Numerous possible remedies are mentioned for tail-biting, but there cannot have been many occasions when the answer was electrical. Yet that is exactly what seems to have happened on a breeding unit in Denmark. Outbreaks of the biting behaviour in this herd have practically disappeared since the owner installed a protective barrier between his pigs and underground power lines.

The scene for this is the south of Denmark's Jutland peninsula, where Claus Petersen has a Specific Pathogen Free (SPF) enterprise of 220 sows producing gilts for breeding that are sold through the Danbred organisation. The farm itself has the health advantage of being about 2 kilometres away from the nearest other pigs. In addition to the fact that Denmark is credited with national Aujeszky-free status, the SPF label means the Petersen herd also enjoys freedom from pneumonia, dysentery, atrophic rhinitis, mange, worms and lice.

A routine of taking samples from random batches of 10 pigs each month tests for other disease agents such as Salmonella. Claus has been even more fortunate in that his animals have escaped from the circovirus ravages of PMWS. As if to disprove the popular misconception that SPF pigs are completely disease-free, however, he reports that the herd has a niggling problem with coccidiosis which requires treating all the piglets with Baycox for the first 4 days of life.

Aid to health

The unit is quite unusual in that it is contained under one roof, which Mr Petersen considers a further health aid by reducing the risk of infection. He comments that the all-in-one design makes pig movements much easier, too, although it does also make the ventilation systems quite complex.

He employs 2 herd attendants for the 220 sows and progeny, which looks a generous level of staffing by modern standards until you remember the extra identification and recording involved on a unit that produces breeding stock. Piglets must be ear-notched on their first day of life; Danbred can carry out spot checks at any time.

Any sick pigs are specially marked using different coloured marker sticks, Claus reports. "We all know the system, so when we are on our own at weekends we can follow it easily to make sure of giving the right treatments." Other time-consuming jobs includes that selected gilts have their underline covered in sticking plaster. It is to protect their teats, he explains, by stopping these being sloughed off on the concrete floors.

His sows farrow on a weekly basis. Results from the 60 farrowing pens are impressive, especially when you consider that all the sows are purebred Yorkshires and the high generation turnover of a genetics unit is reflected in the herd's annual sow replacement rate of 75%. Latest records show a 12-month average of 14.2 piglets born alive per litter and 27 pigs born per sow and gilt per year.

Piglets are collected for routine processing on Day 4 and they will be weaned at 28 days old, a little earlier than the current Danish national average of 31 days. By weaning time they weigh 7.7kg each on average. Although this could appear a little low by some standards, when added to the output of 12.1 pigs weaned per litter it means each sow is weaning over 93kg of liveweight.


Partly slatted floors

After being graded by size, the weaned pigs are housed in nursery accommodation that is typical of Denmark by comprising half-slatted pens with a rear kennel and underfloor heating. Less usual is that this housing includes a pressurised ‘letter-box' ventilation system of directed air inlets, which Claus says work well in summer. He was also the first farmer to invest in a Domino milk feeding system for his weaners. This delivers gruel to the pigs at 6 pre-set times during the day, starting at 06:00 and ending at 21:00. Newly arrived piglets start on a mix of 20% dry feed with 80% warm water for the first 2 weeks before the mix is changed to 50/50 for the rest of the rearing period.

Gilts will go later to pre-selection pens, but the castrates and rejects are seeing a change in their handling regime at present. They used to be sold at 30kg for finishing in Germany, but since March it has become possible for Claus to finish these pigs himself up to 100kg liveweight. Having castrates to sell helped his income stream recently when an oedema problem prevented the sale of gilts for breeding.

Weaned sows move into individual stalls for mating. Danish producers are phasing out stalls in preparation for a partial ban due in 2013. While some have chosen ESF yards as their group housing method for pregnancy, Claus has opted for free-access feeding stalls on the basis of their relative simplicity. Each group gestation box houses 10 sows. They are fed individually, starting at around 2kg per day and increasing to 4kg for the last 3 weeks before farrowing. Their owner feels that they benefit from extra minerals and vitamins and so all his feeds contain 20% extra over and above the recommended levels.

Underground cables

But what of the electrical connection to tail-biting on his unit? He answers by explaining that there had been incidents of bitten tails until he paid attention to some large 3-phase power cables which run underground past his buildings. Aware of claims of electricity having adverse affects on human health and behaviour, such as when people live close to overhead power lines, he began to suspect there may have been some leakage of current from the underground cables.

Any leaks into the ground would have had more chance of reaching the pig-houses during a spell of wet weather, he reasoned, and indeed the outbreaks of tail-biting had been more noticeable when the outdoor climate was damp. His solution was a safety-first course of making sure that electricity leaking into the ground from the cables could not reach the animals. So he dug a ditch around his buildings and sank an underground metal fence into it as a screen between power lines and pigs.

"Since doing this, my pigs have been much calmer," he relates. "The tail-biting we had before has stopped. We have even seen a reduction in the number of stillbirths."

The claims are being taken seriously by Danish researchers. A university team from southern Denmark is monitoring the farm in the hope of determining whether a sub-surface charge from an electrical cable really could be why the pigs were biting tails. PIGI