We’re quick to notice the effects of heat stress in our herds when it causes a drop in production as a result of a decrease in the dry matter intake in your herd.

But oftentimes we do not associate fall and winter hoof care issues with summer heat stress. When summer heat takes the edge off your herd’s appetite, a portion of your cows could wind up lame in the fall.

Making sure your cows eat right through the summer months can help them ward off subacute ruminal acidosis (SARA), which can lead to other health issues such as lameness. In many cases, SARA symptoms are invisible but eventually lead to lameness.

Feeding dairy cows is a delicate balancing act during periods of heat stress. A cow’s maintenance energy requirement can increase by as much as 25 percent during those hot humid summer days, while her dry matter intake is decreasing. But we need to be sure not to exceed 40 to 42 percent non-structural carbohydrates during this time.

One way to ward off the prolonged effects of those hot summer days is to continue to practice proper nutritional herd management. Ensure unlimited access to clean water. Feed more frequently and feed more palatable, higher quality feeds to encourage feed intake. Watch for moldy feed and clean up refusals daily. Ensure minerals, particularly sodium, potassium and magnesium are balanced for the dry matter intake of your herd. Also, be prepared to increase the ration density to offset reduced intakes. PD

—From Virginia Tech Dairy Pipeline, July 2007

Tina Horn
State Dairy Agent
Clemson University Extension