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Preventing Mastitis: Does Breed Matter?

Conflicting literature led researchers to investigate whether Jerseys are more susceptible to mastitis than Holsteins.

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Updated:

June 3, 2024

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Taking milk samples; Photo credit: Cassie Yost

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A recent Journal of Dairy Science article had me questioning: Does breed influence mastitis infections? There is conflicting information in the body of literature regarding Jerseys' susceptibility to mastitis compared to Holsteins. Some studies indicate that Jerseys are more susceptible to mastitis infections, while others indicate the opposite. Hence, researchers from the University of Missouri investigated mastitis in Jerseys. Looking at over 750 Jerseys from 4 different farms, these researchers sampled each cow monthly for three months. The most common pathogens they found were staphylococci (Haw et al., 2024). Haw et al. (2024) determined that the prevalence of mastitis and types of pathogens were similar to studies done with other breeds; other studies also found staphylococci to be the most common pathogens. This led them to the conclusion that management influences cases of mastitis more than breed does.

So, what are common management factors that could prevent mastitis?

Proper milking procedures: Many cases of mastitis can be managed with proper milking procedures. When prepping, using a pre-dip to kill pathogens that are on the teat and may enter the canal during milking is essential. Many pre-dips have a 15 to 30-second kill time, so keeping the dip on for at least that amount of time is necessary.
- The rest of the prep is also essential to ensure that bimodal milking does not occur. To understand bimodal milking, you must first understand lag time. Lag time is the time from the first udder stimulation to when the milking unit is attached. Lag time should be between 60 and 90 seconds to ensure proper milk letdown. This is the ideal amount of time to allow oxytocin to be released from the hypothalamus in the brain to trigger milk letdown. If the lag time exceeds this ideal range, the milking unit must restimulate the udder when attached, creating bimodal milking. So, instead of high milk flow and low vacuum at attachment, the vacuum would be high, and milk flow would be low. High amounts of vacuum for extended periods of time can lead to irreversible teat end damage.
- Fore-stripping of teats should also happen during milk prep. Stripping allows for proper stimulation, enables milkers to look for clinical mastitis, and removes the highest somatic cell count milk from the udder. To accomplish all of this, stripping should occur for 10 seconds per animal.
- Wiping should be the last step before the unit is applied to ensure there is no opportunity for the udder to become dirty again after prepping. Special attention should be paid to the teat end to ensure they are also clean.
- After milking, apply post-dip as soon as possible when the milking unit comes off. Cows should remain standing for at least 30 minutes after milking, as this is the length of time it takes for the teat end to close. Having fresh feed available immediately after milking is an excellent way to keep cows standing.
Know what pathogen you’re dealing with: Knowing if you are dealing with environmental or contagious pathogens is important when trying to control mastitis on your farm; this can be accomplished through culturing. Environmental pathogens spread to the cow on surfaces such as hands, bedding, etc. Contagious pathogens spread from cow to cow, typically through milk carried on milking equipment. The spread of environmental pathogens can be prevented by keeping stalls clean and dry, spreading lime in stalls, stripping into the gutter instead of onto the stall if milking in tie-stall barns, and using proper milking procedures. You can prevent contagious pathogens from spreading by milking infected cows last and using proper milking procedures.
Wear gloves during milking. The cracks and crevices in our hands are a perfect place for bacteria to grow. Coagulase-negative staphylococci (CNS) are the most common family of bacteria that cause subclinical mastitis and live on our hands.
Use a California Mastitis Test (CMT) paddle on fresh or suspicious cows. If you detect mastitis through stripping, or if a cow comes back with a high somatic cell count on your monthly test, use a CMT paddle to determine which quarter or quarters the mastitis is in before treating her. Use a CMT paddle on fresh cows on the fourth day after freshening (depending on the withhold time of dry treatment) before you put her into the tank to ensure you aren’t unknowingly putting high somatic cell count milk into your bulk tank.
Prevent overmilking. One cause of teat end damage is overmilking. Once teat end damage has occurred, there is no way to reverse the damage, and the cow is now susceptible to mastitis. Taking milking units off at the appropriate time is essential, especially on farms without automatic take-offs. Do a strip test at the end of milking to double-check that you aren't overmilking cows. After milking, cows should not be completely dry; some milk should still be left in the udder. Strip each quarter after milking; one cup of milk should be left between all four teats. If your farm has automatic take-offs, ensure they are coming off at the appropriate time.

Preventing mastitis is less about the breed of dairy cows and more about management. Remember the above tips if your herd struggles with somatic cell count issues.