All milking equipment, lines, and utensil surfaces that come into contact with milk or dirt or manure must be thoroughly cleaned and sanitized before the next milking. Bulk milk tanks also must be cleaned after each milk pickup. and sanitized before the next milking. The purpose of cleaning is to remove milk soils, organic and mineral solids that form on equipment surfaces after the milk is removed. The purpose of sanitizing is to kill residual microorganisms present on these surfaces immediately prior to milking. Inadequate or improper cleaning or sanitizing or both allows bacteria to remain on equipment surfaces and to grow and multiply. This results in elevated bacteria counts in milk

Well managed dairy herds with low somatic cell counts (SCC below 200-300,000) often may experience problems with onsets of clinical mastitis. Approximately 40-45% of the mastitis cases in low SCC herds are caused by environmental pathogens which can be difficult to detect because of their short duration. Cows in low SCC herds are most susceptible to environmental streptococci and coliform infections after drying off and just prior to calving but which appear in early lactation.

With the price of milk and the cost of milk production where they have been the past few years, tight control over dairy management decisions will make a significant impact upon farm returns. One decision which will improve profitability is to cull problem cows. A dairy farm's goals should include: (1) Maintaining profitable levels of milk production based upon sound feeding, breeding, and management programs; and (2) An effective herd health program to reduce losses from mastitis and other cow disorders. On most dairy farms, annual culling rates exceed 30-35% of the herd. According to December 1998 DHI summary for Virginia, 36% of all cows enrolled in Virginia's DHI program were culled. 

A herd whose bulk tank somatic cell count exceeds 200,000 or DHI SCC score is above 2.5-3.0, or a herd where more than 3 cows per 100 cows show clinical mastitis over a month's time has a costly mastitis problem because of significant lost milk production and reduced economic returns. Herds with elevated SCC may not have many cows that are clinical, but subclinical mastitis infections may cause permanent destruction of milk secretory cells with permanently lower milk producing ability. In other herds, short duration environmental infections may not have great impact upon SCC, but these cows also have depressed milk yields, and considerable milk may be discarded because of antibiotic treatments. Consequently, dairy herds are losing money through greater culling, increased labor intensity, and greater risk of shipping milk that may be contaminated with antibiotic residues.

The presence of drug or antibiotic residues in milk and meat is illegal. Milk supplies containing detectable concentrations are not acceptable. Unless drug residues are avoided to protect milk's reputation as a healthy, safe food, the market becomes jeopardized. Consumers want to be confident that their food supply is free of contamination by herbicides, pesticides, drugs, or antibiotics. Approximately 5-10 percent of the population is hypersensitive to penicillin or other antibiotics and suffers allergic reactions (skin rashes, hives, asthma, anaphylactic shock) at concentrations as low as 1 ppb penicillin. There is concern that small amounts of certain antimicrobial agents may significantly shift the resistance patterns in the microbial population in the human intestinal tract.

Preventing drug contamination of milk and meat is the responsibility of every farm. Drug residues can be avoided by a well planned drug use program. There is no way that a milk plant can use contaminated milk. The sale of contaminated milk or meat will cause the responsible party to be subjected to severe penalties, including suspension of permits and monetary loss. Milk with drugs can adulterate a whole truckload or holding tank of milk.

According to the National Mastitis Council, using FDA-approved intramammary antibiotics at drying off can decrease the number of existing mastitis infections and prevent new infections during the early weeks of the dry period. Dry cow therapy has the following advantages over lactation therapy: a) The cure rate is higher than that achieved by treatment during lactation, b) A much higher dose of antibiotic can be used safely, c) Retention time of the antibiotic in the udder is longer, d) The incidence of new infections during the dry period is reduced, 

Samples of bulk tank milk are collected regularly and milk quality tests are performed by milk coops, plants, or Virginia Department of Agriculture and Consumer Services. Some milk coops offer bulk tank profiles which involve several tests related to milk quality. The various tests are briefly described below, as well as a list of goals for high quality milk and conditions which adversely affect test results. Hopefully, an explanation of the use of these tests will help Virginia dairy farmers produce high quality milk, which has been defined by the Extension Milk Quality Leadership Council as milk with:

The goal for any dairy farm should be to deliver a high quality product that has consumer appeal. The objective of any heards milk management program should include: (1) maximise yield secreted by the mamary gland, (b) milk cows out in a short peroid of time, (c) prevent damage to teats, teat ends, and the udder, and (d) have no adverse effect on chemical composition of milk. It must be recognized that factors other than milking equipment, such as milking practices, can influence milking performance and quality.