REPRODUCTIVE-PERFORMANCE OF RASA-ARAGONESA EWES MATED ON LUCERNE (MEDICAGO-SATIVA CV ARAGON) PASTURES

Coumestrol and small amounts of isoflavones were present in lucerne (a lfalfa) but only traces were found in ryegrass (Lolium sp.) pastures. A mean of 27.1 mg coumestrol/d was consumed by the ewes on lucerne pas tures. Ovulation rate (1.5) of ewes flushed and mated on lucerne was s ignificantly depressed by 20% relative to ewes mated on ryegrass (1.7) . However, neither barrenness nor embryonic losses were significantly increased when ewes were fed on lucerne cv. Aragon. The results sugges ted adverse effects on ovulation rate of ewes grazing lucerne pastures prior to and during joining that could negatively affect lambing perf ormance.