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The effect of the systemic administration of zinc sulphate (4.5 mg. Zn per day) to rats on a normal dietary intake of zinc was studied with reference to the tensile strengths of healing skin and musculofascial wounds.In comparing control and zinc-treated groups, no significant differences in the tensile strengths of 4-day, 7-day, or 10-day wounds were demonstrated.A new method of testing the strength of anterior abdominal wall wounds by measuring increasing intra-abdominal pressure up to bursting point is described.Sutured incised wounds of the linea alba were of identical strength in control and zinc-treated animals after 4, 7, and 10 days.No toxic effects were observed with the dosage of zinc used.It is concluded that the administration of supplementary zinc has no effect on the healing of sutured, incised wounds in normal rats.

Ram lambs fed on a diet containing 2.4 p.p.m. zinc made poor growth, developed clinical signs of severe zinc deficiency, showed impaired testicular growth, and showed a complete cessation of spermatogenesis within a period of 20–24 weeks. Lambs fed on the same diet supplemented with zinc sulphate to provide total zinc levels of 17.4 and 32.4 p.p.m. had a higher feed intake, made significantly greater liveweight gains, and showed no signs of zinc deficiency. Testicular growth and sperm production were markedly improved by both the zinc supplements. No differences in liveweight gains or feed consumption between the two supplemented groups were observed but testicular growth and sperm production were highly significantly greater in the lambs receiving the larger zinc supplement. It was concluded that a dietary zinc intake of 17.4 p.p.m. is adequate for growth of ram lambs but is inadequate for normal testicular development and function. Lambs in which consumption of the diet containing 32.4 p.p.m. zinc was restricted to that of the zinc-deficient group showed no significant improvement in liveweight gains, but testicular development and sperm production were significantly greater than in the zinc-deficient lambs. Complete remission of all signs of zinc deficiency and full recovery of testicular size, structure, and function were achieved in a zinc repletion period lasting 20 weeks.

The effects of supplementation of the diets of 6- to 12-year-old children in a village near Shiraz in Iran with zinc plus iron or iron alone, together with the indispensable amino acids in the form of egg white protein, vitamins, minerals, and corn oil have been evaluated. Initially 48 of 59 children had zinc concentrations below the minimum found in well-nourished persons. Eight months of supplementation with zinc plus iron (20 mg daily of elemental zinc as carbonate and 20 mg ferrous iron as fumarate) failed to stimulate growth or bone development or to bring about an increase in plasma zinc concentrations. However, supplementation with iron in the above amount was associated with an acceleration of growth in height and weight. The persistence of low concentrations of zinc in plasma and the failure of supplemental zinc to stimulate growth are attributed to the poor availability of both dietary and supplemental zinc resulting from sequestering action of fiber and phytate present in large amounts in the unleavened whole meal bread consumed by villagers. In addition, the results suggest that simultaneous administration of iron and zinc supplements may impair utilization of the metals.

Pig performance was compared on wheat based diets supplemented by two levels of either meat and bone meal or fish meal plus skim milk powder. The dry matter digestibility and nitrogen retention on these diets were determined and the effect of adding zinc to diets containing meat and bone meal was examined. At the higher level, fish meal plus skim milk powder produced greater daily gains between 60-160 lb than the meat and bone meal, but feed conversion and carcase lean were not affected. At the lower level, fish meal plus skim milk powder produced leaner carcases and greater daily gains between 60-160 lb than the meat and bone meal supplement, but had no effect on feed conversion. Between 60-100 lb, feed conversion was affected by level but not by supplement, and the higher level of fish meal plus skim milk powder produced greater daily gains than all other diets. The higher levels of each supplement produced greater nitrogen retentions and leaner carcases than the lower levels. Dry matter digestibility was least on the higher level meat and bone meal. Zinc supplements had no effect on performance.