Debunking pig production myths

Debunking pig production myths JSR researcher says science on feeding and animal welfare at odds with common beliefs. By Stuart Lumb Stuart Lumb is a UK-based freelancer writer. He can be reached at [email protected]. Scientists who enjoy the limelight are unfortunately guilty

Hog slaughter for April 2011 totaled 8.63 million head, down 5% from April 2010.
Hog slaughter for April 2011 totaled 8.63 million head, down 5% from April 2010.

Scientists who enjoy the limelight are unfortunately guilty at times of sensationalism and blowing findings up out of all proportion. That’s the view of Dr. Grant Walling, UK based JSR Genetics Director of Research and Genetics at the 20th annual JSR Technical Conference held at Nottingham University.

One example, Walling says, is Professor Richard Lacey of Leeds University who made dire predictions about bovine spongiform encephalopathy and Creutzfeldt-Jakob back in the 1990s

Likewise, are the alarming predictions about deaths in the United Kingdom from Avian Flu, which thankfully came to nought. More recently, the predictions about HIN1 Flu deaths have been grossly over exaggerated. In fact, quite a few people die from regular flu each winter, but that never seems to make the headlines.

Egypt panicked over H1N1 and slaughtered its entire swine herd. The hogs conveniently ate all the restaurant garbage. Now the streets of Cairo are overrun with a plague of rats, feasting on heaps of festering garbage, which pose a significant health risk along with the rats, Walling says.

Feed conversion myths 
And there are plenty of pig production myths. “Many think that animals that grow faster convert feed more efficiently, “added Walling. “ Not so, according to UK research. “FCR and LWG have been used as production indicators for years, but a better measure would be Kilos of Meat Sold per Ton of Feed (MTF). This encompasses mortality, feed wastage and killing out percentage.

JSR has set a target of 325 Kilos of meat/ton of feed. Another misconception, Walling says, is that when feed costs are high feeding cheaper rations will save money. JSR trials showed that a diet costing ÂŁ3.16/ton more saved 15p/kg liveweight gained, or ÂŁ1.50 per pig.

Defining animal welfare
 Animals that grow slower produce better quality meat. True or false?

False, slower growth equals tougher pork. Animal welfare is a big issue these days, Walling continues, however welfare judgements are very subjective. For example, “Freedom to express Normal Behavior” is highly subjective.

How is “Normal“ defined? Walling proposes using quantitative measures of stress, as low stress equals high welfare. These could be blood cortisol levels, muscle pH post slaughter or white blood cell counts. Muscle pH post slaughter is an ideal indicator of stress.

p H 6 at 24 hours post slaughter is indicative of long term stress , injury or disease.

One of JSR’s customers, Blythburgh Free Range Pigs, rears its pigs outdoors and markets the pork as Blythburgh Free Range Pork. They have recorded post slaughter pH levels and tests showed 5.6% incidence of PSE but 0% incidence of DFD and so have produced data which quantitatively confirms the high welfare status of their production system.

Outdoor production not always high welfare
 Walling says the public tends to associate outdoor pig production with high welfare, but in winter, sows try to walk across frozen paddocks, so there is a lot of slipping and sliding. This is hardly high welfare compared to sows housed inside, Walling says, the latter moving confidently around on level and even flooring. Also, Walling says, extensive and often organic systems produce expensive pork for a very small minority in a world where many are starving.

Intensive systems might be considered far less welfare friendly but are far more efficient in terms of meat production. Recent French research has shown that feeding blood plasma to weaner pigs improves immunocompetence.

However, while this may be the case, it is ill conceived given the previous experience the agricultural industry has had from such practices. Strong evidence is now available to suggest that a genetic solution would be far more appropriate, as immunity traits show reasonable heritability, with, for example, monocyte levels having a heritability of 0.59.

Boar taint
 Another thorny issue is that of boar taint, Walling says, where welfarists are “crossing swords” with producers and processors. Traditionally, pigs have been castrated to prevent taint, due to androstenone and skatole  in the meat.

In the mid 1990s the UK’s MLC (Meat and Livestock Commission) carried out extensive research on slaughtering uncastrated male pigs (entires) and using taste panels to assess meat quality. The outcome was that taint was not considered a problem as it was argued that fast growing genotypes reached slaughter weight before becoming sexually mature. Since then male pigs slaughtered in the UK have been left complete.

Welfarists in Europe are concerned about the pain and stress caused by castration and are pressing to have the practice banned, although countries producing heavy pigs at slaughter such as Italy claim non–castration is definitely not an option for its Parma ham producers. One option being used in Holland is to castrate piglets under anaesthetic using special portable equipment.

Some solutions to the boar taint issue are to modify diets, reduce the weight at slaughter or the use of mechanical and biological noses. JSR is going down the genetic route and in conjunction with the University of Guelph in Canada have identified sire lines which have less than 5% evidence of taint and anticipate having a solution within the next 12 months.

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