Sow lameness: a 'multi-cost disease' for producers
Thursday, December 5, 2013
It's both a welfare and an economic issue, say the experts. And it is underestimated, poorly measured and poorly controlled
by DON STONEMAN
Middlesex County producer Gerald Kodde didn't have a lot of time to spend at a sow lameness workshop in Stratford in October, but what he heard when he was there convinced him that he was on the right track with his own barn expansion.
The Kodde family farrows a modest 125 sows on their farm between Granton and London and finish the hogs as well. Some pork is marketed at the farm gate. Gerald is finishing an expansion to 180 sows this fall into a new building, and sow welfare in gestation groups is high on his mind. That welfare concern includes taking care of legs and feet. He may be at the forefront in more than one way.
Sow lameness is a bigger issue than many in the industry think, says Laurie Connor, head of animal science at the University of Manitoba. She describes lameness as both a welfare and an economic issue. Lameness leads to premature culling of otherwise productive sows.
John Deen, a University of Minnesota College of Veterinary Medicine professor and expert on swine welfare, agrees that the prevalence and cost of lameness is underestimated, not well-measured and not controlled. Lameness is "a multi-cost disease," Deen says. "It affects productivity; it also affects a replacement decision. It affects our labour availability and also the comfort of labour on the farm. When we did surveys of the major welfare concerns of workers on the farm, downer and lame sows came to the top."
Keeping productive sows in the barn longer is a cost saver for producers. Increasing the average parities per sow from 3.4 to 4.4 is estimated to be worth $23 million a year to the U.S. pork industry, Connor says, because of decreased costs relating to replacements. In a study in Ireland, 50 per cent of sows don't make it to the third parity. That's costly, she says. It takes several parities for a gilt to pay for herself before beginning to turn a profit for the producer.
Deen says lameness is neglected in swine industry science and production, as compared to the dairy industry for example. There's "a big book" on cow lameness written every other year by scientists and discussed at a conference but "we've never done that with sows," Deen says. He also wonders why, when welfare codes are reviewed, "50 per cent of the weighting on cow welfare is based on lameness, yet when we assessed sows it hardly showed up."
One reason may be that the economic cost of replacing cows is so high; there's a heifer available with only every other birthing. But the price is still high with pigs.
Another reason is that lameness is hard for producers to see. Considerably more lameness is observed when sows are watched via camera walking to the feeder, rather than when they are herded from gestation room to farrowing room and back. "There is a protective mechanism not to show lameness" when pigs feel they are threatened, Deen says.
Connor observes that on Prairie farms she surveyed, between eight and 15 per cent of sows culled were for lameness, and it is the second most important reason for culling after reproduction. But she wonders if this is accurate. "Maybe they aren't really being culled for reproductive performance. Maybe their lameness predisposed them to losing weight and body condition," Connor proposes. And if they aren't culled and instead are put down on the farm, the salvage value of sows is decreased. Keeping sows in failing health is also a welfare issue.
The Prairie Swine Centre has been in charge of a project on sow lameness, longevity and temperament, funded with levies charged on market hog sales. Those monies are used to leverage more research funding from other sources, including the Going Forward 2 fund from Agriculture and Agri-Food Canada, says Ontario hog finisher Stewart Cressman, vice-chair of Swine Innovation Porc. The research corporation is owned by the Canadian Pork Council.
Deen says this work has significantly increased the scientific knowledge about sow lameness in North America, but he expects considerably more will be published in the next couple of years.
Connor's most recent lameness research compared four systems of management for group-housed sows. The University of Manitoba has two systems for group-housed gestation sows: electronic feeders on conventional slats and also on straw bedding. There is a floor feeding group system in Guelph and also feeding sows in gestation stalls.
Lameness is a risk factor for productivity and longevity of sows, which are important "to ensure competitiveness" for both a particular operation and an industry, Connor says. She links lameness to temperament, nutrition in the sow and early reproductive management.
Lameness occurs partly because of management and also the nature of the pigs currently in barns.
The University of Manitoba study revealed the importance of flooring by comparing group-housed sows, in pens of 25-30, with half on conventional partially slatted floors (58-60 per cent solid floor). The other half were on straw. Management and genetics were identical. Substantially more sows became lame on the slats than on the straw-covered solid floor.
On the slatted flooring, 21 per cent of sows were culled for physical reasons; on the straw, just over seven per cent. "In the alternative floor barn, where there is a compressible material underfoot, sows were culled only for productive reasons." Connor called the lower rate "a voluntary cull." In a commercial setting, the slatted floor sows would be culled "because you had to" and possibly less productive sows might take their places.
A number of factors are at play when it comes to reducing lameness.
Genetic tendencies. Research shows "we have been inadvertently selecting for aggressive animals" in swine and also poultry, says Jennifer Brown, a scientist studying animal behaviour at the Prairie Swine Centre. Aggressive tendencies lead to problems when livestock is managed in groups.
On concrete-floor, electronic sow feeder systems, aggressive sows had higher injury scores, while more confident sows had better body condition scores during gestation. Brown says there are a number of hypotheses as to why that happens.
Selection of non-aggressive animals may change some outcomes for producers. Sows selected for calmness "often don't have the strong maternal behaviour we would have seen in the past," Connor says. Should animals be selected for a housing system or a housing system selected for the animal? "That is the million-dollar question."
Flooring. Certainly flooring has a tremendous impact, as does sanitation and cleanliness, Connor says. There is a correlation between body injuries and lameness on slatted floors. For example, sows are less likely to get a claw caught between slats oriented in the same direction as the pigs are walking towards feeders. Risk of harm increases when there is "an interaction," as Connor terms it, with another sow.
The nature of the floor surface is also important, she points out. Floors should not be so smooth that there is no traction, yet not so abrasive as to damage sows' feet, causing lesions and ultimately lameness. Lesions are an issue and can lead to lameness and even infections.
Low-cost conversions of fully slatted feeder barns to gestation use by simply adding electronic feeders isn't advisable because of the potential to injure sows, says Deen. In the Midwest, he estimates 70 per cent of loose gestation sow housing is in the form of retrofits on top of fully slatted barn floors. A few operators, he allows, have poured concrete to provide solid floor space.
Treatment and prevention. Recovery pens are necessary, Connor says. If lameness is detected early, a sow can be put on a surface with some "give" to it and the likelihood that she will recover increases. Simply putting a sow into a gestation stall on a concrete floor doesn't aid recovery much.
Mixing pens, where groups of sows are first mingled, are not used much in North America but are an option. Any strategy or pen planning that minimizes fighting will reduce lameness.
Feeding systems. Competitive and non-competitive feeding systems are linked to more or less injuries and lameness in sows.
"Floor feeding is considered to be one of the most competitive," Connor says. "Sows can move around and there can be some pretty strong negative interactions," she says.
By contrast, electronic sow feeding is a non-competitive system, as are the walk-in, lock-in systems such as those at the Prairie Swine Centre. While eating, the sow is protected. The placement of the electronic feeder is crucial, Connor says. If there is 180-degree access, sows "will jostle a bit, but there isn't a lot of fighting." More competitive than electronic feeders and less competitive than floor feeding are systems where there are shoulder barriers between the feeding pigs.
These systems can be problematic if the feed isn't dropped at a rate that keeps the fast-feeding animal eating, Connor says. A bully sow may jostle another out of the way to get at feed in the next space.
Cost of culling. Deen argues for measuring cull rates separately for young sows and older sows. There should be no reason to cull sows for reproductive reasons in the first two parities, he says.
Measuring pigs/sow/year might not be the best index of herd productivity when it comes to culling. Deen prefers the measurement of pigs/sow space/year, because if spaces are unused – because sows were culled prematurely – it will be revealed over time.
Measurement has the potential to increase returns, Deen says. As lameness is reduced in a herd, sow retention and gilt requirements become more stable. Facility utilization is a major benefit.
Relatively little research has been published on sow lameness, but that is changing this year, Deen says. "There will be more and more information on measurement, interventions and prevention."
For his part, Kodde decided to go with two-thirds solid, one-third slatted floors and floor feeding, after getting advice from the Ontario ministry of agriculture's Dr. Tim Blackwell, lead veterinarian for swine, Kathy Zurbrigg, who works with the animal health and welfare office of the chief veterinarian for the province, and also independent ag engineer Franklin Kains. "I largely adapted to what they suggested," Kodde says. He considered feeding stations but decided they weren't economical with a barn of that size. He plans to drop feed seven to eight times a day.
"I am curious to see how that works," Kodde says. "I can always change it" if too much feed falls off sows' backs into the slatted area. "The research they've done says the feed conversion is no different." He expects that sows will be pretty good "at licking the feed off each other's backs."
In terms of flooring, Kodde plans to cover slatted floors in specific areas with a thin layer of a hard epoxy coating, installed by Klijn Agri Coatings Ltd. of Lucan. "It is gritty and we hope it isn't too abrasive," Kodde says.
His operation does have slats, for convenient cleaning, Kodde says. He has pondered the question of which is more important for reducing lameness – exercise or the slats?
Exercise won't hurt and Kodde expects sows will get that in group housing, but he is taking that further. To enhance AI breeding rates, he plans to walk sows to the boar room, rather than vice versa. Stu Devries, general manager of Total Swine Genetics, advised him on how to set up a breeding area. Devries explains that, in nature, sows would come to the boar's lair for breeding. Boars do their best work of arousing sows when in their own pen.
Kodde says other producers might think he is crazy for doing this much extra work in taking the sows to the boars for breeding over several days. But he says, "come back in a year to see if I am still doing this."
Bred sows will stay for 35 days in gestation stalls, where they will lie on rubber-covered slats, and Kodde hopes to head off injuries there. He is the first pork producer customer in North America to install a rubber product from EasyFix Rubber Products North America, says sales representative Gaelan Minhinnick, based near Kirkton.
This product is already used extensively in dairy and beef barns. Minhinnick describes it as half an inch thick at the middle, with tapered slopes towards the edges. A clamping mechanism holds the sides down to the slats in the barn floor. Minhinnick estimates that this application will cost less than $7 a square foot installed.
Kodde is installing it in the rear two-thirds of sow stalls, so that the sow's rear legs and udders rest on it. He thinks the front edge will be far enough away from the sow's head that she won't be able to nose it loose.
The housing issue has forced producers to think, Kodde says. Hopefully there is a financial incentive to make changes. BP
Hoof trimming significantly reduces lesions, study finds
When Yolande Seddon, a post-doctoral fellow at the University of Saskatchewan's Prairie Swine Centre, supervised a study of the feet of nearly 3,500 sows in a 6,000-sow gestation stall Prairie operation, she says "we were shocked at how many (sows) we saw with an abnormal gait."
Of the sows examined, 85 per cent had heel overgrowth, 57 per cent had white line cracks and 33 per cent had hoof wall cracks. Ninety-three per cent of parity two and 97 per cent of parity three sows had hoof lesions, along with 39 per cent of gilts and 74 per cent of parity one sows. The high number of low parity sows with lesions raises concerns as to why lesions are developing so early in breeding sows' lives and leads to questions about the robustness of sows, the housing environment and the management program of the barn, Seddon says.
Seddon undertook a 200-sow hoof trimming study, using a $5,000 chute sold by Zinpro Corporation, believed to be the first one in Canada. The chute, which resembles a weigh scale, hydraulically raises the suspended sow so that a trained technician can sit on a stool and trim long dew claws and heel overgrowths. Early research found that restraining gestating sows in a chute at eight weeks of pregnancy was not detrimental to sow productivity. Hoof trimming significantly reduces the incidence of lesions, Seddon's group found.
Seddon describes the hoof-trimming study as work in progress and expects the hoof-trimming chute will be moved to the Prairie Swine Centre barns for use in more studies. In a large operation, Seddon thinks the chute would pay for itself quickly, based on reduced incidence of costly lameness.
Seddon reports that a comprehensive treatment program, a rubber stall mat throughout gestation, anti-inflammatory drugs at four and eight weeks, and a corrective hoof trim at eight weeks reduced the incidence of lameness. Moreover, the non-lame sows weaned six per cent more pigs than lame sows, A six per cent reduction in performance of lame sows, based on cost overheads spread over fewer piglets produced, was equivalent to a $5 loss per market hog sold from the lame sows. BP