Swine research at the University of Minnesota tackles animal welfare concerns

Mama pigs at the University of Minnesota have a somewhat cushy life compared to those in most conventional hog farms. The pregnant sows live together in small groups with straw bedding, unlike the traditional swine housing of individual stalls and slotted flooring above concrete manure pits, where sows have only enough room to stand up or lie down during their 114 days of gestation.

Studying group housing for pregnant sows is one of the ways that researchers at the U's West Central Research and Outreach Center are helping pork producers and processing companies respond to public pressure about animal welfare in the swine industry. Recent studies include housing options for pregnant sows, aggressive behavior of swine in confinement, and how different amounts of living space affect swine behavior, growth rates, stress and other factors.

"A lot of our effort has been to address societal concerns about pork production," said swine scientist and operations director Lee Johnston. "Those concerns are raised by consumers and market chains, and producers in turn are asking themselves and us how to respond to those market signals or satisfy those questions and demands."

Some questions are about animal welfare, he said, and some are about nutrition and feed additives.

Protests against confinement of pregnant sows and treatment of pigs are not new, but they were brought to the surface again two weeks ago when the international animal welfare group Mercy for Animals presented undercover video of what it called cruelty to pigs and sows by a Hormel supplier in Oklahoma, the Maschhoffs. Both Hormel and Maschhoffs said they have strict codes of conduct and policies related to animal care, and both launched investigations.

At the U's center near Morris in west-central Minnesota, Johnston and associate professor Yuzhi Li, an expert in swine behavior and welfare, have been on the forefront of animal welfare and nutrition issues for the swine industry.

The center has barns that accommodate about 60 breeding sows, 900 nursery pigs and 800 finishing pigs (those from about 50 pounds to full-grown market weight of about 280 pounds). The farm is nowhere near the size of some commercial operations, Johnston said, but it's large enough to conduct research that pork producers don't have the time, space, money or expertise to study on their own.

Yuzhi said there's a difference between how activists and scientists approach animal welfare concerns. For advocates, she said, animal welfare is primarily a moral value to be achieved, whereas scientists measure animals' performance, behavior and health.

"We want to assess and evaluate animal welfare objectively, even though it's a value issue," she said. "We want to be sure animal welfare is safeguarded based on science and knowledge, rather than just saying that animal welfare is bad or good."

Johnston said there are economic considerations as well, and sometimes a disconnect between living conditions that consumers want to see — lots of space for sows and pigs — and the reality of what producers can manage or afford.

"If we have a farm with 3,000 sows and we go to a pen configuration with 20 percent more space, all of a sudden you're down to 2,500 sows with pretty much the same cost structure as you had before," he said.

The farmer must either make less money on the smaller herd, he said, or spend more in construction costs to build an addition to the barn.

Sherrie Webb, director of swine welfare at the National Pork Board, said there are benefits and drawbacks to both individual stalls and group housing. Individual stalls allow each sow to get the exact amount of nutrition that she needs, and the animals can be monitored more closely for health problems. But group pens allow more freedom of movement and the ability to interact socially with other sows.

"Most of the time that's positive, but pigs do have to establish social hierarchy and groups," Webb said, "and it sometimes results in aggressive behaviors that can be detrimental to their well-being and cause injuries."

That's something that Yuzhi has studied in Minnesota: whether there may be ways to reduce aggression by mixing the same or different ages of sows in group housing, or changing the manner or time that they are introduced to each other and providing "escape" places in the pens where less aggressive sows can avoid fights.

Webb said that research in Minnesota, which produces more pork than any other state except Iowa and North Carolina, is key as the industry tries to accommodate consumer demands for changes.

Nine states, not including Minnesota, have regulations that require group housing for sows, she said. There are no published data on how much of the national pork industry has switched to group housing for sows, Webb said, but it's clear that animal welfare is a growing research interest, whether it be in livestock production, companion animals or laboratory animals.

One study tested piglets to determine whether the traditional practice of keeping temperatures constantly at 86 degrees in pig nurseries could be dropped 10 degrees at night. Scientists found that cycling temperatures made no difference in growth rates, health or behavior of the animals, and could save producers 20 to 30 percent of heating and electric bills.

One of the largest studies focuses on floor space for pigs as they grow to market weight. Commercial operations typically provide about 8 square feet per pig, Johnston said.

Minnesota and four other universities are now analyzing results of identical studies to see what happens when hogs are raised in five different floor plans with space ranging from 7.6 to 11.6 square feet. The diet, number of pen mates and feeder spaces were all the same, Johnston said, so the only difference was the amount of space per pig.

"We measured growth rate, feed intake, and efficiency of gain," he said, as well as lesions on pigs because of fighting or injury. The researchers also placed cotton ropes in the pens, which curious pigs will chew on, to collect and analyze saliva and hormones that indicate stress levels.

The goal, Johnston said, is to provide data so that producers can choose the best floor space allowance for animals to do well, while still being economical.

"If the objective is that pigs should not be raised for food at all, then it's hard to find common ground," she said. "But if the objective is to achieve good welfare and look for ways to continuously improve how we raise pigs, then we may be able to bridge that gap and address some of those concerns."