It’s no secret that fertility in dairy cows has declined in the last 10 to 15 years. Previous work showed a correlation between clinical mastitis by gram-negative bacteria and reproduction.

New research by the University of Tennessee indicates there may be a stronger relationship between reproduction and mastitis. Findings were presented at the 2010 Dairy Production Medicine Seminar in Tulare, Calif. 

“We wanted to see what the impact of clinical and subclinical mastitis during early lactation on reproductive performance was,” says Neal Schrick, animal science professor at the University of Tennessee.

In this study, cows with clinical mastitis during the first 150 days of lactation were compared with control cows with no signs of clinical mastitis.

Services per conception, days to first service and days to conception (days open) were evaluated. Treatment groups were balanced by lactation number and days in milk. “We saw a lengthening of days to first service (94 vs. 71) for cows that contracted clinical mastitis before first service,” says Schrick.

Cows that contracted clinical mastitis between first service and pregnancy had increased services per conception (2.9 vs. 1.6). Days to conception were also greater (136 vs. 92). Clinical mastitis caused by gram positive and gram negative pathogens reduced reproductive performance in a similar manner, noted Schrick.

Results from a second study performed by the University of Tennessee indicate that clinical and subclinical infections equally decreased reproductive parameters.

These findings give extra emphasis to the recommendation that mastitis prevention and control should continue to be a high priority, especially during the dry period, near calving and early lactation.

More information.