1. The technique for the quantitative estimation of lignin by digestion with 72% H2S04 has been investigated. Two methods of pretreatment designed to eliminate interference products of carbohydrates and proteins were compared, namely (a) acid and pepsin and (b) acid detergent. The latter technique gave low lignin yields owing to the colloidal dispersion of lignin in the acid detergent treatment. Erroneous results arise from an inadequate digestion in 72% H2SO4. It was found preferable to filter the product lignin without prior dilution of the acid since white particles of material, assumed to be cellulose, flocculated from solution on dilution. Also there is some loss due to colloidal dispersion of lignin during refluxing in dilute acid.

2. Analysis of soda lignin and sulphuric acid lignin preparations from hay, duodenal contents and faeces of sheep with exteriorized flow through a re-entrant duodenal fistula provided evidence for the degradation of lignin by digestive processes. Demethoxylation of lignin occurred mainly in the stomach, suggesting that this was the main site of breakdown.

3. A new displacement method of measuring duodenal flow is described. Quantitative results obtained also indicate that lignin is degraded mainly in the stomach to the extent of about 10%.

4. These results suggest that faecal lignin is an adequate marker for the estimation of duodenal flow, and hence of the extent of changes in the stomach and intestines respectively.

1. The effects of ingestion of diets deficient in both copper and iron on storage of these elements and on the red cell indices have been studied in rats.

2. Injection of Cu into rats whose stores of Cu had been virtually exhausted resulted in a temporary increase in the concentration of plasma Fe and depletion of the Fe stored in the liver. Storage of Fe in the spleen seemed to be affected somewhat differently from that in the liver.

3. Fe injected into Cu-deficient rats was transported to storage sites but, although the plasma Fe concentration was presumably transiently increased thereby, there was no lasting effect.

4. The hypotheses that Cu mediates in the release of Fe from ferritin and that of Osaki, Johnson & Frieden (1966) that caeruloplasmin promotes the rate of Fe-saturation of apotransferrin are discussed.

1. The effect of preventing rumen fermentation of feed on the utilization of energy and protein by growing lambs has been studied by theoretical means.

2. Initially, the differences in feed utilization resulting from microbial fermentation compared with digestion by host enzymes were estimated. It was assumed that a diet containing 85% of unspecified carbohydrate and 15% casein was placed directly into the rumen (ruminant lamb) or abomasum (non-ruminant lamb) of animals weighing 20 kg, and that in both instances the diet was completely digested. In the non-ruminant lamb from 39 to 45% more net energy was available for maintenance, and from 22 to 61% more net energywas available for production, than in the ruminant lamb. The smaller differences applied to concentrate diets and the larger differences to highly fibrous diets. When dietary protein was completely degraded by microbes approximately 50% less protein was absorbed from the small intestine in the ruminant lamb than in the non-ruminant lamb. It is suggested that this may significantly reduce tissue synthesis and growth in early-weaned lambs weighing less than 30 kg, but it may not limit growth in heavier animals.

3. Because part of the food of ruminants generally escapes fermentation and is digested by enzymes in the small intestine, and because part of the food of non-ruminants is fermented in the hind-gut, the estimates were adjusted accordingly. In this situation the utilization of digested energy in the non-ruminant lamb was from 30 to 45 % more efficient for maintenance and from 10 to 60 % more efficient for production than in the ruminant lamb. Some dietary proteins are so resistant to microbial degradation that a lower efficiency of utilization in the ruminant lamb when these proteins are given could only result from a limit in availability of energy.

4. Since ruminants digest crude fibre more efficiently than non-ruminants, it was calculated that the level of dietary crude fibre must exceed at least 22%, and in some instances 35%, of the dry matter before the ruminant digestive system results in a better utilization of dietary energy in lambs. Thus, many common feeding-stuffs would be more efficiently used by lambs if they by-passed the rumen. The possible limitations to the adoption of this procedure are discussed.

5. The present techniques available for reducing the degradation of food within the rumen are outlined. It is suggested that an improvement in food utilization in ruminants could be achieved by feeding fats or formaldehyde-treated fat-casein complexes in solid diets, or alternatively, by feeding liquid diets which activate the reticular groove.

1. Rates of disappearance of glucose from ligated loops of small intestine in lambs, adult sheep and young rats were studied. The concentration of glucose in the lumen decreased exponentially with time, suggesting that within a range of concentrations of 166–277 m-moles/l glucose was absorbed mainly by passive diffusion.

2. The rate of absorption of glucose from a 166 mM-solution based on either zero or first order kinetics and expressed as m-moles/m small intestine per h decreased along the intestine from the duodenum to the ileum in lambs and rats. The decrease was slight in adult sheep.

3. The total absorptive capacity of the small intestine of adult grazing sheep for glucose from 166 mM-solutions (06 m-moles/kg body-weight per h) was approximately 25% of that for lambs less than 1 week of age.

4. Young rats had a greater absorptive capacity of the small intestine (12.9m-moles/kg body-weight per h) than adult sheep of about 40 kg body-weight (0.6 m-moles/kg body-weight per h) and this largely reflected a longer small intestine per unit body-weight.

5. The absorptive capacity of lambs for glucose was greater when the level of voluntary lactose intake was increased before an experiment. The absorptive capacity of the ileum of adult sheep given wheat was greater than that of grazing adult sheep.

6. Developmental changes in glucose absorption are discussed in relation to normal changes in diet and to changes in the morphology of the small intestine with age.

1. Young male and female guinea-pigs of similar age and male guinea-pigs of various ages were given daily oral supplements of vitamin C (L-xyloascorbic acid) (AA) on a body-weight basis for periods of 10–15 d and the resulting concentration of AA in several organs was determined.

2. There was no difference between the sexes in the concentrations of AA in the adrenal glands and spleen. The concentration of AA in the spleen, adrenal glands and eye lens was significantly lower in older animals, and in brain it was significantly higher than the corresponding values for the young guinea-pigs.

3. The tissue deposition after oral administration of AA for 10 d was compared with that resulting from intramuscular injection of the same quantity of AA over 10 d in males aged 60 d, males aged 500 d and females aged 500 d. In the 60-d-old guinea-pigs intramuscular injection raised the concentration of AA in the spleen and adrenal glands 35% and 50% respectively above that resulting from oral dosing. In the older guinea-pigs (500 d) the corresponding values were 108% and 127% respectively. It is concluded that reduced gastrointestinal absorption is, at least in part, responsible for the low AA concentrations in certain organs from older guinea-pigs. In the 500-d-old guinea-pigs there was no significant difference between the AA levels in the spleen, adrenals and brain of the two sexes, but AA level in the lens of females was significantly lower than that in males, irrespective of the mode of administration of the AA.

1. The deamination, ureolytic and proteolytic activities and rates of cellulolysis and gas production in large intestinal contents have been compared with those activities and rates in rumen contents of sheep.

2. Large intestinal contents produced ammonia. The rate of ammonia production was greater in caecal contents than in faeces. Incubation of caecal contents under toluene resulted in decreased production of ammonia and volatile fatty acids and an increase in the concentration of αamino nitrogen.

3. Proteolytic activity of large intestinal contents was much greater than that of rumen contents. There was little difference in proteolytic activity between caecal or faecal contents and their liquors whereas the activity in rumen whole contents was greater than in rumen liquor. Some proteolytic activity was present in caecal and faecal cell-free liquors but none was present in rumen cell-free liquor.

4. Deaminase activity was greater in rumen than in caecal contents or faeces. The activity in rumen liquor was less than half that in rumen whole contents.

5. Urease activity of caecal contents was less than that of faeces or of rumen contents.

6. The rate of gas production in rumen contents was less than that in caecal contents. The rate in faeces was low. Less gas was produced in rumen liquor than in rumen contents, whereas there was little difference between rates in caecal liquor and whole contents.

7. Rates of breakdown of cellulose in vivo were similar in the rumen and the caecum.

1. Iodine metabolism was studied using labelled sodium iodide in subjects with endemic goitre which is prevalent in the south-west part of Ceylon, where the iodine content of the drinking water was shown to be low. The study was confined mostly to children of school age.

2. The patients showed raised thyroidal uptake of 181I and 48 h serum protein-bound radio-active iodine, lowered plasma inorganic iodide and urinary iodide.

3. These findings suggest that the goitre which is endemic in Ceylon is due to environmental iodine deficiency rather than to a goitrogen.

1. By means of a cranial transillumination method used in conjunction with lumbar and bregmatic punctures, an increase in the space which contains the cerebro-spinal fluid in the cranial region is suggested in children with severe marasmic malnutrition.

2. The results appear to indicate that this is due to a diminished brain size, creating a space in the interior of the cranium which secondarily fills with cerebro-spinal fluid.

1. Baby pigs were removed from the sow 36–48 h after birth and reared on a diet of reconstituted whole-milk powder until 28 d of age. The whole milk was either mildly or severely heated before spray-drying; the severe heating completely denatured the whey proteins.

2. When the two milks were given at a high level of intake, either at hourly intervals or twice daily, severe scouring and some deaths occurred, the incidence being higher among pigs receiving the severely heated milk. The severe heat treatment also reduced the nutritive value of the milk powder as measured by the performance of the pigs during the 1st week of life. However, no difference in the nutritive value of the two milks was apparent for the surviving pigs over the whole experimental period.

3. There were no deaths when the two milks were given at a moderate level of intake and at hourly intervals. The effect of heat treatment on performance was similar to that at the high level of intake.

4. The apparent digestibility of the nitrogen in the diet was similar for both milks. However, balance trials could not be carried out when scouring occurred, when differences between the milks were most likely to be apparent. The N retention was similar with both milks at 7 d of age, although retention was higher when the severely heated milk was given to pigs between 14 and 21 d of age.

5. The digestion of the two milks was studied in 28-d-old pigs. The ability of the severely heated milk to clot in the stomach was greatly reduced compared with that of the mildly heated milk, but the performance of the pigs was unaffected. No other differences in the digestion of the milks were found. The ability of the diet to clot in the stomach appeared to be unimportant at this age.

6. It is possible that a reduction in the clotting ability of the severely heated milk was responsible for the decreased efficiency of digestion during the 1st week of life.

1. The bodies of twenty-three nestling blackbirds and twenty-one nestling thrushes were analysed at different ages for water, fat, nitrogen, calcium, phosphorus, sodium, potassium and magnesium. These birds grow from a weight of 5 g at hatching to 70 and 50 g respectively when they leave the nest 12–13 d later.

2. The concentration of N in the bodies doubled, while Ca increased seven to eight times during this period, so that the total amount of Ca in the body increased by about 100 times.

3. The femurs of the newly hatched birds were very immature and contained little Ca or collagen but in the fledgelings the femurs were as well calcified as those of 17-d-old chicks.

4. The gastro-intestinal tracts of the birds contained large amounts of Ca. Their food consists of caterpillars, adult insects and earthworms, none of which have much Ca in their tissues but their gut contents may contain much Ca. It is suggested that it is the gut contents of these invertebrates that provide nestling birds with Ca.

1. The effects of dietary supplements of heather at different stages of growth on the breeding of captive red grouse were studied.

2. A supplement of heather which was beginning to grow in spring stimulated captive red grouse to lay more eggs and to lay at a faster rate than birds given a supplement of dormant winter heather.

3. Although laying was stimulated, no significant effect on the date of laying, the hatchability of the eggs or the survival of the young was demonstrated; however, the possibility of such effects occurring in the wild is not ruled out.

4. The experimental effect occurred although the heather formed only a small proportion of a largely artificial diet, which provided a high plane of nutrition in terms of known nutrients.

5. The effect is attributed to an unidentified factor contained in the new growth.

1. Erythrocytes from Ugandan children with untreated kwashiorkor had membranes containing larger amounts of lecithin than erythrocytes collected during the recovery phase.

2. The passive permeability of the erythrocyte membrane to glycerol and thiourea was reduced in kwashiorkor and returned to a more normal value on treatment.

3. The results are discussed in the light of similar findings of high erythrocyte lecithin concentrations in various liver diseases.

1. Experiments are described in which the food intake and the water intake of sheep at a single meal were measured. The sheep were offered lucerne chaff ad lib. for 2 h only each day.

2. Following the peritoneal infusion of physiological saline the food intake increased, while the injection of a diuretic before feeding caused the food intake to be decreased.

3. In eight experiments the osmolality of the ruminal liquor was increased by the addition to the rumen of NaCl, KCl or the salts of volatile fatty acids in 250 ml water. The decrease in food intake was related to the osmolality, but not to the energy content, of the added electrolyte solution. In a further experiment, sheep receiving a highly digestible lucerne chaff, containing 1% (w/w) NaCl, increased their food intake when water was added to the rumen. Other workers have concluded that gastric osmolality is an important variable in the control of food intake in monogastric animals. The results of the eight experiments now described suggest that ruminal osmolality is of similar importance in ruminants.

4. It is suggested that all these observations are consistent with the theory, which has been proposed for non-ruminant animals, that the food intake at a single meal may be related to the degree of tissue hydration at the beginning of the meal.

1. A technique for the separation and colorimetric estimation of 2, 4-diaminopimelic acid (DAP) using automated ion-exchange chromatography coupled with an acid ninhydrin detection system is described.

2. Only traces of DAP were found in rumen protozoa and no DAP was detected in rumen fluid prepared by ultracentrifugation or dialysis.

3. The concentration of DAP in rumen bacteria from sheep on a constant feeding regimen, and the ratio of nitrogen to DAP for these bacteria were found to be constant over a 3-month period.

4. The method has proved suitable for the estimation of bacterial N in the duodenal digesta of ruminants.

5. The contribution of bacterial N to the total N leaving the abomasum of a lactating cow fitted with a permanent re-entrant cannula in the duodenum was found to be 50%.

1. Rats born of well-fed mothers and maintained from weaning on diets having protein values of NDpCal% = 10 or 5 were mated at 3 months of age with well-fed males.

2. The litters produced by the malnourished mothers weighed significantly less (P > 0.01) than those from the well-fed group.

3. The average number of individuals per litter was lower in the malnourished than in the well-fed group, but the difference was not statistically significant ( P < 0.0 5 ).

4. The congenitally malnourished litters weighed less than the well-fed even when litters of equal number were compared.

5. The differences in litter weights were not related to the length of gestation, which was similar in both groups.

6. There was a high neonatal death rate (63%) among the congenitally malnourished animals and the survivors grew very slowly so that at 5 weeks of age they weighed only half as much as the well-fed controls.

1. Concentrations of nucleic acid nitrogen and other nitrogenous constituents were estimated in digesta taken from the proximal duodenum of calves which were given, either, one of a number of stall diets or pasture. These concentrations were compared, using polyethylene glycol (PEG) as a non-absorbed marker, with corresponding concentrations in rumen fluid and ileal contents.

2. There was little net change in amounts of RNA or DNA between rumen and duodenum relative to PEG, but there was a marked increase in amounts of total-N. In duodenal digesta, for any one animal given most diets, nucleic acid-N formed a fairly constant percentage (8–11 for different animals) of the total non-ammonia-N. This value was lower (by about 3) than the corresponding percentage in rumen fluid. Comparison of nucleic acid-N: total-N ratios in duodenal contents and bacteria suggested that, for these diets, about 40–55% of the non-ammonia-N in duodenal contents was of microbial origin.

3. During passage of digesta between the duodenum and ileum the mean percentage disappearances of total-N, RNA and DNA were estimated to be about 67, 85 and 75 respectively. There was evidence that these values varied with the amounts of the constituents entering the duodenum.

4. Ammonia was absorbed in the omasum-abomasum only when concentrations in rumen fluid were high (40 mM), but even moderate concentrations of ammonia entering the duodenum (3 mM) were efficiently absorbed (about 90%) in the small intestine.