1. The effect of vitamin B12 on growth was studied in young male and female rats fed on diets sufficient (+B12) or deficient (−B12) in vitamin B12 containing 30% of the dietary energy as fat, either maize oil (CO) or triundecanoin (TUD).

2. Vitamin B12 deficiency severely depressed growth. After 6 weeks the weight gain of CO(−B12) rats was only 72% of that of CO(+B12) rats and the gain of TUD(−B12) rats was only 47% of TUD(+B12) rats.

3. After fasting 24 or 96 h TUD-fed rats, both + B12 and −B12, had greater glycogen reserves and higher plasma glucose levels than CO-fed rats.

4. It is concluded that vitamin B12 is required for the metabolism and utilization of both an odd-carbon-number medium-chain fat, TUD, and an even-C-number long-chain fat, CO, during growth in rats.

1. Within the limits of this study, neither maternal iron deficiency nor Fe-overload as measured at term appeared to affect the complement of Fe received by the foetus.

2. Infants feeding entirely on breast milk appeared to have normal Fe status 6 months postpartum regardless of the Fe status of the mother.

3. No relationship could be demonstrated between the Fe content of breast milk and the Fe status of the mother.

1. The distribution of radioactive iron in 59Fe-labelled rat muscle extract was determined using ge filtration. This showed that most (approximately 70%) of the radioactivity was associated with the heamatin compounds; myoglobin and haemoglobin.

2. Raw beef and freeze-dried rat muscle were digested in vitro, under simulated physiological conditions, and after centrifugation the supernatants fractionated by gel filtration. The soluble products were haematin Fe complexes of molecular weight above 10 000 and non-haematin Fe compounds of molecular weight below 6000, the major products being the non-haematin Fe complexes. The soluble compounds were also separated by dialysis and, in rat muscle, it was found that the low-molecular-weight non-haematin compounds accounted for more than 80% of the total soluble iron.

3. In vivo absorption studies with rats showed the Fe in a digested muscle dialysate to be more readily absorbed than that from an aqueous muscle extract which itself was more readily absorbed than the Fe from whole blood.

4. It may not, therefore, be the haemoproteins per se which are responsible for the high availability of Fe in meat, but rather the nature of their degradation products, formed by digestion within the meat environment.

1. Concentrations of copper, manganese, zinc, nickel, cadmium and lead were measured in samples of liver, kidney, brain, heart, lung, skeletal muscle and vertebral bone from forty foetuses of 22–43 weeks gestation.

2. Cu concentrations in the liver were up to 100 times those in other tissues, but only those in the brain showed a significant increase with gestational age.

3. Mn concentrations were similar in all tissues; the over-all range was 0.35–9.27 μg/g dry matter (dm).

4. Concentrations of Zn in the liver were much higher than in other tissues and decreased with gestational age, whereas levels in skeletal muscle increased.

5. In all tissues Ni concentrations were within the range 0.04–2.8 μg/g dm and levels in kidney and muscle decreased significantly with age.

6. Cd was detected in most of the tissue samples and concentrations were within the range 0.01–0.58μg/g dm.

7. Concentrations of Pb, where it was detected, varied from 0.1 to 2.4 μg/g dm in the soft tissues and from 0.4 to 4.3 μg/g dm in the bone samples.

1. The objective of this study was to determine whether the chemical and biochemical changes induced by muscle wasting caused by dietary protein restriction are different in various skeletal muscles.

2. Rats were fasted for 3 d and then fed on a 10 g protein/kg diet for 21 d. Thirteen muscles from the trunk, forelimb, and hind-limb regions were analysed for muscle weight, and the content of water, fat, cellular and extracellular protein, DNA and RNA. Results were compared to values for an ‘initial’ control group killed at the start of the experiment.

3. Weight loss was greatest in trunk muscles and least in the distal forelimb muscles. Water content decreased in most muscles, but increased in three forelimb muscles. A significant loss of lipid was found in the gastrocnemius, while the biceps brachii gained lipid. Changes in lipid content of the muscles did not form a distinctive pattern.

4. All muscles except the distal forelimb muscles lost a significant amount of cellular protein, while all muscles except the diaphragm gained extracellular protein.

5. DNA content was unchanged in all muscles. The value for cellular protein:DNA was significantly reduced in the rectus abdominis and the diaphragm. A significant loss of RNA was found in all muscles; the percentage change was greatest in trunk muscles and least in the distal forelimb muscles. The values for RNA:protein and RNA:DNA were significantly lower in all muscles except two distal forelimb muscles.

6. With the exception of the water and lipid content of the muscles, the directions of the changes in the experimental animals were the same for all muscles. The results suggested, however, that the magnitude of changes in certain chemical and biochemical indices of composition may depend to some extent on the anatomical location of the muscle: trunk muscles tended to show the greatest percentage change, while the distal forelimbs changed the least.

1. Sheep given constant feed were exposed to environments in which the oxygen concentration in air was either 200 or 150 ml/l. There were no differences in daily heat production, methane production, urinary energy or faecal energy losses measured over periods of 4 d.

2. When the sheep were fasted there were no differences in heat production to be ascribed to the O2 concentration in air. The thermic response to feed was unaffected by the O2 concentration in the air.

1. Iron absorption from ferrous citrate (monoferrous acid citrate, FeC6H6O7H2O) was studied in normal healthy male and female volunteers using ferrous citrate labelled with radioactive Fe and whole-body counting. Ferrous citrate was either given alone or with a rice-based meal.

2. Fe absorption from ferrous citrate was satisfactory and was comparable to that from ferrous sulphate.

3. Fortification of crude cooking salt with ferrous citrate was not satisfactory due to colour development on storage. Ferrous citrate can, however, serve as an effective Fe fortificant with sugar or wheat flour.