There are lots of ways to raise pigs and with proper management, nearly all of them can be productive and profitable. Because several packers have resolved to move away from individual gestation stalls, some producers are building new facilities with group housing for sows.
In a recent SowBridge presentation, Lee Johnston with the University of Minnesota discussed feeding and management of sows in pens. He says producers need to feed for biological changes in the sow in terms of her true nutritional needs.
"We might need to change our feeding management to address the new welfare needs of the sow," he says.
Studies Show Varied Results
Johnston tells of two studies conducted at the University of Minnesota. In the first, which was a large commercial farm, sows were mated in stalls, preg-checked, and then after 35 days moved to pens. Floor space was the same across the pens and no significant difference was seen in pigs born per litter.
In the second study, sows were mated in stalls and moved to pens one week later. After eight weeks, a second group of sows was mixed with the first. There was a slight depression in live-born litter size in the dynamic group.
According to Johnston, some studies say there might be depression in litter size, while others show no difference. A few studies show an increase in litter size with group housing (see article on page 34).
"With constant output, vitamin and mineral requirements really aren't going to change, but energy requirements might change. Not every group gestation system is going to be managed in the same way," says Johnston.
Stalled sows are generally housed in temperatures between 68 and 55 degrees F. "At 70 degrees, sows are in their thermal neutral zone. In other words, they're not exuding energy to stay warm or cold," notes Johnston. "At 67 degrees, and for every degree of coldness, it will require 6.9 me of calories per day; or 4.85 lbs. of feed per day to maintain herself. If you drop the temperature by 15 degrees, it requires 9 me of energy and the sow would require 6.4 lbs. of feed per day." In addition, sows use more energy in pens because of increased activity.
From an economist's perspective, Johnston says that on one hand, producers have energy savings because of sows" huddling, but on the other hand, they're using more energy with increased activity.
"Keep in mind sow body condition, performance and longevity to determine how to tweak the system," he says. "Producers will tell you to increase feed by 5-10 percent [in group housing] because of increased activity and potential increased wastage."
Every System is Different
When sows are put together, they're going to fight because they need to establish a social hierarchy. It can't be completely eliminated, but how do you control it for the sows" welfare and performance? Dr. Larry Colman, DVM in Broken Bow, Nebraska, works with several large units, some of which incorporate group housing.
"I went back to what they told us originally – the bigger the group the better they socialized together as long as you had the smaller nesting areas," he says. "We made the choice between dynamic or static groups and I consider dynamic groups are the best way to go for efficiency."
Coleman and the managers of the operation sort gilts away from second-litter sows because they aren't as accepting of each other. He recommends three separate groups, one with gilts, one with second and third parity females and another with older animals.
Coleman says they walk females around the pen and through the feed system and let them eat. At that point, they tend not to be as aggressive when they come into a pen. They don't turn the pen static until the first animals start moving into farrowing. At that point they can bring new animals into the pen.
"Animals in their third trimester don't seem interested in fighting," he says. "We load the group dynamic, turn it static and load it again at the end."
Some producers believe the larger the group, the better they work. With larger group, fighting is minimized because sows won't recognize another sow as their enemy because they will forget – you basically eliminate the "bully" sow or dominate sow at the feed system.
"You can minimize fighting because of the flow of the system," says Coleman.
Not "Business As Usual"
Group housing costs more because the footprint of the barn is larger for the same number of animals as compared to an individual sow system. For the most part, the comparison between crates or group housing is the square footage difference.
"There are going to be changes with the move to group pens," says Johnston. "The workers need to adapt just as the sows do and we need to take an animal-metric approach. Those of us who grew up with livestock have an intuitive sense that others may not have, and we need a consistent approach to animal care. The National Pork Board is developing guidelines for feeding sows in groups and those packets will be available soon."
Coleman had his doubts at the beginning: "When first mentioned that we were going to look at group housing, I was a reluctant participant. The feeding of the sows was the biggest issue for me and how you get adequate feed to each individual sow. I thought it would be difficult to improve on something that would be better than individual feeding of the sow in the crate," he recalls. "Electronic sow feeding (ESF) looked like it had the opportunity to even improve upon individual feeding. It answered my question about whether or not you could feed sows in a group setting."
In the next issue of PorkNetwork, we'll continue the discussion on group sow housing and the changes in management that are pivotal to its success.