title: The synchronization of oestrus and subsequent fertility in ewes following treatment with a synthetic prostaglandin analogue (ONO 453).
abstract: ONO 453, a synthetic analogue of prostaglandin F2alpha (PGF2alpha) is a potent luteolytic agent in cycling ewes when given as a single intramuscular injection. The drug was effective in doses of 2 mg when administered after day 3 of the oestrous cycle. It is well tolerated by ewes, producing no apparent signs of toxicity at 5 mg and only a mild transient increase in the respiratory rate at 10 mg. To synchronise oestrus two dosing regimens were examined; a single i.m. dose of 2 mg administered without reference to the day of the oestrous cycle, and 2 injections of 2 mg administered 7 days apart. With the first method 86.6 per cent of the ewes were in oestrus within 24-50 hours of treatment, with the second, 82 per cent were in oestrus within 30-54 hours. To test the fertility of the oestrus following ONO 453-induced luteolysis, both groups of ewes were run with fertile rams and 86 per cent and 70.8 per cent of those induced by the single or double injection respectively, conceived and lambed.
mesh_terms: D000818:Animals; D004971:Estrus / Q000187:drug effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D007273:Injections, Intramuscular; D011247:Pregnancy; D011460:Prostaglandins F / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D012756:Sheep
chemical_list: D011460:Prostaglandins F