The focus in pork production is usually on groups of pigs rather than individuals. But, that line of thinking may need to change as animal-welfare issues continue to surge.

“The key is to look at each pig as an individual,” says Don Lay, research scientist for USDA’s Agricultural Research Service. “You can average nine pigs per litter, but the welfare can’t be measured by group production. If one pig is having problems, its welfare isn’t adequate.”

If you look at pig behavior from an evolutionary standpoint, there’s a mismatch between the animal and it’s environment, he contneds. “As pigs evolved, if they weren’t suited for the environment, they died.”

Enter gestation crates – the most hotly debated animal-welfare topic in the pork industry.

“Gestation crates are more difficult to defend than the farrowing crate,” says Lay. “A farrowing crate can save a piglet’s life because it helps prevent crushing, whereas a gestation crate doesn’t have a direct life-saving aspect.”

One defense of gestation crates is that they make it easier to feed, observe and treat sows, and there’s less aggression than with group housing. Still, group-housing alternatives, such as large-pen systems or hoop structures are making it harder to defend gestation crates. “Much of the issue is the public’s perception of gestation crates,” says Lay. But, that may ultimately be the deciding factor, not science, as to whether U.S. pork producers continue to use gestation crates.

One of Lay’s research colleagues, Jeremy Marchant-Forde, points to Europe’s gestation-crate ban, which will be completed by 2013.

“Coming from Europe, the evidence shows that welfare of most sows is compromised in confinement systems (gestation crates),” says Marchant-Forde.

Which begs the question, Why does the research need to be repeated?

The idea is that U.S. producers won’t accept the results done elsewhere; they need the research to be conducted under U.S. conditions. Marchant-Forde, agrees because a large production unit in Europe has about 1,000 sows, whereas U.S. units can have 10,000 sows and more.

“The limited research on this topic that’s coming out of the United States confirms that group-housing systems can work under U.S. commercial conditions and they can perform at least as well as crates,” says Marchant-Forde.

A research project conducted by Lay’s ARS colleagues shows no difference in production between gilts housed during their first pregnancy in crates versus small groups. These results only apply to the housing systems evaluated.

Results show that group-housed females had more scratches, cuts and wounds on their head, face and body than those housed in crates. Although some of the injuries were caused by aggression between animals, some may be the result of individuals stepping on each other or encountering sharp pen fittings.

The researchers also are studying the pig’s genetic makeup, and how that affects its basic needs. As Lay puts it, some of the pig’s habits are learned while others are instinctive. This causes welfare problems because if the pig has an instinct to do something, but the environment won’t let it that creates stress.

For example, pigs are grazers, which involves walking and moving around. Sows in crates can’t do that, so they bar bite or tongue suck. This shows there’s a conflict between what the body tells them to do and what they are able to do, says Lay.

Another problem with the inability to graze is that pigs lack roughage. Lay points to research that shows fine-ground diets contribute to stomach ulcers in sows. Research also shows that you can reduce ulcers by supplementing roughage.

Lay is interested in the high cull rates and mortality rates facing the U.S. sow herd. “When you view it from a nature perspective, a sow would probably live 10 to 15 years. We’re only getting them through two or three lactations.” Our systems are wearing them down, he contends.

“Pigs can learn to adapt. Even though some behaviors are instinctive, they don’t have to fill all of them to be satisfied,” says Lay.

He outlines welfare considerations for other pigs within the herd. Remember, you need to look at individual needs:

  • For piglets, crushing is huge problem. It’s not normal for a sow not to respond when its offspring are in distress. “When the piglet is screaming and the sow doesn’t respond, either the sow has learned not to respond or we’ve genetically selected animals that are bad mothers,” he says. Farrowing crates can help compensate for bad mothers.

    “We could do a lot as far as selecting for maternal behavior,” says Lay. One idea is to select for non-aggressive sows that are responsive to their piglets.

    Providing the proper space and layout to keep piglets warm, but direct them away from the sow is critical. Also, attending farrowings is wise.

  • Tail docking, teeth clipping and ear notching: These practices are relatively easy to defend, says Lay. With ear notching, pigs likely feel little, because the ear is made up of cartilage. Teeth clipping is more of an issue, but it goes back to finding a balance between the sow’s welfare and that of her piglets’. Some evidence suggests that tail docking may be less painful when pigs are older than younger, so we may need to identify an optimum age.

    The gap between the public’s perception and knowledge is an issue. “The public tends to think we give pigs an anesthetic when we castrate them, but that’s not the case. It could become an issue if the public understood the actual practice,” says Lay. He believes we need to address chemical castration as an option.

  • Early weaning has become a big issue over the past five years. Piglets weaned at young ages tend to continue belly nosing (or navel sucking); it doesn’t go away as soon as it would if pigs were weaned later. This is an issue if pigs don’t have a way to escape from problem pigs. You need to watch for this and provide a solution.
  • Nursery to feeder pigs: This goes back to group dynamics, including group size, and access to food and water. Since there’s usually nothing for these pigs to chew on (a natural behavior), they chew on each other. That’s why it’s beneficial to ensure that pigs aren’t injured or sick, and hiding out in the back of the pen. Providing toys can help redirect their chewing tendencies.
  • Growing pigs: As the pigs grow larger, there’s still nothing for them to do in the pen, says Lay. Therefore, they tend to start tail biting and fighting. Too often there’s no way for a pig that’s being picked on to escape.  

    Typically, pigs in an open environment can choose where they want to go, and when a fight erupts the loser can move away or show submission. In crowded confinement situations, it’s difficult to escape. The dominant animal thinks the loser hasn’t submitted, so the fights continue. This causes a welfare problem because the pig keeps getting beat up.

  • Finishers: The same issues occur in the finisher, but there’s less fighting because pigs are getting bigger and lazier, says Lay. Also, clear social orders are established.

Certainly looking at your herd from an individual pig versus a group standpoint is a different mindset. But it may be necessary as a way to improve your animal-welfare practices and continue to ensure that the public develops a positive perception of pork production. 

Housing Type Effects on Gilts

Are pregnant gilts affected by their living conditions? That’s what USDA-ARS and Purdue University researchers wanted to find out. The scientists compared the effects on production and health of housing gilts throughout one pregnancy in either gestation crates or groups of four with individual feeding stalls.

Overall, the results indicate:

  • Housing had no effect on the amount of weight that the gilts maintained on individual gilt weight during gestation.
  • There was no difference in backfat measurements or skin health between the two gilts housed in crates or groups.
  • The majority of gilts, regardless of housing type, walked normally without limping or showing any signs of lameness.

The results show there was no difference in production between gilts housed during their first pregnancy in crates or small groups.