Lysine requirements and whole-body protein turnover in growing pigs

Abstract

The influence on protein accretion and whole-body protein turnover of changing dietary protein quality while maintaining constant energy intake was studied by varying the degree of lysine supplementation of a lysine-deficient barley-based diet given to growing pigs. Measurements of nitrogen metabolism and whole-body protein turnover, using both classical and 15N end-product methods following a single dose of [I5N]glycine, were made in 49-kg male pigs given diets containing 109 g lysine-deficient protein/kg supplemented to make them (1) 'deficient', (2) 'adequate' and (3) 'in excess' with respect to lysine. The "N dose and protein intake values used to calculate amino N flux from the cumulative urinary excretion of "N in urea and ammonia were corrected respectively for apparent digestibilities of (15N]glycine and total N determined in a separate experiment in pigs fitted with simple ileal cannulas. N retention and biological value were significantly increased by lysine supplementation of the deficient diet to the 'adequate' level, but were not further increased by the higher level of supplementation. Rates of growth paralleled these changes. The poorer biological value of the unsupplemented diet 1 was shown also in a significantly higher excretion of urea N compared with diets 2 and 3. N digestibility was not markedly influenced by the level of lysine supplementation. Both whole-body protein synthesis and degradation increased markedly on 'adequate' supplementation of the diet with lysine, but did not increase further with an excess of lysine. It is concluded that the increase in protein accretion rate observed on supplementation of the diet with lysine was due to a greater increase in the rate of protein synthesis than of degradation, rather than a decrease in degradation rate.Growth : Lysine requirement: Protein turnover: Pig

Whole-body protein metabolism and plasma profiles of amino acids and hormones in growing barrows fed diets adequate or deficient in lysine

“…The increase in whole-body N retention (or PR) achieved by supplementing lysine-deficient diets to reach requirements (NRC 1988) was a result of a greater increase in whole-body PS than in PD. This is in agreement with the findings of Salter et al (1990). In contrast, Fuller et al (1987a) observed that lysine supplementation increased net anabolism as a result of no significant increment of PS and of a numerical decrease in PD.…”

“…Fuller et al (1987a) reported that the increase in protein retention (PR) observed with lysine supplementation of lysine-deficient diets appeared to be achieved through a numerical decrease in protein degradation (PD) without any change in PS. In contrast, Salter et al (1990) reported that the improvement of PR with lysine supplementation was due to the increase in PS exceeding that in PD. Despite an increase in protein retention, no major perturbations of whole-body energy metabolism were observed when lysine deficiency was corrected by dietary lysine supplementation (Noblet et al 1987;Fuller et al 1987b).…”

“…Equivocal results have been observed in the few studies in swine that have investigated the relationship between nutritional protein quality and the regulation of whole-body protein metabolism in vivo (Fuller et al 1987a;Salter et al 1990). Fuller et al (1987a) reported that the increase in protein retention (PR) observed with lysine supplementation of lysine-deficient diets appeared to be achieved through a numerical decrease in protein degradation (PD) without any change in PS.…”

The effect of the apparent ileal digestible lysine-to-energy ratio on growth rate and protein deposition in the body of growing pigs fed a wheat-rapeseed diet

“…On the other hand, excess lysine (diet 4) did not further increase growth or protein deposition rates, which emphasises the importance of the "ideal" protein in feeding of growing pigs. These results are consistent with the observation of Salter et al (1990). These authors stated that the addition of sufficient lysine to meet the requirements of growing pigs fed a diet containing barley and soyabean meal resulted in a significant increase in N retention and protein accretion, however, excess lysine did not increase protein deposition.…”

Responses to nutrients in farm animals: implications for production and quality

“…Similar results have been demonstrated Nutrients for production and product quality in the growing pig (Salter et al, 1990) and in humans (Conway et al, 1980;Meredith et al, 1986). Studies performed using lysine-deficient diets have also revealed the possibility of a major effect of dietary amino acid levels on protein degradation: the fractional rates of proteolysis (values expressed as % per day) measured in the breast muscle of growing chickens are always higher in the lysine-deprived animals, irrespective of age or genotype (Tesseraud et al, 1996a and.…”