1. The changes in the concentrations and solubilities of zinc, manganese and copper in the rumen, abomasum and along the small intestine of cannulated sheep, maintained on dried grass, have been determined. Relationships between the solubilities of the metals and the pH values of the samples were observed.

2. The pattern of change of solubilities could be reproduced in vitro by adjustment of the pH of rumen and abomasal samples.

3. By a combination of gel filtration and continuous-flow high-voltage electrophoretic techniques it was shown that soluble complexes of Zn and Mn occur in the rumen and lower regions of the small intestine. The soluble Zn and Mn in the abomasum, duodenum and upper jejunum appeared to exist in ionic form. The charge and molecular size of these complexes were found to be dependent on the pH of the samples.

4. From detergent treatment of rumen samples it appeared that much of the insoluble metal, particularly Cu, might be associated with microbial matter.

5. The significance of these findings and their relationship to the differences noted in the apparent requirements for trace elements of ruminants on different diets is discussed.

1. Barium sulphate suspensions were given to young sheep by mouth or by injection via an oesophageal catheter. Closure of the oesophageal groove was assessed by observing radiographically whether the suspension passed to the ruminoreticulum or to the abomasum.

2. Complete closure of the groove took place in lambs that were trained to drink small meals from a trough after being weaned from their dams, a finding similar to that for lambs weaned on to a teat-bottle.

3. When barium was injected into the oesophagus of lambs that were excited by being offered their bottle or trough beyond their reach, the barium passed direct to the abomasum if the normal feeding routine was closely imitated. When the lambs were able to discriminate between this teasing procedure and the normal routine, the barium frequently passed to the ruminoreticulum. If the lambs were not teased the barium passed invariably to the ruminoreticulum.

4. It is concluded that the reflex closure of the groove can be conditioned by the feeding procedure adopted at weaning so that it no longer depends on the stimuli associated with sucking and swallowing.

1. In the aetiopathogenesis, in Nigerians, of a degenerative neuropathy known as tropical ataxic neuropathy, chronic cyanide intoxication is believed to be the most important factor. The source of the cyanide is cassava (Manihot) and in Nigerian patients, plasma concentration of thiocyanate, a major detoxication product of cyanide, is high.

2. Since there is considerable doubt as to whether cyanide is readily released from cassava diet after ingestion, rats were fed on 80 and 100% purupuru (a cassava derivative) diets for periods varying between 6 and 18 months and their plasma thiocyanate levels were studied. Control rats were fed on a normal diet for the same periods.

3. Rats fed on the 100% purupuru diet were malnourished. Rats fed on the 80 % purupuru diet appeared normal, although their mean weight was less than the mean weight of rats fed on the normal diet.

4. Plasma thiocyanate was significantly higher in rats fed the purupuru diets than in the rats fed on the normal rat diet.

5. The concentration of thiosulphate Sulphurtransferase, the enzyme that catalyses the conversion of cyanide into thiocyanate was the same in rats fed on the purupuru diets as in the control rats.

6. The results suggest that raised plasma thiocyanate levels found in Nigerian patients with ataxic neuropathy, as in rats fed cassava diet, is the result of detoxication of cyanide, as the concentration of thiocyanate in cassava and most food products eaten by Nigerians is low.

1. A survey was made of ascorbic acid concentrations in white blood cells of apparently healthy European men and women living in the tropical climate of Singapore.

2. The survey showed that there was a significant fall in these concentrations in men who had been resident for more than 4 months. Levels in women did not show a significant decrease.

1. Sixteen lambs were used to compare two methods of administering various protein supplements to weaned lambs. In one method the protein supplement was mixed with the dry feed, consisting mainly of rolled barley, so that it passed to the rumen. In the second method the supplement was suspended in water which the lambs were trained to suck from a bottle; the suspension then passed directly to the abomasum by way of the oesophageal groove and so escaped rumen fermentation.

2. When the protein supplements were given in amounts that provided less than the estimated protein requirement of the animals, giving the liquid suspension led to significantly lower urinary nitrogen excretion (P < 0.001), greater nitrogen retention (P<0.05) and greater live-weight gain (0.05<P<0.1) than giving the feed in the dry form.

3. The body-weight gain was greater with white fish meal than with casein (P<0.05) and soya-bean meal (P<0.001), whichever method of feeding was adopted. There was no significant interaction between method of feeding and protein source, but the faecal nitrogen excretion was highest when soya-bean meal was given in liquid suspension.

4. From a regression of nitrogen retention on nitrogen intake with lambs receiving the basal ration only, it was calculated that the improvement in retention of the protein supplement effected by giving it in liquid suspension was 31 % for casein, 27 % for fish meal and 24 % for soya-bean meal.

1. Salt is a convenient household commodity which is generally used as a vehicle for iodine in the prophylactic treatment of endemic goitre.

2. Iodization of salt depends on the normal requirements for iodine, the intensity of the environmental iodine deficiency, the presence of goitrogenic factors and the daily salt consumption per head of the population.

3. Although the intake of most nutrients has been worked out during the normal course of dietary surveys in the past, the daily salt consumption per head of the population has not been estimated.

4. In this survey a simple method has been described for evaluating salt consumption and this finding will be the basis for planning the iodization programme in Ceylon.

1. The use of deuterium oxide dilution to obtain an indirect estimate of body water in pregnant ewes was examined and the value of such an estimate in predicting body fat was investigated.

2. Deuterium oxide was infused intravenously into fourteen twin-bearing Blackface ewes and blood samples were taken 6–7 h later. The animals were subsequently slaughtered.

3. Deuterium oxide concentration was estimated by infrared spectroscopy and the deuterium oxide space was calculated. Studies on dose rates and equilibration times were made with the Blackface ewes and some non-pregnant Dorset ewes.

4. The amount of body fat in each ewe was estimated from the deuterium oxide space using a prediction equation relating body fat to body water in twenty-five pregnant and non-pregnant ewes which had been slaughtered.

5. Once satisfactory measurement of deuterium oxide concentration had been achieved, body fat predicted from deuterium oxide space differed from values obtained by analysis of the slaughtered animals by -0.8 to +1.7 kg in seven ewes containing 5.2–21.4 kg fat.

6. The standard deviation from regression of percentage of body fat estimated from deuterium oxide space on percentage of body fat measured after slaughter was ±1.2 percentage units. Thus deuterium oxide space was used to provide a useful measure of body fat in pregnant ewes.

1. The time course of digestion of milk protein was studied in the 28-d-old pig given a test meal of homogenized cow's milk after a preliminary starvation period.

2. The milk was found to clot in the stomach 15–30 min after the meal. The soluble or ‘whey’ fraction of the stomach contents rapidly passed into the small intestine. Most of the clotted digesta had also left the stomach z h after the meal.

3. The distribution of digesta was studied in six equal segments of the small intestine. In general, there were no significant increases in the amount of intestinal contents at any time after the meal when compared with those in starved pigs, suggesting that digestion of milk at this age is a very efficient process.

4. Fractionation of the soluble digesta from the stomach and small intestine in Sephadex G-25 indicated that relatively little proteolysis occurred in the stomach, but in the small intestine digestion proceeded rapidly, producing a considerable increase in free amino acids in the mid-region.

5. The level of proteolytic enzyme activity in the stomach wall was elevated at 15 min after the meal, but thereafter returned rapidly to the prefeeding levels. Increasing the level of feeding increased the enzyme activity of the digesta and stomach wall. The enzyme activity appeared to be mainly adsorbed by the stomach clot.

6. The proteolytic enzyme activity in the pancreas was unaffected by the meal. However, the activity in the contents of the small intestine increased after the meal, reaching a maximum value at 45 min. Some accumulation of enzymes was found in the lower part of the small intestine, except in the region of the distal ileum where a marked decline in enzyme activity occurred. Increasing the level of feeding increased the proteolytic enzyme activity in the contents of the small intestine.

7. The soluble marker polyethylene glycol was not entirely satisfactory as an indicator of the rate of passage of digesta. The concentration of the marker was found to be greater in the soluble stomach fraction than in the clot shortly after the milk had been ingested. The transit time of the marker from ingestion to the terminal ileum was 2–3 h.

1. The interaction between nitrogen and water intake was studied in two ewes and two red deer hinds. They were given pelleted diets, at maintenance level, containing equal amounts of roughage but either rich or poor in nitrogen. The deer received 50 % more food than the sheep. Water was given either in large amounts (sheep 5.01, deer 7.0 1 daily) or in small amounts (sheep 1.1 l, deer 2.4 l daily).

2. Nearly three-quarters of the nitrogen of the high-nitrogen rations but less than half of that of the low-nitrogen rations was excreted in the urine. Restriction of water intake reduced urinary nitrogen excretion by only about 1 g daily, mainly as a result of decreases in the excretion of urea and ammonia, but did not affect the excretion of nitrogen in the faeces.

3. The urinary excretions of creatinine, creatine, hippuric acid, uric acid and allantoin were also examined. The excretion of creatinine was not related to either nitrogen or water intake. The excretion of uric acid and of allantoin was greater in the sheep than in the deer.

4. The concentrations of urea in the plasma and of ammonia in the rumen fluid were measured before and after feeding. The plasma urea value was related to dietary nitrogen intake and was higher on the low- than on the high-water regime. The rumen ammonia value also was related to the nitrogen intake but, while it generally increased after feeding when the high-nitrogen diet was given, it fell almost to zero 2 h after feeding when the low-nitrogen diet was given.

5. The sheep digested dry matter, cellulose and nitrogen a little more fully than the deer. The high-water regime slightly increased the digestibility of dry matter and cellulose but did not affect the digestibility of nitrogen.