Delineation of the individual effect that lysine, crude fiber and free gossypol content of cottonseed meal exert on growing pig performance and determination of amino acid availability in screwpress and glandless cottonseed meals

Abstract

Two factorial designed individual pig feeding trials and a digestion trial were conducted to delineate the effect of lysine, crude fiber and free gossypol in cottonseed meal (CSM) on the performance of growing pigs fed sorghum-based diets. Trial I examined three levels of lysine (.60, .70, .80%), two levels of fiber (3.0, 4.5%) and three levels of free gossypol (90, 300, 500 ppm) using specially processed CSM's while trial II examined the same levels of dietary lysine and two levels of fiber (2.56, 3.54%) using a commercial direct solvent CSM. Supplemental iron was added to all CSM diets on a 1:1 weight ratio of iron to free gossypol. The effect of the dietary fiber levels in trial II on energy and protein digestibility was investigated in trial III. In trial I, dietary lysine caused the greatest effect on pig performance followed by crude fiber while free gossypol had the least effect when iron was included in the CSM diets (1:1 weight ratio). Increasing the dietary lysine level gave a quadratic response for pig gains (P<.05) and feed intake (P<.10) and a linear improvement (P<.05) in feed efficiency. Level of crude fiber had no effect on feed intake but daily gains were slightly lower (.82 vs .79 kg/day) and feed efficiency was less desirable (P<.05) on the higher fiber diet. Dietary free gossypol had no significant effect on any production parameter; however, intake and daily gains trended downwards as dietary free gossypol increased..