There is a growing trend
towards on-farm gilt
Hannah Velten reports on
the experiences of one
Norfolk-based unit as it looks
forward to its first litter of
grandparent gilt-bred piglets
AT HIS job interview, Peter Byrd said he would stop bringing in gilt replacements at ADAS Terrington if he became pig unit manager, to preserve its high health status and reduce replacement costs.
Finally, after three years, 24 grandparent gilts are settled on-farm. "As a research-based pig unit, the herd health status is paramount," explains Mr Byrd.
The 240-sow herd is free from pig wasting diseases, but does have quite high levels of enzootic pneumonia, which sows are vaccinated against, and blue ear disease. "But hopefully now the herd is closed, disease will lose its grip," he adds.
Originally the unit was buying in groups of 12 gilts/month at 90 days old. But Mr Byrd changed this to 24 gilts every two months, allowing a seven week isolation period, instead of three weeks.
However, during June 2000, one group of weaner gilts came down with PDNS after three days in isolation and were slaughtered. Because the isolation house was now contaminated, Mr Byrd found a local arable farmer to take in gilts, which added to replacement costs.
After a change in breeding company supplier at the end of 2000, another close health call occurred and then the final straw – foot-and-mouth.
After F&M, the breeding company told Mr Byrd they could not guarantee a supply of disease-free gilts, so it was agreed the herd should be nucleus maintained.
Five months ago, 12 pure Landrace grandparent gilts went into isolation and 12 more arrived a month ago. Each gilt is EP vaccinated and is blue ear positive to fit in with the herd disease profile. "Because these gilts are valuable, we are able to justify the cost of vaccinating them against clostridial diseases," adds Mr Byrd.
Each batch contains six older and six younger gilts at 100kg and 80kg, respectively. "We decided on a wide age range within the group to avoid bringing in more batches.
"Because our dry sows are kept in groups of six, we are able to serve six gilts a month over four months, allowing us to slot them into the five month breeding cycle at the right age, when culls are removed." Oestrus is naturally synchronised to enable gilts to farrow together, he adds.
Nucleus gilts/sows are served with pure Landrace semen, so the unit should never have to bring in grandparent gilts again. The commercial sows are inseminated with dam-line Large White semen to produce F1 replacements.
Because grandparent sows are not managed separately from F1 production sows, its essential nucleus females are identifiable. "All production sows are double ear tagged with yellow tags and nucleus sows with blue tags."
To prevent muddles, which could lead to nucleus replacements being slaughtered as baconers, no female piglets are transferred onto nucleus litters and all nucleus females have a notch made in one ear tip. When older, nucleus replacement gilts will have a red tag inserted.
Rather than understocking weaner and grower pens, all nucleus females will stay within the existing management system. "They will not be molly-coddled, otherwise we will lose production. Hopefully, after exposure to unit diseases and housing types we will end up with well-adapted, strong breeding gilts.
"Groups of six will be selected from the bacon house at 70kg and put onto a gilt breeder ration for 4-8 weeks before service. Replacements will be selected based on growth rate, legs, teats and temperament."
Mr Byrd says the nucleus gilts have caused no problems and financially they provide a cheaper replacement option – an estimated £5000/year saving on bought-in gilts.
Under their contract, a grandparent gilt costs the same as a commercial F1 and now the only outlay is a royalty for semen used on each sow place. "We have no isolation costs. It is cheaper to feed nucleus female piglets to weaning than buy them in as weaners and our reject nucleus-bred females and boars outperform the other slaughter pigs." *
Left: The 24 grandparent gilts will provide replacements for the nucleus herd, dramatically reducing
the number of
Below: Because grandparent gilts will
be managed alongside
F1 production sows, tagging nucleus females is essential,
says Peter Byrd.
• Reduce imported disease.
• Tagging to prevent muddle.
• Justify costs of vaccination.