While the impacts of our new weather system (La Nineo) will not be known until next winter, heat stress can be occurring in your herd now. The following points may be helpful to minimize milk losses, milk component drops, somatic cell count and mastitis increases, and dry matter intake declines. Your heat stress team must zero in on strategies on your farm. A team member has been assigned to each point below.

1. DAIRY MANAGER: Heat stress occurs when the temperature exceed 72 degrees F (depending on humidity). Be sure you do not wait too long to start heat abatement procedures on your farm (fans, water cooling, or shade).

2. DAIRY MANAGER: Once the cow's body temperature and respiration rate have increased, it can take several hours after sun set before body temperatures return to normal. Do not turn off fans or water too soon.

3. NUTRITIONIST AND DAIRY MANAGER: Feed bunk temperatures must be monitored as secondary fermentation can reduce palatability and intake. Corn silage (pH below 4) can stabilize the feed mixture. Adding a mold inhibitor (commercial propionic acid based product) can be beneficial in maintaining feed quality.

4. DAIRY MANAGER: If feeding the ration an extra time, pushing up feed several times a day, or feeding more feed in the evening increases dry matter intake by two or more pounds; continue the new feeding practice or strategy.

5. NUTRITIONIST: Adding a rumen buffer pack can stabilize the rumen environment and fermentation due to feed selection or rumen acidosis. Monitor feed intake to determine if the buffer additive is beneficial.

6. HOUSING SPECIALIST: Add fans and water to reduce heat stress. Michigan workers recommend adding fans and water cooling to the holding pen first, over the feed bunk area second, and in the free stalls third.

7. NUTRITIONIST: Check and increase mineral levels. Sodium levels should be increased to 0.3 to 0.5 percent of the ration dry matter, potassium levels should be increased to 1.2 to 1.5 percent of the ration dry matter, and magnesium levels should be increased to 0.3 to 0.35 percent of ration dry matter. Dietary cation and anion difference (DCAD) should be positive (over +250) using the equation: DCAD: (meq sodium + meq potassium) - meq chlorine

8. HOUSING SPECIALIST: Determine if adequate air exchanges are occurring to increase cow comfort and reduce moisture in the facility.

9. NUTRITIONIST: Insure water quality and supplies are adequate, especially after milking and when feed is being consumed. Water requirements can increase 10-20 gallons per cow per day (total of 40-50 gallons a day).

10. VETERINARIAN AND DAIRY MANAGER: Control environmental mastitis by reducing exposure (clean areas and dry surfaces) and consider a vaccination program for environmental pathogens.

11. NUTRITIONIST: Check selenium (0.3 ppm), zinc (60 ppm), copper (15 ppm), and vitamin E (600 to 1000 IU per day) levels in the ration dry matter to optimize cow health and stimulate the immune system. Providing 25 percent of the trace minerals as organic trace minerals may be beneficial.

Get all team members on the same page of the heat stress play book. You can not afford a loss this summer!