Effects of heat on cows
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Hot temps still challenging reproduction?

October 27, 2016
POSTED BY: Richard Wallace | DVM, MS | Managing Veterinarian | Dairy Technical Services | Zoetis

There’s no question hot temperatures can take a toll on Dairy Wellness. Excessive heat can cause cows to produce less milk and become harder to breed.

High-producing dairy cows produce a large amount of internal heat and have trouble dissipating it when temperatures are high. This causes negative impacts on fertility:

  • Decreased estrous expression, making it difficult to identify cows in heat and inseminate them in a timely manner
  • Lower reproductive performance, including changes in follicular waves, reduced fertility, delayed conception and higher embryonic death1

Knowing this, you likely took preventive measures with cooling systems and ensured your cow pens weren’t overcrowded. But there may have been an impact on the reproductive performance of your cows. The negative impacts of hot temperatures on fertility can last well after summer has come and gone.

To keep cows on track and to help avoid delays in rebreeding dairy cows, work with your veterinarian and Zoetis representative to establish an on-label synchronization program that best fits the needs of your herd. They can tell you about these programs:

  • Fixed-time artificial insemination using FACTREL® Injection (gonadorelin injection) and LUTALYSE® Injection (dinoprost tromethamine injection) or LUTALYSE® HighCon Injection (dinoprost tromethamine injection)
  • Estrous synchronization using LUTALYSE or LUTALYSE HighCon and EAZI-BREED™ CIDR®

These programs allow for more efficient breeding, saving time and helping you protect your bottom line.

If you want to learn more, read about managing breeding on your time.

IMPORTANT SAFETY INFORMATION FOR LUTALYSE/LUTALYSE HIGHCON: Women of childbearing age and persons with respiratory problems should exercise extreme caution when handling LUTALYSE/LUTALYSE HighCon. LUTALYSE/LUTALYSE HighCon 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/LUTALYSE HighCon in pregnant cattle unless cessation of pregnancy is desired. See full Prescribing Information for LUTALYSE. See full Prescribing Information for LUTALYSE HighCon.

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

Avoid contact with skin by wearing protective gloves when handling EAZI-BREED CIDR inserts. Do not use in heifers of insufficient size or age for breeding or in cattle with abnormal, immature, or infected genital tracts. Do not use inserts more than once.

1 De Rensis F, Scaramuzzi RJ. Heat stress and seasonal effects on reproduction in the dairy cow—a review. Theriogenology. 2003;60(6):1139-1151.




  • LUTALYSE HighCon: A new management tool for added reproductive efficiency
  • Five tips for successful synchronization
  • Four keys to reach a 30% pregnancy rate


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