11 February 2000

Boars show more of a benefit at higher weight

PIG producers tempted to make more of their contract by producing heavier pigs should sort boars from gilts.

Increasing gilt slaughter weights from 90kg to 107kg leads to losses of £1.27 a pig compared with boars where there is a 40p advantage.

MLC pig technical manager, Pinder Gill, says: "The UK is still one of the few countries producing lighter carcasses of 69-70kg compared with the Continent, where carcasses are more than 80kg. This means our overhead costs/kg are higher."

But Dr Gill says a decline in feed conversion efficiency in gilts weighing more than 90kg means taking them to higher weights will cut margins.

"MLC studies show that feed conversion efficiency for gilts more than 90kg is 35% poorer than for boars. This leads to a reduction in net margin of £1.27 for gilts whereas for boars, margins are increased by £0.40." (see table.)

Gilt growth rates also slow from 779g a day up to 90kg to 776g a day at more than 90kg as they approach puberty. This can lead to tougher meat, he warns.

In herds with poor growth rates, boar taint may also be a problem when animals are taken to higher weights, says Dr Gill. "The industry average days to slaughter is 175 days which is disappointingly low.

"In units where growth rates are high, the risk of boar taint is low. But where growth rates are only 700g a day it may be a problem."n