SUPPLEMENTATION OF CERTAIN AMINO ACIDS, VITAMINS AND MINERALS TO GRAIN SORGHUM-SOYBEAN MEAL AND LOW PROTEIN DIETS FOR GROWING PIGS

Abstract

Previous research at the University of Kentucky has shown that the performance of growing pigs is not maximized when they are fed a low protein (10.5 %), grain sorghum-soybean meal (SBM) diet, even though the diet is fortified with sufficient levels of the limiting amino acids. This study was conducted to determine whether deficiencies of certain minerals (K, Mg) or B-vitamins (choline, biotin, folic acid), which are more abundant in SBM than in grain sorghum, and which ordinarily are not added to pig diets, were responsible for limiting maximum rate and efficiency of gain. Two 28- d experiments, each involving six replicates of two pigs/pen (19.2 to 35.5 kg) were conducted. The basal diet consisted of 91 % low tannin grain sorghum, 5 % dehulled SBM, 0.57 % HCl Lys, 0.15 % Thr, (10.5 % crude protein, CP; Lys and Thr were added to give a final concentration of 0.79 % Lys and 0.52 % Thr), minerals and vitamins. Treatments in Exp. 1 were: 1) Basal; 2) As 1 + 0.08 % Ile + 0.10 % Met; 3) As 2 + 330 mg kg-1 choline, 2 mg kg-1 biotin + 0.125 mg kg-1 folic acid + 0.27 % K + 0.03 % Mg; and 4) Control (grain sorghum-SBM, 16.5 % CP). Amino acids were added to meet at least 110 % of the NRC requirement for the 20 to 50 kg pig. Growth rate was reduced (p0.10) in pig performance resulted from addition of the minerals or B-vitamins, and pigs fed the control diet performed better (p