Reducing Heat Stress Can Help Lower Somatic Cell Counts

Many dairy producers experience increased somatic cell count (SCC) in their milking herd during the summer and fall. Why does this happen? How can you prevent it? These questions are commonly asked when troubleshooting high somatic cell count issues on farms. 

When producers think of hot weather, they worry about heat stress on their cows. The main concern is often loss of milk production, but heat stress can also cause cows to experience a seasonal high SCC as well. Environmental mastitis and summer heat can cause an economic loss to your herd, but the effect of both can be reduced with some simple management practices.

Somatic cell counts tend to rise with temperature and humidity levels during summer. Environmental stress caused by the high summer temperatures is responsible for the elevated counts. These higher somatic cell counts can stick around on your farm for weeks or months. It is known that cows are physically more stressed when it is hot. We often see decreased production due to cows standing or lying more where it is cooler and spending less time eating at the bunk. Environmental mastitis increases during this time because of the increased exposure of the teat end to bacteria. Research has shown high circulating levels of stress hormones interfere with the ability of the immune system to destroy bacteria. When bacteria enter the udder, an immune response sends somatic cells to fight the invader. Stress hormones cause a depressing effect on the somatic cells, limiting their function to protect against mastitis-causing organisms fully.

The following are some steps that can be taken to reduce heat stressors and lower somatic cell counts:

• Bacterial contamination of bedding material increases during the summer. Increased humidity levels help provide an environment in that bacteria thrive. It is essential to keep bedded areas CLEAN and DRY. This will help to reduce bacteria growth and encourage cows to lay in stalls instead of the alley when trying to stay cool. 
• Fans and sprinklers are commonly used to keep cows cool. It is essential to properly manage these tools to reduce the wet stall beds, overly wet cows, or places in the barn where cows congregate. It is essential to minimize areas that can become overloaded with manure where cows can easily become dirty and increase the incidence of mastitis. 
• Flies are also important vectors of disease. Biting flies significantly increase stress in your herd and carries disease organisms. This may result in a decrease in production as well as spreading mastitis. Flies often spread mastitis-causing organisms among heifers resulting in increased somatic cell counts at freshening. 
• Provide employee training focusing on milking procedures in the parlor. It is important to make sure all employees are following milking procedures correctly. This will help reduce new infections and identify clinical cases of mastitis quickly. 
• It is important to provide fresh, clean water in abundance. Cows drink about 50 percent more water when the temperature is 80 degrees versus 40 degrees. They need water to cool themselves through increased respiration and perspiration.

By implementing these steps to reduce heat stress, provide clean, dry housing, and ensure your milking management routine is up to date, you can easily combat the seasonal swing of your farm's somatic cell count. Not only does implementing better management practices around heat stress help to lower your farm's incidence of mastitis, but it will also increase production and overall farm profitability.

References

Jordan, E., Stokes, S., & Tomaszewski., M. (2001, August). Dairy Heat Stress and Mastitis (PDF). Dollar Saving Tips for Texas Dairies. Retrieved from Texas Cooperative Extension, Texas A&M University.

Riekerink, R. G., Barkema, H. W., & Stryhn, H. (2007). The Effect of Season on Somatic Cell Count and the Incidence of Clinical Mastitis. Journal of Dairy Science, 1704-1715.