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A Vaccine For Boar Taint Coming Soon

Bernie Peet is president of Pork Chain Consulting Ltd. of Lacombe, Alberta, and editor of Western Hog Journal. His columns will run every second week in the Manitoba Co-operator.

An immunological method of eliminating boar taint through vaccination is moving closer to reality in North America, with the vaccine soon to be licensed in both the U. S. and Canada.

Pfizer Animal Health is calling the new product Improvest (although in most other countries it’s called Improvac). In the EU, where there is considerable pressure to eliminate castration, the vaccine has recently been licensed but is not used on any significant scale. Other countries, such as Australia and New Zealand, have been using it for several years.

At first glance, immunocastration seems to be a win-win for both producers and consumers.

“Surgical castration deprives the male pig of testicular steroids that naturally enhance growth rate, feed efficiency and lean tissue growth, and reduce fat content of pork compared with surgically castrated males or barrows,” says Dr. Eduardo Beltranena of Alberta Agriculture and Rural Development.

“(The vaccine) will minimize the incidence of boar taint in pork while allowing male pigs to express their potential for lean growth.”

Pork from immunocastrates has less fat than that of barrows and it is more consistent with that of gilts, he says.

“A review of 28 studies found that immunocastrates averaged 10.2 per cent less backfat than barrows,” notes Beltranena. “The equivalent of years of genetic selection for reduced backfat can be achieved with two injections four to eight weeks apart.”

As would be expected, this is associated with a higher percentage of carcass lean research shows that immunocastrates averaged 4.6 per cent higher lean than barrows, while loin eye area was 1.7 per cent larger. In addition, pork quality is similar to that of both gilts and castrates, says Beltranena.

“A review of 17 studies found no differences in objective pork quality measurements such as pH, drip loss, shear force, and col-our between immunocastrates and barrows,” he says. “From 15 studies, the sensory assessment of pork from immunocastrates was judged by panellists to be similar to pork from either barrows or gilts.”

Not only is carcass quality improved compared to barrows, but immunocastrates divert more feed into lean growth compared with barrows resulting in about eight per cent better feed efficiency. An additional benefit of this is a six per cent reduction in greenhouse gas emissions, Beltranena adds.

For the consumer, the welfare benefits of non-castration may be a good selling point.

“Korean and European consumers found immunization to control boar taint to be preferable on animal welfare grounds compared with physical castration as long as there was equivalent pork taste,” Beltranena says.

In countries such as the U. K. and Australia, where castration is not carried out, the big benefit for consumers is the elimination of boar taint in the meat. In most of the rest of the world, where castration of male pigs is routine, the enhanced carcass leanness of immunocastrates will be more attractive to consumers.

Despite these benefits, there are other factors that must be dealt with.

One is convincing consumers that the new product, and the meat of animals injected with it, is safe. “Consumer education will be important in gaining acceptance of this technology over time,” stresses Beltranena.

However, he points out, this product only triggers an immune response in treated pigs, not in humans consuming pork from treated pigs.

“It leaves no residues in meat, has zero withdrawal and is not active when given by mouth,” he notes. “This product is not a drug, hormone, animal product or genetically modified material of any kind.”

Another challenge is safe injection.

The need for two injections requires good handling facilities in the finishing barn.

“Proper handling when injecting hogs should be implemented to protect animals from injury,” he recommends. “The two vaccinations required also increase the chance of broken needles that need reporting as well as trimming of carcasses in the neck area.”

Worker safety will also be an issue, says Beltranena.

“A safety applicator is provided with the vaccine. However, technicians doing the injecting should wear gloves and leg protectors to prevent accidental self-injection.”

Perhaps the biggest challenge is to ensure that any boars that missed being vaccinated are identified in the barn as soon as possible and segregated.

“Barn personnel must receive training to identify missed males that display aggressive sexual behaviour like chasing, mounting attempts or penis exposure and those that have large testes with a reddened scrotum,” says Beltranena. “Receiving personnel at abattoirs should have similar training. Also, evisceration personnel and line inspectors should be able to distinguish intact boars from immunocastrates.”

While immunocastration offers many benefits, especially where consumers have welfare concerns about castration, clearly there will be some significant challenges ahead in implementation.

When the vaccine becomes available, producers and processors will have to work together to capture the advantages while minimizing the disadvantages, assuming that, overall, there are economic benefits in the pork supply chain.

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bernie peet

Peet on Pigs

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