Five simple tips to reduce the negative impacts of hot weather on dairy cattle.

Bob James
Extension Dairy Scientist, Dairy Nutrition
(540) 231-4770; jamesre@vt.edu

Each year it’s not unusual to see production drop 10 -15 lb. per cow. Waiting until hot weather subsides is not an effective management strategy as milk production lost is never regained once things get cooler. Here are five tips to alleviate summer heat stress.

1. Pay special attention to close up cows. Feed bunks must be covered to prevent spoilage from summer sun and soaking from thunderstorms. Fluctuation of intake prior to calving has very undesirable effects on successful transition to the milking herd and peak milk yield. Shade clothes can provide economical temporary solutions.
   
   
2. Provide cow cooling with 36 – 48” fans 20’ apart and 8’ off the ground angled at 15 to 25° downward. Above the feed lanes place soaker nozzles (10 psi, 180° spray) 8 ft. above the cows and immediately below the fans. Sprinklers run on a timer that soaks cows for 2 – 3 minutes at 15 minute intervals.
   
   
3. The holding pen is the hottest place on the farm! Consider reducing group size to reduce time spent in the holding pen along with ample fans to move hot air away from cows.
   
   
4. Clean water. What’s the water trough look like for your milking and dry cows???? During the summer waterers should be cleaned at least every other day to prevent accumulation of algae and spoiled feed. Wiping the prevents algae growth for several days. Provide at least two waterers per group with a water supply of at least 5 gallons/minute. Consider adding more water trough space near the holding pen during the summer months.
   
   
5. Ration modifications are needed to increase energy supply and decrease heat load on the cow.
   • Add supplemental fat. Whole oil seeds such as cottonseed and whole soybeans can be added to the ration to increase fat to up to 5% of the ration dry matter. Additional fat (up to a limit of 6 to 6.5% fat in the ration dry matter) should come from rumen inert fats which would not have an adverse impact on rumen fermentation.
   • Don’t overfeed protein. Many of the new ration formulation programs will permit your nutritionist to balance rations based upon amino acid supply to the intestine. With the right combination of feed ingredients, ration crude protein can be reduced to 16% or less for high producing cows.
   • Increase potassium, sodium and magnesium to 1.5%, .45% and .35% of the ration dry matter for lactating cows.

Visit Virginia Cooperative Extension