PIG HEALTH has long been a priority for the herd at Farmers Weekly’s Easton Lodge unit, with the herd moving to a high health status in 1989. But pigs still suffer with enzootic pneumonia (EP), and post-weaning multi-systemic wasting syndrome (PMWS) has hit hard in the past 18 months.

A partial depopulation would allow the breeding herd to be fed a medicated feedstuff to eliminate EP and, with rearing and finishing pigs off site, there would be a chance to clean down accommodation fully to limit the chances of reinfection, says farm manager John Lambkin.

“But the big question is can the cost be justified, particularly when, after a change of sire, rearing pig mortality has dropped to just 0.9% for the last 3000 pigs weaned.

“Previous mortality levels were running at about 1.1% up to 40kg and 7% in finishing pigs. Current pigs are growing at about 940g a day, so they must be withstanding the disease challenge pretty well. Renting extra accommodation to house weaned pigs off site would also add to production costs, so is this the right thing to do?”

This farm is in a different situation from the general scenario where partial depopulations are undertaken, says vet Iain Mortimer of Elanco Animal Health. “Most units considering partial depopulations are running at nearer 15-20% mortality. For these units partial depopulation is easy to justify.”

While mortality is extremely low, Easton Lodge pig manager David Neal reckons it could be at about 2.5% from weaning to finishing, with growth rates at about 900g a day in the finishing period.

Mr Neal believes partial depopulation would be beneficial, but questions the wisdom of trying to rear pigs on a separate site. “It may make more sense to sell these pigs as 7kg weaners and let someone else finish them.

“Weaner prices are relatively strong at the moment, so we could probably sell 7kg pigs for about £22 a head and we would be able to keep costs to a minimum, particularly if we are unable to find a suitable site locally.”

Selling 7kg weaners would allow savings of about £50 a sow in reduced staff costs, says Mr Neal. “We would start selling these 7kg weaners eight weeks before the start of the programme. In order to start the programme with empty rearing accommodation, we would need to start selling rearing pigs 12 weeks before the start of medication.”

But selling weaner pigs at 7kg would result in a poorer financial position than when pigs were reared off site in rented accommodation.

Rearing and finishing pigs off site would mean an increased income of more than £31,683 after two years, with costs paid back 18 months after the start, says Mr Mortimer. “But selling all pigs as 7kg weaners would mean a longer payback period and a reduced increase in income after two years.

“The payback period would extend to 22.5 months, while the increased income after two years would be lower at £14,271,” he says.

But the extra hassle of managing pigs on a separate site and the disease risk posed by staff coming back from any satellite rearing and finishing unit may make it worthwhile having a slightly longer payback period and lower improvement in income, reckons Mr Neal.

It is probably too late to consider a partial depopulation this year, says Mr Lambkin. “But it may be an option for next year, depending on how rearing and finishing pigs perform over the next 6-12 months.”

jonathan.long@rbi.co.uk