Mastitis is one of the most costly diseases in dairy cows, with an estimated $444 per case within the first 30 days of lactation. The highest risk periods occur at the beginning and end of the dry period when the absence of milk flow allows bacteria to enter the teat canal. Prevention is key, and proper dry cow nutrition plays a vital role in reducing mastitis risk.
Immune Challenges During Transition
Transitioning from a non-lactating to a lactating state imposes metabolic and immune challenges. Research suggests that immune function changes before and after calving, increasing disease susceptibility. While inflammation is a normal immune response, excessive inflammatory mediators from stressors can impair immune function.
The immune system demands significant nutrients, particularly glucose, amino acids, trace minerals (copper, zinc, selenium), and vitamins A, D, and E. Fatty acids can also influence immune activity, with ketone bodies from ketosis suppressing immune responsiveness. Current dairy nutrient guidelines may not fully address immune cell nutritional needs, highlighting the potential for dietary modifications to improve immune defense.
Nutritional Strategies to Reduce Mastitis Risk
- Vitamin E: Research from Ohio State University found that increasing vitamin E intake beyond National Research Council (NRC) guidelines significantly reduced mastitis incidence. The 2001 NRC raised the recommendation from 350 IU/day to 1,500 IU/day during the dry period, with studies showing additional benefits at 4,000 IU/day. Cows with blood vitamin E levels below 3 µg/ml faced a nearly ninefold higher mastitis risk. Traditional stored forages provide only about 1.5 µg/ml, necessitating supplementation.
- Vitamin A: University of Guelph studies linked higher blood retinol levels to a 60% reduction in mastitis risk for every 100 ng/ml increase, though an optimal threshold was not defined.
- Trace Minerals: While results are mixed, Penn State research found that cows with high serum iron or low serum copper levels had increased mastitis risk. Iron supports bacterial growth, while copper aids immune function and antioxidant activity. Excessive intake of any nutrient can be harmful, so balanced supplementation is essential.
Implementing Effective Dry Cow Nutrition
The dry cow diet is crucial for preventing post-calving diseases, including mastitis. Many dry cow diets minimize supplementation, but vitamins and minerals remain essential. Working with a nutritionist ensures proper supplementation, while veterinarians can monitor cow responses. Variability in intake—affected by overcrowding or heat stress—must be considered, as intake variation in close-up pens can range from 5–8 lb/day.
Nutrient interactions also impact availability. For example, vitamin A degrades in the rumen, especially with high-starch diets. Precision feeding should focus on achieving optimal nutrient levels in cows, not just formulating precise diets.
Conclusion
Optimizing dry cow nutrition is a proactive strategy to prevent mastitis. Ensuring adequate vitamin and mineral supplementation enhances immune function and reduces infection risk. Collaboration between nutritionists and veterinarians can help fine-tune diets and monitor cow health, leading to improved herd performance and productivity.
This article is based on an article by Robert J. Van Saun, DVM, MS, PhD, Extension Veterinarian.
