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Strategies for mastitis control: dry cow therapy and culling
J W Browning1, G A Mein, P Brightling
1Eastern Vet Path, Bairnsdale, Victoria.
Australian Veterinary Journal
|June 1, 1994
Summary
Selective cow treatment is the preferred strategy for dry cow therapy, reducing antibiotic use and new infections. Blanket treatment increases antibiotic use, while selective quarter treatment raises infection rates.
Area of Science:
- Veterinary Medicine
- Animal Health
- Dairy Science
Background:
- Mastitis remains a significant challenge in dairy herds, impacting animal welfare and economic viability.
- Dry cow therapy is a critical intervention point for managing mastitis and preventing infections during the transition period.
- Optimizing selection strategies for dry cow therapy is essential to balance infection control with judicious antibiotic use.
Purpose of the Study:
- To compare the efficacy of three selection strategies for dry cow therapy.
- To evaluate the impact of these strategies on the prevention of new intramammary infections (IMIs).
- To assess the rate of antibiotic usage associated with each strategy.
Main Methods:
- Bacteriological assessment of quarter infection status in 1044 cows across 12 herds at drying off, calving, and mid-lactation.
- Random allocation of uninfected cows to treatment (whole udder) or non-treatment groups.
- Random allocation of infected cows to whole udder or infected quarter treatments.
- Comparison of blanket treatment, selective cow treatment, and selective quarter treatment strategies.
Main Results:
- Selective cow treatment emerged as the preferred strategy.
- Blanket treatment led to higher antibiotic usage (15.5 vs. 6.4 tubes per infection eliminated) without additional benefit.
- Selective quarter treatment resulted in a higher new infection rate (6.4% vs. 3.9% of quarters) during the dry period.
- Dry cow treatment cure rates decreased with increasing cow age (P < 0.001).
- Cows infected in the previous lactation were the primary source of infections at calving (76%) and mid-lactation (70%).
Conclusions:
- Selective cow treatment offers a favorable balance between infection prevention and reduced antibiotic consumption.
- Blanket treatment is inefficient and contributes to antimicrobial resistance concerns.
- Selective quarter treatment increases the risk of new infections during the dry period.
- Culling older, infected cows and preventing new infections during lactation are crucial for herd mastitis control.