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Remember the Basics for Best Milk Quality
This article was first printed in the Sept/Oct 2008 issue of the Organic Broadcaster, published by the Midwest Organic and Sustainable Education Service.
Maintaining high milk quality is one of the key management goals of any dairy, organic or not. Organic milk marketing companies demand and generally compensate for the highest quality raw product. This strict emphasis on quality assures consumers that their organic dairy products will taste—and be—clean and healthy. Many factors, biological as well as mechanical, contribute to the quality of raw milk. Beginning and experienced dairy farmers will benefit from understanding and carefully managing significant contributors in order to consistently produce a clean, quality product.
An organic dairy farm is a unique agricultural enterprise in that it connects a biological system (soil, pasture, herd, and cow) to a mechanical system (milking machine, drip lines, and bulk tank). A successful organic dairy farmer must focus on building the health of the biological system, maintaining the efficiency of the mechanical system, and managing the intersection between the two. The diagram illustrates this concept. Problems can occur at any point, often at multiple points, which can impact either system or both.
Diverse Causes for Poor Milk Quality
A cow, as every organic dairy farmer knows, is not a machine. Conventional dairy producers may “fix” some problems in milk quality by routinely administering antibiotics. But, under the National Organic Program (NOP), an organic dairy farmer is not allowed a quick fix for what is ultimately a systemic problem. He or she must consider the overall health of the farm as well as the specific condition of a cow and/or the herd. Proper management of the biological system before milk even enters into the mechanical system is crucial to producing the highest quality raw milk.
The NOP has not set a maximum allowable somatic cell count (SCC). However, individual marketing companies will often have a maximum allowable SCC level (Organic Valley/CROPP, for example, requires a level of less than 400,000 somatic cells per milliliter of raw milk). Somatic cells are white blood cells; they are produced in the bone marrow of a cow when her immune system is under stress and she is vulnerable to bacteria infection or already has an active infection. Somatic cell count is thus a measure of cow/herd health and of biological system health, as well as of milk quality. Unlike bacteria, somatic cells do not reproduce themselves, nor are they prevented or reduced by clean milk lines and a cold tank. A high somatic cell count will stay the same from the time the milk leaves the cow’s body until it arrives in the bulk tank. (The milking claw is the only part of the mechanical system that may contribute to HSCC because it comes into direct contact with the cow’s body.)
Treatments for High Bacteria Levels
Stress Leads to High SCC
Everything on an organic dairy farm, including cow health, begins (and arguably ends) with soil health. According to Gary Zimmer, author of The Biological Farmer and owner of Midwestern Bio-Ag, healthy soils result in nutrient dense forages, higher quality proteins—and healthier cows. Balanced rations are crucial and the higher quality forage, the less grain is required. Too much concentrated protein, as in a heavy grain diet, burdens the digestive system, challenges the immune system, and can lead to a HSCC. Soil deficiencies can also lead to mineral deficiencies in the herd and contribute to stress. ii
In addition to the quality of food, the manner of food intake is also important for supporting herd health. Cows were built to walk around and eat grass; and, to minimize stress, they need room to roam, graze, lie down, and interact with one another. According to the NOP, organic cows must have “access to pasture.” Managed intensive grazing techniques have been successful in maximizing resources and improving pasture while maintaining herd health. The NOP does not make specific mention of stocking numbers, however, so observation is required to make sure crowding does not contribute to stress. All organic dairy herds have their own dynamic, and introducing new cows and/or heifers (even in a closed herd) will upset the pecking order. The herd will need enough space to make the adjustment. SCC may be slightly higher during these periods; this is expected and usually temporary, but should still be monitored.
Managing the Physical Plant
However, even the cleanest, coolest barn (or milk parlor, or even pasture) may harbor an unseen menace that can stress cows: stray voltage. Cows are extremely sensitive to electricity. A conscientious organic dairy farmer, who has taken steps to provide the best quality feed, water, housing, and habitat for cows but is still seeing higher than acceptable somatic cell counts, should call the power company to have tests run for stray voltage (stray voltage monitors can also be purchased). Although solving a stray voltage problem can sometimes require a large investment, if the barn/parlor/equipment/waterers have to be rewired and electrical outlets properly grounded, a healthy herd producing quality milk should make the time, effort, and money worthwhile.
A healthy, productive herd is the first step to producing the best quality raw milk. But it is not the last. The milking process itself, where the biological and mechanical systems intersect, is very vulnerable to contamination. Even if the farm is healthy, the biological system is harmonious, and the somatic cell count is at a minimum, carelessness or lack of cleanliness during milking can result in unacceptable levels of bacteria or foreign material in the milk. A cow’s udder and teats should be clean and dry prior to milking. Louise Hemstead, Milk Quality Manager of Organic Valley/CROPP recommends using water with a mild sanitizer to wash, and environmentally friendly individual paper towels to dry, rather than re-usable cloths. Several pre-dips and post-dips are also acceptable under the NOP rule and can be particularly effective for a cow who is struggling with mastitis. Because the milking process is the only part of the mechanical system that can directly impact cow health, it is crucial to take steps to prevent the spread of bacteria. It is also important during this process to not over-milk. Some organic dairy farmers use a computer that senses when let-down is over and will automatically shut- off the milking machine. For the cows, this takes getting used to—but a computer is very consistent and, while cows are not machines, they do prefer knowing what to expect. Mechanizing this aspect of the process may allow a farmer to add another cow during milking and/or may reduce the stress of having different hired hands with different (for better or worse) milking techniques.
On to the mechanical system
Prevention is the key—because bacteria, even bacteria that do not survive pasteurization, can change the composition, consistency, flavor, and quality of raw milk. All milking equipment should be cleaned with a forceful rinse cycle to remove soil, followed by a caustic wash to break down fats and proteins, a short rinse to avoid dilution of chemicals, and then an acid wash. This should be followed by a final sanitizing step. It is crucial when cleaning milk lines that the water temperature be at least 140°F (fat is soluble at this temperature and easily removed). The temperature, duration, and concentration of wash cycles will vary depending on the capacity of the water heater, the size of barn/parlor and length of lines, and the chemical supplier recommendations.
Cooling is also essential to prevent bacteria growth. Hemstead states that “the speed with which the milk drops below 38°F has a direct relationship to all types of bacteria counts.” Milking parlors and barns with more than 80 cows generally have cooling plates that drop the temperature as soon as the milk leaves the cow; for smaller barns in-line cooling is not practical and the bulk tank is the primary source of cooling. The tank should be turned on as soon as milking begins so that cooled, stored milk will decrease the temperature of incoming milk. Hemstead also recommends beginning agitation “at the onset of milking when a reserve of milk is in the tank” because this prevents stratification of milk (warm milk will stay at the top). The transfer of temperature will also reduce cooling time. Proper maintenance of equipment, from temperature gauges to tank seals, will help to ensure efficiency and functionality of the mechanical system and will keep raw milk clean for pick up.
Organic consumers may not know everything that goes in to producing that cool, refreshing glass of milk, the creamy, delicious yogurt, or a slice of savory cheese; but they understand that behind the organic dairy product is an organic dairy farmer with an approach to milk production that is compatible with their values. For many people, the image of happy cows in a green pasture (which appears on almost every dairy product in the grocery store) is completely meaningless unless it is accompanied by the USDA Certified Organic label. For dairy farmers beginning or transitioning to organic production this may seem like a huge responsibility—and it is, because the organic label is more than just a marketing tool, it is also a promise. It’s a promise to take good care of cows, to make sure they have appropriate food, shelter, and herd interaction and to keep stress to a minimum. It’s a promise to be a good steward of the environment and to preserve and build natural resources like soil, water, and plant diversity. It’s a promise to make sure that milk is clean, free of unwanted flavors, sediment, unacceptable bacteria levels, or high somatic cell counts. And it’s a promise to do all of this without using pesticides, GMOs, hormones or antibiotics—because clean milk is good milk.
ii. Poor soil will also have more weeds, which may lead to off flavors in raw milk. Louise Hemstead, in her chapter on milk quality in Organic Dairy Farming, edited by Jody Padgham, warns that raw receiving standards call for the rejection of tankers with off flavors caused by malt, garlic, fresh grass, sulfur, alfalfa and weeds. Avoid abrupt ration changes.
iii. For a guide to what specific problems different test results may indicate see Hemstead’s “Farm Milk Quality” in Organic Dairy Farming.
Bridget is a teacher, writer, mother and long-time supporter of sustainable and organic agriculture.Return to TOP