4 August 1995

Hot weather can melt profits if pigs cant keep their cool

By Jonathan Riley

OUTDOOR pig producers must keep pigs cool in hot weather or production levels will fall, says Tony Walker at ADAS Bury St Edmunds, Suffolk.

Pigs have little control over body temperature, as they cant sweat and are prone to sunburn.

"Once clinical heat stress occurs and pigs are panting to try to lose heat, production will have suffered already," says Mr Walker.

Clinical heat stress is uncommon and usually only occurs at temperatures of 30C (86F) and above. "But even below this hot weather will cause reductions in voluntary feed intakes," he says.

"In pregnant sows, reduced intakes restrict foetal growth, lowering birth weights and increasing piglet mortality, while dry sows show more conception losses and returns to service. Piglet mortality is higher because lactating sows produce less milk. And on units using uninsulated huts with no ventilation the sow may leave the hut to search for shade.

"But shade is important and must be provided in the form of netting and tarpaulins on poles or round bales. With lactating sows, in particular, it is best to shade the hut so that she stays in contact with her piglets."

Mr Walker says adequate levels of clean water are vital and will help maintain milk production. "On units that do not have mains water, troughs should be checked regularly and kept topped up so that pigs can reach the water level," he says.

Productivity is also reduced by the boars reluctance to mate and because excessive temperatures reduce sperm quality. "The risk of sunburn should not be overlooked because a sow with sunburn on her back will not stand to the boar and when the boar is sunburnt he will not mate. Producers using indoor strains of Landrace/Large White could consider using pigs bred from Duroc lines, which have tougher skin," says Mr Walker.

"The provision of muddy wallows will reduce sunburn, as the mud sticks to the pigs skin acting as a barrier to prevent sunburn." &#42