|Clean, comfortable freestalls are key to preventing lameness.
While rations and clean, dry footing are critically important to hoof health, they are only the start to reducing and preventing lameness in confinement herds.
Cow comfort, particularly in the transition period and especially for heifers, is absolutely critical to lameness prevention, says Jan Shearer, a University of Florida veterinarian who is nationally known as an expert on bovine lameness.
It's elementary: The more time cows spend lying down, the less time they will spend standing on hard, often wet and sloppy concrete.
Important new research,
however, also suggests that the activation of certain enzymes within the cow's body can actually predispose her to lameness. Of particular concern: metalloproteinases and hoofase.
In animals suffering from laminitis, metalloproteinase enzymes break down suspensory system tissues within the hoof, resulting in sinking and rotation of the third phalanx bone (P3). The sinking and rotation of P3 leads to increased compression of under-lying tissues and the subsequent development of sole ulcers.
Studies from the United Kingdom indicate that metalloproteinases are not acting alone. A new enzyme called "hoofase” is also involved.
Hoofase has been observed in heifers suffering acute laminitis. But recent work found the highest levels of hoofase in pregnant heifers within two weeks of calving and persisting for as long as eight to 12 weeks after calving.
Hoofase not only degrades or damages tissues of the suspensory apparatus, but also has the ability to activate very destructive forms of metalloproteinase enzymes. In other words, the destructive outcome of laminitis does not require rumen acidosis as a precursor, but may be triggered instead by hoofase alone.
Breakdown of the suspensory system of P3 results in the repositioning of this bone downward within the claw capsule. This causes compression of the digital cushion and connective tissues of the corium (tissue that forms hoof horn). Damage to the digital cushion reduces its cushioning capacity, which leads to the formation of sole ulcers and lameness.
Heifers normally have less fat in their digital cushion to start with. So once it is compromised, the animal is at a much greater risk of developing future lameness problems.
"The loss of the digital cushion is permanent, and is replaced by scar tissue,” Shearer says. "Scar tissue doesn't create a very good cushion and may predispose to ulcers. Indeed, one might speculate that this could be one of the reasons some herds lose too many cows too early.”
The UK research
group also suggests that weakening of the hoof bone suspensory tissue may be the result of hormonal changes that normally occur around the time of calving.
The hormone relaxin is responsible for relaxation of the pelvic musculature, tendons and ligaments around the time of calving, and is thought to have a similar effect on the suspensory tissue of P3 as well.
Housing animals on soft surfaces during the transition period (from four weeks prior to calving through eight weeks after calving), may be sufficient to reduce or alleviate the potential for permanent damage to these tissues.
KEEP HER FEET UP
To minimize the effects of the physiological mechanisms of lameness, maximize cow comfort especially during the transition period, says University of Florida veterinarian Jan Shearer.
"Err on the side of keeping cows comfortable and lying in stalls,” he says. Also be sensitive to the amount of time cows are standing. Be especially aware of the time cows are in lockups and in the holding area.
Size groups and pens to ensure cows can move through the parlor in a reasonable amount of time. If possible, house fresh, first-calf heifers and older cows separately. If they're grouped together, the less dominant, more timid heifers spend more time in the holding area and more time standing rather than lying.
Be sure your heat stress strategies are in place and working. When cows are heat-stressed, they tend to stand and bunch more. That means they'll be on their feet more and standing on wet, sloppy concrete.
Recent research at Cornell University suggests that poor body condition may contribute to lameness rather than the other way around. Early results from this work indicate that thin cows have smaller, less effective digital cushions, which may predispose them to claw disease.
So try to maintain good body condition throughout lactation. Avoid dramatic swings in weight loss or gain that could influence the size of the digital cushion or encourage other metabolic disease disorders.
Hoof Anatomy, Care and Management in Livestock
Subacute Ruminal Acidosis in Dairy Cattle