1. Three series of nitrogen balance experiments were performed with growing rats to test the effect of amino acid imbalance on protein utilization. In Expt 1 egg protein was fed as a basal diet and supplemented with one amino acid at a time in the amounts originally found in egg protein. In Expt 2 the procedure was repeated with a barley diet, and in Expt 3 egg and potato proteins were fed together in various combinations.

2. Doubling the single amino acids, especially arginine, in an egg-protein diet reduced biological value (BV) markedly. Also the branched-chain and the basic amino acids reduced BV significantly. In the barley-based diets negative effects were also observed when the concentration of the single amino acid was doubled. However, it was assumed that the observed deleterious effects of amino acid excess were partly due to an exaggerated lysine deficiency in the barley protein when non-limiting amino acids were added.

3. The results with various combinations of egg and potato proteins showed that as potato protein was increased true protein digestibility decreased linearly, whereas BV decreased Curvilinearly. Maximum protein utilization was obtained with egg protein alone.

1. Sheep given ground and pelleted lucerne hay (Medicago sativa) ad lib. were infused intravenously with pentagastrin, secretin, cholecystokinin (CCK) and its analogues to assess their effects on motility of the reticulo-rumen and on food intake. In the latter experiments the animals were deprived of their diet for periods of up to 6 h to induce hunger and the infusions were made before and during 3–10 min periods of feeding.

2. Pentagastrin, an analogue of gastrin, depressed intake by 35–50% (P < 0.05) when it was infused at 9 μg/kg per h during 30 min of feeding. The threshold may however be below 1 μg/kg per h as this dose decreased intake of 12–17%. The frequency of reticular contractions decreased by 13, 35, 39 and 44% when 1, 3, 9 and 27 μg pentagastrin/kg per h respectively was infused (P > 0.025).

3. Secretin depressed food intake 38% after 30 min (P > 0.025) when 8 Clinical Units (CU)/kg per h was infused but the threshold could be less than this dose since 0.5 CU/kg per h depressed intake by 12%. Contraction amplitude but not frequency decreased at 8 CU/kg per h.

4. CCK produced a 39% decrease in intake during the first 10 min of feeding (P < 0.05) and the threshold was between 5 and 15 Ivy Dog Units (IDU) or 425 and 1276 pmol/kg per h. The frequency of reticular contractions was not affected by 1.7 IDU/kg per h but it was depressed 21 and 63% by 5 and 15 IDU/kg per h. Octapeptide at 1.5 and 3 μg (1312 and 2624 pmol)/kg per h depressed intake by 11 and 43% respectively after 10 min (not significant) and 1.5 μg/kg per h depressed motility by 39% (P < 0.01). Ceruletide at 810 ng (599 pmol)/kg per h depressed intake by 31% (not significant) after 10 min and decreased motility by 52% (P > 0.05). The threshold dose for ceruletide on intake appeared to be about 90 ng or 66 pmol/kg per h which is considerably less than that for CCK or octapeptide.

5. The biological significance of gastrointestinal hormones as signals of satiety in normal sheep is not known since doses of pentagastrin and CCK that suppressed intake also interfered quite markedly with motility. However there is good reason to suspect that elevated concentrations of gastrin and CCK in blood of parasitized sheep may account at least in part for their symptoms of rumen atony and reduced food intakes.

1. Distribution of copper and molybdenum was followed in the body tissues of sheep fed on high levels of Cu (82 mg Cu/sheep per d), sulphur (3·77 g S/sheep per d) and different levels of Mo (0·6 20·8, 38.4 and 58.5 mg Mo/sheep per d).

2. Liver Cu content decreased as Mo intake increased from 0.6 to 38.4 mg/d, but increased again at high intakes of Mo. With an Mo intake of 58.5 mg/d, the Cu content of liver, kidney, lung, spleen and muscle tissue was significantly higher than with an intake of 20.8 mg Mo/d. The trend of increased Cu concentrations in kidneys and plasma was already evident at an Mo intake of 38.4 mg/sheep per d.

3. High positive correlations were observed between Cu and Mo in both the kidney cortex and medulla of the sheep at the two highest Mo treatments.

4. At constant S intake, Mo concentrations in the tissues tended to increase in proportion to Mo intakes. No indication of any detrimental effect due to the accumulation of Mo in the tissues was observed.

5. It was suggested that in the presence of an abundance of Mo, Cu and S, compounds containing these minerals in metabolically unavailable forms accumulate in the body, first in the kidneys, but eventually also in the other tissues of the sheep.

1. Serum thymic hormone was assayed in genetically-obese (C57B1/6J ob/ob) mice and lean controls (+/+, +/−) of the same strain.

2. The thymic hormone activity was higher in the majority of the obese animals compared with non-obese mice.

3. The number of antibody-forming cells in the spleen expressed as a proportion of the total mononuclear cells was increased in the obese mice.

4. It is suggested that obesity is associated with significant changes in the thymic hormone levels which may alter the relative proportion of lymphocyte subsets and cell-mediated immunity.