treatments. Diets were formulated to be isocaloric through the inclusion of fat and to contain equal amounts of SID Lys within phase. Pens were assigned to dietary treatment in a randomized complete block design with initial body weight (BW) as the random blocking factor. Each dietary treatment was replicated 15 times and pens contained 27 pigs, balanced for sex. Increasing the SID Val:Lys ratio in diets containing 30% DDGS increased (Quadratic; P< 0.007) 14-d BW, final BW, average daily gain (ADG), average daily feed intake (ADFI) and gain:feed (G:F) for all periods. Providing a SID Val:Lys ratio of 75% resulted in the heaviest 14-d BW and final BW as well as greater ADG and ADFI of pigs fed 30% DDGS for all periods. The G:F response was maximized when a SID Val:Lys ratio of 70% was provided from d 0 to 14 while a SID Val:Lys ratio of 75% maximized G:F from d 14 to 28 and for the cumulative period. The SID Val:Lys requirement was estimated at 66.6% (95% CI:[65.9, 67.4]), 65.7 (95% CI:[64.8, 66.5]), and 68.4% (95% CI:[66.0, 70.8]) for ADG, ADFI, and G:F, respectively, using the straight broken line (SBL) method and 69.9% (95% CI:[68.2, 71.5]), 67.6 (95% CI:[65.4, 69.8]), and 72.8% (95% CI:[69.8, 75.8]) for the quadratic broken line (QBL) method. Pigs fed the corn-SBM diet had heavier 14-d BW, final BW, and greater ADG, ADFI, G:F (P< 0.032) compared to pigs fed diets containing 30% DDGS, except for cumulative ADFI compared to pigs receiving 75% SID Val:Lys (P = 0.167). In conclusion, these results suggest that when feeding 30% DDGS during the growing period, a SID Val:Lys ratio of 68% would yield more than 99% and 97% of the maximum ADG and G:F response for the 39 to 68 kg pig. However, growth performance of pigs fed diets containing 30% DDGS did not equate to pigs consuming the corn-SBM diet regardless of SID Val:Lys ratio.