1. The presence of transaminase activity in rumen contents has been demonstrated. The level of activity varied with time after feeding and was influenced by the nature of the diet.

2. Rumen contents from a sheep given a diet containing casein showed greater transaminase activity at 2 h than at 6 h after feeding. Conversely, with a diet containing urea and maize, the activity was higher at 6 h than at 2 h after feeding.

3. The greater part of the transaminase activity of rumen liquor was associated with the fraction containing protozoa and food residues while the cell-free fraction contained no transaminase activity under the experimental conditions.

1. The ingestion of doses of up to 6 g sodium tungstate (56 mg W/kg body-weight) by goats was found to diminish the amount of xanthine oxidase secreted in their milk so that, in some samples, the enzyme became undetectable. This effect occurred whether the goats were eating a semi-synthetic or a conventional diet.

2. Tungstate ingestion by goats did not affect the concentration of riboflavine in their milk.

3. The ingestion of sodium tungstate by young goats for 3–5 months diminished the amount of xanthine oxidase in their livers.

4. When given in early lactation to two cows, doses of sodium tungstate (up to 20 g) diminished the titre of xanthine oxidase in their milk with no concomitant effect on the yields.

5. Much later in lactation the milk phosphatase of these two cows was poorly correlated with milk xanthine oxidase. Reasons for this are discussed.

6. Under anaerobic conditions, with xanthine as substrate and triphenyl-tetrazolium chloride as hydrogen acceptor, neither molybdate nor tungstate affected the xanthine oxidase activity of cow's or goat's milk in vitro. Molybdate in vitro did not enhance the very low titre of human milk.

1. A previous dietary survey has reported some very low calorie intakes in a farming community in rural Jamaica. Subsequently, ten subjects were specially selected on the basis of being very poor and underfed and individual dietary surveys were carried out in their homes for 7 days.

2. The accuracy of the dietary surveys was tested in a metabolic ward by feeding the subjects with the same meals as were recorded in their homes. Body-weight, calorie and nitrogen intakes, and urinary and faecal N outputs were measured.

3. Basal metabolic rates and the calorie expenditure during sleep were measured to investigate whether any metabolic adaptations to the low calorie intakes had occurred. The calorie cost of performing a standard step-test was measured and compared with that of well-fed control subjects to find out if there were differences in physical efficiency.

4. Nine of the subjects were found to be thinner than the average person of the same age and sex in their district, and were considerably thinner than the average American.

5. Five of the dietary surveys were thought to have given a correct picture of the normal dietary pattern. The remaining five surveys were unsatisfactory.

6. In the five correct surveys, calorie intakes were 61, 69, 72, 78 and 98% of the FAO recommended requirements.

7. No clear-cut evidence of an adaptive change in basal metabolic rate was found.

8. Few calories were available for physical exertion and there was an apparent increase in the physical efficiency of work.

1. Pigs, held by undernutrition to a weight of about 5.5 kg till they were a year old, were then rehabilitated on an excellent growing ration, and killed when they were fully mature.

2. Undernutrition of this degree of severity delayed the growth and development of the teeth, but relatively less than that of the body or the jaws.

3. The teeth became abnormally sited and the shape of the mandible changed.

4. During rehabilitation, some of the crowns and most of the roots of the molar teeth failed to reach their proper size.

5. Some of the molar teeth remained permanently impacted and out of alignment.

6. The fine structure of the teeth, particularly of those parts formed during the period of undernutrition, was still abnormal when the animals were killed.

1. A mathematical treatment is given of the marker technique for studying water balances in the rumen. The treatment is extended to cover non-steady-state conditions and emphasis is placed on the underlying assumptions and practical limitations of the technique.

2. The 51Cr complex of ethylenediamine tetra-acetic acid (51Cr EDTA) was used as a marker in the rumen of sheep.

3. The 51Cr EDTA entered 95–98% of the water in the rumen. Mixing in the rumen, though adequate, was usually not quite complete even 1·5 h after injection of the dose. The techniques of injecting the dose and of withdrawing the sample were found to be important; some techniques often led to poor mixing.

4. Provided that the time of injection of the dose was suitably selected, reliable estimates of the volume of water in the rumen could readily be made, but reliable estimates of flow rates needed stringent attention to details of technique.

1. The 51Cr complex of ethylenediamine tetra-acetic acid was used as a soluble marker substance in sheep fed restricted amounts (700 g daily) of roughage diets. It was injected into the rumen at various stages of the feeding cycle and rumen volumes and flow rates were calculated.

2. The average resting rumen volume for sixteen sheep (average body-weight 39 kg) was 3.9 l.; the average resting dilution rate was 0.077 h-1 so that the net inflow rate averaged 0.29 l./h; the average rate of absorption of water from the resting rumen into the blood was 0.05 l./h.

3. There were marked differences in all these values, both within sheep on different days (coefficient of variation nearly 20%) and between sheep (coefficient of variation more than 25%). The resting salivary inflow rate was also found to fluctuate considerably.

4. During feeding, the salivary inflow rate increased; there was usually both an expansion of rumen volume and an increased rate of outflow. There was no evidence of diffusion of water from the blood into the rumen.

5. Following eating, return to resting conditions was slow.

6. When the sheep drank, there was an expansion of the rumen volume and usually an increased outflow rate. The rate of absorption of water from the rumen increased slightly, but only for a short time. Occasionally after drinking it was found that rumen marker concentrations were slightly higher than expected probably because a small part of the imbibed water bypassed the rumen down the reticular groove into the omasum.

7. Most of the water drunk in a day was consumed in a few minutes. Compared with this rapid rate of drinking, the rate of absorption of water from the rumen was always a very slow process; this finding is in disagreement with recent views expressed in the literature. However, when considered over the whole day, the amount of water absorbed from the rumen may have been approximately equal to the amount of water drunk.

8. During periods of both feeding and drinking, the mean outflow rate was about 0.7 l./h in several series of experiments.

9. When sheep were held without food or water past their normal time for eating and drinking, the net inflow rate into the rumen soon started to decrease, but there was no immediate effect on rumen volume.

10. The present work reveals the potential usefulness of the soluble marker technique in defining the changing patterns of fluid movement in the rumen throughout the day.

1. Lambs fed on skim milk containing either maize oil or cod-liver oil or both were observed for signs of muscular dystrophy, changes in serum enzymes and increases in the susceptibility of red cells to haemolysis by peroxide (peroxide haemolysis).

2. Four lambs fed on the milk containing cod-liver oil, and not receiving α-tocopheryl acetate injections, developed acute muscular dystrophy, but no abnormal changes occurred in peroxide haemolysis, packed cell volume or haemoglobin concentration in the blood. Marked increases occurred in the aspartate transaminase, alanine transaminase and glutamate dehydrogenase, and in lactate dehydrogenase isoenzyme activities of the serum, presumably due to leakage from the degenerating tissues. One lamb given weekly injections of 100 mg α-tocopheryl acetate remained clinically normal and maintained normal serum enzyme levels. Treatment of dystrophic animals with 200 mg α-tocopheryl acetate by injection produced prompt clinical recovery and an exponential decline in the raised serum enzyme activities.

3. In the five lambs fed on the skim-milk containing maize oil, muscular dystrophy did not occur. Small but significant increases occurred, however, in serum aspartate transaminase and glutamate dehydrogenase activities. In all five animals peroxide haemolysis was greatly increased, but in only two did packed cell volume and haemoglobin values fall slightly below the lower limit of normal (mean − 2 × SD). Injections of 100–200 mg α-tocopheryl acetate neither prevented nor cured the abnormally high levels of serum enzymes and peroxide haemolysis, although a change in the diet was followed by a gradual return to normal. In one lamb given massive doses of α-tocopherol by mouth, peroxide haemolysis was not reduced. Large amounts of α-tocopherol added in vitro to erythrocytes from the lamb did, however, prevent peroxide haemolysis.

4. Peroxide haemolysis did not increase in any of three lambs fed on skim milk containing both maize oil and cod-liver oil, although two of them, which were given much larger amounts of cod-liver oil than the third, developed muscular dystrophy with elevated serum enzyme levels.

5. Peroxide haemolysis in lambs is evidently not a measure of vitamin E deficiency. It is suggested that increased peroxide haemolysis in lambs, like encephalomalacia in chicks, depends on the fatty acid composition of the unsaturated lipids in the diet.

1. Diets containing various sugar mixtures together with polyethylene glycol of high molecular weight as a marker were fed to pigs 1, 2 and 3 weeks old. The piglets were slaughtered 2.5 h later, and the ratio of sugar to marker was determined in the contents of the alimentary tract as far as the caecum.

2. The greatest fall was found in the first part of the small intestine.

3. Glucose had always disappeared by the third quarter of the small intestine.

4. Xylose and fructose disappeared more slowly, especially in the younger pigs, but were usually absent from the contents of the last quarter of the small intestine.

5. Sucrose was removed far less completely, and the ratio of sucrose to marker frequently did not decrease along the second half of the small intestine. Sucrose was removed much less efficiently when it formed 15% of the diet than when it formed only 5%, and much less efficiently by the younger than by the older pigs.

1. Polyethylene glycol (PEG) of high molecular weight, used as a dietary marker, did not distribute uniformly in the water present in a high-casein diet as did glucose, a low-molecular-weight substance.

2. This distribution effect also occurred with the contents of the stomach and, to a smaller extent, with the contents of the first quarter of the small intestine of piglets given such a diet.