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TIME OF ONSET OF OESTRUS IN THE EWE

The time of onset of oestrus in relation to the time of day has received little attention in sheep. McKenzie & Terrill (1937) considered that the onset of oestrus in the ewe was not associated with any particular time of the day. Kelley (1937) thought that there was a tendency for ewes to come into oestrus more frequently during the day than at night. Hutchinson, O'Connor & Robertson (1964) found that during the months of October, November and early December a high proportion of animals (Welsh Mountain) were mated between 06.30 and 07.30 hours and this was attributed either to an increase in the activity of the ram or to an increased number of ewes coming on oestrus during this time.

As part of an experiment carried out during the period 12th October to 28th November it was necessary to maintain a flock of forty Cheviot (North country) ewes under