The apparent ileal digestibility, determined with young broilers, of amino acids in near-isogenic lines of peas (Pisum sativum L) differing in trypsin inhibitor activity

Two pairs of near-isogenic lines of peas were developed to have high and low concentrations of seed trypsin inhibitor. HA5 and LA5 contained 8.73 +/- 0.19 and 1.45 +/- 0.19 trypsin inhibitor units per mg dry weight respectively, whereas HB5 and LB5 contained 7.40 +/- 0.65 and 1.78 +/- 0.15 trypsin inhibitor units per mg dry weight respectively. The four pea samples were included in semi-synthetic diets and evaluated in a poultry metabolism experiment, using birds aged 3 weeks, to determine the coefficient of apparent ileal amino acid digestibility (CAID). There was a significant difference in CAID for the amino acids reported that correlated with pea genotype. Thus, for example, CAID for cystine was 0.738 +/- 0.0196 and 0.812 +/- 0.0128 for HA5 and LA5 respectively and 0.721 +/- 0.0139 and 0.804 +/- 0.0178 for H135 and L135 respectively. Corresponding data for methionine, the other main nutritionally deficient amino acid in peas, were 0.887 +/- 0.0103, 0.930 +/- 0.0089, 0.885 +/- 0.0083 and 0.929 +/- 0.0125 respectively. Other amino acids followed similar patterns. These data provide information on the nutritional consequences of variation in trypsin inhibitor content of pea seeds in nearisogenic backgrounds. Plant breeding for low trypsin inhibitor activity in seeds accordingly offers potential for improving nutritional value. (C) 2003 Society of Chemical Industry.