14 June 1996

Heavier sow cant cope with too much heat

SOWS that are over-condition are more prone to heat stress. "Heavier sows cannot dissipate heat as easily and their core temperature rises," says Suffolk-based vet John McKinnon. This causes oxygen tension which affects the embryo and increases the likelihood of abortion.

Mr McKinnon stresses that careful management of the boar is vital in summer. Semen quality drops due to the heat and the boar is also lethargic and less likely to mate.

"Aside from the effect of the heat, hormone changes occur as the daylength begins to shorten after mid summers day. This reduces the boars sperm count and AI should be used to sustain conception rates.

Replacement gilts

A higher proportion of replacement gilts should also be bought in between May and September to cover for the reduction in conception rates.

But Mr McKinnon warns that gilts, especially those reared indoors, are prone to sunburn.

"Sunburn causes inflammation, resulting in the production of prostaglandins which in turn can cause abortions. Wallows and shades will help to reduce the risk. But wallows work best when they are muddy with an emulsion-like consistency so that mud forms a protective coat against the sun after the animal has left the wallow," he adds.