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

1.A technique for measuring gastric emptying in growing pigs by complete removal of digesta through a gastric 2. Four pigs were fitted with gastric cannulas and each was used in three trials. 3. The effects of level of feeding (trial I), cellulose (C), maize-oil (MO) or sucrose (SU) supplementation (trial 2) and the level of water intake (trial 3) on gastric emptying of digesta, dry matter (DM) and nitrogen from a barley-weatings-soya-bean (B) diet were measured during 4 h after the morning feed. 4.In trial 1, pigs were given 0.66,0.83, 1 .OO or 1.17 times their standard level of feeding. As the level of feeding rose, so the weight of digesta, DM and N emptied in the first hour after feeding increased. This trend continued to some extent in the second hour, but no effects of level of feeding were seen in the third and fourth hours. 5.In trial 2, maize-oil addition to the diet significantly reduced the gastric-emptying rate of DM in the second hour after feeding, compared with the rates for diet C. The rate of N emptying was significantly slower for diets MO and SU than for diet C.6. In trial 3 there were no significant effects of water intake level (1.75, 2.50 and 3.25 times the weight of diet) on the rate of DM or N emptying from the stomach. The rate of digesta (and thus of water) emptying in the first hour after feeding increased significantly as the water intake rose.7. It was concluded that because the pattern of gastric emptying was very similar despite large differences in nutritional inputs, an important property of the process appeared to be resilience. cannula is described.A major role of the stomach in the pig is to act as a reservoir of food. It provides the small intestine with a relatively continuous supply of nutrients for digestion during periods lasting several hours, between meals which are usually eaten in a few minutes. This process in turn is a determinant of the time-course of absorption and metabolism of nutrients. It is thus of interest to know whether the pattern of gastric emptying can be modified by nutritional means; any effects found could perhaps provide the basis for manipulation of metabolism and growth.At present little is known about whether changing specific components of the diet modifies the rate of gastric emptying in pigs given meals with a high dry matter (DM) content. The only direct comparisons have been made by Laplace et al. (1981) who found that there were minor differences in the patterns of gastric emptying of digesta, DM, starch and nitrogen from semi-purified diets containing maize or wheat starch together with fish meal or wheat gluten. These authors concluded that gastric emptying did not appear to be a major factor limiting the efficiency of nutrient use in the four diets used. There is no information on whether changes in meal size or the proportions of diet and water may affect gastric emptying in pigs. Furthermore, it is not known whether lipids or hyperosmolar amounts of sugars reduce gastric emptying rates, or whether dietary fibre (in the form of cellulo...