The bacteria that cause mastitis, reflected in the somatic cell count (SCC), multiply faster during summer weather, summer heat can depress a cow’s immune system, resulting in more cases of mastitis or higher SCC and also summer heat and humidity can wear on the people doing the milking. Sometimes corners get cut on milking procedures and protocol. For all these reasons, summer is a good time to review milking practices that help to minimize mastitis infections and keep SCC low.
Moving groups of cows into the holding pen is the first step in the milking process in a parlor system. If cows are stressed during this time, it directly impacts the milking process. Stress is often accompanied by a release of adrenaline. Adrenaline prevents the release of oxytocin, which is necessary for milk let down. Avoid crowding cows in the holding pen, the recommendation is 20 sq. ft/cow. Provide fans and misters to keep cows cool and comfortable. Manage timing to ensure that cows are in the pen less than one hour. Make sure flooring in the holding pen is not slippery. Most importantly, move cows in an out of the holding pen calmly, as quietly as possible, allowing cows to move at their speed and pace.
In the milking parlor, teats need to be cleaned, pre-dipped and fore stripped before the milking unit is attached. Parlor workers should wear nitrile or latex gloves to reduce the risk of mastitis causing bacteria being transferred from the skin of hands to teats. Gloves are easier to disinfect compared to bare hands. Even with gloves, wash hands periodically throughout milking. Cleaning teats should involve wiping with a single service, clean cloth, or paper towel. If water is consistently needed to clean teats, this should raise a flag because often the use of water will result in increased incidence of mastitis and higher bacteria levels in milk. If cows are excessively dirty upon entering the parlor, put more effort into barn, stall and pasture management to increase cow cleanliness in those environments. The goal is for cows to enter the parlor clean so that any dirt can easily be removed with a dry towel or cloth.
Pre-milking dipping of teats is a proven mastitis management strategy. Pre-dipping of teats can immediately follow teat cleaning. To be effective the dip should cover at least ¾ of the total teat area and it needs to remain on the teat for at least 30 seconds before it is wiped off. After the teat dip is wiped off each teat and before the milking unit is attached, strip 3 to 4 streams of milk from each teat. This fore stripping stimulates milk letdown, flushes bacteria from the teat canal and allows for a visual examination of milk to determine if there is any abnormal coloration, flakes or clots which could indicate a mastitis infection.
Fore stripping can be done either before or after the pre-dipping practice. The timing of these practices is important. Attaching the milking unit either too soon or too late can increase milking time and/or reduce milk yield. Oxytocin is a hormone that causes milk letdown and it reaches peak levels 60-90 seconds after the cow is stimulated by handling of the udder. Therefore, teat cleaning, fore stripping, pre-dipping, wiping/drying the pre-dip off the tea needs to occur in a timely manner that allows the milking unit to be attached within 60-90 seconds after the start of those practices.
Managers should schedule periodic maintenance of the milking system with the equipment dealer to ensure correct vacuum level in the milking units and to make sure that pulsators are functioning properly. Liner/inflations should be replaced on a regular basis. Once the milking unit is attached, the key is not overmilking. Overmilking damages teat ends which increases the risk for mastitis infections. Once milk let down stops, the milking unit should be removed, either manually or automatically. The goal is NOT to get every drop of milk removed from the udder. The vacuum should be turned off before the milking unit is removed.
Post-milking management includes post-dipping and the return to the free-stall barn. Studies indicate post-dipping can reduce new infections by at least 50%. To be effective, at least ¾ of the entire teat surface must be covered and the dip must have time to dry on the teat. After milking it takes about 30 minutes for the teat sphincter muscle to close and it can take about that long for the post-dip to dry. If a cow lies down before 30 minutes has passed post milking, there is an increased risk of bacteria entering the teat canal. To keep cows standing after milking it is recommended that fresh feed be made available so that cows are motivated to eat and continue standing after milking.
This is my final column as a Wayne County Extension educator as I retire from the OSU Extension system. My time in Wayne County has been blessed. It was a privilege to work here within the agricultural community. I leave with many fond memories and friendships.
Rory Lewandowski is an OSU Extension Agriculture & Natural Resources Educator and may be reached at 330-264-8722.
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