Real-time ultrasonic scanning of pregnant ewes has become popular, and offers many potential advantages in flocks lambing at 110-170%. This experiment was set up to quantify the beneficial effect on sheep performance that can be obtained, from correct late pregnancy feeding of outwintered, twin-bearing hill ewes.

A hill flock numbering 369 Scottish Blackface ewes in regular ages were pregnancy scanned in mid-February 1985 and 1986 (45-92 days post-conception). From the identified twin-bearing ewes, 102 ewes in 1985 and 166 ewes in 1986 were randomised into two groups in early March, six weeks before lambing was due to commence.