1. Eighty bull calves, comprising forty-eight ayrshire and sixteen each of the Friesian and Jersey breeds, were used in a randomized block experiment. Forty calves were maintainted at a mean environmental temperature of 21° and forty at 14·5°. Within each temperature, twenty calves were reared from birth on a liquid milk substitute diet (pre-ruminant calves) and twenty were weaned at 35 d of age on to dry food (ruminant calves). Each type of diet was gien either ad lib. or at a restricted level. The calves were slaughtered at about 100 d of age.

2. The incidence of a high rectal temperature (> 39·39°) was greater for the pre-ruminant than for the ruminant calves during the first 14 d of life and throughout the whole experimental period, and was higher for calves at an enviromental temperature of 21° than for thosekept at 14·5°. During the experimental period as a whole, but not during the first 14 d of life, the incidence of diarrhoea was greater for the pre-ruminant calves. Mean rectal temperature was higher for the pre-ruminant calves and also higher for the calves reared at the high environmental temperature.

3. The incidence of lung lesions at slaughter was significantly higher in the ruminant than in the pre-ruminant calves, and tended to be higher at the high environmental temperature. There was a highly significant positive relationship between severity of lung lesions and incidence of a high rectal temperature (> 39·33°) and mean rectal temperature. Jersey and Friesian calves, but not Ayrshire calves, showed increased severity of lung lesions with increasing relative humidity at the low environmental temperature. When the results at the 'high' environmentaltemperature were combined with those obtained in an earlier experiment, the severity of lung lesiogs for Jersey and Friesian calves increased with decreasing relative humidity. At the ‘high’ but not at the ‘low’ temperature, severity of lung lesions was inversely related to skin weight/kgO·73.

4. Live-weight gain was much lower for the ruminant calves, but was unaffected by environ-mental temperature. Daily dry-matter intake from liquid diets given ad lib. did not differ be-tween breeds at the same live weight. In contrast, daily dry-matter intake from dry food given ad lib. was greatest for the Jersey and lowest for the Friesian at the same live weight. The same daily dry-matter intake from liquid as from dry diets was achieved at similar percentages of mature weight for the three breeds. Relative weight gain within type of diet was similar for Jersey and Ayrshire calves, but tended to be higher for the Friesian calves.

5. Carcassweight, carcass weight0·73, perirenal fat deposition, skin weight and killing out percentage were much lower for the ruminant calves. When adjusted for differences between treatment means for carcass weight0·73, perirenal fat deposition was greater at the ad lib. levels of intake and was 36% greater for pre-ruminant calves given milk substitute ad lib. at an environmental temperature of 21° than for those maintained at 14·5°.

6. It is concluded that there is no advantage to be gained from rearing calves at an environ mental temperature above 14·5°, unless increased fat deposition is required in veal calves.

1. Twenty herbages at different stages of maturity containing from 0·77 to 5·23 g nitrogen/100 g organic matter were harvested, and green herbages were rapidly frozen and stored at - 1·5°. Each herbage was offered at levels approximating to ad lib. to a group of three sheep, individually penned. Intake, digestion and retention of N were studied during a 10 d collec-tion period after a 9 d preliminary period.

2. General regressions relating apparently digested N (NA, g/d), urinary N excretion (UN, g/d) and retention of N (NR, g/d) to N intake (NI, g/d) were established: NA= 0·88NI-3·25 (±1·14; SEb = ±O·013); UN = 2·48+0·35 NI+O·0049 NI2 (±3·09; SEb1, =±0·156; SEb2 = ±0·003); NR = 0·25 NI- 1·92 (±2·40; SEb = ·o·029). These equations accounted for 99% of the variability in N apparently digested, 86% of the variability in urinary N excreted, and 63 % of the variability in N retained.

3. Concentrations of ammonia and trichloroacetic-acid-precipitable N in the reticulo-ruminal digesta and of urea and a-amino-N in plasma were determined immediately before feeding, and at I and 4 h after feeding. Relationships between concentrations of metabolites in the reticulo-ruminal digesta and in plasma, and N intake, N apparently digested, urinary N output and retained N were examined. Estimates of urinary N loss and of retained N based upon metabolite concentrations at individual sampling times were characterized by high residual variabilities. Error terms were in some instances reduced significantly when both thebasal (before feeding) metabolite concentrations and the increments in metabolite concentra-tions after feeding were included in the one equation. The best relationships, based on plasma urea concentrations, accounted for only 74 % of variability in urinary N output.

4. In multiple regressions a significant portion of the variability in urinary N output and in retained N which was not accounted for by N intake could be accounted for by inclusion of metabolite values.

5. The concentration of urea in plasma was the most effective basis for prediction of N utilization. However, no prediction equation accounted for more than 90% of the total variabilityin N output, and no equation accounted for more than 71 % of the total variability in N retention. The feasibility of developing techniques for examination of efficiency of N utilization by a particular class of animal, based upon digesta and plasma metabolite con-centrations is discussed.

1. The relative rates of passage of polyethylene glycol (PEG) and lignin through the alimentary tracts of sheep were examined through the ratio of these two markers in the fodder and in the contents of various segments of the gut. A much faster turnover of PEG than of lignin in the stomach compartments suggested that samples from these organs could not be representative of the digesta flowing through them. Average PEG:lignin ratios in the small and large intestines were close to the ratio in the fodder, indicating that sampling from the duo-denum in the living animal could possibly yield material representative of that flowing from the stomach to the small intestine. Similar results were obtained for high and low levels of fodder intake.

2. A procedure was developed for automatic sampling from the duodenum for prolonged periods, and the material collected was shown to be representative of digesta flow. Simpler methods of sampling from the duodenum were shown to be liable to relatively large errors.

3. The amount of nitrogen reaching the duodenum in sheep given lucerne hay pellets was found to be equivalent to practically 100 % of the dietary N, whether the intake of fodder was 600 g/d or 1500 g/d.

1. An attempt was made to measure body volume and body fat in malnourished children using the same closed-circuit apparatus for both determinations. If these measurements were sufficiently accurate, they would enable total body protein to be calculated.

2. A helium dilution technique was used to estimate the volume of the child. Although highly reproducible measurements were obrained for the volume of inanimate objects by this techinque, the results with children were erratic.

3. The fat stores of the child were determind by measuring the amount of cyclopropane (C2H4) which would dissolve in the body. This technique gave acceptable answers with marasmic children who have little subcutaneous fat, but with obese children equilibrium could not be obtained in an acceptably short period of time. It is not practicable to calculate the equilibrium concentration by extrapolation of the uptake curve in obese children.

1. NaH14CO3, was infused at a constant rate either subcutaneously or intraperitoneally into sheep kept in a uniform environment and consuming a standard amount of food each hour. After 3 h of infusion the specific radioactivity (SR) of COe obtained by acidification of samples of blood taken from the right atrium showed no significant change with time until after 22 h when the infusions were stopped.

2. Entry rates of COa (I/h) in sheep were estimated from the ratio of rate of infusion of 14CO2, as NaH14C08 (µCi/h) to the SR of CO2 (µCi/l) in samples of jugular venous blood, urine and exhaled gas taken after infusions had been in progress for at least 3 h. Concurrently, rates of energy expenditure were calculated from the gaseous exchanges over periods of 60–90 min which were determined for grazing sheep by use of re-entrant tracheal cannulation and meter-ing and analysis of exhaled gas, or for housed sheep by measurement in respiration chambers.

3. Significant positive relationships were found between entry rate, the independent variable, and the contemporary energy expenditure. Equations obtained for grazing sheep were not significantly different from those obtained for other, housed, sheep when both groups were infused subcutaneously and COz for assay of radioactivity was obtained in all instances from blood, or in all instances from urine.

4. With subcutaneous infusion the equation relating energy expenditure to entry rate estimated from the SR of urinary COa differed significantly from that where entry rate was derived from radioactivity assays of blood or exhaled CO2. There was also a significant differ-ence between two equations where entry rates were determined from the SR of blood CO2 but route of infusion was in the one instance intravenous and in the other was sub-cutaneous. Reasons for the differences between equations are discussed.

5. Changes in the rates of energy expenditure of sheep effected by intermittent exercise on a treadmill were reflected in changes in CO2 entry rates. Values for the energy cost of hori-zontal locomotion by the sheep were derived from the entry rates and were similar in magni-tude to those reported by other workers.

6. I t is suggested that the method of determining energy expenditure from COz entry rate may be adapted for use on many species of animal in a variety of environments.

1. Free amino acid entry rates, rates of portal uptake of amino acids and rates of glucose synthesis from amino acids have been measured during the continuous intravenous infusion of [U-14C]-labelled mixed amino acids in six sheep receiving diets that supplied different amounts of protein.

2. In four of these sheep and in one other, total rates of glucose production have been measured using continuous intravenous infusions of [U-14C]-labelled glucose.

3. A signiiicant correlation was found between total amino acid entry rate ( Y mg/min.kg) and daily protein intake ( X g/kg): Y = 2·14+ 1·38X (r = 0·878, 0·02 > P > 0·01).

4. A significant correlation was found between the rate of absorption of amino acids into the portal system ( Y mg/min.kg) and the daily protein intake ( X g/kg): Y = 0·58 + 0·58X (r = 0·884, 0·02 > P > 0·01).

5. A highly significant correlation was found between total glucose production rates ( Y mglmin. kg) and daily protein intake ( X g/kg): and daily protein intake ( X g/kg): Y = 2.14+ 1.38X (r = 0·878, 0·02 > P > 0·01). Y = 0·375f0·702X (r = 0·866, 0·005 > P > 0·001).

6. The mean proportional contribution to total amino acid entry made by portal absorption was 33·5 f 1·8 yo (six animals).

7. A significant correlation was found between the rate of glucose production from amino acids (Y mg/min.kg) and the rate of entry of amino acids ( X mg/min.kg): Y = 0-189X-0·414 ( r = 0·84, 0·01 > P > 0·005).

8. The best approximation of the proportion of glucose derived from amino acids was 28·16 f 5·1 % (six animals).

9. The specific radioactivities of amino acids in liver, kidney and muscle did not approach those found in plasma during infusions of [U-14C]-labelled mixed amino acids of up to 6·75 h.

1. Twenty pigs were reared to a weight of 90 kg on various dietary regimens so that their lipid content varied from 16 to 38%;. They were injected intravenously with ~ 400 μCi of 42KCl. The animals were killed ~ 28 h after injection and their contents of water, lipid, sodium and potassium were determined.

The specific activity of plasma reached equilibrium 10–12 h after injection, that of urine not until 20 h after.

Losses of activity in urine, faeces and gut contents in the 24 h after injection amounted to 3·1, 0·3 and 1·5% of the injected dose, respectively.

Total body K was more accurately estimated from urine specific activity than from plasma specific activity.

Exchangeable K, estimated from urine specific activity Ke(u), was highly correlated with the weight of fat-free tissue (r = 0·93), the residual standard deviation of the regression being 1·8 kg fat-free tissue.

Percentage extractable fat was equally well correlated with Ke(u) (r = −0·92).

1. A combination of balance and isotope techniques has been used to study the effects of age and dietary calcium content on Ca metabolism in forty-two wether sheep.

2. The amount of Ca absorbed by young growing animals varied significantly with intake. The percentage of the dietary Ca absorbed, however, remained unchanged. In older animals the amount of Ca absorbed was not altered by changes in intake, but decreased slightly with age.

3. Retention of Ca was directly related to the amount of Ca absorbed and was independent of age or breed. Furthermore, nearly all the Ca absorbed above the minimum mean amount required for maintenance was retained.

4. Faecal endogenous loss of Ca also was related to the amount of Ca absorbed. Values for faecal endogenous Ca were much lower than those used in the calculation of dietary require-ments by the Agricultural Research Council (1965).

5. Urinary Ca excretion was variable, and was not related to age or changes in dietary Ca intake.

6. Increased absorption of Ca in young growing animals was accompanied by a decreased rate of bone resorption, but the rate of bone accretion remained unchanged. Changes in dietary Ca in older animals had no effect on either of these two processes. Results indicate that bone resorption is the main pathway governing Ca homoeostasis. Both the rates of Ca accretion into bone and resorption from bone decreased with age.

7. Neither the rapidly exchangeable Ca pool (P) nor the slowly exchangeable bone pool (E) was altered by changes in dietary intake in young or mature animals. Both, however, decreased in size with age.

8. The size of the slowly exchangeable pool (E) was directly related to the rate of Ca accretion into bone. 9. The results were used to calculate dietary Ca requirements of sheep gaining weight at different rates, and these values have been compared with values recommended by the Agricultural Research Council (1965).

1. The object was toinvestigate the importance of urea a source of ammonia in the large intestine of herbivores. Urea was present in small intestinal contents of slaughtered horses in concentrations similar to those in blood but, in the small intestine of salughtered sheep, the urea was less than in blooc.

2. There was little ammonia in small intestinal contents of slaughtered horses but consider-able ammonia was present in small intestinal contents of slaughtered sheep. The ammonia in small intestinal contents of the slaughtered sheep was probably formed from urea, as ileal con-tents taken from a sheep with an ileal cannula contained considerable urea and little ammonia.

3. The ammonia concentration in caecal contents of sheep was related to the concentration of urea in blood except when ileal contents were prevented from entering the caecum.

4. Ileal digesta of sheep contained more free amino nitrogen than did caecal digesta.

5. Ammonia was absorbed more rapidly than water from the caecum of sheep. The rate of absorption was related to the concentration of ammonia in the caecum.

1. The plasma and blood volumes of twenty-eight Iraqi children were measured. Twenty-four of them were malnourished in varying degrees and four were normal children who acted as controls. None of the children was anaemic.

2. There was an increase in the plasma and blood volumes per unit body-weight correlating with the degree of malnourishment (P < 0·001).

3. There was little variation in the values for plasma and blood volumes when calculated per unit body length; the values were less constant when calculated per unit body surface.

4. The effect of age on the plasma and blood volumes per unit body-weight was less than the effect of the degree of malnutrition.

5. There was no correlation between the plasma volume of malnourished children and their corrected venous haematocrit, if children with severe anaemia were excluded.

1. The Knoop test of hardness of materials has been used to test the hardness of human nail.

2. The range of hardness of nails was found to be small in healthy persons and large in malnourished children.

3. Nails from malnourished children were in general much harder than those from healthy persons. The nails of a small group of three children became softer while they were recovering from malnutrition.

1. The effect of drying and ensiling ryegrass on the site of digestion of the energy andcarbohydrate fractions was studied in sheep fitted with rumen cannulas and re-entrant can-nulas in the proximal duodenum and terminal ileum.

2. The sheep were given fresh (frozen) grass, dried grass, wilted and unwilted silage pre-pared from herbage harvested from the same sward. The grass diets were offered twice dailyto each animal and paper impregnated with chromium sesquioxide was administered twicedaily into the rumen. Twenty-four hour collections of duodenal and ileal digesta, adjusted togive 100 yo recovery of Cr2O3, were analysed to determine the extent of digestion in the fore-stomachs, the small intestine and the caecum and colon.

3. Total digestibility of the gross energy was similar for the fresh grass, dried grass andwilted silage diets (67·4,68·1 and67·5 %)but higher for the unwilted silage (72·0 %, P < 0·01).There was an increased flow of energy into the small intestine when the sheep were given driedgrass and unwilted silage. The proportion of the apparently digested energy lost within thesmall intestine was greater when the dried grass was given (302 yo) than when the fresh grasswas given (23·6 yo).

4. Drying or ensiling of wilted material affected digestion neither in the entire alimentarytract nor in the different sections of the tract, of some carbohydrate fractions. About 97 yo ofthe digested water-soluble carbohydrate, over 90 yo of the digested cellulose and over 70 yo ofthe digested hemicellulose were digested before reaching the small intestine. The increasedamount of energy entering the duodenum of the sheep given the dried grass was notaccounted for by changes in the fate of these carbohydrate fractions in the digestive tract. Withunwilted silage, digestibilities of the cellulose and hemicellulose fractions were higher, andlower proportions of the digested carbohydrates were lost before the small intestine.

1. Lambs were removed form their dams at 2 d of age, and at 5 weeks of age eitht of one group were incoulated with a mixed rumen ciliate and seven in a second group were maintained ciliate-free throughout the 61 weeks of the experiment. Performance of the groups was compared when given a 2:1 roughage:concentrate diet as a set ration and with ad lib. roughage.

2. Mixed ciliate populations developed in all faunated lambs and average-sized populations were maintained. Large numbers of flagellate protozoa developed in the ciliate-free animals after flagellates had been introduced into the building with the ciliate-free animals after flagellates had been introduced into the building with the ciliate inoculum.

3. Higher numbers of rumen bacteria were found in the ciliate-free group.

4. Only between the 14th and 21st weeks was there a significant different between groups in weight gain and this was infavour of the faunated group. The only significant different in body measurements was greater girth in the ciliate-free lambs.

5. Only minor differences were found between the groups in calorimetric trials, digestibility and nitrogen balanes. There were no differences between groups in concentration of total protein N and soluble sugar in the rumen. The ammonis concentration was significantly higher in the faunated group.

6. The concentrations of total rumen volatile fatty acids (VFA) were higher in the faunated group. Differences, between groups, in proportions of VFA were attributed to the activity of the rumen bacteria rather than the ciliates per se.

7. No differences between groups were found in the concentrations of blood sugar and haemoglobin.

8. It was concluded that the changes due to the presence of rumen ciliates were not great enough to be reflected in animal performance under the conditions of this experiment.

1. Experiments in children and in animals seem to demonstrate that in marasmic malnutrition there is a reduction in the secretion of growth hormone. To study this problem the fasting, resting plasma concentrations of growth hormone were determined, before, and 45 and 60 min after, stimulation with an intravenous dose of arginine, in six infants with marasmus, in six infants with kwashiorkor and in five normal infants.

2. The values of plasma growth hormone (4·5 ± 0·97 ng/ml) in marasmic infants were significantly (P < 0·001) lower than those of the controls (7·8 ± 2·6 ng/ml), and responded little to stimulation with arginine (5·1 and 5·8 ng/ml at 45 and 60 min respectively), in contrast to those in the control group, which rose to 16·4 and 14·6 ng/ml. In children with kwashiorkor the values were very variable, but generally high, and showed little response (25·6 ± 13·3 before and 25·0 ± 17·6 and 14·2 ± 5·3 ng/ml at 45 and 60 min after stimulation respectively).

3. These results demonstrate that the responses of the hypophysis to deprivation of calories and protein (marasmus) and to protein deprivation (kwashiorkor) are different: in marasmus there is a progressive adaptation, with low secretion and poor reaction to stimulation, whereas in kwashiorkor the process is acute with high basal values of plasma growth hormone.

1. Constant intravenous (3 h) infusions of a fructose solution were given on a rate for body-weight basis (0·6 g/kg per h) to thirty patients who had no evidence of diabetes mellitus or liver disease. Concentrations of blood fructose, pyruvate and lactate formed a plateau during the last 1–1·5 h of the infusion period.

2. Although the numbers were small, the individual pyruvate and lactate concentrations at plateau varied greatly and assumed a bi-modal distribution, suggesting two distinct groups. The group to show a lower pyruvate and lactate rise (group A) contained more males of a lower age and more patients who had ischaemic cardiac disease than the other group (B); none of these differences was, however, statistically significant. The fructose concentrations at plateau were not significantly different between the groups. Serum triglyceride glycerol concentration during the infusions rose markedly in three patients in group A but in none in group B. Minor changes in concentration of blood glucose, insulin, inorganic phosphate and uric acid during the infusions were not significantly different between the groups and did not fall into a bi-modal pattern.

3. Constant intravenous (3 h) infusions of 0.15M-sodiurn lactate at the same infusion rate in eight of the patients (four from group A and four from group B) did not produce a significant difference in the blood lactate concentrations at plateau between patients from the two groups.

4. These results reflect qualitative differences in fructose metabolism in the patients studied. The difference in pyruvate and lactate production may be associated with total carbohydrate intake. However, the bi-modal distribution strongly suggests a genetically determined difference in metabolism between the two groups.

1. Gastric motility was studied in a young bull and two sheep which had retained their sucking behaviour. Pressure tracings or electromyograms were recorded from all compart-ments of the stomach.

2. During the sucking of milk or water reticulum contractions either became more fre-quent but weak, or ceased altogether. After sucking, or after the introduction of fluid directly into the abomasum, reticulum contractions slowed down but retained their strength. The rumen and omasum were more fully inhibited than the reticulum.

3. It is concluded that the inhibitory response to sucking has two phases, a cephalic phase dependent upon the eagerness of sucking which mainly influences the strength of the contractions of the forestomach, and an abomasal phase dependent on the degree of distension of the abomasum which mainly affects the frequency of the contractions.

1. Two experimental groups, each of thirteen boarding schoolboys, were given either 400 mg α-tocopheryl acetate or placeboes daily in addition to their normal diet during training in swimming and various athletic activities over a period of 6 weeks. Evaluation of the experimental treatments was made from tests of anthropometric status, cardiorespiratory efficiency and motor fitness and performance, which were administered at the beginning and end of the experimental period.

2. Whereas training significantly improved physiological function and performance in both groups (P < 0·05), vitamin E did not.