Abstract
Spring postpartum reproductive performance was investigated in 19 Awassi and 15 Finn x Texel x Awassi (FTA) crossbred ewes, weaned at 2 months postpartum and simultaneously exposed to rams for a period of 48 days. The study was conducted in 1991/92 in the Bekaa Valley of Lebanon.
Postpartum FTA ewes tended to have higher fecundity and prolificacy than those of Awassi ewes. Forty percent of the FTA ewes conceived and gave birth to 1.3 lambs per lambing, while 31.4% of the Awassi ewes conceived and lambed (1.1 lambs per lambing). Lambing to lambing and ram introduction to lambing intervals were similar in both genotypes and confirmed that a sizeable proportion (30-40%) of Awassi ewes and their crosses may rebreed during spring postpartum anoestrus and lamb at c. 8 months interval. Furthermore, relative progesterone values revealed continuous ovarian activity in 16 % of Awassi ewes and 40 % of FTA ewes and confirmed estimates of conception in ewes. All ewes with continuous ovulation mated and lambed. Weekly estimates of milk production over a 2-month period, starting the second week of lactation, showed that daily milk yields were almost twice as much in Awassi as in FTA ewes (P < 0.01). These results indicate the potential for Awassi ewes and their crosses to be incorporated into frequent lambing systems. Reproductive efficiency in these ewes could be monitored efficiently by measuring progesterone at 2-weekly intervals.