While summer is one of the more pleasant times to look forward to after a rough winter and wet spring, it requires a bit of annual thought to protect the production level the dairy farm seeks to achieve. Weather variability, too, can provide challenges that influence foot health of dairy cattle.
There are three elements of weather variability.
The wet, cool summer
As cows like cool weather, this is a challenge more to the producer in order to get forage off in decent shape. Temperature ranges from 64ºF to 75ºF with humidity ranging from 0 to 70 percent. One thing that needs to be constantly monitored is the moisture content of feed, especially when using TMR.
You will know you are in trouble when the cows clean up the bunk too early. The problem is: The weight of haylage due to excess moisture is not giving enough dry matter in the ration, but the grains are true to weight and moisture. This provides overloading of grain and can induce a bout of acidosis due to the fall of the pH level in the rumen.
If the weather is so wet cattle on a dirt yard or lane gateways allow mud to accumulate, the horn and sole of the claw can become soft, allowing fine material to enter the white line between the sole and the surrounding wall. When trimming, you need to recognize the soles will be much softer, and as such, care must be taken not to remove too much sole.
The moderate summer
Moderate temperatures and humidity allow the dairy to get forage off of the fields in good condition; thus, the effects on moisture levels are not so severe. Temperature will range from 75ºF to 82ºF with humidity levels of 20 to 80 percent. Cattle will usually withstand the small heat bouts of more than 86ºF for a few days.
As the period of heat persists, more stress is applied to the claw. Herd stress is minimal with the exception being the fresh cows, especially 2-year-olds. Trimming is usually normal as the drier air allows the horn to maintain a hardness that protects the claw from injury. This is the same for pasture cattle and well-ventilated freestall barns.
The heat-wave summer
This is the element most trimmers fear most. During the hottest of summers, as hoof trimmers, our blocking of unhealthy claws due to white-line lesions increases greatly.
Cows are officially stressed when confronted with waves of extended heat periods as temperatures soar up above 84ºF and into the 100s with humidity levels as high as 90 percent. Cattle will begin to pant excessively to help dissipate body heat, and to make matters worse, cows tend to group together as a herd reaction to stress.
Temperatures of more than 113ºF with 60 percent humidity or greater can be fatal. This heat prevents proper feed intakes as the cows just simply don’t have the drive to eat. As a result, they start picking or sorting through their food, taking in more carbohydrate feed and finer forage.
This, in turn, creates the chain of events to create acidosis as a herd outbreak rather than just a few individual cases. As the cow pants, she releases respiratory alkalosis (elevated blood pH as a result of increased respiration), increases urinary bicarbonate and saliva loss due to drooling, and the rumen pH drops.
Great care must be taken in trimming during this period so as to not remove too much sole. This is especially true in herds where cows have to walk great distances on concrete. This soft sole is very prone to wearing down at a faster rate.
Monitoring lameness is very critical during periods of high temperatures and humidity. Train yourself and your employees to look for cows with reduced feed intakes as well as slight limping in one rear foot.
If you milk in a parlor, monitor the color of the hair line at the foot and the claw. If it is white or a nice flesh color, the cows’ metabolism is working fine. If, however, the hair line is slightly swollen and pink, then that animal is probably in an acidotic state. That is a clear signal to call your veterinarian and nutritionist.
If required, call the trimmer in to inspect feet and block any animals with white-line lesions. Blocking the healthy claw is the best practice. Cows with blocks can walk right away with reduced pain and typically heal approximately 50 to 60 percent faster than non-blocked cattle.
Keeping cows cool is the best practice. Check your fans, sprinkler or misting system and, as always, keep an eye on the weather. PD
PHOTOS
MIDDLE: White-line lesions can be common during summertime heat. Blocking the healthy claw can cut the time to heal the ailment in half. Photo 1 shows a cow that had a block put on to allow accelerated healing from a white-line lesion.
BOTTOM: Photo 2 shows how 21 days later, the white-line has healed nicely, enabling the outer wall to regrow. P hotos courtesy of Vic Daniel.
Vic Daniel
Hoof Trimmer
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