1. The incorporation of [14C]sucrose in to serum triglyceride was shown to increase in both male and female baboons after a period of high sucrose intake. During the same period of high sucrose intake there was an increase in the fasting serum triglyceride concentration of the male baboons but not of the females.

2. When the male baboons were given a parenteral oestrogen preparation in addition to the sucrose diet the increase in fasting serum triglycerides was greatly reduced but there was little alteration in the extent of the incorporation of sucrose into serum triglyceride compared to that with the diet and no oestrogen.

3. A parenteral testosterone preparation given to the female baboons in addition to sucrose diet had no effect on either the extent of incorporation of sucrose into triglyceride the fasting serum concentrations of triglyceride.

4. The findings suggest that the differing patterns of fasting triglyceride response in the male and female baboons to the sucrose diet may have resulted from oestrogen enhancing the removal of triglyceride from the serum of the female animals.

1. Factors affecting the release of methionine from kaolin-saturated-fat capsules in the intestine of cattle were investigated. Bile and pancreatin were shown to be necessary for appreciable solution of the capsule.

2. The relationship between site of release and site of absorption was ascertained. One site was shown to be in the proximal duodenum the second longer site is in the distal duodenum and proximal jejunum. Encapsulated methionine was carried past the first absorption site.

3. The results of in vitro incubations confirmed by those of in vivo studies show that 60–65% of the methionine becomes available for absorption in the intestine.

1. Protein digestion in the gastro-intestinal tract of cattle receiving diets with either low or high content of maize was investigated. Digesta obtained from the duodenum and ileum were separated into three fractions; soluble, microbial and particulate, and the amino acid composition of the three fractions and that of the total digesta were determined. The proportion of particulate material digested in the intestine was less from the high-maize than from the low-maize diet, but more of the particulate fraction entered the duodenum from the high-maize than from the low-maize diet, so the absolute amount of particulate fraction which was digested was greater for the high-maize diet.

2. More protein was digested in the rumen from the low-maize diet (high-roughage) than from the other diet. Total digestion of protein from the low-maize diet was also higher.

3. Although more protein from the high-maize than from the low-maize diet reached the duodenum, the protein from the low-maize diet was more digestible in the intestine, so the total amount of dietary protein digested in the intestine was the same for both rations.

1. 15NH4Cl was continuously infused for periods of 120–216 h into the rumens of sheep which were allowed to feed 2 out of every 10min. These treatments achieved steady metabolic states and allowed the assessment of nitrogen conversions by means of tracer methodology. The sheep were given either a barley diet or one of three hay diets. In two trials, the flow of abomasal material was determined using lignin and polyethylene glycol as markers. The amounts of dry matter (DM), gross energy, total N, soluble N, microbial N and microbial DM in abomasal digesta, and the concentration of ammonia in the rumen liquor were measured. The concentrations of 15N in the N of urine, faeces, rumen and abomasal bacteria and protozoa, rumen and abomasal bacterial and protozoal protein, abomasal particulate matter and in rumen ammonia were determined.

2. Comparisons of the steady-state concentrations of 15Nin the microbes with that in rumen ammonia indicated that from 50 to 65% of the bacterial N and from 31 to 55% of the protozoal N were derived from rumen ammonia in vivo.

3. An amount of N equivalent to 60–92% of the daily intake was transformed into ammonia N in the runen.

4. Some 17–54% of the ammonia was absorbed from the rumen, but this was not readily converted into urea.

5. Microbial growth in the rumen resulted in the assimilation of 1.7–2.6 g N/100 g DM fermented.

6. The generation-time of bacterial protein in the rumen was calculated from the rate of in- crease of 15N concentration in this fraction, and values of 38 and 42 h were obtained for sheep given barley and hay diets respectively.

7. The combined results allowed quantitative estimates to be made of the complete metabolism of rumen N, and from these the possibility of fixation of N gas in the rumen was suggested.

1. There is an association between iron overload, ascorbic acid deficiency and osteoporosis in middle-aged South African Bantu males. The iron overload contributes to the ascorbic acid deficiency by accelerating its oxidative catabolism. The object of the present investigation was to explore the possibility that the osteoporosis results from chronic ascorbic acid deficiency.

2. On quantitative microradiography, percentage bone-formation surface was normal but percentage bone-resorption surface was significantly increased in ten osteoporotic subjects compared with seven control subjects.

3. There was a significant inverse correlation between bone mineral density and liver storage iron concentration in thirty-five Bantu subjects. In thirteen individuals aged 39 years or less, liver storage iron concentration was significantly correlated with percentage bone-resorption surface.

4. Guinea-pigs deprived of ascorbic acid for 21 d exhibited both significantly diminished percentage bone-formation surface and increased percentage bone-resorption surface.

5. Guinea-pigs overloaded with iron by injections of iron dextran developed significantly reduced hepatic ascorbic acid concentrations and bone mineral densities; percentage bone-formation surface was significantly diminished and percentage bone-resorption surface significantly increased. Ascorbic acid injection largely prevented the bone changes.

1. Adipose tissue was obtained simultaneously from subcutaneous and deep sites in children undergoing elective surgery, and from different subcutaneous sites in adults. The lipid content and fatty acid composition were measured using gas-liquid chromatography and the number of cells counted after fixation in osmium tetroxide. The mean amount of lipid per cell was used as a measure of the size of the cells.

2. Cells from deep sites in children were significantly smaller (P > 0.001) than those from subcutaneous sites in the same individual. Cells from different subcutaneous sites were of similar size.

3. The fatty acid composition of the lipids was similar in tissue taken from the abdominal wall and from deep sites.

4. The fatty acid composition of adipose tissue from the lower leg showed an increase in the monounsaturated fatty acids and a decrease in the saturated fatty acids compared with the fatty acid composition of tissue from other subcutaneous sites.

1. Results are presented of three experiments involving 112 individually fed pigs, covering the growing period between 20 and 90 kg live weight, in which the potential performance-stimulating properties of three different compounds were studied in relation to those of a dietary supplement of 250 mg Cu/kg diet.

2. The three compounds studied and the levels of supplementation used (mg/kg diet) were: Expt I arsanilic acid (100), Expt 2 sodium salicylate (200), Expt 3 a mixture of bromide salts (200); each was added to the diets either alone or with 250mg Cu/kg diet given as CuSO4, 5H2O.

3. The diets were given wet, ‘to appetite’ twice daily up to a daily maximum of 3 kg feed/pig. Measurements of length and of back-fat thickness at a number of points were made on all carcasses at slaughter.

4. Arsanilic acid and sodium salicylate alone gave growth responses similar to those obtained with Cu alone, whereas the bromide salt had no effect on performance. None of the three compounds when added to diets in conjunction with 250mg Cu/kg diet gave results superior to those obtained with the Cu supplement alone.

5. When added to the diets alone, none of the three compounds tested nor Cu had any marked effect on any of the carcass measurements.

6. Arsanilic acid reduced total liver weight and markedly reduced the large increase in total liver Cu stores that resulted from supplementation of the diets with 250 mg Cu/kg diet.

1. The effect of malnutrition early in life on the subsequent learning ability of male rats was studied when they were malnourished and after they had been rehabilitated. The HebbWilliams Test of animal intelligence was used.

2. Animals were malnourished from weaning, from birth, or from conception.

3. The rats used for tests were fed on a (1) low-protein, (2) low-calorie, or (3) stock diet.

4. The mean number of errors made by all groups of malnourished animals, tested when they were 13 weeks old, was always greater than that made by the corresponding controls. The same was true after rehabilitation for 5 weeks.