Lameness and claw horn lesions in lactating dairy cows may very well have started in the dry period, according to University of British Columbia Professor Nina von Keyserlingk.
“Sole ulcers that cause cows to go lame often do not become apparent until two to three months after they begin developing, due to the time it takes for the damaged horn tissue to present itself on the sole of the hoof,” von Keyserlingk said. “The dry period is a sensitive time for foot health. If damage to the hoof occurs around the time of calving, we frequently see sole hemorrhages or ulcers at about eight to 10 weeks after calving, just as cows are reaching peak lactation.”
Hormonal changes around the time of calving cause the suspensory tissue in cows’ feet to slacken. This can lead to a temporary weakness in how the pedal bone is supported within the hoof. Add to this the extra weight that pregnant cows and heifers are carrying, plus a highly competitive environment, and it is easy to see how the structural integrity of the hoof is at risk in the transition period. In one study, von Keyserlingk showed that dry cows that were diagnosed with either a sole ulcer or a severe hemorrhage at peak lactation stood 1.5 hours longer in the week before calving compared to cows that had healthy feet.
von Keyserlingk added that immunity levels in the dry and early fresh period also become suppressed, making cows more susceptible to infections, including in their vulnerable feet.
For cows that already are lame entering the dry period, the outlook is serious. “Lame cows are most susceptible to competition at the feed bunk and thus may have reduced dry-matter intake,” von Keyserlingk said. “This may in turn negatively affect the well-being and development of the calf. Reduced dry-matter intake in the dry period has also been associated with metritis and ketosis.”
Her recommendations for supporting dry-cow foot health include:
- Provide facilities for dry cows that promote lying and resting behavior. Good-quality pasture is ideal. If that is not possible, a well-bedded straw pack is desirable. Make sure that every cow has access to a dry comfortable lying area at all times. Do not overstock.
- Make sure that cows have easy access to feed. Do not overstock. Ideally dry cows should each have at least 30" of bunk space and feed twice a day through a head-lock barrier. Head-lock feed barriers will reduce competition at the feed bunk.
- Avoid obese cows, as over-conditioned dry cows have to support the excess weight with their feet and are prone to more calving problems.
- Reduce competition. Cows will fight for access to feed and water, which in turn can increase the risk of claw horn lesions, as they are particularly vulnerable to injuries in the time around calving.
- As cows freshen, transition to a higher-concentrate diet gradually. Even though cows are in negative energy balance, they need time to adjust to new diets.
“Managing your dry cows so that they are able to lie and stand comfortably and not have to compete for access to resources, including feed and water, is an important first step in preparing your cows for the lactation period,” von Keyserlingk said.