A first-ever conference, which focused on sow lameness, served as a forum for changing attitudes and taking action to improve performance and animal welfare.

The latest chart from a USDA survey on swine health depicting sow lameness in the United States (Figure 1) indicates that lameness represents 15.2% of the reasons why pork producers cull sows.

“But our farm surveys today show the number of lame sows is far greater. Many sows culled for other reasons than lameness are also lame,” comments Mark Wilson, reproductive physiologist, Zinpro Performance Minerals at Zinpro's Feet First Symposium in Minneapolis.

Lame sows often go unrecognized and remain in the herd longer today because artificial insemination (AI) requires less structural soundness for breeding than the rigors of natural mating, says Wilson.

“Lameness is the biggest predictor of sow performance. The prevalence is quite high in sow barns,” says John Deen, DVM, University of Minnesota. He estimates that 80-90% of sows have some sort of claw lesions that are not being addressed.

These problems are ignored because of apathy, lack of education/training and a general reluctance to deal with them at the production level, Deen says.

Lameness is unmeasured and underestimated, says Deen, who adds that not all sows with lesions exhibit signs of lameness. That's partly due to the fact that lame sows have been shown to exhibit guarding behavior, says Deen. In other words, they may be experiencing painful or mechanical difficulties, but exhibit normal behavior to avoid detection.

Regardless, compromised sows will be challenged by a number of factors that affect their welfare: painful movement that exacerbates lameness the more they move, resulting in reduced feed intake; socialization issues; and poor reproductive behavior.

Increased levels of lameness add to staff workload in terms of treatment and euthanasia duties, extra time spent moving sows and picking replacement stock. Because treatment options are relatively few, frustration sets in, Deen says.

Minnesota Lameness Study

In a prospective study of sow lameness reported by Deen, 700 sows in a commercial herd in Minnesota were observed for one year. Sows were examined for lameness at entry into the farrowing crate, then researchers followed their productivity and longevity after weaning.

“The results were more marked than we expected,” he says. The 21% of sows identified as lame produced 0.02 less pigs/sow space/day and had an 18% greater likelihood of being removed, and these removals occurred much earlier. Also, these removals were more likely due to euthanasia or mortality.

The Minnesota research team estimated the economic impact of lameness at entry into the farrowing crate at about $180/sow. This figure is based on lower productivity, higher replacement costs and lower salvage values. It excludes the potential effects on preweaning mortality and the added pressures on the farm workers.

Claw Health

Prevention and early treatment of lameness and claw injuries are the best ways to help maintain feed consumption and appetite — and stave off early culling, Wilson notes.

Deen says their studies bear out the link between claw quality and lameness. Claw lesions are seen in 90% of cull sows.

Claw health needs to be improved and the following steps should be evaluated:

• Measurement methods are needed for proper evaluation and intervention success.

• Analgesia: the use of pain medications should be considered not only for the effects on the sows, but on subsequent productivity.

• The Value of Trace Minerals

  Nutrition: Lactating sows are in extreme need of optimum nutrition to perform and reduce lameness problems.

• Genotype: Conformational aspects need to be studied in more detail, particularly the relationship with specific claw lesions.

• Flooring obviously can exacerbate the expression of lameness and contribute to the development of lesions.

• Housing: Aggressive behavior appears to lead to more lesions and should be recognized as a factor in the development of lameness.

At the University of Minnesota Southern Research and Outreach Center at Waseca, Deen reports a much higher incidence of claw lesions have been observed in pens than in stalls. “It's going to be a challenge as we make the switch from stalls to pens,” he says.

A pyramid of factors (Figure 2), affect the development of lameness — not just one issue, Wilson expresses.

Economic Losses

It is suggested that zinc improves claw integrity. Wilson reports that several studies have shown that cows fed more available forms of zinc, manganese, copper and cobalt from Zinpro Performance Minerals led to reduced claw lesions and improved foot integrity, he says.

“Given the similarity in production environments and productivity expectations between cows and sows, it is logical that this response is likely for the sow also,” Wilson notes.

‘Feet First’ Symposium is Staged

In Denmark, there has been a dramatic increase in sow mortality over the last 15 years, reports Hans Aae, head of nutrition at Vitfoss in Denmark.

“The big reason is farmers are fined very heavily if they deliver lame sows to slaughter,” he says. “Sows are killed because 70% have locomotion or claw lesion problems.” Only 20% of sows reach the sixth parity.

Because there are restrictions on use of copper and zinc in the European Union, the option was to try trace minerals from Zinpro, says Aae. Combination organic performance minerals including copper, zinc and manganese were tested on two Danish hog farms. Today more than 100 farms are on this program. The use of trace minerals has cut sow mortality rates on these farms by more than half.

“I strongly believe that the use of organic trace minerals plays a role in improving sow longevity,” Aae says. “Producers face low hog prices in Denmark, but none of them have dropped this program.”