18 August 1995

Tupped ewes, less feed

EWES are more likely to hold to service if energy levels are reduced post-tupping.

This is because a high plane of nutrition suppresses progesterone levels, says Dr John Robinson, a reproductive physiologist with the Scottish Agricultural College.

"The level of progesterone in the blood stream rises three days after service. And it must remain strong to establish pregnancy and ensure a maximum lamb crop. But when ewes are fed well nearly 95% of that hormone is destroyed as blood flows rapidly through the liver clearing it from the system," he says.

He therefore advises producers to feed for maintenance only after service. "Normally nature takes care of the problem because grass values wane post tupping."

A typical 70kg lowland ewe requires 10MJ/kg to 11MJ/kg of energy a day to maintain itself, which is about 40% less than required at flushing. "It is easier for producers with synchronised lambing flocks to work the theory as they can move the flock off lush grass immediately post tupping," he says. "In other situations dont hold back a pile of grass for ewes after the rams have come out. Let them have it up to tupping."