Yes, sow body condition really does matter

Editor's note: The following article was written by PORK Network Editor JoAnn Alumbaugh, and published in the

May issue of

PORK Network

Goldilocks wanted to find a chair, a bowl and a bed that were "just right," neither too big nor too small. That's the same mentality you need to have about the body condition scores (BCS) of your sows, because if they're too thin or too fat, you're not optimizing production.

"Thin and fat sows reduce profit," said Dr. Mark Knauer, swine extension specialist at North Carolina State University. "They'll have a reduced farrowing rate, they're less likely to breed back and they're more likely to have smaller litters. We need to take into consideration the animal welfare component too. Especially with the Pork Quality Assurance program, we want to make sure we don't have sows that are too thin."

Knauer shared research results to confirm his assertion on the importance of sow body condition in a recent SowBridge session. In one study, he compared BCS between two farms: Farm A exhibited sows that were mostly in the "ideal" category, meaning they had a caliper score between 12 and 15; Farm B's sows were overweight, falling primarily in the 16 to 20 range (see Figure 1).

Ironically, Farms A and B are from the same production system, said Knauer.

"They have the same facilities, the same genetics and receive feed from the same feed mill. The only difference between these two farms was the person adjusting the feed-drop boxes. Farm B sows are over-conditioned and this farm has higher feed costs and lower reproductive throughput," he said.

In Knauer's research, heavy sows wean fewer piglets. On the other hand, sows that are too thin are less likely to exhibit estrus and will have a reduced farrowing rate.

No Excuses
Knauer pointed out that producers have tools to help them monitor BCS, so there's really no excuse for having a majority of sows fall outside of the optimum range. One of the most effective methods for measuring body condition is with a sow caliper, which Knauer and his counterparts developed. The caliper is placed across the sow's back and should be within the 12 to 15 range (on the caliper scale).

The caliper is used in 14 countries and 18 states and allows producers to look at the angularity over the top of sows. Light-muscled and lean animals have an angular top, and as they put on weight they become much wider and flatter when viewed from the rear.

A-mode ultrasound is another method (such as the hand-held Renco Lean Meter, which measures backfat). Scales in the barn can be used to monitor BCS as well.

"Typically we don't see scales at sow farms, though I would recommend producers consider installing one in new facilities to capture body weight as sows go into and come out of lactation," Knauer said.

"We know any type of technology we incorporate to quantify body condition is going to require labor," Knauer said. "The caliper approach might take longer than a visual body condition score, but both are faster than the Renco machine."

According to his research, a visual appraisal takes 5 seconds, the sow caliper takes slightly more than 5 seconds, and the ultrasound method takes about 14 seconds. He noted, too, that the more often a person uses the caliper, the more adept they become at visually identifying sows that are too thin or too fat. For this reason, producers should consider using one person to spot-check BCS on a regular basis rather than assigning multiple people to the task.

Drain on Profitability
The bottom line is that when BCS is either too high or too low, you're losing money. The feed loss alone is sizeable. For example, reducing feed intake in gestation by just 4 oz. per day could save about $15 per sow per year. Research shows that fatter sows are more likely to have farrowing problems, reduced colostrum production and increased preweaning mortality.

"Given the increase in litter size over the years, the importance of colostrum yield, to make sure all the piglets have sufficient colostrum, is that much more important," Knauer said.

Heavier sows wean fewer piglets, too. Knauer found that a 100-lb. increase in sow weight reduced the number of weaned pigs by .74 piglets (primarily due to preweaning mortality).

"In fact, sow weight is a greater predictor of preweaning mortality than parity in multiparous sows," Knauer said. "We've found the same thing in all the studies we've done: heavier sows raise fewer pigs. When we put weight and parity into the same model, it's really sow weight that's driving preweaning mortality."

Thinner sows also have impaired production. Knauer said they will have a reduced farrowing rate and are less likely to exhibit estrus. Research by Schenkel, et al. found that thin parity 1 sows had smaller litters in parity 2. The "ideal" caliper score in relation to piglets weaned appears to fall between 13 and 15.

Focus on Prevention
The key to avoiding over conditioned sows is prevention, Knauer pointed out.

"Do not try to 'fix' BCS during gestation with modern diets, and don't bump-feed in late gestation. Based on research on average piglet birth weight, sows should not be fed less than 3.5 lbs./day during gestation or it may impair piglet birth weight," he said. "A one-pound decrease in daily feed intake (below 3.75 lbs.) reduced birth weight by .31 lbs. per piglet."

In one study, Knauer fed heavier sows on average less than 3 pounds throughout mid-gestation and their caliper score was virtually unchanged from day 35 to day 100.

He said, "Collectively this data suggests lowering a sow's BCS during gestation with modern corn-soy diets does not work. Hence "preventing" fat sows is key."

Maximize feed intake during lactation, he recommended. "Prepare the sow in late gestation and manage feed intake and lactation length based on a sow's BCS." Research on bump-feeding the last two weeks of gestation improved BCS by one-third of a score at weaning.

Consider weaning pigs earlier if a sow's BCS falls below the threshold (a caliper score of less than 8) and creep feed the piglets, he said, but keep in mind, weaning sows before 14 to 16 days into lactation may not allow the uterus ample time to repair for the next lactation.

"After weaning a thin sow, feed her ad libitum until she expresses estrus," Knauer said.

The caliper appears to be effective across genetic lines, parities and production systems, though Knauer said group housing offers unique challenges. He suggests producers focus on using the caliper at weaning, rather than trying to measure sows when they're in group gestation. He also reiterated his suggestion that scales be used as another way of monitoring BCS.

Each farm should find its "baseline," and make improvements from there by minimizing variation in BCS. Even small improvements will offer significant advantages both in productivity and profitability over time.