This blog provides information about milk quality & udder health issues
of importance to dairy producers &
farm advisors.

Posts by Sandy Costello Ph.D.
Milk Quality & Mastitis Specialist

Monday, April 2, 2012

Recommended Mastitis Control Program - Keys To Milk Quality


Part 1: Dry Period


One of the greatest contributions from the National Mastitis Council has been the 10-point mastitis control program. This plan provides a complete checklist for comparing your farm mastitis control practices with NMC recommendations.

Future milk quality articles will use this 10-point mastitis control plan as a guide through the key elements to producing quality milk. The first few articles will focus on the dry period – one of the most important times for strategic mastitis control planning and action. This article provides a general overview of critical mastitis control practices during the dry period.

Why Dry Period Mastitis Control Strategies are Important

The dry cow period, specifically, time periods from dry-off to two weeks after dry-off, and two weeks before and after calving are most critical for prevention of new mastitis infections (Figure 1).

Figure 1.

By nature and just when it is most important, cows have the worst ability to fight off bacteria in the environment at these times of the dry period. Herd conditions are primed for new mastitis infections unless attention is paid to key practices and strategies to maintain low new infection rates, and reduce existing mastitis by curing infections in chronic mastitis cows.

The overall goal of the dry period is to prepare cows well for calving, and create conditions for optimum production and well-being in the next lactation. To meet this overall goal, sub-goals likely include: negligible new mastitis cases during the dry period; high cure rate of existing infections; no measurable physical discomfort of cows through dry-off and dry period; maintenance of body condition; conditions that enable all mastitis control practices to work well, including vaccinations, teat sealant, antibiotic treatment, nutrition, etc.; and a positive benefit to cost ratio for decisions.

Dynamics of Infections

To evaluate effectiveness of dry period mastitis control decisions it is important to record and track how many cows are not infected (clean) and how many are infected going into the dry period and then again after freshening. It is also important to calculate historic rate of new infections and cure rates in dry cows and springers (heifers) over the last 3-months, 6-months, 9-months, and year. This will provide a baseline of how your herd has done and periods of challenge.

Large herds may have enough freshenings to reduce these intervals to cows freshening in a given month. The objective of choosing evaluation periods is to have sufficient number of animals to be meaningful and recent enough to reflect current practices and pinpoint periods of variation from the norm for your herd. Goals should be set to improve upon what has happened in the past and using documented achievable goals as a reference.

Most control strategies are designed to prevent cows from getting new infections during the dry period, while others are designed to eliminate or cure existing mastitis cases. Cows with existing mastitis at dry-off are ones that did not cure during lactation and require an opportunity to cure between lactations. Hopefully they are also cows that warrant additional costs to cure existing infections. Factors such as how long cows have been infected; number of quarters infected; organism (e.g., bacteria) responsible; damage to teat end and teat canal; cow’s health and immune status; and antibiotic used for dry cow treatment, will determine the chance that existing infections will cure over the dry period and before the next lactation.

Herd goals should be unique to herd conditions and should be set for new infections and cures based on current level of infection in the herd and to improve upon previous baseline levels. As a general guideline and at minimum, 85% or more of cows should freshen without a mastitis infection. Goals at 90% and above would be considered excellent. Cure rates are more difficult to provide standards for herd use, as levels will vary within a herd by many factors, including those mentioned previously.

In general, cure rates of existing infections should be above 60% with 70% and higher considered excellent. If long-term chronic mastitis cases have been removed from the herd and ‘existing cases group’ consists mainly of shorter-term chronic mastitis cases and younger animals, the cure rates should be higher and goal rate for cures should be adjusted accordingly. In this case, cure rates of chronic mastitis cases during the dry period may be as high as 80 to 90 percent. If not, adjustments may need to be made to mastitis control program during lactation as well as possibly the dry period to achieve higher cure rates and further reduce new infections during the dry period. Without measuring these values you are assuming that all mastitis control expenses are worthwhile and will not benefit from fine-tuning based on herd unique characteristics and changes over time.

NMC Recommendations for Dry Period

Future articles will provide more in-depth background on individual elements of the dry cow management mastitis control program. For now, the elements are listed with a brief statement on purpose and whether the overall purpose is for prevention of new cases of mastitis, for cure of existing cases, or both. This becomes important when evaluating effectiveness of dry period control elements on intended outcome. Indirectly, all best management practices will likely impact cure rates of cows with pre-existing infections.



SUMMARY
• Goals for dry period mastitis should be set based on herd baseline levels with eye to industry guidelines
• Planning, acting, and evaluating are essential steps for dry period mastitis control
• Dry period is the time period of greatest risk for new mastitis infections and for curing existing infections in your herd
• Economics and best decisions can only be evaluated when dry period mastitis control is planned rather than just happens
The Milk Quality article in April will focus on recent research findings on dry-off methods.
The NMC Mastitis Control Program is available at the following website:
http://nmconline.org/docs/NMCchecklistNA.pdf

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Dr. Sandy Costello is owner and mastitis/milk quality specialist at Milk Quality Pays and provides on-farm milk quality consulting, training, and product and applied research to aid producer decisions. The mission of Milk Quality Pays is to ensure clients produce and sell milk of the highest quality while maximizing profitability from milk income and maximizing customer assurance of product quality, safety, and worker & animal well-being. Dr. Costello can be reached at 570-768-6140 or scostello@milkqualitypays.com.