Veterinarian Dr. Jessica Scillieri Smith, of Quality Milk Services in New York, says when it comes to foul ups in milking systems, there’s usually more going on than just the milking system.
“When we look at the herd to work on problems and trouble-shoot, we like to look at everything,” she said. “If a farmer says, ‘I think it’s the milking system’, more often than not there’s more than one thing going on.”
Smith explained that Quality Milk Production Services started as the New York State Mastitis Control Program in 1946 when the governor of New York was having trouble with milk quality in his own herd. After veterinarians from Cornell determined that streptococcus agalactiae (strep ag) was the problem, the governor decided all dairy farms in the state should have access to the same service. Today, QMPS helps dairy farmers in New York and other states address milk quality issues.
“Mastitis is usually due to a bacterial infection,” said Smith, “but it can also be due to other pathogens such as yeast, molds, fungus and algae. Chemical irritants and other irritations can also be the culprit. The body sends white blood cells to the area to respond to the infection or irritant, and we see that as an increase in somatic cell count (SCC).” Smith says a SCC of under 200,000 is considered healthy, and that a higher count without clinical signs might indicate a subclinical infection in a quarter or the entire udder.
Smith says farms that have SCC issues don’t always see clinical illness. “We have to figure out which cows are infected, figure out why they’re infected and how to manage them appropriately,” she said. “It’s a costly disease for dairy farmers so we want to do everything we can to mitigate that.”
Setting achievable goals for mastitis reduction can help reduce mastitis levels. Reasonable goals can be defined by management, and might include no contagious mastitis, fewer than 2 percent of cows with clinical mastitis and fewer than 5 to 7 percent new or chronic infections.
Although many factors contribute to mastitis, some of those factors can be changed to achieve a solution. The milking routine is one aspect that can be managed for mastitis reduction. “It’s the area we have the most control over,” said Smith. “It also has the most variations. Even if a farm has standard protocols in place, no two people will milk the same way. Cows like things the same every day, they like to know what to expect.” Smith says she has seen that one person milking every day and every milking can compensate for a lot of issues in procedures simply because it’s the same thing every day for the cows.
“There’s no perfect milking routine,” said Smith. “It has to be a routine that is feasible for whoever is doing it. They have to buy into it and agree to do it. If you set a procedure that they don’t like or believe in, they may not do it so the protocol doesn’t matter. It’s all about the people. Hopefully we can find a routine that won’t vary by who’s doing it, and they can all buy into it and do the same thing every day.”
Smith says the milking routine starts when cows are moved. “If the movement is a stressful experience for the cows, they won’t let down as well as if it were a quiet, calm atmosphere,” she said. “If cows are out on pasture, there might be that ‘one spot’ they have to walk through every day. It might be muddy and they run through it, splashing dirt and mud onto their feet, legs and udder. Now there’s dirt and bacteria. If we move cows calmly and quietly, walking not running, we’re starting off on the right foot.”
Good dairy farms have established preparation steps that include disinfection, forestripping, teat-drying, milker attachment within the appropriate time period, alignment, on-time detachment and post-dipping. “Our objective is to dip clean, dry teats,” said Smith. “It’s that simple. You should feel comfortable drinking that milk right from that teat.” The goal is to have as little bacteria on the teat as possible at the time of attachment to prevent the risk of mastitis and reduce bacteria count. Smith suggests occasionally using alcohol swabs on teat ends after prepping to check cleanliness.
“I’m a fan of gloves,” said Smith. “The main goal of wearing gloves is to reduce the risk of spreading disease on our hands. There is no way to get our hands as clean as latex or nitrile gloves – there are too many cracks and crevices.” Another good practice is one towel per cow, whether they’re soft, washable towels or paper.
There are numerous pre-dipping options, and Smith says she prefers foams or dips rather than sprays. “If you pre-spray, wrap a paper towel around the teat to see what kind of coverage you have,” she said. “It’s actually hard to achieve good coverage with spray compared to dip.”
A well-stimulated teat means good oxytocin release. “Forestripping will give the best oxytocin release,” said Smith. “She can feel your fingers on her teats, and her pituitary gland releases oxytocin which goes into her bloodstream. The epithelial cells of her mammary gland contract and release milk, then push it down into the teat cistern.” Smith says that process takes about 60 seconds. Tie-stall milking requires more careful timing simply because isn’t easy to gauge when one unit comes off and goes on the next cow. “Sometimes we prep the next cow too early, and we miss the oxytocin let-down,” said Smith. “If the unit is attached too early, milk-out will take longer.”
The first milk released is what was present at the time of attachment, and accounts for about 10 to 15 percent of the total milk yield. The rest comes from the alveoli that have contracted and pushed milk to the teat. “Because the unit is pulsing, it’s constantly stimulating her,” said Smith. “As long as oxytocin is primed, oxytocin will continue to work throughout the milking. She won’t stop letting milk down unless something happens to interrupt the flow, like being frightened.”
Without good stimulation, bi-modal milk flow can be the result. Smith says this can occur even in cows that are properly prepped. “It’s easy to see if the bottom shell of the claw is clear or if you have the units with a clear, circular window,” she said. “You put the units on, see milk and all of the sudden it’s dry. You wait and wait, then about 30 seconds later milk starts coming again. That’s because you’ve harvested the cisternal milk first, and the oxytocin finally kicked in and the other milk is released. This increases the amount of time the unit is attached, which means higher vacuum at the beginning, and longer to milk out. The way to avoid it is to stimulate properly and time unit attachment carefully.”