Effects of depilatory doses of epidermal growth factor on subsequent fertility, pregnancy rate and lambing performance in Merino ewes [sheep].
1994
Brown B.W. | Stockwell P.R. | Panaretto B.A.
Murine epidermal growth factor (mEGF) and genetically engineered methionine epidermal growth factor (met-EGF), were given at depilatory dose rates (120 microg mEGF per kg body weight (82 ewes) and 250 microg met-EGF per kg body weight (100 ewes) respectively, to Merino ewes. All ewes were joined for 6 weeks. The majority (97 percent) of 100 control ewes were in oestrus at expected times during the joining period, whilst significantly fewer ewes in the mEGF (75 percent) and the met-EGF (65 percent) treated groups exhibited oestrus at the expected time. The majority of the ewes that were delayed in onset of oestrus were at the mid to late luteal stages of the oestrous cycle at the time of EGF treatment. There was no material difference between the 3 groups in the number of ewes returning to service during the joining period, or in the number of empty ewes. The 3 groups were also similar in the proportions of ewes bearing single or twin lambs, in the overall lambing percentage and survival of lambs to weaning. No abnormalities were found in any of the lambs. It appears that an interval of 5 weeks between dosing and joining is sufficient time for EGF-treated ewes to resume normal cyclicity and fertility.
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