MN Dairy Quality Cares

Just like a car or tractor, milking equipment needs regular maintenance and replacement of parts that experience wear and tear. Failure to properly maintain milking equipment can lead to cow comfort and udder health issues, including increased clinical mastitis and SCC, improper cleaning and high bacteria counts, as well as parlor inefficiency. Dairies that milk round-the-clock must pay even more attention to preventive maintenance, as unscheduled down time for repairs can be particularly costly.

Whether a dairy contracts out for equipment service or has dairy staff perform regular maintenance, it’s critical that an owner or manager take responsibility for ensuring that important tasks get accomplished on schedule. Too often, without a schedule and check system, things get pushed aside until what could have been a simple preventive measure becomes a costly repair.  Tasks can be spread out over the year, which helps with budgeting and reduces parlor down time. Work with your equipment dealer to make sure all necessary items are included in the schedule according to the manufacturer’s recommended maintenance interval. Some examples of the most common preventive maintenance items include:

Replacement of Rubber Goods

     ♦ There are many liners on the market, and all have a definite lifespan for optimal performance. Replace liners according the manufacturer recommendations.

     ♦ Milk hoses should be replaced at least every 6 months.

     ♦ Pulsation hoses, wash hoses, milkline and other gaskets should be replaced at least yearly.

Milking Claws

     ♦ Regularly check for cracks and buildup of milk film on internal surfaces. If vented, check that vents are open and use the right size tool to open plugged vents.

     ♦ Claw gaskets should be replaced at least every 6 months.

Pulsators

     ♦ Pulsators should be rebuilt according to the recommended interval (depending on manufacturer, may be every 1500-3000 milking hours). If not following manufacturer recommendations, rebuild at least 1-2 times per year.

Filters & Drains

     ♦ Check and clean or replace filters on airlines, regulators and pulsators regularly.

     ♦ Airlines should have drains installed at low points and vertical elbows. Check and clean drains (and airlines) regularly to prevent leaks and bacterial growth.

Routine Assessment of Cleaning System

     ♦ Don’t forget air injectors, chemical pumps, mechanical valves and rubber goods associated with the cleaning system.

Pump Maintenance

     ♦ Vacuum and milk pumps need regular service to maintain capacity and prevent failure. 

Vacuum level should be recorded at the beginning of each milking shift. Vacuum gauges that are permanently mounted in the system may become inaccurate over time, so it is best to use a portable vacuum gauge to check the vacuum level. Making a regular vacuum check part of the milking routine ensures early detection of problems with the Variable Speed Drive controller or regulator, or accidental changes to the vacuum setting that can seriously affect cow comfort and teat health. 

Every pulsator should be checked by a professional or trained dairy worker on a regular interval, as determined by the dairy (recommend every 1-2 months). If many pulsators are found to be outside tolerance ranges on test day, the testing interval should be shortened. The lead milker should also check pulsators by listening or feeling for functional pulsation at the beginning of each shift. 

(see Best Practice: Milking Procedures)

The lead milker should be responsible for checking milk temperature, either by signing off on the chart recorder, or on a Milk Temperature Log. A manager should periodically verify that the temperature recording is correct.

(see downloads under #4 below)

(see Best Practice: Care of Milking Equipment)

Bacteria levels are reported by the milk processor (may be called Bacteria, Standard Plate Count, Total Plate Count). Differential bacteria counts, such as Lab Pasteurized Count (LPC), Preliminary Incubation count (PI), and Coliform count, can also be used when needed to help troubleshoot a bacteria problem.

Milking time hygiene practices include:

1. All milkers wear clean, disposable gloves.
2. Milkers wash hands or change gloves frequently throughout milking, but particularly after handling a cow with mastitis.
1. Milking units are thoroughly flushed (ideally with a sanitizing solution) after milking a cow with mastitis. In a herd with a high prevalence of infection, units should be back-flushed after every turn. Minimally, units should be back-flushed after each turn in the fresh pen and hospital pen.
3. Milk infected cows last in the milking order, or use different milking units for infected cows. Milk the most vulnerable cows, fresh cows, first in the milking order.
4. Towels used in milking prep are single-use only, and, if cloth, are laundered appropriately with hot water, detergent, +/-sanitizer, and dried thoroughly before re-use.
5. Parlor surfaces and equipment are kept clean and free of milk residues. Teat cup plugs should be stored in a sanitizing solution between uses.
6. Excellent teat coverage with an effective germicidal pre- and post-dip.

1. The first goal is early identification of cows infected with contagious pathogens. Work with your veterinarian to design the best screening strategy for your herd. Options include:
   1. Culture all cases of clinical mastitis - this is highly recommended if contagious pathogens are known to be present in the herd (from previous cases or bulk tank cultures).
   2. Culture any cases of clinical mastitis that do not cure after treatment, that recur within 1-2 months, or when multiple quarters of the same cow are infected (high risk for contagious mastitis).
   3. Culture all fresh animals.
   4. Culture all cows with a high SCC for 2 or more consecutive test days.

2. After identifying cows infected with contagious pathogens, some management action will have to be taken to limit their exposure to other cows in the herd. The best option from an udder health perspective is to cull these cows immediately. However, when that is not possible, the next best option is to segregate contagious cows in a separate pen and milk them last in the milking order (and cull from this pen preferentially). The last option is to clearly mark these cows as contagious using multiple, highly visible methods (colored leg-bands, udder paint, special ear tags, etc.), and use excellent milking time hygiene when milking these cows (see above).

3. Treatment may be considered in some cases. Strep agalactiae can be effectively treated with intramammary antibiotics. Few cases of Staph aureus mastitis will cure with intramammary antibiotics. Work with your veterinarian to design a treatment protocol for Staph aureus that selects only the cases most likely to respond to treatment (younger cows with new cases and no history of chronic infection). Mastitis caused by Mycoplasma spp. cannot be cured with intramammary antibiotics.

Bulk tank cultures will alert you to the presence of new contagious pathogens, as well as to changing levels of contagious pathogens in your herd. Frequency of bulk tank culture can vary depending on the known status of the herd with regard to contagious pathogens, and whether new cows are being added to the herd. Monthly bulk tank culturing is the lowest risk strategy, but at least 3 times a year is recommended. Be sure that the bulk tank culture includes detection of Mycoplasma.

Replacement animals that are purchased or raised off-site pose a risk for both biosecurity (introducing new diseases) and drug residues. The best practice would be to collect a milk sample, culture for contagious pathogens and test for drug residues before milking any new animals. At minimum, request a recent bulk tank culture and individual treatment records from the source herd. Additionally, frequent bulk tank culturing for contagious pathogens can help reduce the risk by alerting you to the presence of new contagious pathogens early.

Cows with clinical mastitis should be identified by milkers (see Best Practice: Milking Procedures).

However, up to two-thirds of the infected cows on a dairy will be subclinical, meaning no visible symptoms of mastitis. If bulk tank SCC is above 200,000 (or some other dairy-specific goal), it is necessary to have a program in place to identify subclinically infected cows. Utilizing monthly DHI test data is the easiest way is to identify subclinically infected cows (SCC > 200,000 cells/ml). Many dairies with an excellent milk quality program will examine cows that have had 2 monthly tests in a row over 200,000 cells/ml (or other dairy-specific target), and will take some action to address the infection. Other dairies that do not have monthly test day data may use other tools, like milk culture, the California Mastitis Test, or other cow-side SCC tests, to identify cows that are at high risk of being subclinically infected, such as fresh cows.  

Work with your veterinarian to design mastitis treatment protocols for your dairy. Chronic infections, and infections caused by certain mastitis pathogens are unlikely to cure, even with antibiotic treatment. Mastitis treatment protocols should include some criteria for which cows are eligible to receive treatment, and which do not qualify because of chronic infection or other concurrent problems.

Cows that are infected, but not eligible for treatment should be managed in a way that lessens the risk of transmitting the infection to other cows in the herd. This could include culling, early dry-off, drying off a quarter, or segregating into a high SCC pen and milking last. Highly visible identification of these cows is essential so that milkers can take extra precautions when milking them.

Approximately 20% of quarters are subclinically infected at the time of dry-off, and up to another 20% of quarters may develop a new infection during the dry period. The majority of US dairies utilize blanket dry cow therapy, where every quarter of every cow is treated with a long-acting intramammary antibiotic at dry-off, to treat subclinical infections present at dry off, and to help prevent new infections in the early part of the dry period. In addition, many dairies utilize an internal teat sealant as extra protection against new infections during the dry period.