Experimentally induced Staphylococcus aureus mastitis in selenium-deficient and selenium-supplemented dairy cows

Area of Science:

• Veterinary Medicine
• Animal Nutrition
• Dairy Science

Background:

• Selenium is a crucial trace element for immune function in livestock.
• Dietary selenium levels can impact a cow's susceptibility to mastitis, a common dairy cattle disease.

Purpose of the Study:

• To investigate the effect of dietary selenium levels on the severity of Staphylococcus aureus-induced mastitis in Holstein cows.
• To determine if selenium supplementation influences bacterial load, somatic cell count, and infection resolution time.

Main Methods:

• Holstein cows were divided into two groups: selenium-deficient (SeD) and selenium-supplemented (SeS).
• Cows were challenged with Staphylococcus aureus in their udders during early lactation.
• Blood selenium concentrations, milk bacterial counts, and somatic cell counts (SCC) were monitored over an 8-week period.

Main Results:

• Selenium-supplemented cows exhibited significantly lower peak bacterial concentrations in milk compared to selenium-deficient cows.
• The time to reach peak bacterial concentration and peak SCC was significantly longer in selenium-supplemented cows.
• While infection was established in both groups, SeS cows demonstrated a reduced bacterial challenge severity.

Conclusions:

• Dietary selenium supplementation can mitigate the severity of Staphylococcus aureus mastitis in dairy cows.
• Adequate selenium levels appear to enhance the cow's ability to manage intramammary infections.
• Selenium supplementation may be a valuable strategy in mastitis control programs for dairy herds.