Sexual behaviour in ovariectomized cows treated with oestradiol benzoate and testosterone propionate

Sexual behaviour was not induced in ovariectomized cows by single doses of 100 or 250 micrograms oestradiol benzoate or by 3 injections of 50 micrograms oestradiol benzoate given at 12-h intervals. Treatment with 3 doses of 250 or 500 micrograms oestradiol benzoate at 12-h intervals produced plasma levels that were similar to those during pro-oestrus and oestrus in intact cows, and 11 of 12 treated animals showed oestrous behaviour. The higher dose resulted in a more pronounced response in 'mounting' and 'mounted' behaviour and a shorter interval to the onset of behavioural signs of oestrus. Oestrous behaviour was not observed in any ovariectomized cows treated with 1,2 or 20 mg testosterone propionate, doses that resulted in plasma levels comparable to those in intact pro-oestrous animals. Treatment with pharmacological doses of testosterone propionate resulted in transient mounting and interest in similarly treated females, but the results were inconsistent.