Turning down the heat

Written by Dr. Jim White on .

Heat can be hard on the feet—of cattle, that is. It’s well known that heat stress can negatively affect milk production, calf growth and reproductive performance, but did you know it can also lead to lameness?

Hot cows stand more to try to cool off. When cows are standing, blood does not flow as effectively to the feet, and there is naturally more pressure and compaction on the hoof structure. The cow’s internal cooling mechanisms also cause blood to be redirected away from extremities, including feet and legs, and poor circulation can cause a host of hoof-related problems.

Needless to say, providing relief from the heat is important. Beef cattle are most productive in temperatures between 41 and 77 degrees. When temperatures exceed this range, cattle are less productive and at greater risk of heat stress. However, cattle can tolerate summer temperatures and remain productive when managed properly.

Available water and adequate shade can effectively reduce the effects of heat stress. Water is the most important nutrient and should be clean and abundant enough to meet summer demands. The amount of shade required is 30 to 40 square feet for mature cattle, 20 to 25 square feet for feeder cattle and 15 to 20 square feet for stockers. Heat stress is compounded by animals crowding, which happens when shade is limited. If natural shade is inadequate, construct permanent or portable structures.

Permanent structures are more suitable for feeding pens but are frequently placed in pastures, too. Portable structures are more expensive to construct but can be moved with the cattle. Advantages of portable structures include more uniform grazing, less pasture damage and better manure distribution. Locate shade structures in areas to take advantage of prevailing winds during the summer. Select areas with minimal slope to prevent erosion from animal traffic.

All shade structures should allow adequate airflow. Permanent structures will require manure removal in some situations. Inexpensive UV-resistant shade cloths that block at least 80 to 90 percent of light or two offset layers of snow fence provide adequate shade and allow for good airflow. Solid coverings are more expensive and last longer but are more susceptible to wind damage. If a solid covering is used, then the structure will need to be taller.

Summer nutrition also plays a role in helping cattle handle the heat. First, reduce forage to minimum effective fiber levels. Practically, this is a difficult task since many beef cattle primarily eat forage diets and dairy rations usually push the lower limit of fiber feeding. The best tactics are to feed the highest-quality forage available and use additives to alleviate heat stress.

We recommend MFA Ricochet FesQ Max products. Ricochet minerals have been tremendously successful, are easy to use and offer several significant benefits. Feeding a yeast culture helps with the heat as well. Feeding rate depends on the product. All MFA Gold Star Minerals and dairy feeds have yeast culture as do Trendsetter, Cattle Charge and Full Throttle feeds.

Proper amount of potassium in the diet is also a consideration. Usually beef animals on mostly forage diets are long on potassium, but when concentrate is fed, potassium content declines. Under heat stress, potassium is added to make up 1.5 percent of the entire diet. The potassium source that works best is potassium carbonate, but since this is an expensive mineral, many producers use potassium chloride.

Adding fat to the diet is another hot-weather strategy. Feeding fat increases energy while reducing fiber content and heat increment load but does not increase acidosis risk. Overfeeding fat, however, especially vegetable fat, will reduce fiber digestion and intake. That’s exactly what we don’t want for milk production in heat-stressed cows.

When heat stress is a possibility, avoid overfeeding urea or soluble protein. Evaluate the amount and degradability of the protein/nitrogen fed. Excess nitrogen-protein needs to be excreted; it is an energy drain, and tough on their kidneys.

Other nutrition strategies to beat the heat include altering feeding times to coolest parts of the day, pulling unpalatable feed from the ration and using higher-quality feedstuffs to encourage intake.

A proactive approach is best for dealing with heat stress in cattle. Once animals are severely affected, it may be too late. Before extreme temperatures arrive, be prepared to provide proper shade and water and adjust your feeding program according to your herd’s situation.

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