How much intramuscular fat should your pigs have?

Monday, October 3, 2011

A national project is underway in order to determine the amount of intramuscular fat in Durocs and determine an Estimated Breeding Value. This, in turn, will help producers tailor the amount of fat or marbling to meet their customers' needs

by DON STONEMAN

On a swelteringly hot summer  morning, Mount Elgin breeder Simon VanDyk and his son David herd market weight Duroc pigs one at a time onto a scale for weighing and then into a crate where each animal has the full attention of Ontario Swine Improvement technician Chris Crump.

Crump takes 10 ultrasound images of each Duroc. One will be used to estimate backfat and another one is for loin depth. (Images are taken at the same locations on white pigs for the same reasons.) Another eight measurements are taken on the Durocs to determine the amount of intramuscular fat or marbling. Later, a computer program will count the grains of fat in the muscles in the live pigs. The average of the eight images will be used as the score for that animal.

It's all in aid of developing an Estimated Breeding Value for Durocs for meat quality. The VanDyks, with their 200-sow breeding herd, are taking part in Alliance Genetics Canada's national project to pinpoint breeding animals with a proclivity for producing meat with particular amounts of intramuscular fat. They produce purebred Duroc, Landrace and Yorkshire boars for AI studs such as Ontario Swine Improvement, for other farmers who prefer natural breeding, and both boars and gilts for export via Donaldson International.

The project is only in its second year, but breeders are already able to order semen from a high- or low-fat boar as part of the Estimated Breeding Value calculation. At some point, they will be able to order high – or low – intramuscular fat (IMF) gilts for their breeder barns.

The focus of the intramuscular fat selection program is the Duroc pig, the terminal breed of choice for pork producers in Canada. The project is scanning 6,000 Durocs to determine their intramuscular fat content. Geneticist Brian Sullivan, CEO of the Canadian Centre for Swine Improvement (CCSI), says early studies show that intramuscular fat content has a higher predictability rate, 60 or even 70 per cent, than does backfat, at only 50 per cent.

In this province, Ontario Swine Improvement (OSI) is testing pigs for the national project, run by the CCSI. Durocs are known to be higher in intramuscular fat and they are responsible for more of the meat production side. Yorkshire and Landrace selection is largely focused on maternal traits.

Dave Vandenbroek, OSI's general manager, says the project is part of developing Estimated Breeding Values for pigs. More marbling is generally desirable for domestic and Japanese markets. But Vandenbroek points out that it is a misconception that the IMF project, as it is known, is aimed only at increasing intramuscular fat, although "the fact that we can select for either side of the average is important," Vandenbroek says.

An intramuscular fat content of between 2.5 and three per cent is common in Ontario hogs. Some markets, however, want less and Vandenbroek cites Australia as an example. Australian consumers want very little intramuscular fat and a lighter-coloured pork meat. On the other end of the spectrum, Japanese consumers want much more intramuscular fat and darker meat. Three per cent IMF would be a good target for our domestic market, somewhat more than the current average, Vandenbroek says.

Sullivan adds that, domestically, makers of processed products, hams and deli meats, also want pigs with lower intramuscular fat. Restaurants, on the other hand, want higher intramuscular fat levels. "Consumer studies are pretty clear," Sullivan says. "They prefer higher levels on the plate." They just don't want to see fat before it is cooked.

Cooking quality is also an issue, says Mary Ann Binnie, manager of nutrition and food industry relations with the Canadian Pork Council (CPC). Consumers want lean meat, yet complain that it is dry after they cook it. "It is a quandary," she says.

Ultrasound testing
The beef industry has been selecting for intramuscular fat for nearly 10 years and has been grading beef in the meat case A, AA and AAA according to the amount of marbling. A factor for carcass marbling was introduced to the national swine improvement program in the last couple of years, says Sullivan.

So what took pork so long? Testing wasn't possible until ultrasound technology was adapted a few years ago to work on pigs, Sullivan responds. "Even three or four years ago, you couldn't do it." Pigs have a much lower level of marbling than do beef cattle, so it is much harder to evaluate, he says.

In pork, the differences between fat and lean meat are more difficult to distinguish than in beef, says OSI technician Chris Crump. When he began ultrasounding pigs in 2004, Crump, a former dairy farmer working under the name Agriculture Ultrasound, was mostly determining if sows were pregnant. The technology has advanced substantially since then. He has merged his company with OSI.

Crump measures backfat between the third and fourth rib. Loin size is measured at the same location. IMF is measured one rib forward at any angle to enhance the fat in the grain. The average of the eight measures is used for an Estimated Breeding Value calculation.

"The images today are very, very distinct. You can see the marbling and the grains of fat," Crump says. "The more graining, the more marbling in the animal itself."

The "numbers" Crump records on each pig are adjusted to an average 115 kilograms weight and the images are sent to the CCSI in Ottawa. At its laboratory at the Central Experimental Farm, a dedicated technician interprets the images to predict the amount of marbling when an animal is processed.

Evaluation at the CCSI lab "takes the bias out of the equation," Crump says. The interpreter "doesn't know where the images are coming from. They are all unbiased predictions and unbiased numbers."

"We take the average of the eight images at different locations. If we do 3,000 Durocs a year, that's 30,000 images (the interpreter) is looking at."

In addition, the project is looking at 20,000-25,000 images a year of white pigs' back fat and loin depth and loin muscle.

Jim Donaldson, owner of Donaldson International at Innerkip and president of the Canadian Swine Breeders Association, proudly recalls exporting Duroc pigs to Denmark in the 1980s. "Canada, genetically, has had a big influence on world swine genetics," he says. He believes it is no coincidence that Durocs are the terminal sire of choice in Denmark, Canada and the United States, the three largest pork exporters in the world.

High-energy feeding
Feeding is the next step in the swine improvement program and there are two feeding programs in progress, Sullivan says. The sires come from across Canada. Testing is in two locations, in Manitoba and in Quebec. The Manitoba test is in progress, while the breedings were just completed in July in Quebec, he says.

In this phase, 700 commercial hogs sired by two boars with either high or low breeding values for IMF groups of boars will be submitted to regular or high-energy feeding programs. This is done to study the respective effects of genetics and feeding on IMF levels and their potential interactions.

Pork quality will be measured on loin samples from each of the four combinations of genetics and feeding, and consumer panels will assess them.

"We are looking to demonstrate the use of genetics, along with tools to target different levels of intramuscular fat, and then follow that through to consumer taste panels to confirm that, if we do achieve the target levels, it makes a difference," Sullivan says.

Feeding companies are also interested in IMF testing. Ian Ross, president of Grand Valley Fortifiers, says intramuscular fat fits in with projects such as feeding for enhanced omega-3 fatty acid content, as it is found in the fat in muscle meats. "We've been looking at the impact of IMF feeding for a number of years," he says.

Grand Valley is a feed supplier to Loblaws' "Free From" President's Choice program. "We are part of the supply chain for that brand, so we are interested in further differentiating" the meat product, says Ross.

So where is meat quality going as far as intramuscular fat is concerned? "We've reached a limit to leanness in the pork industry," says Donaldson. "If we go any leaner, we are going to affect the taste. Consumers like beef with intramuscular fat, because it makes it tender and juicy and it adds flavour. Pork is the same way."

Back to the issue of what consumers say they want and what they prefer on their plate, there are questions that remain unanswered. "Do you reinstate intramuscular fat or teach them how to cook it properly?" asks CPC's Binnie. "Maybe it is a bit of both."

Industry initiatives
Binnie notes that there is no national strategy in place to solve this issue. There are niche markets for well-marbled meat, such as Berkshires. Certainly, more intramuscular fat would be a substitute for moisture enhancement in pork products. She says there are industry initiatives under way to establish different levels of intramuscular fat, as there is in the beef industry with single A, AA and AAA graded beef.

The beef industry has been served on the promotion side for many years by the Beef Information Centre (which was recently absorbed into a wider group serving the beef industry.)

The pork industry is still trying to develop a parallel group for its industry, tentatively known as Pork Marketing Canada. The program was being developed jointly by Ontario Pork and Alberta Pork, says Keith Robbins, director of communications and consumer marketing for Ontario Pork, but it didn't gain support beyond those two provinces.

Ontario Pork did some studies on the attributes of pork, Robbins says. Results were presented to several processors across Canada.

The program would likely focus best on food service industry, restaurants and caterers. A two-pronged approach would work best. Conventional pork, which is generally regarded as "extra lean," would be targeted to health-conscious consumers. The best taste experience would be with well-marbled pork.

The program needed to go national in order to get recognition and also to be eligible for federal funding.

"That all sort of came to a head" during the H1N1 crisis, says Robbins. The federal government couldn't put money towards Pork Marketing Canada "because it wasn't funded by the entire national industry. The project is now sitting in limbo, says Jacques Pommerleau, president of Canada Pork International. Each province is still funding its own generic activities, he says.

While the domestic market may be dithering on what sort of pigs it wants to buy for consumption here, Simon VanDyk is happily selling pigs to a stream of international buyers who visit the well-kept family farm in the fertile Oxford County countryside. BP