Epoxiconazole causes changes in testicular histology and sperm production in the Japanese quail (Coturnix coturnix japonica)

The fungicide epoxiconazole (Epox), a triazole, belongs to the group of azole compounds that are extensively used as fungicides in various fruit crops. The frequent use of agricultural lands for wintering by migrating birds can be the source of their increased dietary intake of agricultural pesticides. We investigated whether exposure to Epox causes effects on avian fertility and reproduction, using the Japanese quail (Coturnix coturnix japonica) as a model species for the assessment of reproductive effects of pesticides in wild birds. Epox was administered to adult Japanese quail for three weeks at dietary levels of 10, 50, and 500 ppm, and possible effects on reproduction were investigated. Epox administration resulted in a significantly decreased number of spermatids in the 50- and 500-ppm dose groups. Histopathology showed a reduced number of testicular canaliculi with visible germ cells and a reduction in spermatid number. However, testis weight was not affected up to the highest dose level. No impact was observed on hormone levels, fertility, and reproductive outcome, as laying rate and percentage of fertile eggs were not altered. Likewise, treatment had no influence on the egg or chick parameters evaluated. A time- and dose-related transfer of Epox into the eggs was determined in all treatment groups. We conclude that dietary treatment of Japanese quail with 50 and 500 ppm of the triazole fungicide Epox resulted in a clear impact on the testis. The evaluation of the additional endpoints spermatid count and testicular histology have proven useful and are recommended for future studies on avian reproduction.

Effects of fentin hydroxide on reproduction of the Japanese quail (Coturnix coturnix japonica)

In a one-generation reproductive study, the fungicidal compound triphenyltin hydroxide (fentin) was administered to adult Japanese quail for 6 weeks at dietary levels of 3 and 30 ppm. Reproduction was significantly impaired in the high-dose group. The principal adverse finding was a marked increase in embryonic mortality, resulting in a lower hatch rate. Furthermore, a reduction in egg production was observed with ongoing duration of treatment. Most of the other reproduction-related parameters were not affected. The in ovo losses are assumed to result from a direct toxic effect of the test substance on chick embryos. At the low dietary level, reproduction was not altered. In contrast to the obvious reproductive toxicity, there was only limited evidence of adverse treatment-related findings in the adult birds. However, because such minor effects as an increase in mean liver weight, which was accompanied by macroscopic liver findings and a decrease in T4 serum concentration, were still seen at 3 ppm, a no-observed-effect level could not be established.

Effects of methyltestosterone on reproduction in the Japanese quail (Coturnix coturnix japonica)

Although the hormone-mediated effects of the synthetic androgenic hormone methyltestosterone (MT) are well characterized in mammals, little is known about endocrine and other toxic effects on reproduction in birds. In a one-generation study, MT was administered to adult Japanese quail (12 pairs per group) at dietary dose levels of 0, 10, 50, and 110 ppm for a period of 3 weeks. Reproductive performance was severely affected in the groups receiving 50 and 110 ppm MT. In females, the egg-laying rate was reduced not only related to the dose administered but also to the duration of treatment. The administration of 110 ppm, and to a lesser extent, of 50 ppm MT resulted in an immediate and dramatic decrease in the total number of eggs laid, which complicated reliable assessment of other reproduction-related parameters. In males, the findings suggested inhibition of spermatogenesis at dose levels of 50 ppm and above, resulting in a subsequent reduction in male fertility.

Effects of vinclozolin on spermatogenesis and reproductive success in the Japanese quail (Coturnix coturnix japonica)

In a one-generation reproduction study, the major agricultural fungicide vinclozolin was administered to adult Japanese quail for a period of 6 weeks at dietary levels of 125 and 500 ppm. Fertility and reproductive performance were not affected up to the highest concentration, although the examination of additional endpoints in the drakes (spermatid count, histology of the testis) provided some evidence of an inhibition of spermatogenesis at both dietary concentrations. Likewise, there were no indications of systemic toxicity in the adult birds. Plasma hormone concentrations (estradiol, testosterone, progesterone, T3, and T4) showed a large interindividual variance but treatment-related differences between the groups could not be established. There were no clear-cut indications of antiandrogenic effects in quail, although a limited transfer of the test substance into the eggs was proven.