1. The anabolic agent trenbolone acetate (3-oxo-17 β-hydroxy-4,9, 11-oestratriene acetate; TBA) given subcutaneously to female rats increased their growth rate compared with that of the placebo-treated controls.

2. The increased growth rate of the TBA-treated rats was not a consequence of an increased water retention. The TBA-treated rats had a significantly higher (P < 0.01) total carcass nitrogen content but the total carcass fat content decreased by a non-significant (P > 0.05) 8.3%.

3. There was evidence of a time-lag in the response of the fractional synthetic rate of certain individual tissues to TBA. The fractional synthetic rates of the uterus and skeletal muscle mixed tissue proteins were significantly reduced in the TBA-treated rats.

4. The measured reduction in fractional synthetic rates was concluded to reflect true changes in the synthetic rate rather than a result of an alteration in the specific activity of the tyrosine pool used for protein synthesis.

1. In order to establish whether or not there is a relationship between the blood ketone-body concentrations and the potential ability of the liver to synthesize ketone bodies in sheep on varying nutritional regimens, a study has been made of the concentrations of acetoacetate and 3-hydroxybutyrate in blood and the activities of enzymes concerned with ketogenesis in liver of developing sheep from mid-way through gestation to maturity, in pregnant ewes from mid-way through pregnancy and in starved pregnant and non-pregnant ewes.

2. During development the most marked change in blood 3-hydroxybutyrate concentration occurred when the lambs were weaned. Blood acetoacetate concentrations did not change during development. When mature ewes were starved both 3-hydroxybutyrate and acetoacetate concentrations in blood were increased.

3. Changes found in the activity of 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) in the liver were correlated with the changes in blood 3-hydroxybutyrate concentrations during development but no such relationship existed in pregnant or fasted ewes. No correlation was found between the ability of the liver to synthesize acetoacetate and blood ketone body concentrations in either developing or pregnant adult sheep. The rate of acetoacetate production expressed per g liver increased during foetal life but values observed in lambs 1 d after birth were similar to those found in suckling and mature sheep. During the last month of pregnancy and when non-pregnant sheep were starved the hepatic potential for ketogenesis was increased. During development the activity of acetyl-CoA acetyltransferase (EC 2.3.1.9) was correlated with the rate of hepatic acetoacetate production.

4. These changes have been contrasted with those that occur in developing and starved adult rats.

5. It is concluded that hepatic production of ketone bodies cannot be the only factor in the regulation of blood ketone body concentrations in developing and pregnant sheep.

1. Homogenates of pig kidney incubated in vitro convert 25-hydroxycholecalciferol to the dihydroxy-metabolites almost as efficiently as homogenates of chick kidney under similar conditions.

2. The cortex of the kidney carries out this conversion more efficiently than does the medulla.

3. Kidneys from pigs given low calcium or low phosphorus diets produce about 40 % more 1,25-dihydroxy cholecalciferol than those from pigs given diets containing normal levels of Ca and P.

1. Two experiments, involving six lactating Landacre x (Landrace x Large White) sows were undertaken to study the lysine requirement of the lactating sow and to identify the second limiting amino acid by means of interpretation of plasma amino acid and blood urea levels.

2. A basal diet composed mainly of equal amounts of ground barley and ground wheat supplemented with mineral and vitamin mixtures was used. This diet was supplemented with synthetic amino acids (lysine, threonine, tryptophan, methionine and isoleucine).

3. Plasma amino acid and blood urea values showed a close agreement and indicated that lysine intake above 38.4 g/d was in excess of the requirement level.

4. Plasma amino acid values suggested tryptophan to be the second limiting amino acid whereas blood urea values suggested threonine to be the second limiting amino acid.

1. The changes in serum levels of uric acid and lipids during 1 month of starvation-refeeding were measured in sixteen male volunteers.

2. Uric acid levels increased linearly with the duration of the experiment. The increase was positively correlated with the increase in serum triglycerides but not with cholesterol or phospholipids.

3. Triglycerides increased at a faster rate than uric acid implying that the increase in uric acid was secondary to that of the lipid.

4. It was concluded that the purine and lipid synthetic pathways are linked through a common small-molecular-weight effector rather than through the sharing of a common enzyme.

1. The effects of defaunation of the rumen of cattle on low-protein diets was studied using animals given free access to a basal diet of liquid molasses and 1500 g oaten straw/head per d. These diets induced moderate numbers of protozoa in the rumen.

2. Nonyl phenol ethoxylate (trade name teric GN9) was used for defaunation; 100 g teric GN9 was found to be sufficient to eliminate protozoa from the rumen.

3. In cattle given the basal diet without bypass protein supplementation, defaunation had no effect on growth rates. Addition of 240 g of a feed pellet containing bypass protein increased growth rate significantly. Growth rates were significantly increased by 43 % in cattle on the higher protein intake and where protozoa were removed. Intake of molasses was apparently stimulated by a protein supplementation but not by defaunation and this finding is discussed.

4. The results demonstrate that in cattle given a molasses-based diet, low in bypass protein, growth rates can be stimulated by defaunation without an effect on feed intake, the main effect apparently arising through an increased efficiency of utilization of feed.

1. The amounts of copper and zinc in the foetuses of ewes carrying from one to four lambs were measured at different stages of gestation and estimates were made of the amounts of these metals in their livers.

2. The accretion of Cu and Zn could be described by growth equations of the Gompertz form, from which could be derived estimates of the instantaneous and fractional rates of deposition of these metals in the foetal body.

3. Between the 80th and 144th day of gestation the instantaneous rates of deposition of the metals increased exponentially, and at the end of pregnancy were calculated to be 0.24 and 2.0 mg Cu and Zn/d respectively in the triplet lamb foetus. The corresponding total accretions were estimated to be 10 and 69 mg respectively.

4. The fractional rates of live-weight gain and of deposition of Cu were similar and decreased at similar rates; that of Zn deposition decreased much more slowly.

5. The proportion of whole-body Cu estimated to be in the liver was always greater than 50 %. The amount of Zn in the liver remained constant and contributed 72 % of the total body Zn at 80 d but only 8 % at 144d.

6. The relative amounts of Cu and of Zn accrued per unit body-weight gain were not constant during the development of the foetus. As foetal numbers increased the amounts of each metal deposited in the foetus decreased more rapidly than did foetal weight.

7. The results are discussed in relation to the demands for Cu and Zn during pregnancy in sheep.

1. Fluid intake, urine output and evaporative water loss were measured and fluid balance calculated in sixteen subjects for 1 d before Ramadan, during weeks 1–5 of fasting and on the 10th day after the end of Ramadan.

2. Plasma osmolality at 06.00 hours, the beginning of the fast, at 18.00 hours, before breaking the fast and at 19.00 hours, 1 h after breaking the fast, and urine osmolality during the day and night were measured before, during and after Ramadan.

3. All subjects developed an initial negative fluid balance which was maximum at the beginning of week 3 of fasting and that deficit was compensated for during the later weeks.

4. Compensation was brought about by an increase in urine concentration, a decrease in urine volume by day, and salt retention.

5. No significant changes were observed in plasma osmolality during the days of fasting and the ‘setting’ of plasma osmolality during Ramadan also was not changed.

6. It was concluded that healthy young adults maintain good control of fluid and electroytes during Ramadan.

1. Amaranthus spp. leaves contain high amounts of oxalates which affect the calcium absorption. This study was done to determine whether removal of the water-soluble oxalates from the leaves by cooking would reduce this deleterious effect.

2. Experimental work done with two types of basal diets on six adult male subjects has shown that the milk Ca absorption was low when leaves cooked without draining away the water were included in the diet. However when the soluble oxalates were removed by throwing away the water after cooking the leaves, the absorption of milk Ca was unaffected.

1. The effect of 1-α-hydroxycholecalciferol (1 α-OH-D3) on calcium and phosphorus metabolism has been studied in ewes at peak lactation by a combination of a mineral balance and a radioisotope technique.

2. The rate of Ca absorption was substantially higher in the treated ewes than in controls. The rates of endogenous loss of Ca into urine, faeces and milk, however, were only slightly higher.

3. In consequence, the net retention of Ca was increased and the loss of skeletal reserves of Ca normally associated with peak lactation, prevented.

4. Although the rate of bone accretion increased slightly, the increase in skeletal retention of Ca resulted mainly from a decrease in the rate of bone resorption.

5. This finding conflicts with the generally held belief that bone resorption is increased by cholecalciferol treatment.

6. The rates of apparent absorption and retention of P were increased by the treatment probably as a result of a direct effect of the 1α-OH-D3 on P absorption.

7. These results provide a possible explanation of the beneficial effect of 1α-OH-D3 in preventing parturient paresis (milk fever) in the dairy cow.

1. Breath hydrogen and methane were measured in eight normal individuals after acute and separate administration of different chemical components of dietary fibre.

2. Hemicellulose, raffinose and lactulose increased H2 production, while cellulose, pectin and lignin did not. Methane production was found to be individual and unaffected by any of the substances. Differences in physical properties of the same chemicals appear to have no influences on H2 and CH4 production.

1. Male Sprague–Dawley rats were given 630 g/kg sucrose or starch with 2 mg/kg aflatoxin B1 for periods of 75, 145 and 200 d, and the 24 h urinary excretion of aflatoxin M1 was measured.

2. Less aflatoxin M1 was excreted by the rats fed on the sucrose-rich diet compared to those fed on the starch-rich diet. This difference was especially marked when expressed per g metabolizing tissue.

3. It is concluded that sucrose probably decreases the activity of aflatoxin B1 metabolism in a similar way to its previously found effect on the drug-metabolizing enzyme.