1. Studies were carried out in vitro to examine the effects of phytate on the solubility of the trace elements zinc, copper and manganese. Appropriate volumes of a solution of sodium phytate were added to a mineral solution to achieve phytate: Zn values of from 0: 1 to 45:1. In a second series the same values for phytate: Zn were achieved by varying the amount of added Zn at a fixed phytate concentration.

2. In both experiments > 85% of the Zn was rendered insoluble at pH 6.5 even at the lowest value for phytate:Zn (5:1). The effect of phytate on Zn solubility was greater than effects on Cu or Mn.

3. In a dietary study, rats were offered a semi-synthetic egg-albumin-based diet with added phytate. Two series of diets were prepared, the first had a constant Zn content (18.5 mg Zn/kg) and the amount of sodium phytate varied so as to achieve values for phytate: Zn of from 0:1 to 40:1 (series 1). In the second series, the same values for phytate:Zn were achieved by adding a fixed amount of phytate (7.4 g phytic acid/kg) while the amount of Zn was varied (series 2).

4. Dietary phytate caused significant reductions in growth rates, plasma Zn concentrations and hair Zn concentrations and greying of the coat at values for phytate:Zn of 15:1, 10:1, 10:1 and 15:1, respectively.

5. While phytate was apparently slightly more effective in reducing Zn status when phytate:Zn values were achieved at the lower absolute levels of phytate and Zn (series I diets), the differences at equivalent phytate:Zn values were small. It was concluded that phytate:Zn values can be used as an indicator of Zn availability from phytate-rich diets.

Rats offered three diets containing soya-bean-based textured-vegetable-protein (TVP) exhibited low rates of weight gain compared with rats offered an egg-albumen-based diet of similar Zn content (14.5 mg Zn/kg). Additional Zn supplied in drinking-water (25 mg Zn/l) was without effect on rats consuming the egg-albumin diet but significantly improved the weight gain of rats on the TVP diets.

7. It was concluded that phytate naturally present in TVP behaves similarly to phytate added to an otherwise phytate-free diet and that the reduced availability of Zn in TVP diets can be accounted for entirely by their phytate contents.

1. L-[U-14C]methionine was used to study methionine metabolism in sheep fed on untreated silage, silage treated with formaldehyde and untreated silage plus intraperitoneal infusion of L-methionine.

2. Over-all the values ranged from 0.43 to 0.86 mmol/h for methionine turnover rate, from 13.3 to 19.9 for the percentage of methionine oxidized to carbon dioxide and from 245 to 1089 μmol for methionine pool size.

1. Male and female rats with histories of up to twenty generations of protein malnutrition were found to be at a higher risk for the development of ulcerative dermatitis than rats maintained on a low-protein diet for one generation or in controls on an adequate-protein intake.

2. In all groups, female rats were more likely to have dermatitis than male rats.

3. Bacteriologic examination was performed in the intergenerationally malnourished and control animals; Staphylococcus aureus was isolated from the skins of animals in both groups, whether or not any lesion was present. In these two groups of animals, experimental inoculation with S. aureus produced dermatitis only in the malnourished animals.

The proportion of long-chain polyunsaturated derivatives of linoleic and linolenic acids in the erythrocyte lipids of infants fed a cow's milk formula was lower than in breast-fed infants. Although the formula provided only 0.55% of the total energy as linoleic acid, essential fatty acid deficiency was not detected; the triene:tetraene ratio was 0.09.

Total body water was determined in vivo by tritium dilution in thirty-two male and female rats. Body water obtained by tritium dilution and body fat calculated from this value correlated significantly with body water and fat obtained by analysis (r 0.985, 0.855 respectively). There was no significant difference between values for fat assessed by the direct and indirect methods.