PART 1 OF 2
Hoof cracks are a common occurrence in all beef cattle across Western Canada. Often they don t cause a problem for the commercial beef herd, but in some cases they can cause lameness, and certainly for the purebred operator, it s not a good sign to be selling breeding stock with hoof cracks. Some measure of hoof tracks can be prevented through nutrition and management, and where warranted, severe cracks can be treated rather than culling the animal.
Chris Clark, associate professor of Large Animal Medicine, Western College of Veterinary Medicine (Saskatchewan) says many of the older beef cows on the Canadian Prairies are affected.
You can expect to find sand cracks on almost 25 per cent of older cows, says Clark. These cracks most commonly occur on the outside claw of the front foot, and the vast majority of these don t cause any signs of lameness or ill health.
In a research project to determine causes, he says dryness is probably the biggest factor. On the whole, I think cracks are mainly a consequence of raising cattle in certain environments, says Clark.
There are basically two types of cracks vertical (often called sand cracks) and horizontal. Paul Greenough, professor emeritus, Western College of Veterinary Medicine, Saskatoon, has studied hoof cracks, especially sand cracks (vertical fissures) for many years, examining feet of thousands of cattle.
He says sand cracks are more common in heavy cattle than in light cattle. Size of the foot in relation to weight of the animal possibly plays a role, but there are probably several causes and contributing factors. Dry feet become brittle.
Our Prairies in summer are quite dry, Greenough says. In sandy soils, the protective outer layer of the hoof wears off and moisture evaporates through the hoof wall.
There are no simple answers. Aberdeen Angus get very few cracks, in my experience, but when they do, unlike other breeds, the cracks are usually in heifers that are over fat. The weight of the animal pushes the foot down into the hoof and splits it from the top down.
In other cases cracks may be caused by different factors. A nutritional change or some type of stress causes the horn to stop growing for a period of time. There are always growth rings in the hoof, but some become deep horizontal grooves, says Greenough. A groove means something abnormal happened to that cow, such as retained placenta, or a difficult calving, or some other stress.
As the groove grows down the claw and reaches the middle portion, pressure of the toe (as weight is placed on it) tends to bend the claw. There s a bit of movement there, like the instep of your shoe. When that happens, the horn may split open at the groove, usually splitting downward from that groove, he says.
Some cracks move upward from that stress line/groove. But a deep horizontal groove may eventually split open and the part of the hoof wall farthest away from the coronary band becomes detached. These detached fragments are called thimbles, he says. This area becomes very, very painful. These thimbles need to be removed, or the cow will be in constant pain and won t walk. Then she won t eat.
In Saskatchewan actually from Manitoba clear across to Alberta there s a low level of copper in the soil, says Greenough. Copper deficiency can be a contributing factor in causing sand cracks because the hoof horn is not as strong. There can also be an associated zinc deficiency. Shortage of these two trace minerals can be part of the underlying problem.
In cattle, one sign of copper deficiency is a change in hair color. Black animals appear reddish. Dark-coloured animals get areas of light hair growing around the eyes. With acute zinc deficiency, we see a skin disease, parakeratosis, which causes hair to fall out, says Greenough. These deficiencies are area-specific. Some regions don t have these problems.
In most herds affected with horizontal hardship grooves in the feet, it s a result of some kind of nutritional stress such as the seasonal stress of switching between high and low fibre and high-and low-protein feeds.
In Saskatchewan we keep cattle confined in winter so they can be fed and watered and don t ruin the pasture, he says. By late fall, pasture fibre levels of mature plants are extremely high. The cow comes into a paddock and is fed hay or straw and concentrate, a diet high in fibre.
In spring, cattle are turned out to grass once it is green and growing. The lush grass has very low fibre content and very high protein content. Winter feed is low in protein and high in fibre, so when cattle go to green pasture there s a sudden change in both protein and fibre. This change causes a reaction in the feet. This creates a different rate of hoof growth.
Another change occurs if there s rain after a dry spell. Sometimes you get very green fall pasture from new regrowth, says Greenough. Some hoof grooves and cracks can be associated with this change and seasonal patterns.
Cattle producers should check soils in pastures to see whether copper and zinc levels are adequate. Water should be checked for mineral levels. In some regions, high levels of iron or sulphate in the water inhibit the uptake of certain trace elements including copper and zinc. A problem with hoof cracks may be specific to any given area depending upon climate, soil and multiple other factors, including how the stockman manages his farm and cattle. There s no one cause for hoof cracks, and overriding all of these factors is a genetic tendency.