1. Five groups of male Sprague Dawley rats were given for 6 months a diet with high protein and fat contents but a very low dietary fibre content (group B), and this diet mixed with (g/kg) 50 low-methoxyl pectin (groupL), 50 high-methoxyl pectin (group H), 50 guar gum (group G) and 200 wheat bran (group WB, corresponding to 100 wheat fibre) respectively.

2. The weight increment was significantly lower in group G than in the other groups. Assuming no energy value of the dietary fibre, the weight increment (/kJ) was the same in groups B, L and H, lower in group G and higher in group WB, indicating that a proportion of the bran fibre might in fact be available as a source of energy.

3. Wheat bran increased total plasma cholesterol and high-density-lipoprotein cholesterol after 6, 12 and 26 weeks. Group G had significantly lowered plasma cholesterol after 12 weeks. Pectin on the other hand did not significantly influence total or HDL-cholesterol levels. It is therefore possible that the plasma cholesterol lowering effect of pectin previously demonstrated in the rat is dependent on the presence of significant amounts of dietary cholesterol as our diets did not contain added cholesterol. Plasma triglycerides decreased with age but were similar in all groups.

1. The feasibility of intrinsically labelling poultry meat with the stable isotopes 68Zn and 70Zn was investigated.

2. Chickens (I-d-old) were gavaged with solutions of 68Zn and 70Zn several times over a 42 d period.

3. Isotopic analysis of edible tissues has shown that they were significantly enriched with respect to the gavaged isotope and that the extent of isotopic enrichment achieved was sufficient to permit their use in human feeding experiments designed to investigate availability of native Zn from such food models.

4. The absolute efficiency of retention of the stable isotopes from gavage solutions in the edible tissues has been calculated to be 2–3%.of the administered dose; methods have been suggested to enhance this value, based on considerations of utilization of dietary Zn.

1. One thousand individuals were asked whether they avoided any foods. Of the 560 replies 33% stated that they avoided one or more foods because they caused ‘unpleasant physiological reactions’.

2. Adverse reactions to one of thirteen foods were reported by 1–4% of the respondents and it is suggested that this number might be regarded as a standard with which to compare reactions to novel foodstuffs. A total of sixty-seven foods were specifically mentioned as a cause of an adverse reaction.

1. The fractional rate of protein synthesis (FSR) in tissues of nine growing lambs (4–5 months of age) was estimated following continuous infusion of L-[4,5–3H]leucine for a period of 7 h. Minimum and upper estimates of FSR were obtained assuming that the specific radioactivity (SRA) of leucine in blood plasma and tissue homogenate respectively defined that of leucyl tRNA.

2. Mean upper estimates of tissue protein FSR (/d) were skin 0·35, longissimus dorsi muscle 0·05, biceps femoris muscle 0·04, liver 0·54, rumen 0·79, cardiac muscle 0·09. Minimum estimates of tissue protein FSR ranged from 0·03 (muscle) to 0·15 (liver).

3. Plasma leucine flux was closely related to body protein content and dietary leucine absorption (r 0·94).

4. The rate of whole-body protein synthesis (WBS) derived from plasma leucine flux corrected for oxidation and localized recycling of leucine into protein was similar to that calculated from the sum of daily protein synthesis in individual tissues using the upper estimate of FSR, i.e. 610 g/d v. 581 g/d.

5. The estimate of WBS derived from plasma leucine flux directly (241 g/d) was similar to that calculated from the sum of minimum estimates of daily protein synthesis in individual tissues (214 g/d).

6. The ratio, intracellular leucine SRA:plasma leucine SRA tended to increase with increasing dietary leucine absorption in all tissues although these factors were only significantly correlated (P < 0·05) in cardiac muscle, skin and rumen. Such relationships suggest an increased exchange of plasma leucine with intracellular leucine with increased food intake.

7. It was estimated that the energy cost of protein synthesis accounted for approximately 42% of daily heat production.

1. Four groups of six rabbits were given purified diets in which the dietary variables were protein source (isolated soya-bean protein or cow's-milk protein) with or without saponin supplementation (10 g/kg).

2. Rabbits given soya-based diets showed significantly lower serum concentrations of triglyceride and cholesterol (P < 0·01). The latter changes were confined to the cholesterol fractions of β-lipoproteins.

3. These changes in serum cholesterol were associated with a significantly increased excretion of acid and neutral sterols in animals given soya-bean protein.

4. There was no evidence to suggest that the effect of dietary protein source on serum lipids and the excretion of total and individual sterols was influenced by saponin supplementation.

5. These results do not support the hypothesis that the hypocholesterolaemia associated with plant proteins is due to the presence of saponins.

1. Dry matter (DM), organic matter (OM), nitrogenous constituents, carbohydrate constituents and pH were estimated in digesta taken from eight different sites in the small intestines of slaughtered steers given different diets. Amounts of constituents passing different sites were compared using cellulose as a non-digestibte marker.

2. Amounts of the different constituents entering the small intestines varied with the type of diet given but the patterns of removal of each constituent were similar regardless of diet.

3. DM and OM were removed uniformly down the length of the small intestines. Net digestibilities of 0·62 and 0·63 for DM and OM respectively of the amounts measured in segment 1 digesta (first 3 m post-pylorus) were found at the terminal ileum. DM and OM contents of segment 1 digesta were 5 and 8% higher respectively than in abomasal digesta. Significantly smaller amounts of digesta were found in the proximal quarter of the small intestines than in more distal sections. There was a 10% addition of water to digesta in segment 1 compared with abomasal digesta. Of the water entering the small intestines a net 65% was absorbed therein, most absorption occurring in the first half.

4. Ammonia nitrogen was removed uniformly down the length of the small intestines to a net extent of 75% of that in segment 1 digesta. There was an apparent increase of approximately 18% in the total N (TN) content of segment 1 digesta compared with abomasal digesta. There was an approximate net removal of 80% of the TN measured in segment 1 digesta during passage down the small intestines. Over 95% of the digestible TN was removed in the section of tract between 3 and 15 m from the pylorus. Net removal of nucleic acid N (NA–N) up to the distal ileum was 78% of that in segment 1 digesta, most removal occurred in the proximal quarter of the small intestine. Little or no net loss of diaminopimelic acid–N (DAP–N) occurred in the small intestine.

5. Of the carbohydrates entering the small intestines, there was little or no removal of rhamnose, arabinose or xylose. Net removal of ribose, mannose, galactose and ‘starch’ glucose up to the distal ileum was 82, 76, 54 and 70% respectively of the amounts found in segment 1 digesta. All disappeared uniformly down the length of the small intestine.

1. Q-strain mice selected for high (QLF) or low (QSC) body-weight at 6 weeks of age were compared with respect to their body-weight increases, gross body compositions and food intakes.

2. DNA, RNA, protein and hydroxyproline contents were measured.

3. QLF animals were larger at all stages of development but ate more food and gained more body-weight per unit food intake with an apparently improved efficiency of utilization compared with QSC mice.

4. The efficiency of deposition of dietary energy in Q-strain mice was found to be significantly lower than that of other growing mammals receiving similar energy intakes.

5. Body water, protein and fat of both strains were similar at birth and at 42 d of age but the contribution of fat to body-weight in the preweaning phase was greater for QLF while QSC accreted more fat per unit weight gain in the postweaning period.

6. An increase in cell number made a greater contribution to the growth post partum of the QLF mice, but by 42 d of age little difference between the number of cells per unit weight in the two strains was evident.

7. Despite increases in RNA concentrations at all stages of development, of QLF mice compared with QSC, measurements of body composition do not indicate any accompanying increases of protein concentration in these animals.

1. Six sows were housed in solid-floored farrowing pens and fed daily with approximately 200 μCi 198Au, three of them from 3 d before farrowing until their piglets were 10 d old and three from 10 d after farrowing until their piglets were weaned at 21 d.

2. The sows' faeces and sawdust bedding became radioactive but their milk remained free of radioactivity. The piglets' radioactivity was measured daily in a whole-body counter after they had been washed to remove external contamination.

3. The piglets' mean whole-body radioactivity was equivalent to 20·9 ± 2·5 g (range 5·7–85 g) of faeces and bedding. If the average passage time of the digesta through the gastrointestinal tract is assumed to be 24 h these values are equal to the average daily intake of faeces and bedding by the piglets.

4. This intake of faeces could possibly prevent the piglets becoming anaemic if the sow's diet were supplemented with iron to increase the Fe concentration of her faeces to approximately 2 mg Fe/g fresh faeces.

1. Twenty-six sheep were used in experiments designed to test the effectiveness of ammonium tetrathiomolybdate in the prevention and treatment of chronic copper poisoning.

2. Intravenous injections of 100 mg ammonium tetrathiomolybdate twice weekly (a) prevented the occurrence of haemolytic crisis in sheep repeatedly dosed with copper sulphate and (b) minimized tissue damage and prevented further haemolytic crisis when given to sheep already in haemolysis.

3. Thiomolybdate prevented excessive depostion of Cu in the liver of sheep receiving orally large amounts of Cu and decreased liver Cu levels in sheep that were not given additional Cu. In the latter sheep, 50 mg ammonium tetrathiomolybdate given twice weekly did not produce histologically-detectable tissue damage even though liver and kidneys contained high levels of molybdenum, and kidneys contained elevated levels of Cu.

4. It is concluded that chronic Cu poisoning can be successfully prevented or treated by intravenous injection of appropriate doses of ammonium tetrathiomolybdate.

1. Fourteen sheep were dosed repeatedly with a solution of copper sulphate (2 g/l) in order to induce chronic copper poisoning and four similar undosed animals acted as controls.

2. Thiomolybdate (TM) was intravenously administered to all control sheep and to all except two of the test sheep. A variety of biochemical factors were studied before and after injections of TM.

3. The direct-reacting Cu, whole-blood Cu and plasma Cu concentrations were elevated in animals given TM injections and at the ‘haemolytic crisis’ of untreated chronic Cu-poisoned animals. But most of the increased Cu observed on injecting TM was insoluble in trichloroacetic acid (TCA) and did not enter erythrocytes. The results indicate that uptake of Cu by erythrocytes is essential for haemolysis to occur and that for this to happen the Cu must be in a direct reacting, TCA-soluble form.

4. Increased amounts of Cu were excreted in the urine at haemolysis and at the commencement of TM injections. High levels of direct-reacting Cu were found in plasma at these times.

5. Marked changes were not found in caeruloplasmin activity, packed cell volume or the osmotic fragility of erythrocytes except at haemolysis. TM injections did not alter these factors in any of the sheep studied.

1. Three adult dairy cows were fitted with cannulas in a mesenteric, portal, hepatic and jugular vein and a carotid artery. They received infusions of step-wise increasing amounts of ammonia as ammonium acetate via a mesenteric vein until NH3 intoxication occurred. Sodium acetate was used in control infusions. The maximum rate of uptake of NH3 by the liver and the concentrations of glucose, urea, lactate, acetate and bilirubin in blood were measured.

2. During the infusions of ammonium acetate the liver extracted almost all the NH3 present in the portal vein until an infusion rate of approximately 15·0 mmol/min was reached. The maximum capacity of the liver to remove NH3 during its first pass was on average 1·84 mmol/min per kg wet weight. The cows became intoxicated when arterial plasma ammonia concentrations reached 0·8 mmol/1. Concentrations of NH3 in jugular venous blood were between 66 and 74% of those in the carotid.

1. The excretion of 75Se and stable Se in bile and urine was measured in four steers during 6 h after intravenous injections of 75Se as either selenite or selenate containing either 5 or 5000 μg carrier Se.

2. When 5000 μg Se were given, the rate of urinary excretion and plasma clearance of 75Se was similar for both salts. Approximately 23% was excreted in urine and plasma clearance was triexponential, the mean half-life (t½) of the successive components, α, β and γ, being 2·3, 15·2 and 465 min respectively. The amount of 75Se excreted in bile was small; 1·94% of the 75SeO32− and 0·86% of the 75SeO42− dose.

3. When 5 μg Se were given the plasma clearance of 75Se was initially biexponential but the entry of 75Se-labelled protein from the liver caused an increase in plasma radioactivity after 30–40 min. The effect was most marked after 5 μg 75SeO32− when plasma 75Se radioactivity returned to 60% of the activity present at 2 min. Values for t½ of the two components of clearance for 75SeO32− and 75SeO42− were respectively α 2·6 and 2·5 min, and β 15·9 and 36·6 min. Similar amounts of 75Se appeared in bile (0·2% of the dose) after injections of either salt but much less 75Se was excreted in urine after 75SeO32− (6%) than after 75SeO42− (37%).

4. At low dosage rates (5 μg) Se is more readily incorporated into tissues from SeO32− than from SeO42−.

1. Rainbow trout (Salmo gairdneri) of mean initial weight 15 g were given either a low-manganese or control diet containing 1·3 and 33 mg Mn/kg dry diet respectively.

2. Weight gains over a 24-week feeding period were the same for both groups of trout.

3. Hepatosomalic index, blood packed cell volume and haemoglobin concentration, plasma protein and the activities of aspartic aminotransferase(EC 2.6.1.1)and alanine aminotransferase(EC 2.6.1.2) were unaffected by dietary Mn intake.

4. Plasma potassium and iron levels were increased in the trout given the low-Mn diet.

5. The hepatic levels of magnesium, sodium, K, zinc, copper, Mn and phosphorus were significantly reduced in the fish given the low-Mn diet.

6. In those trout given the low-Mn diet the levels of Mn and calcium in the vertebral ash were significantly reduced.

7. The hepatic activity of Cu-Zn superoxide dismutase (EC 1.15.1.1; Cu–ZnSOD) and of Mn superoxide dismutase (EC 1.15.1.1; MnSOD) in cardiac muscle and liver was reduced in the group of trout given the low-Mn diet. The fall in Cu–ZnSOD and MnSOD activities coincided with reduced tissue levels of their respective metal components.

1. Surgical removal of the forestomach, the caecum or both the forestomach and the caecum, was performed on growing male golden hamsters (Mesocricetus auratus) given a low-or high-fibre diet.

2. In Expt J, 18 d after surgery, the hamsters which were given a concentrate before surgery were given an experimental low-fibre diet containing urea or [15N]urea (10 g/kg diet) for 9 d. In Expt 2, 5 d after surgery, the hamsters which were given a forage diet before surgery were adapted to an experimental high-fibre diet containing urea (10 g/kg) and dried Italian ryegrass (Lolium italicum) powder (400 g/kg diet) for 5 d, and 10 d after surgery, given a diet containing [l5N]urea (10 g/kg diet) for 9 d.

3. In both experiments, removal of the caecum resulted in a significant lowering of both weight-gain and the digestibility of the dry matter, and removal of the forestomach resulted in a significant decrease of both accumulation of 15N in the body protein and proportion of l5N retained in the body protein as a proportion of the administered dosage.

4. The effect of removal of the caecum on the utilization of [15N]urea was not apparent in Expt 1, but the utilization of [15N]urea was significantly lowered by removal of the caecum in Expt 2.

5. These results suggest that the caecum may play a more important role in food utilization than the forestomach. However, the forestomach of the golden hamster plays a significant role in the utilization of dietary urea. It is presumed that the role of the caecum in the utilization of urea may vary under different dietary conditions.

1. A slope-ratio assay was developed to determine the availability of lysine in protein concentrates for chicks, Two protein concentrates were assessed per assay, using three levels of incorporation into the basal diet.

2. Availability of lysine, expressed as a proportion of total lysine in five protein concentrates was: cottonseed meal 0·83, fish meal 1·00, meat-and-bone meal 0·86, soya-bean meal 0·93, sunflower meal 1·01.

3. The five protein concentrates had previously been assayed for available lysine with slope-ratio assays for pies and rats (Batterham et al. 1979; Batterharn et al. 1981), There was little relationship between the results for chicks and those for pigs and rats. For pigs, availability estimates ranged from 0·43 for cottonseed meal to 0·89 for fish meal. For rats, availability estimates ranged from 0·49 for sunflower meal to 1·04 for fish meal.

4. The results for chicks were in closer agreement with values obtained using the Silcock available-lysine assay (Roach et al. 1967) and the direct 1-fluoro-2,4-dinitrobenzene procedure (Carpenter, 1960). By contrast, there was litlle relationship between the chemical tests and results for pigs or rats.

1. Male lambs that had been born in autumn and wintered on forage diets were cannulated in the abomasum, confined indoors in individual pens, and fed on fresh primary growth ryegrass (Lolium perenne) – clover (Trifolium repens) pasture ad lib, for a 12-week period during spring. Mean diet organic matter digestibility (OMD) was 0/76, nitrogen content 29 g/kg dry matter (DM) and metabolizable energy (ME) content 11.1 MJ/kg DM. Thirteen lambs were infused into the abomasum with 44 g sodium caseinate +0/5 g L-methionine/d and 12 lambs were similarly infused with equivalent amounts of inorganic sodium and phosphorus. Initial live weight was 16/5 kg.

2. The twenty-five treatment lambs were slaughtered at the end of the experiment, and thirteen similar lambs were slaughtered when the experiment commenced. Body composition was determined and rates of protein, fat and energy deposition were calculated using comparative slaughter procedures.

3. Voluntary herbage DOM intakes tended to be slightly greater for control than protein-infused lambs, but calculated ME intakes including that infused as amino acids were similar for the two groups. Live-weight gains were 79 and 99 g/d for control and protein-infused lambs respectively (P < 0/05) and corresponding values for carcass gain: live-weight gain were 0/44 and 0/50 (P < 0/01), Wool growth was markedly increased by the amino acid infusion.

4. Carcass and whole body protein content was increased 10 g/kg by the protein infusion (P < 0/01) and fat content depressed approximately 25 g/kg (P < 0/05). Rates of protein deposition in both carcass and wool-free whole body were markedly increased by protein infusion, and total deposition including wool was 12.6 and 21.0 g/d for control and protein-infused lambs (P < 0/001). Energy deposited in protein as a proportion of total energy deposition was 0/27 and 0/41 for control and protein-infused lambs (P < 0/001), but total energy retention and the efficiency of utilization of ME for growth did not differ between the two groups of lambs.

5. It was estimated that 60 and 100 g total amino acids/d were absorbed from the small intestine in the control and protein-infused lambs respectively, corresponding to 0.16 and 0/25 of total ME intake. It was concluded that absorption of protein from the small intestine was limiting protein deposition in the growing lambs fed on fresh ryegrass-based spring pasture in this study. Absorption of cystine+methionine was specifically shown to be limiting. However, the protein deficiency was not a major factor in the low value for the efficiency of utilization of ME for growth for this diet (0/30).

1. The rates of transfer of plasma urea to the rumen of six sheep given brome grass (Bromus inermis) pellets alone or with supplements of sucrose or urea were determined using [14C]urea and 14C-labelled sodium bicarbonate infusions during three periods.

2. The sheep were slaughtered after the third period and samples of rumen epithelium were taken for assessment of numbers of adherent bacteria.

3. Maximum transfer (0·31 g nitrogen/h) of urea to the rumen was observed for sheep given supplements of 150 g sucrose/d plus 20 g urea/d. Maximum clearance of plasma urea to the rumen (rate of urea transfer to the rumen per unit plasma urea concentration, 5·8 1/h) was observed for sheep given 300 g sucrose/d.

4. Urea clearance to the rumen was negatively related to rumen ammonia concentration; the slope of the relationship was increased with each addition of sucrose to the diet.

5. Numbers of facultative bacteria adherent to the rumen epithelium were increased by urea and sucrose supplements.

6. The results are discussed in relation to a hypothesis which relates the ureolytic capability of the bacteria adherent to the rumen epithelium to the control of the rate of transfer of urea into the rumen.

1. The incidence of diarrhoea, digestibilities of nutrients and the faecal bacterial flora were compared among three groups of Holstein male calves up to 3 weeks of age. Two groups of four calves were given a milk-substitute containing tallow by nipple-pail (group TN) and by open-bucket (group TB). The third group of four calves was nipple-fed a milk-substitute containing soya-bean oil (group SN). Each of the milk-substitutes contained approximately 300 g milk-protein and 100 g fat/kg dry matter (DM).

2. Mean faecal DM contents (g/kg) were 217, 185 and 112 for groups TN, TB and SN respectively and the corresponding pH values were 7·21, 7·00 and 6·50. The difference between groups TN and SN was statistically significant (P < 0·05).

3. No difference was observed between groups TN and SN in the apparent digestibilities of DM, crude protein (CP; nitrogen × 6·25), diethyl ether extract (EE) and total reducing sugars. But in the group TB, the digestibility of EE was significantly lower (P < 0·05), and that of CP tended to be, though not significantly, lower than in the other two groups.

4. Bacterial flora in faeces showed considerably wide quantitative variations among individual calves, but there was a tendency for increased viable counts of Lactobacilli in faeces of group SN.

5. The present results suggested that an appreciable difference in the mechanism would exist between diarrhoea occurring when milk-substitute was offered by bucket and when highly-unsaturated vegetable oils were contained in it. Possible mechanisms were also discussed.