Sexual behaviour of ewes with clover disease treated repeatedly with oestradiol benzoate or testosterone propionate after ovariectomy

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Abstract
Ovariectomized ewes, 14 with permanent clover disease infertility ([after grazing estrogenic clover pastures for several years] affected ewes) and 14 controls, were injected daily with 40 .mu.g estradiol benzoate for 12 days, and run with 2 rams fitted with marking crayons. The control ewes were mated sooner (P < 0.05) but both groups became refractory at a similar rate. In a 2nd experiment, 20 similar affected ewes and 19 controls were injected daily with 5 mg testosterone propionate for 31 days and observed daily for 50 min with rams. Affected ewes again were slower to show female behavior (P < 0.05) but faster (P < 0.05) to show aggression against the rams and other ewes. Over the 31 days, the incidence of female sexual behavior declined at a similar rate in affected and control ewes. When examined in individual pen tests with estrous ewes on day 28, affected ewes showed more male-like courting behavior than did controls (P < 0.05). The changes in behavior are too slight to account for the infertility but they do support the hypothesis that phytoestrogens can act on the ewe by some of the pathways of sexual differentiation, even after puberty.

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