標題: Lameness costs in sow reproductive performance [打印本頁] 作者: bonderic 時間: 2008-9-17 08:56 標題: Lameness costs in sow reproductive performance Can nutritional solutions slow the escalating problems of lameness in breeding herds?
Overgrown tissue and erosion are features of the most common type of claw damage found in sows. Photo by Zinpro Performance Minerals.
The impact of nutrition is one of the least-studied contributing factors to foot health. Recent estimates put the cost of lameness suffered by sows to be around US$180 per animal, a sobering figure and yet one that many consider to be on the conservative side. But no matter what the exact figure, more lame sows add up to lower sow performance and higher replacement costs, in addition to the obvious animal welfare issues and reduction in salvage values.
Those were the messages at the first sow lameness symposium organized by Zinpro Performance Minerals and held in April in Minneapolis, Minnesota, USA. Lameness takes a heavy toll on breeding herd economics, underscored each speaker at the conference. But those speakers also agreed that the subject has not been researched adequately to tell herd managers what they need to know about the control of feet problems. And perhaps even more of a wake-up call: few are aware that the industry is confronted by an international surge in such problems and that the economic consequences are escalating at shocking pace.
Growing global problemHans Aae, head of nutrition at Vitfoss in Denmark, discussed tests of mineral sources in feeds for Danish sows. He called bad claw quality a source of increased sow mortality as well as a cause of increased risk of shoulder wounds that could interfere with the marketing of culled animals. Bad claws also mean more work for attendants in moving affected sows and in applying antibiotic treatments to them, he told meeting participants. There may even be a depression in the milk yield of sows with poor feet.
Danish national data demonstrate a marked rise in sow mortality rates over the past two decades. In 1990, the level of sow losses nationally had been under 5 percent. By 1998, they were exceeding 10 percent and in 2007 they had reached 15 percent. When the causes were investigated, joint disorders came up as the number one culprit—responsible for 37 percent of all instances of lameness. Next place went to bone fractures, at 17 percent.
A closer look at breeding units in Europe and elsewhere have suggested that many sows cannot stand or walk properly because of injuries to the load-bearing zone of their heel on each foot. Symposium speakers agreed that in various countries, overgrown or eroded heels seem the most prevalent claw disorder. The presentations also referred repeatedly to reports that group or pen gestation systems are associated with more foot troubles than what is found in sows housed in individual stalls. Slatted floors represent another risk, according to researchers. Sows kept in stalls are seen to be more likely than others to suffer from cracks in the side-wall of the claw.
Calling lameness an under-studied disease, the speakers outlined recommendations for checking it at herd level as a way of monitoring foot health on a regular basis. The evaluation procedure would allocate a score to the condition of the claws with particular reference to the hind feet, therefore compiling a series of scores over time as a guide to any change that might be occurring and any response to methods tried for prevention or treatment.
Nutritional influenceOne scoring system was proposed specifically for application to sows in the farrowing house, as these would be easier to inspect while they rested rather than when walking around a pen. Doing hind-claw checks in lactation need not be time-consuming, the speakers pointed out. A two-person team should be capable of evaluating 100 sows per hour. Over a long enough period, it might be able to show whether feed adjustments have any effect. Nutrition is one of a whole host of influences on foot health in the sow, as the symposium underlined. It has also been one of the least investigated. Most of the links to nutrients described by research have involved deficiencies, with few studies done to establish whether there might be benefits from supplementing with extra minerals and vitamins over the basic requirement.
Among the minerals, the ones most often proposed as influencing the hardness of the claw material in sows are zinc, calcium, copper, selenium and manganese. The principal amino acids put forward for consideration are methionine and cystine. Then there are the vitamins, notably types A, D, E and biotin, making for quite a list. Remarkably enough, the only item on it that has received any real study in pigs so far is biotin. The rest are included anecdotally or by extension from more thorough work with cattle. But some new investigations have started to fill in the knowledge gap, not the least tests in Denmark that have reported almost a 50 percent drop in sow mortality in a target herd after changing its feed minerals to a mix of organic and inorganic sources.
Overgrown tissue and erosion are features of the most common type of claw damage found in sows. Photo by Zinpro Performance Minerals.