a1 International Center of Agricultural Research in the Dry Areas, PO Box 5466, Aleppo, Syria
Ninety Awassi ewes managed at different levels were used to study the effect of live weight mating on fertility over 3 years in semi-arid north-west Syria. During the 56-day pre-mating period fertile ewes had higher daily live-weight gains than infertile ewes (P < 0·01), frequency of oestrous cycles increased as live weight increased (P < 0·001) and fertile ewes tended to have more frequent oestruses than infertile ewes (P > 0·05). Ewe fertility was related (r = 0·87) to live weight at mating and twinning reached a maximum (four per 100 ewes lambing) in 51· to 56-kg ewes then decreased fP > 0·05). Maximum fertility can be expected in Awassi ewes weighing over 48 kg at mating in north-west Syria.
(Received December 03 1987)
(Accepted May 20 1988)