Controlling milk somatic cell count levels

This paper explores the direct connection between various dairy management issues and their potential impact on SCC and milk quality.

The somatic cell count (SCC) is important to dairy producers both because counts that are too high can lead to poor quality or even unsaleable milk and SCC can be used to monitor mastitis incidence in the herd. In addition, SCC is frequently used to determine quality payments to dairy producers. While most people immediately think about mastitis control when tackling an SCC problem, other aspects of dairy management need to be considered. Dairymen and milkers need to understand the direct connection between these various management issues and their potential impact on SCC and milk quality.

Many mastitis control articles deal with proper milking procedure and managing existing infections. Controlling mastitis will reduce somatic cell counts. Basic mastitis control involves maintaining a properly functioning milking system, milking cows whose teats are clean and dry, attachment and removal of the milking units with a minimum of air being admitted, and prompt removal of the milking cluster when the milk flow reaches a low level.

To develop a comprehensive mastitis management program, producers must go beyond proper milking procedures and dry and lactating cow treatment. A number of factors will influence the rate of new infections that will, in turn, influence the somatic cell count.

Make sure that both cows and waterers are clean.

A dirty environment will lead to a build up of environmental bacteria. High levels of environmental bacteria will increase chances of opportunistic udder infections.

Removal of udder hair.

Long udder hair allows dirt, water, and bacteria to accumulate on the udder. These can enter the liner during milking and lead to mastitis. They may also enter the bulk milk and contribute to raw milk bacteria counts.

Clean free-stalls.

A common rule-of-thumb is to kneel in the stall beds. If the knees of your pants aren’t dry when you get up, the stalls aren’t clean enough. In addition, some bedding sources may harbor large numbers of bacteria. Very fine powdery forms of bedding tend to support high levels of bacteria growth because of the large surface area they provide. Green sawdust bedding for example has frequently been associated with Klebsiella mastitis problems. Culturing your bedding sources and/or working with local mastitis control experts can help remove this source of environmental bacteria. Changing free-stall bedding frequently and using more bedding might also be helpful in reducing environmental bacterial loads.

Daily checking of dry cows for evidence of clinical mastitis.

Dry cow therapy is much more effective than antibiotic therapy during lactation.

Clean those dry cow pens.

A cow’s immune function is at its lowest around the time of calving. Make a habit of kneeling in dry, pre-fresh and calving pens. If you come away with dirty and/or wet knees, start cleaning more frequently and consider using more bedding.

Pay special attention to calving pens.

When a cow is calving, both her udder and reproductive tract are open to the environment. Add in the fact that her immune system isn’t functioning very well and you will understand why udder and uterine infections are common at calving. Ideally, every cow should calve in a clean, freshly rebedded pen.

Disinfecting calving pens between cows is even better. The best way to disinfect a calving stall is to clean it and leave it unbedded and unoccupied for a day or so. Most disease causing bacteria aren’t able to tolerate exposure to light, air, and drying conditions. On many dairies, leaving a calving pen unoccupied for even 24 hours isn’t practical. In these cases, disinfectants or even hydrated lime can help. Keep in mind that organic matter (manure & bedding) will reduce the efficacy of your disinfectant, so you may need to increase disinfectant concentrations. Don’t ignore this idea because it is difficult to implement, work with your herd veterinarian to develop a plan that works for you.

Remember that milk let-down and loss of the cervical plug can happen well before active labor. If your standard protocol is to move cows into the calving pen when the calf’s feet are visible, you will need to consider the cleanliness of the pen from which she is moved, also.

Increase cleanliness of milking parlors.

Dirty pulsators and vacuum controllers can malfunction and cause teat-end damage which will, in turn, lead to increased rates of new infections. Also, any time liner slips occur, milk and any bacteria present can be propelled through the teat end into the udder. By maintaining the highest possible levels of cleanliness, the bacterial load in the milking parlor will be minimized. This will reduce the chances of infection occurring during the milking process.

Don’t overlook milking personnel as a possible source of bacterial contamination that could lead to mastitis. Anyone who works on other livestock operations should change clothing and wash arms and hands thoroughly (better yet, shower) before milking your cows. Encouraging milkers to wear gloves while milking has also been shown to reduce exposure to bacteria. Remember to encourage the milking crew to change gloves as soon as they become soiled.

Fresh cow milk held from bulk tank longer.

Milk from fresh cows is generally higher in SCC. Witholding this milk from your bulk tank can reduce tank SCC, but may not be economically feasible or practical. In addition, milk from a fresh cow that has no problems will typically have a cell count of 300,000/ml or less within 5 days of calving providing she has no infection problems. It is not very practical and tends to be economically non-viable to hold out milk from fresh cows beyond the standard 72-96 hours post-calving depending on the dry cow product used.

Consistency among milkers in post-milking teat dip use.

A consistent post-dip program will pay dividends in mastitis control. With turn-over on dairy crews, it is very easy for milking procedures to change without management’s knowledge. Many dairies now post standard operating procedures for the milking crews. It describes how to prep cows, attach units, remove units and apply post milking teat dip. It also details the need to wear gloves and when to clean and sanitize the hands. This approach helps everyone understand what is expected and helps remove inconsistencies associated with different people and crews.

Consistent dry cow treatment program for all cows.

Dry cow antibiotic treatments are one of the most effective ways to eliminate existing infections. Treating during the dry period is 80-90% effective in eliminating infections, while treatment during lactation is only 30-40% effective. This is because antibiotics designed for dry cows can be formulated to provide higher levels of antibiotic activity over longer periods of time without worry about milk residue.

When administering dry cow treatments, make sure that teat ends are thoroughly scrubbed with cotton-alcohol pads. Otherwise, dry cow treatments can end up introducing large numbers of bacteria into the udder and causing more harm than good.

Some research has shown benefits in using dry cow treatments on heifers. If mastitis in fresh heifers is a problem on your herd, discuss antibiotic treatment of heifers with your veterinarian.

Teat sealant should also be considered as part of dry off treatment procedures. After the teats have been infused with dry cow antibiotics teat sealant should be applied to help seal off the teat end to prevent environmental bacteria from entering during the early dry period.

Solid, consistent nutritional program for springing heifers, as well as for dry and lactating cows.

Springing heifers should go through the herd pre-fresh program to ensure proper nutrition prior to calving. A solid nutrition program, with special attention to vitamin and mineral nutrition, will improve the overall function of the immune system.

Low stress environment for all cows.

Stressed cows have higher levels of hormones that suppress immune function in their blood. Good cow comfort, appropriate cow handling procedures, and sufficient stall, water, and feed space can go a long way towards reducing the stress levels of a herd. A herd with lower stress levels will have better immune function.

Authors

F.A.R.M.E. Institute

F.A.R.M.E. Institute

FARME Institute's goal is to provide top quality, client-oriented, independent and confidential research and product development in ruminant nutrition.

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