A note on the seasonal oestrous period in three breeds of Greek dairy sheep

Abstract

Fourteen adult ewes from each of three breeds, Karagouniko (K), Serres (S) and Chios (C), were maintained, barren, as a single flock at Diavata (latitude 40·5°N) for 2 years. Oestrus was checked twice daily by vasectomized rams for 17 months from April 1979. For K, S and C ewes, respectively, the mean dates of onset were 7 August (s.e. 6·5), 31 July (s.e. 8·2) and 28 July (s.e. 7·3) (P < 0-05) and the spread of first oestrus extended to 100, 94 and 95 days, respectively. Over all breeds, the dates of first oestrus ranged from 23 May to 19 September. Mean dates of last oestrus were 16 April (s.e. 8·5), 5 April (s.e. 9·5) and 20 May (s.e. 7·0) (P > 0·01) and the mean durations of the breeding period were 253 (s.e. 11·0), 247 (s.e. 12·2) and 301 (s.e. 10·2) days, respectively (P > 0·01). In the second season, the mean dates of first oestrus were 4 September (s.e. 2·4), 28 August (s.e. 5·1) and 25 July (s.e. 6·2), respectively (P < 0·01).