Summer Heat Stress Season Has Already Started
The dairy industry is celebrated throughout the month of June with Dairy Breakfast and Farm City Days. These are excellent events where dairy producers are able to offer the food consumer a glimpse into the daily activities and workings of a dairy farm. Farms that are hosting these events deserve a big THANK YOU from not only the visiting consumers but from the rest of the agriculture community. Collectively, the animal agriculture industry needs more of these type of events to foster a higher level of consumer confidence in the safety of the food supply and a better understanding of the effort and dedication it takes to care for our animals. Heat stress abatement strategies and feeding management is one of the areas we can highlight for the consumer. Officially, summer begins on June 21st, however heat stress is beginning to impact dairy cattle in many parts of the country.
Cows Experience Heat Stress Before Humans
The Temperature Humidity Index (THI) takes both ambient temperature and humidity into account. Cows are negatively impacted by Heat Stress at 72 degrees Fahrenheit and 40% humidity or the THI of 68. Humans are negatively impacted by at 80 degrees Fahrenheit and 40% humidity. Humidity must be considered because expelling water from the body is how the cow transfers and dissipates heat load from her body. Cows most efficiently cool themselves through evaporative cooling as they evaporate sweat from their skin. As humidity increases this process is greatly diminished and cows resort to increased open mouth breath to expel moisture through their breath, loss of saliva due to drooling and standing for longer periods to increase body surface are exposed to the air. All these responses greatly reduce the cow’s natural buffering ability and greatly increases the risk of Sub Acute Rumen Acidosis (SARA).
Summer Crash Timeline
Heat Stress by the Numbers
- >68 THI Heat stress begins
- 80 TI : Moderate to severe heat stress
- 2 Hour : Hours more per day cows are standing
- 4 lb : Pounds of lost milk due to less time lying and decreased rumination
- 10-25% : Percent drop in total milk production possible
- 1-2-3 Punch : The rumen health impact of heat stress is cumulative. The late summer milk crash started at the first heat stress event
- 1000-2000 lb : Pounds of milk lost in the subsequent lactation of dry cows that experience heat stress – DO NOT FORGET THE DRY COWS
Heat Stress Abatement Strategies
- Fans to move air over the cattle
- Sprinklers and soakers to wet the cattle and aid evaporative cooling
- Nutritional adjustments
- Feed the highest quality most digestible forages
- Increase bypass fat, niacin and vitamins in the diet
- Increase DCAD delivery – sodium, magnesium and potassium
- Feed at cooler times of the day and or multiple times per day
Address the increased risk of SARA during Heat Stress
CRYSTALYX® Buffer-Lyx® is a self-fed supplement designed to deliver buffers and alkalizing agents in a very palatable low moisture block. Yes, often there is buffers already in the TMR. Considering the changes in eating and rumination if the cow is going extended periods without eating she is not getting enough buffers in the TMR alone. In addition, the meals will be larger during heat stress and the rumen’s natural buffering capacity may be over whelmed by the amount of fermentable carbohydrate consumed at once. When cattle are not eating the TMR, they will be attracted to the Buffer-Lyx® due to the palatability of the dehydrated molasses. The licking action required to consume the product will help stimulate saliva recirculation and partially restore the natural buffering properties of recirculating saliva. Buffer-Lyx® can replace free choice buffers and it has the advantage of more consistent intake to act as a preventative buffer delivery system compared to intake of free choice sodium bicarbonate after the cow experiences low rumen pH. Buffer-Lyx® will also have ZERO shirk and waste.
Effective heat stress abatement is best accomplished by using multiple tools to address the challenges that hot weather brings. I hope you take time to celebrate June as the Dairy Month and plan now to keep your cows productive through the summer months and beyond.