Some Like it Hot, but Cows in Heat do Not

Heat hurts dairy health. Warm surroundings can be especially detrimental to reproduction. In fact, at just 72°F, a cow can experience heat stress.1 Pay attention to ambient environmental temperatures and use heat stress management in warm weather to ensure cow comfort, health and productivity.

Cows show more noticeable signs of heat stress when they are not consuming enough dry matter. Leftover feed at the feed bunk is a solid clue. Decreased dry matter intake leads to decreased milk production. However, the onset of reproductive problems resulting from heat stress isn’t always obvious, and it happens more quickly for some than for others.

“When a cow suffers heat stress, it affects reproductive performance at all stages, starting with follicular development through post-calving,” said John Lee, DVM, managing veterinarian, Dairy Technical Services, Zoetis. “The impact on fertility can be long-lasting.”

Your farm’s profitability depends on how proactive you are at making cow cooling a priority. Economic studies show each additional day a cow is open beyond 90 days post fresh can cost between $1.50 and $3.2  Cows under heat stress can experience an additional 45 to 60 days open, costing you time and money. In addition, heat-stressed dairy cows can suffer a drop in production of 1,000 to 2,000 pounds of milk during the next lactation.3

Cool is the rule. Help ensure healthy cows and a successful reproduction program in hot weather by considering these factors when activating your heat abatement program.

  1. Availability of drinking water — Cows will consume more than 30 percent of their daily water intake within 30 minutes of milking. They will drink 25 to 50% more water when temperatures are above 80°F.4 Clean and cool water must be readily available.
  2. Sprinkler systems – Keep your cows cool and comfortable with thermostat-regulated water sprinklers in the holding-pen and return-alley. Water sprinklers should wet the cow’s back, while avoiding moisture accumulation on the udder or in the freestalls. 
  3. Adequate air movement — Provide constant air movement by opening sidewalls and ridge vents and flipping on fans if you have them.
  4. Resting areas — Cows need clean, dry bedding, especially in cooler, shaded areas in barns and lots, where cows gather more frequently.

Beyond minimizing heat stress, synchronization programs can benefit reproduction programs. Synchronization programs using fixed-timed artificial insemination (AI) with FACTREL® Injection (gonadorelin injection) and LUTALYSE® (dinoprost tromethamine) Sterile Solution can help improve breeding success and prevent bottlenecks, not just in summer and fall, but year-round.

“It’s important for veterinarians to understand that this flexible FACTREL Injection label gives them the opportunity to choose the timed AI program that best fits their clients’ needs,” Dr. Lee said. “It also will allow veterinarians and producers to continue the timed AI programs they’ve been using and that are approved by the FDA and Dairy Cattle Reproduction Council.”

Work with your veterinarian to develop and evaluate your reproductive program, including heat stress management, to help ensure healthy cows and a profitable bottom line, regardless of the weather.

IMPORTANT SAFETY INFORMATION FOR FACTREL: FACTREL injection is for use in cattle only. Please see full Prescribing Information.

IMPORTANT SAFETY INFORMATION FOR LUTALYSE: Women of childbearing age and persons with respiratory problems should exercise extreme caution when handling LUTALYSE. LUTALYSE is readily absorbed through the skin and may cause abortion and/or bronchiospasms, therefore spillage on the skin should be washed off immediately with soap and water. Aseptic technique should be used to reduce the possibility of post-injection clostridial infections. Do not administer LUTALYSE in pregnant cattle unless cessation of pregnancy is desired. See full Prescribing Information.

About Zoetis

Zoetis (zō-EH-tis) is the leading animal health company, dedicated to supporting its customers and their businesses. Building on more than 60 years of experience in animal health, Zoetis discovers, develops, manufactures and markets veterinary vaccines and medicines, complemented by diagnostic products and genetic tests and supported by a range of services. In 2013, the company generated annual revenues of $4.6 billion. With approximately 9,800 employees worldwide at the beginning of 2014, Zoetis has a local presence in approximately 70 countries, including 27 manufacturing facilities in 10 countries. Its products serve veterinarians, livestock producers and people who raise and care for farm and companion animals in 120 countries. For more information, visit

Zoetis is the proud sponsor, with the Smithsonian Institution Traveling Exhibition Service, the American Veterinary Medical Association and the American Veterinary Medical Foundation, of the mobile educational exhibit Animal Connections: Our Journey Together. Families visiting the exhibit will explore the vast bonds between people and animals and learn about the important role veterinarians play in protecting animal and human health.

For further information, Contact:
Jillian Spector 

Kristina Hopkins
Bader Rutter

1 Donnelly M. Economic impacts of heat stress. Available at: Accessed July 24, 2014.
2 Smith RD, Oltenacu PA, Erb HN. The Economics of Improved Reproductive Performance. Available at: Accessed July 24, 2014.
3 Payne M. CDQAP Ruminations: Heat Stress in Dairy Cows. California Dairy Research Foundation. Available at: Accessed July 24, 2014.
4 Washington State University Veterinary Medicine Extension. Heat Stress. Available at: Accessed July 16, 2014.



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