Utilization of ileal digestible amino acids by pigs: Lysine

E. S. Batterham, L. M. Andersen, D. R. Baigent, S. A. Beech, R. Elliott
1990 British Journal of Nutrition  
Two experiments were conducted to determine the utilization of ileal digestible lysine by pigs. In the first, the apparent ileal digestibility of amino acids in cottonseed meal, meat-and-bone meal and soya-bean meal was determined in pigs fitted with 'T'-shaped cannulas. In the second experiment, three lysinedeficient diets were formulated to 0.36 g ileal digestible lysine/MJ digestible energy (DE), with lysine contributed from the three protein concentrates as the only source of lysine in
more » ... e of lysine in sugar-based diets. An additional three diets were formulated with supplements of lysine to verify that lysine was limiting in the first three diets. The growth performance and retention of lysine by pigs given the six diets over the 20-45 kg growth phase were then determined. The apparent ileal digestibility of lysine in the three protein concentrates (proportion of total) was : cottonseed meal 0.74, meat-and-bone meal 0.78, soyabean meal 0.89. Growth rates (g/d) of the pigs given the three diets formulated to 0.36 g ileal digestible lysine/MJ DE were significantly different (P < 0001): cottonseed meal 377, meat-and-bone meal 492, soya-bean meal 541. The response of pigs to the addition of lysine confirmed that lysine was limiting in these diets. Crude protein (nitrogen x 6.25) deposited by the pigs was significantly higher (P < 0.001) for those given soya-bean meal (77 g/d), relative to meat-and-bone meal (66 g/d) and cottonseed meal (38 g/d). The proportion of ileal digestible lysine retained by pigs given the three protein concentrates was: cottonseed meal 0.36, meat-and-bone meal 0.60, soya-bean meal 0.75. The results indicate that values for the ileal digestibility of lysine in protein concentrates are unsuitable in dietary formulations as the assay does not reflect the proportion of lysine that can be utilized by the pig. It appears that, with heat-processed meals, a considerable proportion of the lysine is absorbed in a form(s) that is (are) inefficiently utilized. Interest has centred on the use of the ileal digestibility assay to estimate amino acid availability. This assay has the advantage that the digestibility of all amino acids can be assessed at the same time and only small numbers of pigs are required per assay. The assumption is made that, if an amino acid is not recovered at the terminal ileum, then it has been absorbed in a form that can be utilized by the pig. With weaner pigs, Leibholz (1985) reported that the retention of apparently absorbed lysine at the terminal ileum was 0.860.94 for five diets containing different protein sources, and suggested that the apparent digestibility of lysine could be used to predict lysine availability. However, in a previous study (Batterham et al. 1990a), there was close agreement between ileal digestibility and lysine availability in soya-bean meal (0.89, 0.90 respectively) but not for cottonseed meal (0.58-0.72 ileal digestibility, 0.274-30 lysine availability). Formulating diets containing cottonseed or soya-bean meals on an available lysine basis
doi:10.1079/bjn19900070 pmid:2124924 fatcat:gvzm43ocovdjloegdlo3gogrse