Volume 8, No. 8
HEAT STRESS TAKES ITS TOLL
By: Russ Schnepper, D. V. M.
High temperature and/or high humidity causes extreme stress on the young calf. A dark colored calf that is born in the hot sun is suffering from heat stroke before it is a few hours old. Heat causes death loss and reduced rates of gain and feed efficiency. A bovine animal (unless it is a hump breed) can not sweat. They breathe faster with open mouths in an attempt to get rid of heat. A baby calf has a poorly functioning heat regulating mechanism and its body temperature may go to 110 degrees, resulting in convulsions and possible permanent brain damage.
Many veal barns and calf ranches have drip or misting systems in place for cooling. Plastic hutches need to be placed in shade or painted or covered with something to prevent direct exposure to the sun. It is extremely important to supply ample quantities of fresh water and move enough air. I worked in Iraq in the 1980's, where the temperatures were often above 110 degrees. There was usually a brisk breeze with low humidity and the Holstein cattle were quite comfortable under a "California style" sun shade.
Trucking calves can be a challenge in hot weather. Naturally it is best to move them at night in well ventilated trucks. Many truckers, that take hogs to market, bed the trailers with wet sand. This technique works well with baby calves. If you are going to do this, please contact the recipient of the calves and let them know what you are doing. Calf raisers will think you hauled them in a soupy, manure laden trailer when they come off wet.
If the rectal temperature of a group of calves is 104 degrees or higher, you had best be getting them cooled down. The fatter the calf the more prone to heat stress. If a barn of calves is in trouble - cool them down immediately. In emergency situations, we have put cool water directly on the backs of the calves and succeeded in cooling them off. We may have been lucky, but have not had a respiratory problem following this sudden cooling. Putting water on the floors, etc. is helpful if you are not already in trouble. Don't be reluctant to put the water directly on the calves. It is better than dragging them out dead.
I use five ml of 2 mg/ml Dexamethasone per 100 pounds of body weight as treatment, along with cooling them off. Oral water and/or electrolytes are also helpful. Dehydration makes the heat stress more acute. Some calf feeders reduce feed intakes five per cent on the hot days, and this is also helpful. KEEP COOL!!!
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www.calfdoctor.com email: rschnep@mhtc.net