Nutritive value of Nigerian rubber seed ( Hevea brasiliensis) meal and oil. III. Performance characteristics, relative organ weights, hematocrit and plasma metabolites of growing female rats fed corn diets containing rubber seed meal, soya bean meal or casein

Abstract

Growing Sprague-Dawley female rats were used to compare the effects of feeding corn diets containing rubber-seed meal (RSM), soya bean meal (SBM) or casein (CA) on their performance characteristics, relative organ weights, hematocrit and some plasma metabolites in a 21-day experiment. The 30 rats used were randomly divided into 5 equal treatment groups of 6 rats, kept in individual cages and fed 5 different 12% protein isocaloric diets consisting of corn plus (1) RSM, (2) RSM + lysine + methionine, (3) SBM 1, (4) SBM 2, and (5) casein + methionine. All diets supplied equal proportions of protein from corn and protein sources (6.7:5.3, corn:protein source) except Diet 4 which had a ratio of 7.5:4.5. Rats fed RSM Diet 1 had significantly lower daily gains (ADG), higher feed:gain ratios, and lower relative liver weights, total plasma protein, plasma albumin, and protein efficiency ratios (PER) than the rats fed all the other diets ( P < 0.01). Supplementation of the RSM diet with amino acids (Diet 2) significantly improved all those traits relative to the unsupplemented diet and produced performance similar to that obtained with the SBM and casein diets. There were no significant differences among treatment means for the relative weights of kidney, spleen, reproductive tract and heart, nor in values ( P > 0.05) for HCT, plasma urea N or cholesterol. The diet which contained casein plus 0.2% DL methionine did not significantly improve any of the traits measured as compared with SBM diets, but it did significantly improve the total plasma protein and reduced liver weight relative to Diet 1. It is concluded that growth performance of rats fed a corn-RSM diet is inferior to that of rats fed a corn-SBM diet and that supplemental methionine and lysine in RSM diets promoted performance similar to that obtained with SBM.