The volume of cervical mucus produced in the ewe appears to be controlled by the circulating levels of oestrogen (Vickery & Bennett, 1968), and is greatest during pro-oestrus and oestrus (Grant, 1934). The volume produced is of the order of 20 ml (Restall, 1967) and in spayed ewes is a linear function of the quantity of exogenous oestrogen (Lindsay & Francis, 1968).
It seems, therefore, that the disturbance in the pattern of oestrogen production in the ewe in which oestrus is controlled with progestagen-impregnated sponges (Smith & Robinson, 1970) may be reflected in the production of cervical mucus and that this could account for the changed pattern of transport of spermatozoa following progestagen treatment (Quinlivan & Robinson, 1967, 1969).
Forty-five Merino ewes, aged 5 years, randomized into three progestagen-dose-level groups of fifteen ewes
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