Advice on reducing sheep rejections at abattoir

Lamb producers should study their kill sheets to see where they may be losing out and how they can reduce future risk, so they maximise financial returns.

Whether it is a simple fix such as ensuring lambs are clean or a more complex health issue that needs addressing, the kill sheet can identify trends as well as flag anomalies.

See also: Practical advice on reducing lamb losses from joint ill

From lung and liver damage caused by parasites, to arthritic joints that stem from bacterial infections in the lambing shed, the effect of poor health is revealed in the abattoir.

Resulting losses range from trimming of affected areas to whole organs or entire carcasses being rejected.

Checks before loading lambs

As prey animals, sheep will avoid showing any sign of weakness (disease or injury) in a stressful environment such as an abattoir, says vet Charlotte Lazell of Hallmark Veterinary and Compliance Services.

But signs will be seen on farm – an animal that hangs back or doesn’t come up to feed, for example. They should be checked for any open wounds or signs of lameness before leaving the farm.

“Animals should be fit for transport, so they shouldn’t be lame. Any lameness will make it hard for the sheep to withstand transportation to the abattoir without getting knocked about,” she says. “And any animal dead on arrival goes straight in the bin.”

Charlotte is contracted to the Food Standards Agency to conduct ante-mortems (stunning and killing checks) and post-mortems in a Gloucestershire abattoir.

Every animal coming through the facility must be checked, and she will assess as many as 4,000 lambs a day. Post-mortems involve a red offal check – lung, liver (cut through) and heart (surface) – plus a visual inspection of green offal (stomach and intestinal parts).

© MAG/Judith Tooth

Liver contamination

She says that examining the liver can reveal extensive damage caused by Fasciola hepatica (liver fluke).

Even in a dry year, this parasite can be a risk, as the mud snail (the intermediate host in its life cycle) can thrive around high-traffic areas such as around a leaking water trough. Some farms will always have naturally wet areas that pose a higher risk.

As well as the health effects of fluke, which leads to lower carcass weights and poor conformation, entire livers from infected animals can be rejected.

At certain times of year, up to 50% can be condemned because of fluke damage, according to AHDB statistics.

Liver fluke © Charlotte Lazell

Contamination caused by canines

There is an increasing risk from pet dogs. Hard, white, modular scarring can indicate a parasitic infestation of dog tapeworms. Cysticercus temicolis, also known as sheep bladderworm, causes scarring in the liver, while Cysticercus ovis, sometimes called sheep measles, affects the heart muscle, diaphragm and skirt area.

Both worms rely on dogs (and foxes) to complete their lifecycle, and sheep become infected via dog faeces.

A rising population of pet dogs, and of feeding them raw meat, are risk factors. So too are dog walkers failing to pick up after their pets or letting them off the lead to defecate near sheep. And not all wormers cover dogs for tapeworm.

“Prevention is very important,” says Charlotte. “Keep stock away from footpaths if possible. Try to educate dog owners [using signage] on footpaths to keep dogs on leads and pick up poo.

“Remember to worm your own dogs, and ensure deadstock are picked up promptly: if you can stop the dog or fox eating the carcass, you’ll stop the life cycle.”

Lung damage

Dark spots on the usually soft, spongy, pink tissue of the lungs indicate lungworm. In sheep, this is commonly caused by Dictycaulus filaria worms.

“Unless a sheep is suffering from a very heavy infestation, there is not such an impact for the farmer – drenching is rarely economically viable – but we see it a lot,” she says.

Animals do not always show obvious symptoms – coughing, nasal discharge and ill thrift are the main ones, but only if they are badly affected – so the kill sheet can be the first alert the farmer gets about the issue. Infection spreads from sheep to sheep, so buying in stock is a risk, she adds.

If a sheep is coughing and in chronically poor condition, it may be suffering from pleurisy.

Caused by the same pathogens as pneumonia, pleurisy results in serious damage to the lungs, which then fail to come away cleanly from the carcass, slowing down the production line.

To reduce risk, Charlotte advises good ventilation during housing, correct stocking densities, vaccination and quarantining incoming stock.

Pleurisy © Charlotte Lazell

Swollen joints

Swollen hocks (also described as hock lesions) will also attract the attention of the abattoir vet and can indicate arthritis.

“This is a big welfare issue,” she says. “If there are multiple signs of arthritis, for example, in the shoulder, the whole carcass will go in the bin.”

The initial cause may be joint ill in the young lamb, she adds.

“So be very thorough and consistent with hygiene practices at lambing, dipping navels properly and cleaning and disinfecting lambing pens. Check for signs of lameness any time sheep are being handled, for example, at weaning or weighing.”

Hygiene and handling

Dirty sheep may be refused entry to the plant because they breach food safety and hygiene regulations, and slow down the production line. “Send in clean, dry animals, and dag or completely shear them,” Charlotte advises.

Lambs bruise easily, and bruising caused by rough handling or pulling the wool will require extensive trimming for aesthetic reasons, downgrading the carcass.

Injuries caused by nipping sheepdogs and poor lorry conditions (these can be improved by fitting non-slip floors and partitions) also result in contamination.

In addition, injection site lesions are very common, particularly in the neck, where abscesses are caused by dirty needles or poor injection technique. Even if the abscess has cleared up, it will leave scar tissue that will have to be trimmed out.

“All of these issues have an effect on the carcass to varying degrees, so use the kill report to make an action plan [to improve outcomes],” says Charlotte.

Charlotte Lazell was speaking at a recent AHDB event at Ashford livestock market, Kent