1. The B-vitamin status of fifty-nine patients, mainly from the lower socio-economic classes in Bombay, with a history of chronic malnutrition, and of alcoholism of 1·5–20 years’ duration, was studied before and during treatment, and in relation to their clinical, especially neurological, condition. These patients were divided into two neurological categories: (1) those with peripheral neuropathy (mainly sensory and distal) alone, (2) those with mental changes (mainly confusion and disorientation) also. Both categories frequently showed pellagrous pigmentation and mucocutaneous signs of B-vitamin deficiency.

2. Thiamin and erythrocyte transketolase (EC 2.2.1.1) activity, riboflavin, nicotinic acid, pantothenic acid, total and pyridoxal fraction of vitamin B6, folate and total vitamin B12 were estimated in the blood and the cerebrospinal fluid (CSF) of these patients, and also in the blood of sixty-nine control subjects and in the CSF of some of them. The concentrations of all the vitamins, except vitamin B12, were highly significantly lower in the blood of patients of category 1 compared to the controls, and erythrocyte transketolase activity and pyridoxal concentration in patients of category 2 were significantly lower than those of category 1 patients. Blood pantothenic acid and folate concentrations were reduced less consistently.

3. Serum vitamin B12 concentration was significantly increased (though within normal range) in the patients compared to the control group, probably because of the moderate hepatic insufficiency (as assessed by liver function tests) in the former.

4. The concentrations of thiamin, riboflavin, nicotinic acid and total vitamin B6 were also highly significantly lower in the CSF in patients of category 1 compared with controls. Furthermore, thiamin, nicotinic acid and total vitamin B6 concentrations were significantly lower in patients of category 2 than those of category 1 patients, indicating that CSF levels reflect better the neurological status of these patients.

5. There was a moderate increase in the blood concentration of all the vitamins tested, after a relatively poor hospital diet alone. There was a concurrent increase in the blood levels of thiamin, riboflavin, nicotinic acid and pantothenic acid after parenteral treatment with either thiamin or nicotinic acid. The administration of pyridoxine resulted in a significant increase in the blood levels of riboflavin and the pyridoxal fraction of vitamin B6.

1. Cataract formation in streptozotocin-induced diabetes in rats was reduced by approximately 85% when a diet rich in maize oil (300 g/kg diet) (fat diet) was given, thus confirming results of earlier studies. However, the concentration of sorbitol in the lens of diabetic animals remained high, the values for diabetic rats given the standard diet and the fat diet being 65 and 40 μmol/g protein respectively.

2. With the standard diet, the fatty acid profile of the triglycerides of the epididymal fat pads was characterized by a greater relative proportion of saturated fatty acids for the diabetic animals compared to that for the normal animals. The fat diet moderated the tendency towards saturation in the diabetic animals.

3. The fat diet had other effects on the diabetic animals; these included a reduced mortality rate, increased body-weight, a decrease in the daily water intake, and in the daily urinary excretion of glucose and urea.

4. In the diabetic animals the fat diet had no effect on the specific activities in the liver of hexokinase (EC 2.7.1.1), glucokinase (EC 2.7.1.2), phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40). However, the specific activity of glucose-6-phosphatase (EC 3.1.3.9) was reduced, while that of malate dehydrogenase (decarboxylating) (NADP) (EC 1.1.1.40) was increased. The NAD+: NADH ratio, as calculated from liver pyruvate and lactate concentrations, tended to increase.

5. The results suggested that the fat diet moderated the long-term metabolic effects of diabetes.

1. Pangola grass (Digitaria decumbens) grown with and without calcium fertilizer was cut at three stages of regrowth to measure voluntary intake of dry matter (DM) and digestibility of various components of the dried-grass diet by sheep kept in metabolism crates. To determine the extent of a simple Ca deficiency half the sheep on each diet were supplemented with 1·4g Ca/d. Retention times of the various dietary components in the reticulo-rumen were also determined.

2. Feeding a Ca supplement had no effect on voluntary intake or digestibility.

3. Ca fertilizer increased the Ca content of the grass from 2·2 to 3·8 g/kg DM and DM digestibility from 0·455 to 0·476 (P < 0·01) due to an increase in the digestibility of the hemicellulose.

4. Voluntary intake was increased from 38·8 to 43·2 g/kg body-weight0·75 per d by Ca fertilizer due to an 18% reduction in the period of time the DM was retained in the reticulo-rumen.

5. Regressions relating voluntary intake to DM digestibility for the Ca-fertilized and control grass were significantly different (P < 0·01). When compared at the same DM digestibility the voluntary intake of the Ca-fertilized grass was 2·6 g/kg body-weight0·75 per d higher than that of the control.

6. It was concluded that Ca fertilizer increased both DM digestibility and voluntary intake as a result of changes in the structural composition of the grass and not by a simple increase in the Ca content of the diet.

1. The influence of a 24 h fast on the concentrations of free amino acids in the plasma, and upon the oxidation rates of methionine, isoleucine and threonine was studied (using early weaned, 4-week-old piglets which were receiving a semi-purified diet.

2. There was no change in the total concentration of the essential amino acids as a result of the 24 h fast: the concentration of the branched-chain amino acids increased, but the effect of this was offset by decreases in the concentrations of arginine, histidine, lysine, methionine and phenylalanine. There was a reduction in the concentration of the non-essential amino acids.

3. The piglets received infusions of L-[1-14C]methionine, L-[U-14C]isoleucine and L-[U-14C]threonine, and the recovery of the label in carbon dioxide was determined. Less than 5% of the activity from methionine was recovered in the CO2 from the fed piglets, whereas 12% was recovered from the fasted piglets. The corresponding values with threonine were 11 and 19% but there was no effect of fasting on the recovery of the label from isoleucine in CO2.

4. The initial dilution of a single dose of a labelled amino acid infused into the bloodstream depends on the plasma concentration of the amino acid. Nutritional regimens may effect the free amino acid concentration in the plasma. Thus comparisons based upon direct determination of activity recovered in CO2 from the labelled dose of an amino acid with animals on different nutritional regimens could be misleading, unless the differences in the concentrations of the amino acid in the plasma are considered.

1. Calves were given a basal diet of straw and flaked maize (12 g nitrogen/kg dry matter (DM)) or diets with some flaked maize replaced by untreated (UT) casein or formaldehyde-treated (FT) casein to give 19, 26 or 34 g N/kg DM.

2. At all intakes rumen ammonia concentrations were lower and amounts of total-N, non-ammonia-N and amino acid-N entering the duodenum were higher when FT-rather than UT-casein supplements were given.

3. Direct measurement of casein entering the duodenum indicated that giving FT rather than UT casein led to much greater amounts of dietary casein escaping degradation in the rumen (70–90% compared to 10–20%). Calculated values for fermentable N indicated that with this low degradability diets containing FT-casein would have provided inadequate N for maximum microbial synthesis in the rumen, and this probably accounted for the marked reduction in amounts of non-casein-N entering the duodenum when FT rather than UT casein was given.

4. Amino acid patterns in duodenal digesta samples after giving the basal diet or diets containing UT-casein were similar. Giving diets containing FT-casein led to changes in this pattern which could sometimes, although not always, be accounted for by estimated differences in proportions of dietary and microbial proteins.

5. At the highest level of N intake FT-casein-supplemented diets led to significantly higher concentrations of most essential amino acids and lower concentrations of most non-essential amino acids in plasma than did UT-casein-supplemented diets. Plasma urea concentrations increased with increasing N intake but were not significantly different for UT- and FT-casein-supplemented diets.

1. In order to study the ability of the ileum of the sheep to digest and absorb protein, casein or gluten were infused into the intestine of rams through cannulas inserted at distances of 0·05, 7, 9 and 15 m from the pylorus. Amounts of casein or gluten containing 10–20 g nitrogen were infused during 24 h, in animals given a low-N diet.

2. N balance was negative during the preliminary period when no infusion was given; infusion of casein or gluten increased the daily N retention to 5–15 g.

3. Infusion of proteins into the intestine did not induce an increased activity of pancreatic proteases in digesta withdrawn from the lower part of the intestine.

4. The increased N retention after the infusion of proteins into the lower part of the intestine indicates a considerable capacity of this section of the intestine to digest and absorb proteins.

1. Free amino acid concentrations in the plasma have been compared with those in liver and quadriceps muscle, in rats fed on diets containing 209 (control) and 31 (low-protein) g protein/kg. The effects of the low-protein diet on diurnal variations in these values were also measured.

2. In the plasma, the total amino acid concentration was significantly lower in animals given the low-protein diet, at all times of day except 12.00 hours. In the liver, and to a lesser extent the muscle, total amino acid concentration was maintained.

3. In the control animals, diurnal variation in the concentrations of both essential and non-essential amino acids was very similar in plasma, liver and muscle. In animals given the low-protein diet, although the same diurnal pattern was maintained for non-essential amino acids, that occurring among the essential amino acids had virtually disappeared.

4. In plasma, the mean 24 h concentration of essential amino acids decreased from 24· mmol/l in control animals to only 1·29 mmol/l in the low-protein-fed animals. Concentrations in muscle and liver were reduced by a similar proportion (from 8·6 to 5·56 μmol/g and from 8·67 to 5·05 μmol/g respectively). Conversely the concentrations of non-essential amino acids in animals given the low-protein diet were increased in plasma (from 1·53 to 2·00 mmol/l), muscle (from 12·5 to 14·3 μmol/g), and liver (from 16·8 to 20·5 μmol/g), muscle showing the lowest increase.

5. With the exceptions of lysine, threonine, cystine and tyrosine, the concentrations of all other essential amino acids were reduced more in liver than in muscle. The relationship between this and the failure to maintain plasma albumin concentrations is discussed.

1. Six closely shorn sheep were given brome grass (Bromus inermis) pellets at 1 h intervals and maintained at ambient temperatures of −1 to 1° and 18–21° for 28 d. Measurements of digestion were made during the last 10 d of temperature exposure.

2. Cold exposure resulted in a reduction in apparent dry matter (DM) digestibility from 0·482 to 0·450, and of apparent digestibility of organic matter (OM) from 0·511 to 0·477. Neither apparent digestibility nor retention of nitrogen was affected.

3. Apparent digestibility of OM in the rumen decreased from 0·300 to 0·242 with cold exposure, and was highly correlated with turnover time in the rumen of 108Ru, which was used as a particulate marker.

4. The efficiency of microbial synthesis (g N incorporated into microbial cells/kg OM apparently digested) was correlated with the dilution rate of the solute marker (51Cr) and with the turnover time of the particulate marker (103Ru) in the rumen.

5. Digestion in the intestine of DM and OM accounted for significantly more of apparent digestion in the whole gastrointestinal tract for sheep kept in the cold than for sheep kept in the warm. The apparent digestibilities of DM and OM entering the intestines were similar in sheep on both treatments, but significantly more non-ammonia-N was digested in the intestines of cold-exposed sheep.

6. The influence of dilution rate of rumen fluid on the efficiency of synthesis of microbial cells in the rumen is discussed.

1. The effects of copper and zinc on organ cultures of chick embryo cartilage and bone maintained in low-trace-metal, chemically defined media for up to 8 d were studied macro-scopically, histologically and histochemically. Length and wet-weight measurement of explants were assessed statistically.

2. No effects were found with Cu concentrations of 0·5–1·5 μg/ml medium. Between concentrations of 5 and 40μg Cu/ml medium, lengths and wet-weights of cartilage cultures decreased significantly (P < 0·001) compared with controls. The decrease was directly proportional to increasing Cu concentration, and that of the length was greater with increasing period of culture (P < 0·001).

3. With 5–20 μg Cu/ml medium cartilage and bone became yellow in colour, and chondrocytes were swollen, rounded and basophilic. They were detached from their lacunae and the quantity of matrix was reduced. Loss of alkaline phosphatase (EC 3.1.3.1) activity and disappearance of glycogen accompanied the degeneration. Osteogenesis ceased, cells failed to divide and mature, lost their enzymes and died. Cu did not accumulate in the bone matrix.

4. The direct toxic effects of Cu for cartilage and bone may underlie some of the skeletal changes in hepatolenticular degeneration (Wilson’s disease).

5. As Zn concentrations were increased from 2·5 to 7·5 μg/ml medium, lengths and wet-weights of cartilaginous cultures were significantly increased (P < 0·001). As Zn concentrations were further increased (from 10 to 40 μg/ml medium), lengths and wet-weights were significantly decreased (P < 0·001).

6. Zn stimulated chondrocyte division and vacuolation of cytoplasm. With higher Zn concentrations toxic changes of granular basophilia, lacunar detachment and necrosis were seen. Differentiation and functioning of osteoblasts, osteoclasts and chondroclasts were stimulated by Zn.

7. Zn was found in bone matrix, osteoblasts, osteocytes and hypertrophied chondrocytes.

1. Deficits in weight- and length-for-age, and serum albumin and transferrin concentrations were determined for children who were either marginally undernourished (twenty-five children) or suffering from either marasmus (thirty-two children) or kwashiorkor (twenty-six children) defined according to the Wellcome Classification (Waterlow, 1972). The measurements were also made in eight children with kwashiorkor after the loss of oedema, and in sixteen children who were recovering from either marasmus or kwashiorkor.

2. The mean concentration of serum albumin was similar for children from the ‘under-nourished’ group and from the group with marasmus, but was significantly reduced in those with kwashiorkor.

3. The concentration of serum transferrin was significantly reduced in both the group of children with marasmus and those with kwashiorkor. The serum transferrin concentration was significantly lower in children with kwashiorkor when compared with the level in those with marasmus.

4. Seventeen children (seven with kwashiorkor and ten with marasmus) died. These children were neither lighter nor shorter than the severely malnourished children who survived. The concentration of serum albumin was not lower in the children who died than in those who survived.

5. In contrast to the results for serum albumin concentrations, the children who died had significantly lower levels of serum transferrin than those who survived.

6. There was a significant linear relationship between serum transferrin concentrations and the deficits in length-for-age (P < 0·05) and weight-for-length (P < 0·001) in the marginally undernourished children. The deficit in weight-for-length was also linearly related to the serum transferrin concentrations (P < 0·001) in children recovering from severe malnutrition.

7. It is suggested that the measurement of serum transferrin concentrations provides an index of severity in severely malnourished children, and should prove useful in field assessments of nutritional status.

1. In a preliminary experiment, growth of conventional chicks given a basal diet containing adequate amounts of all the essential but none of the non-essential amino acids was improved by supplements of 10·3 g urea or 50·4 g glutamic acid/kg diet or both.

2. In the main study the effects of supplementing the basal diet with 2·6 g urea/kg were compared in groups of sixteen germ-free and conventional chicks.

3. The germ-free chicks did not benefit from the urea supplement whereas the conventional birds showed improved food conversion efficiency and significantly better growth.

4. In both environments nitrogen retention ((mg N intake – mg N excreted) ÷g food intake) was higher in the birds given urea, but N utilization ((mg N intake – mg N excreted) ÷ mg N intake) was reduced. This reduction was greater in the germ-free birds.

5. There was a small increase in plasma ammonia concentration in the germ-free birds given urea but a significantly greater increase in the corresponding conventional group.

6. Plasma uric acid concentrations were variable in both groups, and much lower than the normal range. They followed a similar pattern to the plasma ammonia values.

7. More insoluble N was excreted by the conventional chicks given urea than by the corresponding germ-free group, or by either group given the basal diet.

8. It was concluded that the gut micro-organisms are responsible for the growth-promoting effect of urea, presumably through release of ammonia by bacterial urease (EC 3.5.1.5) and its consequent incorporation into amino acids.

1. Rats were maintained for 10 d on a semi-synthetic diet containing 700 g glucose or 700 g fructose/kg. Individual enzymie reactions in bile acid synthesis and metabolism were studied by measuring the 7α-hydroxylation of [4-14C]cholesterol, the 12α-hydroxylation of 7α-[6β-3H]hydroxy-4-cholesten-3-one, the 26-hydroxylation of 5β-[7β-3H]cholestane-3α,7α-diol and the 6β-hydroxylation of [3H]lithocholic acid in liver homogenates.

2. The serum cholesterol level was approximately the same in both groups of animals, but the serum triglyceride level was almost twice as high in the fructose-fed rats compared to the glucose-fed rats.

3. The 6β-hydroxylation of [3H]lithocholic acid was increased by about 20% in the fructose-fed rats compared to the glucose-fed animals. The activities of the other enzymic reactions studied did not differ significantly between the two groups of animals. The findings are discussed in relation to previous knowledge concerning mechanisms regulating triglyceride, pre-β-lipoprotein and bile acid synthesis.

1. The effect of a diet containing a trypsin inhibitor on the incorporation of radioactively labelled leucine into the pancreatic proteins secreted during stimulation with cholecystokinin-pancreozymin (CCK) was studied in rats.

2. The total output of protein was significantly greater in the rats given raw soya-bean flour (RSF) compared with those given heat-inactivated soya-bean flour (HSF) (controls) in response to the sub- and supramaximal stimulation with CCK, but similar responses were obtained to maximal stimulation with CCK. Total protein output decreased continuously with time after reaching peak values at 90–120 min after the start of stimulation with CCK.

3. The total output of radioactively labelled protein in RSF-fed rats was not different from that of the controls with sub- and supramaximal dose rats of CCK, but was significantly lower than that of the controls in response to the dose rate of CCK which produced maximal rates of pancreatic secretion.

4. The specific activity of radioactively labelled protein increased continuously, while the output attained a constant rate during stimulation with all doses of CCK.

5. We concluded that feeding the trypsin inhibitor-containing diet led to increased secretion of stored pancreatic protein, while secretion of newly synthesized protein was not altered. During the course of prolonged stimulation with CCK, irrespective of diet, there was increasing secretion of the newly synthesized protein compared with the pre-existing stored proteins of the pancreas, but it was unable to compensate for the decreased secretion of pre-formed protein.

1. Meals were prepared from the seeds of fifteen varieties of cowpea (Vigna unguiculata), one of lima bean (Phaseolus lunatus) and one of yam bean (Sphenostylis stenocarpa), and their methionine content was determined by six different methods.

2. Total methionine content was determined by two chemical methods (ion-exchange chromatography and a colorimetric procedure) and by two microbiological methods. The ‘available’ methionine content was determined by microbiological assay with Streptococcus zymogenes.

3. All the different methods for total methionine determination gave similar results, with much the same high extent of precision.

4. The values for ‘available’ methionine content were similar to or marginally higher than the corresponding microbiological assay values for total methionine content. There was no indication that the methionine in any of the test samples was not completely available.

A system for collection and removal of urine has been developed, consisting of a peristaltic pump controlled by an electronic switch activated by the presence of urine in a funnel and in tubing. For optimum performance, it is necessary to clean parts at regular intervals.

1. Serum caeruloplasmin (ferroxidase I; EC 1.16.3.1) activity has been used as an indicator of copper status of cattle to survey beef herds in Northern Ireland.

2. The main survey covered some 20000 cows on 1200 farms.

3. The results are reported in the form of a map showing areas where herds of low and very-low Cu status predominate. Clinical signs of Cu deficiency in calves were encountered in only two areas.

1. The effect of oven-drying on the heat of combustion of rat carcasses was studied and found to produce losses of 10% of the original energy content. Oven-drying also produced a small loss of nitrogen.

2. A method of carcass preparation not involving oven-drying was tested and found to produce suitably homogeneous samples for analysis without any loss of energy.

1. A procedure is described for using pivalic acid as an inert reference substance in determination of changes in concentrations of volatile fatty acids (VFA).

2. Pivalic acid in concentrations of up to 80 mmol/l had no effect on production of methane or VFA by rumen contents.

3. Pivalic acid was inert during incubation with rumen contents from sheep given different diets and with samples taken at different times with respect to feeding.