Synchronisation of lambing with low doses of dexamethasone in Chios ewes--short communication.

The purpose of the present study was to investigate the feasibility of improving the synchronisation of lambing after oestrus synchronisation and artificial insemination (AI). To this end, low doses of dexamethasone 21-isonicotinate (DEX) alone or in combination with prostaglandin F2a (PG) were used in five treated groups (n = 20 each) and one control group (n = 136) of Chios ewes. On day 143 of pregnancy 1.5 mg DEX was given in Group 5, while on day 146 the following treatments were applied: 0.0375 mg PG in Groups 4 and 5, and 1, 1.5 and 2 mg of DEX in ewes of Groups 1, 2 and 3, respectively. The control ewes received no treatment. The 1.5 and 2 mg dose of DEX was more effective in synchronising labour as regards the treatment to lambing interval and the proportion of ewes that gave birth within 3 days. However, obstetrical manipulations were needed, and dead lambs were born when 2 mg DEX was used. It was concluded that lambing can be safely synchronised in Chios ewes with 1.5 mg DEX given on day 146, without affecting the viability of lambs and without parturition complications.