1. Eight groups, each of five steers, were given a basal ration of sorghum grain plus urea and minerals (0.003% sodium) ad lib. and demineralized water. Two groups, one given coarsely rolled and the other finely ground grain, were given the basal ration alone or the basal ration supplemented with 3.25, 6.50 or 13.0 g Na/animal daily as NaHCO3. Mean daily intakes of Na per animal for each of the four treatments were 133 mg, 3.1, 6.0 and 11.4g, respectively.

2. The mean growth rate of steers given the basal ration was 059 kg/d, which was significantly less than that of steers ingesting 3.1 g Na/d (093 kg/d). There were no significant differences in the growth rates of steers ingesting 3.1, 6.0 and 11.4g Na/d.

3. The concentration of Na in the saliva from the steers fed on the basal ration was significantly less and the concentration of potassium significantly greater than those from steers with Na intakes of 3.1 g or more per d. The mean Na:K ratio of the saliva from steers given the basal ration was less than unity, whereas the ratio in the saliva from steers ingesting 3.1g or more Na/d varied between 11 and 21.

4. The concentrations of Na in the ruminal fluid were significantly less in steers given the basal ration than in those ingesting 3.1 g or more Na/d.

5. The widths of the cortex and the zona glomerulosa as a percentage of the adrenal cortex were significantly greater in steers given the basal ration only than in those given Na intakes of 3.1 g/d. There were no significant differences in the width of the zona glomedosa of the adrenals from steers ingesting 3.1, 6.0 or 11.4g Na/d.

6. A Na and K balance conducted on two steers given the basal ration only for a further 112 d after the other steers were slaughtered indicated that faecal and urinary Na losses approximated to the Na intake, but there was a positive K balance. When these steers were subsequently given a supplement of 380 m-equiv. Na/d for 16 d they retained 370 m-equiv. Na/d and were in negative K balance.

7. It is suggested that the value given by the Agricultural Research Council (1965)for the Na requirement of steers for growth is excessive.

8. Steers given coarsely rolled grain ate significantly more feed per d than those given finely ground grain, but rate of body-weight gain was not affected by the method of grain processing.

1. The protein quality as evaluated by nitrogen incorporation efficiency (NIE) and protein efficiency ratio (PER) was determined for twenty-eight breeding lines of peas (Pisum sativum L.) which had been grown under similar field conditions.

2. Different lines of peas, when given as the sole source of protein to weanling rats at a 10 % level in an otherwise adequate diet, varied from 18 to 78% of that of casein in their ability to support growth and nitrogen retention. There was close correlation between PER and NIE values.

3. From analysis of rat growth curves, the pea lines were separated into those that produced fairly good growth and those that barely maintained the initial body-weight. However, growth rate alone did not rank pea lines in the same order as PER or NIE.

4. Carcass protein, as a percentage of body-weight, was higher in pea-fed (20.4%) than in casein-fed rats (18.8%).This was probably associated with a difference in body fat content.

5. There was no correlation between protein quality and the protein content of the different pea lines.

1. The responses of serum lipids of weanling and adult male rats to different diets have been examined. Total cholesterol, phospholipids and triglycerides were measured. The proteins used in the diets were casein and wheat gluten, the carbohydrates were starch and sucrose, and the main lipid source was groundnut oil supplemented with either gluten oil or maize oil.

2. In general, the type of carbohydrate did not influence the experimental results, whereas the type of protein had a marked effect. Compared with casein, gluten caused an increase in concentration of serum triglycerides, phospholipids and cholesterol in weanling rats, but there was no change in adult animals. Much of this ‘gluten effect’ in weanlings was not ob- served when the diet was supplemented with 0.7% L-lysine hydrochloride.

3. When 1% cholesterol was added to the gluten diets, the serum cholesterol concentrations were only slightly and variably affected in weanlings. Serum triglycerides and phospholipids were not altered in adult rats by the dietary cholesterol, whereas there were reductions in these lipid components in the weanlings, whether the protein was supplemented with L-lysine hydrochloride or not.

4. Gluten oil was not shown to be responsible for any major portion of the differences observed between gluten and casein in their effects upon the lipids of rat serum.

1. Four sheep were given four diets containing proportions of rolled barley and soya-bean meal varied to provide 10.3, 13.3, 16.1 and 19.9% crude protein in the dietary dry matter; the treatments were given according to a 4 x 4 Latin square design. The mean daily intake was 989 g dry matter. The apparent disappearance of protein, ash, ether extractives and carbohydrate before the abomasum, between the abomasum and terminal ileum and between the terminal ileum and rectum was measured.

2. The amount of non-ammonia crude protein (Y1, g/d) disappearing from the small intestine increased with protein intake (X, g/d) according to the equation Y1 = 2.12X – 0.0057X2–83, reaching a maximum when there was about 19% crude protein in the dry matter of the diet.

3. The treatments had no significant effects on the disappearance of starch, ether extractives or ash. About 93% of starch disappeared in the rumen and 6% in the small intestine. The total mean daily intake of ether extractives was 21 g; 9 g were added in the rumen, 24 g disappeared from the small intestine and 6 g were excreted in the faeces. The total mean daily intake of ash was 67 g; 26 g were added in the rumen, 37 g disappeared from the small intestine, 9 g from the large intestine and 47 g were excreted in the faeces.

1. One reason, based on indirect evidence, advanced in explanation of the low nutritional value of raw soya bean (RS) is that it stimulates the pancreas to secrete massive amounts of protein which are ultimately lost in the faeces. This theory has been investigated directly.

2. The expected outpouring of pancreatic protein did not occur when the secretion of enzymes and protein in pancreatic juice from chickens and rats given successively heated soya bean (HS) and RS diets was measured directly.

3. It is suggested that RS, acting upon intestinal proteins, forms trypsin inhibitor-protein complexes which, in spite of adequate proteolytic activity, escape digestion and are lost with the faeces, thus decreasing the nutritional value of the diet.

1. Diets of rolled barley supplemented with urea or fish meal at four different levels were given in a change-over experiment to four sheep with cannulas in the abomasum and in the terminal ileum.

2. Estimates were made of the disappearance of protein, ether extractives, starch, and ash in the various segments of the alimentary canal, and of the production of volatile fatty acids when the urea supplements were given.

3. The disappearance (Y, g/d) of non-ammonia crude protein from the small intestine increased with increasing protein intake (X, g/d) on the fish-meal diets according to the equation Y = 0.37X+44. There was no increase in the disappearance with the urea supplements.

4. In agreement with earlier work, it was shown that faecal nitrogen excretion was influenced to a much greater extent by fermentation in the large intestine than by that in the rumen. There was an apparent synthesis of ether-extractable lipid in the rumen at rates of 21and 18 g/d with the urea and the fish-meal diets respectively.

5. The energy of the volatile fatty acids produced when the urea diets were given was estimated to be 59% of the digestible energy consumed.

1. The mechanisms by which an oral dose of glucose can stimulate the uptake of essential amino acids from serum was found to be operative even in children with severe, untreated kwashiorkor.

2. Although the percentage fall in the concentration of the essential amino acids in response to glucose was the same before and after treatment, the absolute fall was greater on discharge. The results indicated that the magnitude of this fall might depend on the initial fasting concentration of each individual amino acid.

3. These results have been discussed on the basis of possible long-term pathological effects of a distorted serum amino acid pattern typified by low concentrations of valine, leucine and threonine. The protein-sparing action of carbohydrate, achieved by the preferential synthesis of muscle protein in response to insulin secretion, might be less effective because of substrate limitation.

4. Of the non-essential amino acids, the concentrations of alanine and glycine also fell markedly before treatment, but this did not occur on discharge. The significance of this difference is also discussed.

5. The results also indicate that slightly high, spurious amino acid ratios can be obtained if a child is given a drink containing sugar before a blood sample is taken.

1. Twelve castrated male pigs were kept at each of three temperatures and given food at one of three levels of intake. The temperatures and daily food intakes (expressed as g/kg0.73) were 23° (80, 100, 120), 13° (100, 120, 140), 3–5° (120, 140, 160). Growth and nitrogen metabolism were measured during growth from 20 kglive weight until slaughter at gokg live weight, when the body contents of N and fat were estimated.

2. Growth rate increased with each unit of daily food intake (I g/kg0.73 live weight) by 7.73 ± 0.74 g/d. This value did not vary significantly with temperature. Daily growth rate was depressed by 17.8 ± 2.3 g for each I° fall of temperature.

3. Daily N retention estimated by the balance method exceeded by 2.59 g/d that estimated by the comparative slaughter technique. Both results led to the same conclusion, which echoed that found with growth rate, that there was no significant effect of temperature on the response of N retention to increasing food intake. Taking the mean of the two estimates, N retention at a constant food intake fell by 0.38±0.055 g/d for each I° fall of temperature.

4. The N content of the ingesta-free carcass at slaughter fell with each increase in daily food intake by 0.007±0.002%, and the fat content rose correspondingly by 0.116±0.027%. These regressions did not vary significantly with temperature. When considered at a constant food intake, body composition did not alter significantly with temperature.

1. Changes in serum creatine kinase activity, creatinine excretion, mid-upper arm and thigh muscle circumference and the ‘X-ray muscle shadow weight’ of the upper arm and thigh muscles have been compared in children recovering from kwashiorkor.

2. Creatine kinase activity rose as the health of the child improved but was subject to large fluctuations mainly associated with the Occurrence of infections. For this reason it is unlikely to be of value in assessing nutritional status on the basis of changes in musculature.

3. Creatinine excretion also increased with treatment and was more consistent. This measurement should be of much greater value than serum creatine kinase.

4. The anthropometric measurements were relatively insensitive to quite large changes in limb musculature.

5. Assessment of musculature by soft-tissue X-rays of the limbs appeared to be a sensitive method of potential value.

1. The yeast grown on normal paraffins (British Petroleum Proteins Ltd, London) contained 62% crude protein and, except for lower content of methionine, its amino acid composition was similar to that of white fish meal.

2. The value to growing pigs of yeast + methionine as a protein supplement to diets based on barley and fine wheat offal was compared with that of white fish meal. The two protein supplements supplied the same amount of total nitrogen and were compared at a ‘standard’ level, commonly used in practice, and at a ‘low’ level. Two experiments were conducted: a feeding trial covering the live-weight range from 20 to 90 kg, and a metabolic trial (20–60 kg live weight) in which N retention and digestibility were measured.

3. There was a small but significant difference in favour of the yeast treatment for growth rate and feed conversion ratio, but there were no consistent differences in the linear measurements of the carcasses due to protein source.

4. In the metabolic trial there was no significant difference in performance, N retention, apparent N digestibility or linear carcass measurements and no consistent difference in tissue components, between the diets supplemented with yeast or fish meal.

5. In pigs given the ‘low’-protein diets, performance and most of the other variables measured were significantly poorer than in those given the ‘standard’ protein diets, irrespective of whether yeast or fish meal was the source of supplementary protein.

6. It is concluded that yeast (+ methionine) may be closely equated with high-quality fish meal as a protein supplement in diets for growing pigs. The small differences found are discussed in relation to possible differences in availability of amino acids and energy values in the diets.

1. Vitamin B12 activity in the milk of rats on various diets was measured by microbiological assay at intervals throughout lactation. The concentration of sodium and calcium in the milk was also determined.

2. At all stages of lactation the milk of rats fed on commercial rat cake contained much more vitamin B12 activity than that of rats receiving a semi-synthetic diet containing at least as much vitamin B12 as the rat cake. The milk of the latter group of animals contained more vitamin B12 than that from rats fed on the same diet without added cyanocobalamin. The levels of sodium and calcium were much less variable than those of vitamin B12 and the changes did not appear to be related to differences in diet, stage of lactation or litter size.

1. Single meals of protein (24.3 mg nitrogen/100 g body-weight) were fed with and without carbohydrate (167 mg/100 g body-weight) to groups of rats kept in anticoprophagy cages after an 18 h fast. The contents of the gastro-intestinal tract were collected and analysed and the rises in plasma amino acid concentrations were also determined.

2. After ingestion of different proteins with sucrose, the passage of protein from the stomach was delayed compared with that when the meal was of protein alone: the initial stomach emptying was little affected by the nature of the protein in the diet, but subsequently the relative rates of evacuation of different proteins were similar to those when the proteins were given alone.

3. When proteins were given with different carbohydrates the subsequent digestion and absorption of the meal was modified in a way which could be explained by the observed properties of the carbohydrates given alone, particularly with regard to solubilization in the stomach.

4. The rises in concentration of plasma free amino acid were lower after ingestion of proteins with carbohydrate than when the proteins were eaten alone, and different carbohydrates affected these rises to different degrees.

1. Duodenal contents were collected from cannulated sheep that were fed on dried grass cubes. After high-speed centrifugation, the distribution of long-chain unesterified fatty acids between the aqueous and particulate fractions of the digesta was examined.

2. The unesterified fatty acids of the digesta were found to be predominantly associated with the particulate matter.

3. When gall-bladder bile was added to the digesta at 37° and pH 4.0, in vitro, it was observed that unesterified fatty acids were transferred from the particulate matter to micellar solution. This transfer was due largely to the solubilizing effect of bile salts acting together with biliary phospholipids.

4. These findings are discussed in relation to the absorption of unesterified fatty acids by the sheep.

1. A comparison of human tissue organo-bromine residues has been made from specimens obtained in the UK, West Germany and Holland.

2. These findings, in conjunction with previous animal studies and with the geographical differences in the use of brominated vegetable oils as food additives, suggest that the high bromine levels found in the fat of tissues from UK children are due to the use of these compounds.