Determination of the duration of oestrus, oestrus cycle and the optimal insemination time in the Karacabey Merino ewes

All animals were maintained before and during wark on normal rations; usually given in state farm. A total 150 ewes and 8 rams were used. Oestrus control was made using 40 aproned rams.

Oestrus cycle were cheked fourtimes with 6 hours intervals starting at 6 a.m.

150 ewes were divided in to three equal groups and insemination were performed cervically 3, 12 and 26 hours after onset of oestrus for the 1. st, 2. and 3 nd ewe groups respectively.

Oestrus durations varied from 6 to 40 hours averaging 30.09  0.56 hours; and oestrus cycle durations varied from 10 to 28 days averaging 17.6 days. Oestrus duration in 75 % of the ewes was found between 25-33.30 hours. The 81.4 % ewes oestrus cycles were fell between 16 to 18 days.

The none returne rates were found to be 72, 72 and 48 % for inseminations 3, 12 hours after the onset of oestrus. Keywords :