Dairy farmers encouraged to breed mastitis out of their herds


CRV is encouraging dairy farmers to carefully consider the bulls they select for mating this season to help them address ongoing herd health issues like mastitis and reduce the need for antibiotics.

Udder health was the topic of conversation for CRV’s recent podcast featuring DairyNZ Senior Scientist Dr Jane Lacy-Hulbert and CRV Breeding Programme Manager Aaron Parker.

Jane says mastitis is a costly condition for farmers to manage and its treatment often means using antibiotics.

“Farmers are coming under increasing pressure to reduce antibiotic use on farm, to help reduce the risk of bacteria developing antimicrobial resistance.

“It’s a normal phenomenon, but our problem is that we cannot develop new antibiotics fast enough to keep up with the rate at which they develop resistance. So, it really comes down to us and how we use the existing products we have in a wise and prudent way.”

DairyNZ Senior Scientist, Dr Jane Lacy-Helbert

Jane says farmers worldwide are making changes to the way they use antibiotic products.

“We’re looking at ways to try and reduce the amount of antibiotics we use, particularly at drying off. This is a time when we’ve traditionally used dry cow products to prevent infections. Now there is a trend towards using more non-antibiotic alternatives, such as the internal teat sealants, to prevent new infections.”

Jane and the team at DairyNZ have been working to help farmers and vets do things differently.

“We’ve been carrying out research over the last few years to give vets more confidence about using internal teat sealants, give them more information about cow selection, and which cows to reserve the dry cow therapy for.

“We’ve also been providing them with more information about hygiene techniques to use when administering the products to help reduce the risk of mastitis infections at that time of the season.”

Minimizing mastitis risk during lactation

DairyNZ has Healthy Udder resources available to help farm teams to do a good job at drying off. But Jane says there are other things farmers can do throughout the lactation period to help reduce mastitis.

“The classic one is getting teat spraying right and making sure you’re getting a good coverage of spray onto each cow’s teats.

“It’s also important during milking time that we’re reducing the likelihood of teat damage by not overmilking.”

Jane says using herd testing data and identifying cows with a high Somatic Cell Count (SCC) can help farmers choose which animals should receive dry cow antibiotics and make wise culling decisions.

“A key part of mastitis prevention is actually removing from your herd cows with high SCC or those with long-term infections.”

Jane says a lower incidence of mastitis not only means more milk in the vat, but also better animal health.

“No one likes to see cows in pain and mastitis is a painful disease. Less mastitis can also lead to better fertility and we have seen the positive impact mastitis prevention can have on reproduction. It also means less hassle at milking time. Milkings are shorter because farmers have less cows to treat and deal with at the end of the milking, which leads to happier milking teams!”

Breeding for healthier udders

CRV Breeding Programme Manager Aaron Parker explains that CRV incorporates SCC traits in its breeding programme.

“We’ve put emphasis on SCC in our breeding programme to address the issue and that’s exactly what farmers can do as well. Farmers can use their herd testing data to target their high SCC cows and use low SCC bulls as part of their breeding programme to improve that.

“Selecting the right bulls to use will absolutely help reduce the incidence of mastitis,” he says. “It’s a slow process, but it is also a permanent one and you never lose the gains you make.

“Sub-clinical mastitis is not visible and can go undetected. Using data from herd testing is crucial for identifying cows with subclinical mastitis. This information is valuable in terms of identifying the right cows to treat, but also informs farmers’ breeding decisions to help reduce SCC in their herds.

“While the trait for lower SCC is only about 15 per cent heritable, it is still high enough to make a significant difference. For example, if a farmer has a cow with a 150,000 SCC and mates her with a sire that has a breeding value of around negative one, that would reduce her SCC to 75,000, which is a massive improvement.”

Somatic Cells is a trait included in BW, which means farmers who select for index, will be improving the somatic cell count of their herd. In addition, this is included in CRV Health.

Aaron says there are also other traits that influence cell count.

“As Jane mentioned, there is a strong link between fertility and high cell count. Healthy cows generally have less issues and produce more milk. A high SCC, therefore, is a really good indicator of other health-related issues a cow might have.

“From a breeding point of view, when we’re looking at elite cows, we use milking speed as an indicator because it is related to SCC and mastitis. Farmers like cows that are quick to milk so they can move them through the shed quickly. However, we know that high milking speed can result in high SCC and that is undesirable.

“We look closely at a cow’s udder in our breeding programme. It’s not just about her good looks! It’s about her longevity in the herd. Obviously, if she has a good udder, you want to keep her because she’s easy to milk. But the look of an udder can also be related to SCC. So, things like teat placement can have an effect on SCC. If an udder blows out and is in damp conditions on the ground or rubbing on the cow’s legs, it can potentially cause a higher SCC and lead to mastitis.”

CRV includes SCC as a trait in its own internal index, which helps the team select better bulls for farmers to use.

“With our myHERD animal management tool, we’re picking up more accurate and representative clinical and subclinical mastitis information from high recording herds. This data will help us develop new indexes, like our better life health and efficiency indexes, and genetic solutions to help farmers reduce mastitis and SCC in their herd.

“This is a global problem facing our industry and it’s up to us to play our part. That means using whatever tools are available to us. Adopting short-term on-farm management practices will help, but breeding for an animal that is healthier and more resilient should be our ultimate goal.”

Tools and resources to assist farmers with understanding mastitis can be found on the DairyNZ website.



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