Crystalline amino acid supplementation of grain sorghum-based low protein diets for growing-finishing pigs

A study was conducted to evaluate the effectiveness of crystalline lysine, threonine, methionine and tryptophan supplementation of grain sorghum based, low protein diets for growing and finishing pigs (from 31 to 114 leg avg. body wt.). Three similar trials, each with 60 crossbred pigs! were done and each involved a comparison of nutritionally adequate grain sorghum-based diets formulated with 1) soybean meal (47%) as the supplemental source of amino acids (control) or with 2) L-lysine HCI, L-threonine, DL-methionine and L-tryptophan plus enough soybean meal to meet the requirements of the other amino acids. Overall, dietary treatment had no effect (P>0.10) on average daily gain, average daily feed intake, feed conversion efficiency, average loin area, backfat thickness or estimated carcass lean percentage. Overall average daily lean gain, however, was lower (P<0.10) for pigs fed the low protein, amino acid supplemented diets compared to pigs fed the control diet. Results indicated that the diet crude protein concentration can be reduced substantially upon amino acid supplementation with no detrimental effect on pig growth performance, however, there was some evidence of decreased lean gain.