During fall season, 18 multiparous Corriedale ewes were divided into two equal groups for the continuous (CON) and intermittent (INT) presence of a ram. Oestrus was synchronized with fluorgestone acetate intravaginal sponges (Chronogest) that were left 14 days, plus an injection of 200 micro g of a prostaglandin F-2 alpha analogue (Glandinex) at sponge removal. Oestrus was detected three times a day (at 06.00, 14.00 and 22.00 h) by using rams with harnessess and markers. Ovulation time was determined by laparoscopy, starting 24 h after oestrus detection. Oestrus onset was (mean+or-S.E.M.) 32.9+or-1.6 and 45.3+or-4.4 h for the CON and INT groups, respectively (P<0.01). Oestrus duration was 31.1+or-0.9 and 30.2+or-1.2 h, for the same groups, respectively (P>0.05). Ovulation time and the interval from sponge removal to ovulation (ISRO) for the CON and INT groups was 29.0+or-1.5, 62.0+or-2.0, 26.7+or-1.3 and 72.0+or-4.2 h, respectively. Ovulation time was not different (P>0.05), but ISRO was shown to be different between treatments (P<0.05). It is concluded that the continuous presence of a ram after sponge removal hastens oestrus onset and reduces the interval between sponge removal and ovulation, without modifying oestrus duration and time between oestrus onset and ovulation.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Large Animal Medicine & Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4475, USA.|
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