RAPESEED, PEANUT AND SOYBEAN MEALS AS PROTEIN SUPPLEMENTS: DIETARY AMINO ACID COMPOSITION AND POSTPRANDIAL PLASMA AMINO ACID PATTERN AS INDICES OF PERFORMANCE OF PIGS

Abstract

Postprandial plasma amino acid concentration and chemical score were compared with average daily gain to assess the supplemental values of prepress solvent-extracted rapeseed (RSM), solvent-extracted peanut (PNM) and solvent-extracted soybean meals (SBM) by identifying the limiting amino acids in each of the supplements. Eight diets utilizing these supplements as sole or combined supplements were involved, and to one of these diets lysine was added. Blood was sampled by anterior vena cava puncture at 13–14 wk of age following 8–9 wk on test. Preprandial samples were taken after a 24-h fast followed by other samples at 1, 2, 3 and 4 h postprandial, respectively. A quadratic equation was used to estimate the peak and peaking time for each replicate by treatment combination. Chemical score based on National Academy of Sciences–National Research Council (NAS–NRC (1973)) requirement identified lysine as the first limiting amino acid. The deficiency was most acute with PNM, followed by RSM, which was consistent with dietary lysine analysis. Postprandial plasma amino acid levels corresponded with dietary levels, but in diets containing RSM, relatively high plasma lysine values were not reflected in high average daily gain, suggesting that plasma lysine levels are doubtful indicators of expected performance for pigs fed different protein supplements. Significant (P < 0.01) variation in peaking time between plasma amino acids within each diet could explain some of the discrepancies in the relationship of plasma lysine levels to average daily gain.