MARKETS WANT LEANNESS
MARKET requirements and not the breeding companies are behind the drive for selection for leanness in gilts.
Production manager for pig breeders Cotswold Development Company Reg Joseph says, that unlike the rest of the world contracts on the UK market are driven by P2 measurements.
"Progeny are selected to produce P2s of 10.5mm at 95kg. But this conflicts with the need for gilts to have a P2 of at least 20mm. This fat is needed to provide sufficient fat cover for lactation to limit the nutritional impact on the gilt.
"The problems could be reduced by producers buying gilts at a younger age and encouraging the deposition of adequate fat reserves long before first service," says Mr Joseph.
He explains that though traditionally producers buy gilts in at about 105kg liveweight and 160 days old, to serve nine weeks later, it is possible to buy gilts at 32kg liveweight.
"Producers could then grow gilts to match requirements, and it is now possible to buy feed formulated for young breeding gilts. This has a high energy content at 13.4MJ/kg DE and a low protein level of 14% to restrict the gilts frame and put on fat.
"By feeding this diet as early as 30kg liveweight, the gilt will have time to accumulate fat reserves, and there will be an opportunity to control an excessive increase in body size and limit maintenance requirements.
He estimates that on farm the effect of a high energy diet could be to add 2mm to backfat.
But, he warns that encouraging fat deposition which is gained less efficiently than lean, adds cost to gilt production and must be taken into account. *