I . Four pigs initially of 30 kg live weight were surgically prepared with two re-entrant cannulas in the jejunum 1.0 m apart which allowed an isolated loop to be formed through which solutions were perfused. Wr-EDTA was used as a marker for measuring net secretion or absorption.2. A new Ringer solution was made, the ionic content of which resembled more closely that found in the jejunum of pigs given similar diets, than Krebs-Ringer solution.3. The absorption of glucose and water from Krebs-Ringer and new Ringer solutions was compared. 4.The effect of guar gum on the absorption of glucose and water from solutions of glucose and maltose was studied.5. There was a trend (not significant) for greater absorption of glucose and water from the new Ringer solution than from the Krebs-Ringer solution.6. Guar gum significantly reduced the net absorption of glucose from glucose or maltose solutions from 74.2 to 41.4% (P i 0401) and 71.1 to 35.0% (P < 0.001) respectively. 7.Guar gum significantly reduced the net absorption of water from the glucose solution from 42.7 to 8.3% (P < 0.01) and from the maltose solution from 49.2 to 5.1% (P < 0@01).8. The lack of differences between the absorption of glucose from solutions of glucose or maltose suggested that maltase (EC 3.2.1.20) activity was not inhibited to the extent that this limited the rate of glucose absorption.The beneficial effects of guar gum on glucose tolerance in normal (Jenkins et al. 1977) and diabetic (Jenkins et al. 1976) man are well established. The principal effect of adding guar gum to the diet is a decrease in postprandial hyperglycaemia. However, its mode of action remains unclear. Several hypotheses have been proposed to explain its action within the gut. These include a reduced rate of emptying of the stomach, altered motility in the stomach and small intestine, poorer mixing of digesta and enzymes in the gut lumen, slower hydrolysis of dietary components by brush-border enzymes in the small intestine and a reduction in the rate of absorption across the epithelial cell membrane (Low et al.

1. We have investigated the relations between changes in plasma insulin and 3,5,3'-triiodothyronine (T,), and muscle growth and protein turnover in the rat in response to diets of varying protein concentrations.2. Young rats were fed ad lib. on a control (180 g casein/kg) diet or low-protein diets containing 80, 45 and 0 g casein/kg in four separate experiments. Measurements were made of food intakes, muscle and body-weight growth rates, muscle protein turnover in vivo, plasma insulin, and plasma free and total T,.3. The food intakes of the 80 and 45 g casein/kg diet groups were variable, with the 80 g casein/kg diet group consuming either the same or more than the controls, and the 45 g casein/kg diet group consuming less or more than the controls. Body-weight and skeletal-muscle growth rates varied with the protein but not energy intakes, which in turn reflected both dietary composition and the food intake, with the hyperphagic 80 g casein/kg diet group of rats growing almost normally and the 0 g caseinlkg diet group losing body-weight and muscle mass. 4. Changes in rates of muscle growth were accompanied by parallel changes in rates of protein synthesis and degradation, as well as parallel changes in concentrations of plasma insulin and free T,, to the extent that all these variables were highly correlated with each other.5. Partial correlation analysis was used to separate interactions between variables. This indicated that dietary energy had no identifiable influence on muscle growth. In contrast dietary protein appeared to stimulate muscle growth directly by increasing muscle RNA content and inhibiting proteolysis, as well as increasing insulin and free T, levels. Insulin and free T, stimulated each other as well as muscle protein turnover; insulin stimulating the RNA activity particularly at low insulin levels, free T, stimulating the RNA content and both hormones stimulating proteolysis.6 . These apparent relations are shown to be consistent in the main part with previous studies of the mechanism of action of insulin and T,, but the possibility cannot be discounted that other anabolic hormones not measured in these studies are involved, particularly in the apparent direct influence of dietary protein on muscle.

No abstract

Four sorghums, ranging widely in tannin content, and yellow corn were evaluated in two 5 x 5 Latin square digestion trials and a growth trial. All grains were grown in the same field under similar conditions. The sorgums and their tannin contents (milligrams of catechin/100 mg of dry matter, as determined by a modified vanillin-HCl method) were: Ga615, 3.40; NK300, 3.17; TAM680, .83, and G766-W, .88. Diets were supplemented with casein to provide .70 and .60% lysine in digestion trials 1 and 2, respectively. In trial 1, conducted with noncannulated, 25-kg pigs, digestibilities of dry matter, gross energy and N averaged for the low tannin sorghums (TAM680 and G766-W) were higher (P greater than .01) than the corresponding digestibilities averaged for the high tannin sorghums (Ga615 and NK300). N balance data indicated that utilization of absorbed N was not reduced in pigs fed the high tannin sorghums. Corn and the low tannin sorghums had similar digestibilities. In trial 2, conducted with 50-kg pigs fitted with T-cannulas at the terminal ileum, digestibilities of dry matter, gross energy, N and all amino acids again averaged higher (P greater than .01) for the low tannin sorghums than for the high tannin sorghums, whether measured at the end of the small intestine or over the total digestive tract. The one exception was methionine digestibilities at the terminal ileum, which did not differ between the high and low tannin sorghums. Among the amino acids, digestibilities of glycine, proline and histidine appeared to be the most depressed in the high tannin sorghums, as compared to the low tannin sorghums. Digestibilities of most nutrients were higher for NK300 than Ga615, suggesting a difference in type of tannin, or other compound, between grains. Corn and the low tannin sorghums, averaged together, had similar digestibilities for most nutrients. In the growth trial, 10 pigs, individually fed form 20 to 94 kg, received grain-soybean meal diets based on each grain except NK300. Gains were not affected by diet, but feed consumption was 9% higher (P greater than.05) and feed efficiency 10% (P greater than .01) poorer for pigs fed Ga615 than for those fed low tannin sorghums. Performance was similar (P greater than .10) for animals fed the low tannin sorghums and those fed corn.

I. The fractional synthetic rates of tissue proteins were studied in growing pigs using the constant-infusion technique of tracer-labelled amino acids ( [l4C]1eucine and [14C]lysine) and the mathetmatical model for calculation, employed in rats by Garlick, Millward &James (1973).2 . During a 6 h infusion, samples were taken from blood and muscle and at the end of the infusion from liver, muscle, pancreas, heart, duodenum, jejunum, ileum, colon, and skin. The specific radioactivity of free and protein-bound leucine and lysine was estimated. 3. A quasi-steady-state in the specific radioactivity of free plasma leucine and lysine was reached within approximately z h, the rate-constants being 35 and 48/d respectively.4. The specific radioactivity of free leucine and lysine in plasma was used to calculate the flux of these amino acids. It was found to be higher than the daily intake.5. The average fractional rate of protein synthesis in muscle and heart was 8.1 %/d, in small and large intestine the values were 50 and 33 %/d respectively and in liver and pancreas more than Ioo%/d.6. The calculation of protein synthetic rate in pig tissue using the constant-infusion method of labelled amino acids seems to be a suitable tool for study of this species.