13 October 1995

Best feed for pregnant sows

MODERN hybrid sows fed a low protein diet during pregnancy have higher energy reserves for lactation, and produce piglets with heavier birth weights.

So said BOCM Pauls national pig adviser Dr John Boyd at a company conference held at the Institute of Animal Health, Compton, Berkshire.

He recommended a two feed system. A low protein ration from three weeks post-service to two weeks before farrowing and a high protein/energy diet fed during lactation to preserve critical fat reserves and sow condition.

"Modern hybrid females are capable of daily lean tissue gains of about 300g to 350g," said Dr Boyd.

"These sows have little or no fat to mobilise for milk production, and high protein diets will only encourage excess deposition of lean, leading to increased body size and higher maintenance requirements.

"The breeding female is also efficient at digesting protein during pregnancy and becomes increasingly so as pregnancy proceeds," he said.

Dr Boyd suggested that sow requirements for protein during the dry period were only 12%.

"In excess of this level protein cannot be used from the body and has to be excreted. A process costly in terms of energy.

"So low protein diets fed during pregnancy save on energy required to excrete the excess protein," he said

This could then be used to deposit extra fat in the carcass and increase the weight and energy reserves of the developing piglet giving a twofold benefit:

ncreased energy reserves for lactation, so extending the longevity of her reproductive life

&#8226 producing piglets with heavier birth weights and increased energy reserves, so that even those at the lower end of the liveweight range are more viable and better able to survive.

The high protein/high energy ration fed for the rest of the cycle then promoted milk yield and boosted fat content and quality of the milk.

"This will result in heavier weaning weights and minimise body weight loss, hence improving rebreeding performance," said Dr Boyd.

"Sows in good condition at weaning will also require less feed to restore and maintain condition during the dry period, improving feed intake in the following lactation." The benefits were cumulative and over a period of time would lead to more economic production, due to the lower feed intake and the energy saving from using a low protein diet during pregnancy.