Hypogonadism is a major manifestation of zinc deficiency in both humans and animals. In this study, we try to elucidate the main role of zinc in regulating the testicular function. Ninety male weanling albino rats were divided into three groups: control, zinc-deficient (ZD), and zinc-supplemented (ZS) groups. Six rats from each group were sacrificed every two weeks over a total period of ten weeks. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone (T) were estimated by radioimmunoassay technique. Serum zinc concentrations were also determined. Data revealed that serum zinc concentrations were significantly low in ZD group compared to both control and ZS groups. Normal FSH and LH but low PRL and T levels were demonstrated in sera of ZD group compared to both control and ZS groups. We came to the following conclusions: zinc deficiency has no effect on the pituitary gonadotropin output. Zinc deficiency affects the testicular function either directly through its effect on the testicular steroidogenesis and/or indirectly through its effect on the pituitary synthesis and/or secretion of PRL.

Zinc deficiency affects the testicular tissues adversely. The testes of zinc-deficient rats showed variable degrees of degeneration compared to both control and zinc-supplemented ones. Initially, there was an early pronounced spermatic arrest followed by a series of degeneration of the cellular layers constituting the seminiferous tubules in the zinc-deficient rats. Degenerative changes were additionally demonstrated in the interstitial tissue cells of the zinc-deficient rats. These histopathological observations in testes of zinc-deficient rats run in parallel provide an additional support to our previous publications in which we recorded a significant reduction in both serum and testicular levels of testosterone in the same group of animals, since spermatogenesis in rodents appeared to depend primarily on testosterone level.

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A total of 128 samples of Egyptian buffalo meat were collected from animals differing in age, sex, season and cuts. Their samples were analysed for iron, zinc and copper contents. Statistical analysis of the data obtained shows, that zinc and copper differ significantly at 0.01 level in relation to cut variation. In case of female, they differ also at the same level in relation to season. Zinc differes significantly at 0.01 level seasonally and in male in relation to season. On the other hand copper differs significantly at 0.05 level for green season in relation to sex. Iron and copper show significant differences at 0.1 level due to sex and in dry season in relation to sex, respectively.

The effect of age, sex, season and cut on the phosphorus, calcium and magnesium contents of buffalo meat was studied in 128 samples. Statistical analysis for the data showed significant difference to 0.01 level for phosphorus in relation to sex and in dry season in relation to sex. There is also significant difference for both calcium and magnesium in relation to season and also in case of both male and female in relation to season. At 0.05 level, phosphorus shows a significant difference in green season in relation to sex and at 0.1 level in relation to season.