On the trail of a genetic solution to boar taint

Monday, October 6, 2014

This CCSI project to eliminate the need to castrate male pigs is scheduled to be finished just in time to meld with the European Union's eight-year long plan to end the practice. But some producers have their doubts

by DON STONEMAN

Later this fall, crossbred offspring of specially selected boars will be going into a test station feeder barn in Quebec.

It is part of a genetic program, funded by Agriculture and Agri-Food Canada through Growing Forward 2, as well as the ministry of agriculture in Quebec and industry, to produce commercial male pigs that don't have to be castrated before they are sold into meat markets.

The first group of commercial pigs was sired by Quebec boars. A second group, sired by Ontario boars, will be tested later. A third group was selected from genetics from Puratone/Fast Genetics on the Prairies. This program offers a genetic solution to boar taint, says Millbrook breeder Rod deWolde, chairman of both Ontario Swine Improvement and the Canadian Centre for Swine Improvement (CCSI).

Producers will be watching carefully. Commercial pork producer Jim Bloxsidge, among the largest in Ontario, is of two minds about eliminating castration.

"Wow, that would be a real plus," he said initially, when the program was described to him. There would be time saved in the farrowing room and he's heard that intact males grow faster than barrows. But, he adds, "It could be jumping out of one fire and into another one" because of problems with boars' sex drive. "It might take the taint away, but it sure doesn't take the drive away unless we are marketing 220-pound pigs, which I think is what they do in Europe."

Average shipping weights of hogs in North America have been climbing in recent years to meet packer demands and are now nearly 300 pounds. Intact males "start riding around on each other" when they get to 250 pounds. "Honestly," Bloxsidge says, after some moments of consideration, "I would like to leave (castration) the way it is."

Also expressing concerns is marketer Louis Roesch of Chatham-Kent, who sells pork from pigs he raises at his farm store. Customers "don't give a crap about castration," says Roesch, but a stinking pork chop on the stove is a turnoff. He fears a backlash if he sells boar-tainted pork to consumers. "They won't be back in my door again," Roesch says, adding that consumers are less forgiving of a small brand name store than a supermarket.

Meat quality in general is also an issue for Roesch, who is concerned that European genetics, which he considers less meaty, might be adopted. Some popular cuts such as ribs might be sacrificed to eliminate boar taint. So CCSI might find that selling no-castration boars to producers isn't easy, at least at first.

More optimistic is John Otten, swine production manager for Professional Pork Alliance, with 2,500 sows, farrow-to-finish, in a three-site system. Otten keeps five intact "teaser" boars in the sow barn to aid in heat detection. His eyes light up as he describes their "ballistic" growth compared to their castrated counterparts. Feed economy and growth potential has been given up because young males are castrated to eliminate boar taint, he allows.

Genetic markers
The CCSI project is about putting high technological molecular genetic techniques to work. CCSI screened 459 Duroc boars from Canadian breeders for genetic markers that indicate a propensity to produce the chemicals responsible for boar taint. Androstenone is produced by bacteria in the guts of male pigs, skatole in the testes. The presence of either chemical can render meat unpalatable. The markers that indicate a propensity to produce these chemicals are on a number of genes in any given pig, says Brian Sullivan, CCSI's CEO.

A genetic marker in this case comes in the form of SNPs, the short form for Single Nucleotide Polymorphisms. An SNP is a single piece of information in the DNA of an animal. Each individual has a pair of nucleotides, one from each parent. They can be different and individuals can get different combinations of these nucleotides.

Sullivan says University of Guelph's Jim Squires, working with Mohsen Jafarikia, CCSI's genomic specialist, identified SNPs in and around genes that control the metabolism of the boar taint compound. As Sullivan explains it, there are two possibilities of the variation in the SNP. Pigs with one variation of the SNP may have higher levels of boar taint than pigs with the other variation. There are about 100 of these SNPs affecting taint in various genes across the genome (the genetic material of the pig.) A project funded by Ontario Swine Improvement and completed last year looked at how variable those were among the purebred population of Yorkshire Landrace and Duroc breeds and how good those SNPs were at explaining variability in boar taint levels.

Sullivan says the project found that, for each of the different SNP locations across the genome, the higher number of favourable SNPs that a pig has in terms of boar taint, the lower level of boar taint. A higher percentage of unfavourable SNPs had the highest boar taint levels. "The idea is you can test new pigs for these SNPs and see which ones they have. If they have favourable ones, they will predict that their boar taint levels will be lower," Sullivan explains.

A previous test of 3,000 boars had determined, via fat samples, that about 64 per cent of pigs did not contain detectable amounts of the chemicals causing taint. That leaves about one pig in three as a potential boar taint carrier. "One in three is too many," Sullivan says, but the high percentage of pigs not prone to taint indicates that it can be eliminated.

From those 459 Duroc boars from CCSI breeders, the 30 with the lowest genetic propensity for boar taint were selected, along with the 30 with the highest propensity. The selected boars, in turn, were used to inseminate sows whose offspring will be fed to market weight in the test barns in Quebec and Manitoba. (There was no test station available in Ontario as this test is being conducted.) A total of about 1,000 pigs will be tested in three groups, with about 350 hogs being fed in the first group, says CCSI geneticist Laurence Maignal.

Four test groups
The 1,000 hogs on test will be comprised of four groups: conventionally castrated barrows, intact males, immunocastrates (using the product Improvest), and gilts. The effect of feed on boar taint will be taken into account. The target slaughter weight will be 130 kilograms, in line with current market demands.

Maignal confirms that the testing will include monitoring of animal behaviour as well as assessment of injuries at the packing plant. The pigs in all of the groups will be treated in the same way, other than the pigs from Western Canada. Prairie pigs will get a barley-based diet, unlike the rations fed to pigs from Ontario and Quebec, Maignal says.

At the same time, CCSI is working with Maria DeRosa, associate professor of biochemistry at Carleton University in Ottawa, to develop a test for boar taint, says Sullivan. This test could be used on the packing plant floor to detect skatole and androstenone that did slip through.

"There is a lot happening around the world with this," says Sullivan, particularly in non-castration markets such as Europe and Australia. Most tests involve people smelling fat that has been cooked. "We would like something that doesn't depend upon people." BP

Europe moves to eliminate castration
The CCSI's boar taint genetic program is scheduled to be finished in 2017. There is a European plan, in the works since 2010, to eliminate castration by Jan. 1, 2018. Also, the newest rendition of the pig production code in Canada calls for producers to administer painkillers when baby pigs are castrated starting in 2019. "Castration of pigs is painful regardless of age," says the draft pig code, which was released last year. Not nearly all producers agree, but it's still pressure for producers to reconsider castration.

Terms of a Comprehensive Economic Trade Agreement (CETA) that might open up the continent to Canadian pork imports remain unreleased, but there have been reports leaked to credible media. "To our knowledge there is no chapter in CETA" that refers to animal welfare, says Martin Rice, executive director of the Canadian Pork Council. He adds: "There is a consumer market there. Buyers do have preferences. You have to be aware of buyer demands. I see this as more of a marketplace than a regulatory matter."

Brian Sullivan, CEO of the Canadian Centre for Swine Improvement, agrees. Ahead of regulations, some European retailers have required that meat come from non-castrated males. So there may be some markets there, Sullivan says. BP