1. The effect of chronic alcohol intoxication on metabolic disturbances and fatty infiltration and degeneration was studied in genetically obese, hyperlipoproteinaemic, fa/fa Zucker rats.

2. Sixteen obese Zucker (fa/fa) rats, sixteen lean Zucker rats (Fa/-)and sixteen Wistar rats, all male rats aged 7–8 weeks, were given either a control (C)diet (13% of energy from protein, 37% from fat, 50% from carbohydrate) or an ethanol (E) diet (13% of energy from protein, 37% from fat, 14% from carbohydrate, 36% from ethanol) for 4 weeks.

3. The fa/fa rats given diet E consumed more energy than those given diet C, but after 4 weeks the weight gains and degrees of obesity were similar for both groups. With both diets, the developed hyperlipidaemia could be explained by the hyperinsulinaemia. Both hypertriglyceridaemia and hypercholesterolaemia were lower in fa/fa rats eating diet E than in those given diet C. Fatty infiltration of the liver, as assessed by hepatic triacylglycerol and cholesterol contents, was observed with both diets, but for fa/fa rats it was less extreme in those given diet E.

1. Sixteen obese (fa/fa) Zucker rats, sixteen lean (Fa/-)Zucker rats and sixteen Wistar rats, all male rats aged 7–8 weeks, were given either a control (C) diet containing no ethanol or an ethanol (E) diet in which 36% of the energy was supplied by ethanol, for a period of 4 weeks.

2. The activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49), glucose-6-phosphatase (EC 3.1.3.9) and glycerol kinase (EC 2.7.1.30) and the glycogen content in the livers of obese (fa/fa)rats were lower in animals given diet E than in those given diet C. As a result, hepatic lipogenesis and fatty degeneration of the liver were reduced in obese (fa/fa) rats given diet E.

1. Groups of rats were given a fibre-free diet containing none or one of the three fibre components: pectin, cellulose or galactomannan.

2. After feeding for 16 weeks, total protein level and β-glucuronidase (EC 3.2.1.31) activity in the contents and mucosa of jejunum and ileum, and in the contents only of the caecum, were determined.

3. The pectin supplement reduced protein concentration in jejunal contents while cellulose reduced protein concentration in the ileal and caecal contents.

4. β-Glucuronidase activity of caecal contents was significantly reduced in both the pectin- and cellulose-fed groups.

5. Cellulose affected the β-glucuronidase activity of both the ileal contents while pectin reduced the β-glucuronidase of the ileal but not the jejunal contents.

6. Dietary fibre components did not significantly affect jejunal or ileal mucosal β-glucuronidase activity.

1. Six growing pigs (30–75 kg) were fed on semi-purified diets containing either 30 g maize oil/kg diet (LFM), 30 g soya-bean oil-tallow mixture (1:1, w/w)/kg diet (LFST) or 160 g soya-bean oil-tallow mixture (1:1, ww)/kg diet (HFST) without and with the addition of guar gum (40g/kg diet).

2. Plasma glucose and insulin concentrations following twice daily feeding at 09.00 and 21.00 h were measured, during 24 h periods, in blood sampled from a permanent indwelling vena cava catheter.

3. The source and level of dietary fat had no significant effect on pre-prandial plasma glucose or insulin concentrations except for insulin with diet LFST in the morning (P<0.05). Addition of guar gum to the diets had no significant effect on pre-prandial plasma glucose and insulin levels.

4. The peak post-prandial plasma glucose and insulin levels were not significantly affected by dietary fat. The addition of guar gum, however, significantly reduced (P < 0.05) the peak post-prandial plasma glucose concentration with diets LFM and LFST and also the peak plasma insulin concentration for all diets except for diet HFST in the morning.

5. The time taken to reach the peak post-prandial plasma glucose and insulin concentrations was not significantly affected by dietary fat but it was increased by the addition of guar gum, although the differences were not always significant.

1. The effect of nutrition on the incidence of pancreatic damage was studied. Injection of excess arginine was found to cause more massive necrosis of the acinar cells after 24 h in malnourished rats (those given 50 g casein/kg diet) than in well-nourished rats (those given 200 g casein/kg diet).

2. Ultrastructural examination showed that whorl formation of the endoplasmic reticulum, decreases in the number of zymogen granules and formation of vacuoles in the cytoplasm were more marked in rats given 50 g casein/kg diet. Degradation of zymogen granules within vacuoles in the damaged cells was frequently observed in rats given 200 g casein/kg diet.

3. Necrosis of adipose tissue was associated with pancreatic damage more frequently in rats given 200 g casein/kg diet; rats with large amounts of zymogen granules in the acinar cells showed particularly severe necrosis of adipose tissue. Rats given 50 g casein/kg diet did not show necrosis of adipose tissue.

4. These results indicate that in the malnourished state there were more marked arginine lesions of the pancreas in which to study cellular and histologic changes than in the well-nourished state and that the occurrence of necrosis of adipose tissue may be related to a high content of zymogen granules in the acinar cells before pancreatic damage.

1. The excretion of aliphatic amines, methylamine, dimethylamine and trimethylamine in the urine and faeces of rats fed on a control diet and diets supplemented with creatinine, lecithin or choline were measured over a 14 d feeding period.

2. The rats were then killed and concentrations of amines in small and large intestinal contents measured.

3. Adding creatinine to the diet resulted in a significant increase of methylamine excretion in the faeces and urine. The amount of methylamine found in all parts of the intestine increased, especially in the caecum.

4. Adding lecithin to the diet resulted in an increase in the methylamine excretion only, and no change in the concentrations of amines found in the intestine, except for trimethylamine which was significantly increased in the caecum and colon.

5. Adding choline to the diet resulted in a significant increase in excretion of trimethylamine and, to a lesser extent, methylamine. The levels of amines found in the gut increased, dimethylamine being increased in the small bowel, and methylamine and trimethylamine in the caecum.

1. Intestinal absorption of sorbitol was studied in a duodeno-jejunal loop of anaesthetized rats. The acute effects of exogenous sorbitol on glucose homeostasis were also evaluated in male and female rats.

2. In the presence of lumen concentrations of sorbitol ranging from l μM to 200mM, a fairly constant low percentage (about 12%) of the loop's contents was absorbed after 30 min. This amount increased only slightly with time, but this was not due to sorbitol accumulation in the mucosal layer of the loop.

3. 3-O-methylglucose was absorbed much more quickly than sorbitol, but did not interfere with sorbitol absorption. The latter was not impaired by omission of lumen sodium ions nor by phloridzin, both of which inhibited 3-O-methylglucose absorption.

4. Gastric administration of sorbitol did not affect plasma glucose or insulin levels. Glucose or sucrose administration caused a similar rise in plasma glucose, but the increase in plasma insulin levels was larger after glucose than after sucrose administration.

5. Intravenous administration of sorbitol slightly increased plasma glucose and insulin levels. These changes were, however, considerably smaller than those occurring after glucose administration.

6. In the normal rat, intestinal absorption of sorbitol is passive and proceeds at a low rate. Acute oral administration of sorbitol does not affect glucose homeostasis, which is only slightly disturbed by a large intravenous load of sorbitol.

1. Protein-deficient weanling rats fed on a 30 g casein/kg diet for 3 weeks lost albumin but maintained the level of serum α-1-antitrypsin, the most abundant protease inhibitor in blood.

2.α-1-Antitrypsins from malnourished rats and control rats (given 250 g casein/kg diet) differed; the protease inhibitor from protein-deficient animals: (1) was more acidic, (2) appeared slightly larger (57400 v. 56000 daltons) on sodium dodecyl sulphate (SDS)-polyacrylamide gels, (3) had a more acidic Pi type and increased anodal mobility at pH 8.9, (4) bound more concanavalin-A and contained more carbohydrate, specifically two to three extra sialic acid residues. The amino sugar and neutral sugar contents of both preparations of α-1-antitrypsin were the same.

3. Analysis of the products of cyanogen-bromide cleavage revealed that α-1-antitrypsin preparations from protein-deficient rats contain an extra glycopeptide that was not present in α-1-antitrypsin from control animals.

4. In vivo studies showed that the increased sialic acid content of α-1-antitrypsin of protein-deficient rats did not alter the half-life of the molecule in the blood of control rats. However, the fractional catabolic rate of α-1-antitrypsin from either well-nourished or protein-deficient rats was significantly (P < 0.01) lower in protein- deficient rats than in control rats (0.0247/h v. 0.0406/h).

5. The decreased fractional catabolic rate could not be explained by changes in hepatic mannosyl-, galactosyl- or N-acetylhexosaminyl receptors since liver perfusion studies showed that bovine serum albumin, when covalently modified separately with each of these ligands, was extracted from the perfusion medium as rapidly or more rapidly by livers from malnourished animals.

6. Perfused livers from protein-deficient rats secrete three times more α-1-antitrypsin than do livers from well-nourished animals.

7. The decreased fractional catabolic rate and increased rate of biosynthesis and secretion of the glycoprotein by livers from protein-deficient animals may account for the maintenance of α-1-antitrypsin levels during protein malnutrition.

1. Iron retention from 3 g wholewheat flour was measured in male Wistar rats previously given one high-Fe or control diet meal 12,24, 36,48 or 60 h before the test meal (Expt 1). The control diet was given at all other times. The procedure was then repeated in rats given one high- or low-Fe meal 12, 24, 36 or 48 h before the test meal (Expt 2).

2. There was a significant difference between groups given a high- or medium-Fe meal at 12,24,36 h (P < 0.001) and 48 h (P < 0.05) but not at 60 h. In the second experiment, there was a significant difference between groups given a high- or low-Fe meal at 12, 24 or 36 h but no difference when given the two diets 48 h before the test meal. The high-Fe meal depressed and the low-Fe meal enhanced subsequent 59Fe retention: the effects were greatest at 12 h and diminished as the time interval between the high- or low-Fe meal and the test meal increased. The estimated mean time for the absorptive capacity of the mucosal cells to return to equilibrium was 54.0 (SEM 7.6) h.

3. Male Wistar rats were given high-, control or low-Fe diets for either 3 d or 28 d before an in vivo investigation in which the luminal loss of 59Fe-labelled ferric citrate from duodenal and ileal loops was measured, and the proportional distribution between the carcass and the washed loop measured (Expt 3).

4. The luminal loss of 59Fe-labelled ferric citrate was significantly affected by the previous diets (P < 0.001). Rats given a low-Fe diet absorbed more than those given a high-Fe diet but the period of time on the diet (3 or 28 d) had no effect on luminal loss. Significantly more 59Fe was lost from duodenal than from ileal loops in all groups.

1. To characterize the hypercholesterolaemic effect of casein further, four groups of young male rabbits in two separate experiments were placed on cholesterol-free semi-purified diets for 12 weeks. The diets were similar in composition, with either casein or soya-bean-protein isolate providing the protein source (250 g/kg). In two of these diets the salt mix was reduced by 45% (normally 40 g/kg) and replaced by potassium bicarbonate.

2. Growth was unaffected by these alterations in dietary salts except for one group given the soya-bean-reduced-salts diet.

3. The mean concentrations of plasma cholesterol were significantly higher in all casein-fed groups as compared with their soya-bean-fed counterparts but the response was much greater in those given the casein—reduced-salts diet.

4. Contrary to expectations, analysis of the diets showed the zinc and copper concentrations of the casein diets to be less than those of the soya-bean diets. This was due to the greater concentrations of Cu (threefold) and Zn (twofold) in the soya-bean-protein isolate compared with casein.

5. The mean concentration of Zn in fur was significantly decreased in casein-fed rabbits and these animals also excreted less Zn but more Cu in their urine than those given the casein—reduced-salts diet.

6. The rabbits given the casein diet with the least salt mix showed the greatest degree of hypercholesterolaemia, suggesting an interaction between trace elements and the casein effect.

1. Inclusion of raw kidney bean (Phasealus vulgaris) proteins in the diet for rats was shown to affect the weight of some internal organs. Of these, in addition to the well-known hypertrophy of the pancreas attributable to dietary trypsin inhibitors, the observed atrophy of the thymus and the doubling in weight of the small intestine are related to the protein or lectin content of the bean diet, or both.

2. Changes in tissue composition of the small intestine were also recorded. Its protein content increased by about 40–50% and carbohydrate content doubled suggesting the occurrence of increased mucinous glycoprotein secretion. Increased DNA content (by about 30–40 %) however also indicated mucosal hyperplasia.

3. Changes were also observed in mineral content, urea concentration and some enzyme activities in sera and urine, possibly as a result of disturbances in systemic metabolism or hormone levels, or both.

4. The results gave further support to previous suggestions that the oral toxicity of kidney-bean lectins involves local reactions in the small intestine in combination with their effects on the systemic immune system and general metabolism.

1. Studies on the quantitative significance of protozoa on carbon and nitrogen digestion and metabolism in the rumen were carried out in sheep given a diet of pelleted concentrate (500 g/d) and chopped hay (500 g/d).

2. Measurements were made of apparent digestibility; flows of organic matter and dietary and microbial non-ammonia N (NAN) (using 15NH+4) to the duodenum; and rates of production, interconversion and metabolism of the major C fermentation end-products (from mathematical modelling of 14C isotope values).

3. The population density of bacteria in the rumen increased as a result of defamation (28.6 compared with 8.2 x 10° organisms/ml). This high density was associated with greater utilization of volatile fatty acids (VFA) within the rumen.

4. The rate of irreversible loss (IL) of bicarbonatefcarbon dioxide from the rumen was greater in the defaunated animals (98.5 v. 57.2 g C/d) but the IL from the blood was greater in the faunated group (138.6 v. 106.1 g C/d). This is consistent with the hypothesis that the high population density of bacteria found in the rumen fluid of defaunated animals may result in increased fermentation of rumen VFA and digestible dietary carbohydrate, thereby increasing the output of CO2 from the rumen and reducing the quantity of VFA (hence energy) available to the host.

5. There was no difference in the flow of organic matter (OM) to the duodenum but there was a higher faecal excretion of OM in defaunated animals (apparent OM digestibility: 0.72 in faunated, 0.67 in defaunated).

6. Defamation did not significantly increase the flow of NAN to the duodenum, the percentage of duodenal NAN of bacterial origin or the quantity of microbial NAN synthesized/g organic matter fermented. Faecal excretion of NAN was higher in defaunated animals (5.3 v. 3.6 g N/d).

1. The conversion of methionine to cyst(e)ine was determined in sheep infused with different amounts of methionine (0-5 g/d) into the duodenum by assaying the incorporation of 36S from intravenously-infused L-[35S]methionine into cyst(e)ine in wool, plasma albumin and the free plasma pool.

2. The percentage of cystine-S in the plasma originating from methionine increased linearly from 4.5 to 18 with increasing supplemental methionine supply.

3. The percentage of cysteine-S in albumin increased from 15 to 50; methionine supply increased to 3 g/d but then remained constant, indicating that the transsulphuration pathway of the liver was exceeded.

4. The percentage of wool cysteine-S originating from methionine was high (∼ 70) at all methionine supplementation rates.

1. The effect of the gut microflora on protein turnover in pectoral muscle (M. pectoralis profundus) was studied by means of dietary infusion of L-[UJ-14C]phenylalanine and of massive dose injection of L-[4-3H]phenylalanine in chicks fed on a semi-purified casein—gelatin (SCG) diet until 19 d of age, and in those subsequently given either a nitrogen-free (NF) diet or NF supplemented with methionine and arginine (MA) for a further 9 d.

2. Time-course changes in radioactivity released in expired carbon dioxide during the 8 h infusion period showed that isotopic equilibrium was reached in 4 h with the SCG diet and in 5 h with the MA diet. However, with the protein-deprived chicks given the NF diet, isotopic equilibrium was not achieved since radioactivity in CO2 increased linearly throughout.

3. On feeding the NF diet, fractional protein synthesis rate and the absolute amount of protein synthesized in chick breast muscle were reduced. These reductions were partially alleviated by supplementing the NF diet with methionine and arginine.

4. The fractional degradation rate of breast muscle was increased in chicks given the NF diet, while the absolute amount of protein degraded was decreased. The addition of methionine and arginine counteracted these changes brought about by protein starvation.

5. Generally speaking, the presence of the gut microflora had little, if any, effect on protein turnover rate in chick-breast muscle.

1. Three experiments were conducted to examine the effect of monensin on growth performance, feed utilization and volatile fatty acids (VFA) in the forestomach and caecum of hamsters.

2. In Expt 1, monensin was fed at levels of 0, 5, 10 and 20 mg/kg to the growing male and female hamsters given a commercial diet (major component: lucerne (Medicago sativa) meal). In Expt 2, monensin was fed at levels of 0, 5, 15, 45 and 135 mg/kg to the growing male hamsters given a semi-purified diet containing 10 g urea/kg (main components: maize starch, sucrose, casein and cellulose). In Expt 3, monensin was fed at levels of 0 and 40 mg/kg to the growing male hamsters given the commercial diet containing lucerne meal or a semi-purified diet.

3. In Expt 1, monensin improved feed conversion efficiency and growth performances in the young growing hamsters, but monensin did not affect the hamsters at a later growing stage.

4. In response to monensin the proportion of acetic acid increased and that of propionic acid decreased in the forestomach, whereas the proportion of acetic acid decreased and that of propionic acid increased in the caecum in Expt 2. The hamsters given 135 mg monensin/kg ate less, developed diarrhoea and died.

5. The apparent digestibility of crude protein (nitrogen x 6.25) was improved by monensin but those of dry matter and neutral-detergent fibre (NDF) were decreased in hamsters given the semi-purified diet in Expt 3. Monensin did not appear to have a significant effect on the apparent digestibility of the diet containing lucerne meal.

6. The responses to monensin in hamsters are compared with those in ruminants.

1. After Nr-methylhistidine (Nr-MH) distribution among the various organs or the tissues was determined in male broiler chickens of 15 d of age, the rates of degradation of myofibrillar proteins in male layer and broiler chickens at different stages of growth were determined by means of Nr-MH.

2. About 75 and 8% of the total Nr-MH in the tissues occurred respectively in skeletal muscle and stomach, and most of the remainder in the intestine and the skin.

3. The rates of degradation of myofibrillar proteins in the male layer and broiler chickens of 21, 42 and 63 d of age were calculated to be 6.1, 4.5 and 2.4%/d (layer) and 5.0, 2.8 and 0.9%/d (broiler) respectively. These calculations involve the assumption that 80% of the total excreted Nr-MH was derived from skeletal muscle.

4. The results strongly indicate that the rapid growth of the broiler chicken is facilitated by the reduced rate of protein degradation.

1. Diets of fresh kale (Brassica oleracea) and ryegrass (Loliumperenne) – elover (Trifolium repens) herbage were fed to growing sheep in three experiments. In Expts 1 and 3 the sheep were confined indoors and fed at hourly intervals, and all were given supplementary iodine to counteract kale goitrogens. Lambs grazed the two forages for 24 weeks in Expt 2, with and without intramuscular injections of iodized oil. The kale and herbage contained respectively 11 and <0.1 g S-methyl-L-cysteine sulphoxide (SMCO)/kg dry matter (DM) and values for readily fermentable: structural carbohydrate (CHO) were 3.1 and 0.8, respectively.

2. Blood samples were withdrawn from indwelling catheters (Expts 1 and 3) or venipuncture (Expt 2) and the plasma analysed for a range of hormones using radioimmunoassay procedures. Glucose irreversible loss (GIL) was measured in Expt 1 using primed continuous infusions of D-[U-14C]glucose. Samples of adipose tissue were removed from the shoulder area in Expt 3, and rates of D-[U-14C]glucose and [U-14C]acetate incoporation and oxidation were measured in vitro, together with the rate of glycerol release.

3. In the presence of supplementary I2, kale feeding was associated with an elevation in plasma concentration of free thyroxine (T4) Regardless of I2 supplementation, sheep fed on kale had much higher plasma growth hormone concentrations than sheep fed on ryegrass-clover herbage, and this was accompanied by reduced plasma somatostatin concentrations.

4. Plasma insulin and glucagon concentrations were similar for sheep fed on the two diets; GIL tended to be slightly but not significantly greater (9.4%) for sheep fed on kale than for those fed on ryegrass-clover herbage.

5. Kale feeding was associated with increased uptakes of acetate and glucose into adipose tissue, reduced rates of oxidation of both substrates and no difference in rate of glycerol release. Each 1 nmol increase in glucose uptake was associated with 8.7 nmol acetate uptake ( P < 0.001).

6. It is proposed that ruminants counteract protein inactivation, caused by production of dimethyl disulphide from SMCO in the rumen, through increasing circulating concentrations of growth hormone and T4, which then stimulate synthesis of replacement body proteins.

1. Nitrogen kinetics were studied in six sheep (45–55 kg live weight) consuming either a high-N grass silage or a low-N dried grass made from swards of perennial ryegrass (Lolium perenne). The diets were fed hourly at a level of 600 g dry matter/d and supplied 19.5 and 11.0 g N/d respectively.

2. The amounts of organic matter (OM) consumed and flowing at the duodenum and ileum and excreted in the faeces were similar (P < 0.05) with both diets. Each diet supplied 23 g digestible OM/d per kg live eight0.75, which was sufficient to maintain body-weight.

3. There were no differences (P < 0.05) between diets in rumen fluid volume, fractional outflow rate of fluid from the rumen, total concentration of volatile fatty acids or molar proportion of acetate in the rumen. The pH and molar proportion of propionate in rumen fluid were higher (P < 0.01), and molar proportion of butyrate lower (P < 0.001) when the silage was given.

4. There was a net loss of N (4.0 g/d) between mouth and duodenum when the silage was consumed but a net gain (5.5 g/d) when the dried grass was consumed. As a result, total non-ammonia-N (NAN) flow at the duodenum did not differ (P / 0.05) between diets. Rumen microbial NAN flow at the duodenum, based on 15N as the marker, also did not differ (P < 0.05) between diets but the efficiency of microbial N synthesis in the rumen (g/kg OM apparently digested) was higher (P < 0.05) with the dried grass.

5. When the sheep were consuming silage they had a higher concentration of ammonia in rumen fluid (P < 0.01), a higher rate of irreversible loss of ammonia from the rumen (P < 0.05) and a higher rate of absorption of ammonia across the rumen wall (P < 0.01). The rate of absorption was found to be more closely related to the unionized ammonia concentration in rumen fluid (r2 0.85) than to the total ammonia concentration (r2 0.36).

6. Endogenous N entry into the forestomachs was calculated to be 5.5 g/d when the silage was given and 9.4 g/d when the dried grass was given, of which 1.7 and 3.5 g/d respectively were in the form of urea. Thus, approximately 4–6 g N/d were derived from non-urea materials.

7. Within the small intestine the apparent absorption coefficient of rumen microbial NAN (0.72) did not differ (P < 0.05) between diets but the apparent absorption coefficient of total NAN was lower (P < 0.05) when the I silage was given, owing to a lower (P < 0.01) absorption coefficient of the non-microbial NAN fraction (undegraded feed and endogenous).

8. Within the large intestine, diet had no effect (P < 0 05) on the apparent absorption coefficients of total N (0.22) and rumen microbial NAN (0.63).

9. Plasma urea concentration, the rate of urea synthesis in the body and urinary urea excretion were higher (P < 0.001) when the silage was consumed. However, the transfer of urea to the whole digestive tract and to the post-ruminal part of the tract did not differ (P < 0.05) between diets; urea transfer to the rumen was higher (P < 0.01) when the dried grass was given.

10. The results were used to construct a whole-animal model of N flows between the digestive tract and the tissues.