DairyNZ senior scientist Jane Lacy-Hulbert explains.
Antibiotics are a valuable tool for managing mastitis and other bacterial diseases in dairy cows. But, as in humans, the overuse of antibiotics in animals can lead to resistance. Consequently, there is an international focus on finding prudent ways of using antibiotics to treat food-producing animals.
Mastitis control accounts for about 85 percent of the antibiotics used on New Zealand dairy farms. So, it’s vital we understand the most effective ways to prevent and treat this condition.
For many diseases, including mastitis, good animal husbandry practices can help reduce infections and hence minimise the need for antibiotics. In the case of mastitis, blanket or wholeherd antibiotic dry cow treatment is used by some farmers to cure existing infections and prevent mastitis in the dry period and after calving. However, treating all cows in a herd results in some uninfected cows being unnecessarily treated with antibiotics.
A more prudent alternative is to use antibiotics only for cows that are likely infected. New mastitis cases can then be prevented in the remaining cows using non-antibiotic alternatives, such as internal teat sealants. Some farmers and vets may be wary of using teat sealants on their own - particularly in systems with an inherently higher risk of mastitis - due to concerns about the risk of introducing infections at drying off.
In 2015, DairyNZ conducted a pilot study on two farms in Southland: one wintered cows on fodder beet and the other wintered cows in a cubicle barn. Seven hundred low somatic cell count cows received either no treatment or one of three treatments at dry off. The consequences on risk of clinical mastitis over the dry period and into early lactation were measured. Check out the results of this study in the enclosed copy of Technical Series.
A larger study funded by DairyNZ and the Ministry for Primary Industries (through its Sustainable Farming Fund) begins this month, involving up to 40 herds. It aims to clarify what information is required to allocate the right cows to treatments at dry off. It will also test the effectiveness of internal teat sealants across different farm systems.
These studies are part of a wider industry strategy to meet the challenge of antimicrobial resistance by developing long-term responsible solutions.
- Farmers may need to change the way they use antibiotics in future.
- Treatment selection will become more reliant on herd test and health records of individual cows.
- DairyNZ is supporting the vet profession to develop guidelines for use at drying off.
This article was originally published in Inside Dairy March 2017