Producing great-flavored milk is an art. If your farmer is wanting to create more "wow" milk, show him/her this list and offer to help if you can. Maximizing flavor requires dedication and diligence and may require higher milk prices to cover additional costs. Be patient and supportive.
1) Lower those bacteria counts: The lower the counts, the better the milk tastes - period. Udders that are washed but not completely dried are a primary cause of high bacteria counts. "Unclean", "malty" or "acidic" flavors result.
2) Improve the macro nutrient balance: When a cow is in peak form, not coincidentally, her milk will taste the best. Peak form requires exactly the right balance of carbohydrate, protein, and fat. Protein influences the flavor the most. Too much in the diet and the milk will taste grassy. Too little and the milk lacks sweetness.
3) Eliminate mastitis and lower those somatic cell counts: Yes, this can be done! High somatic cell counts (SCC) cause the protein concentration to be low and sodium and chloride ions to be high, giving the milk a salty, or even bitter, flavor.
4) Change the feed type: Feed can affect the flavor of the milk within 30 minutes of ingesting it. "Feedy" or "weedy" smells and flavors usually come from ingesting a lot of strong-flavored weeds, silage, legume hay, or brewer's grains close to milking time.
5) Clean up the barn: Odors travel from the lungs to the blood to the milk, and can affect milk flavor within minutes. "Barny", "cowy", or "musty" flavors come from cows breathing the air in dirty barns. "Chemical" or "metallic" flavors can come from breathing in fly spray or other chemicals.
6) Prevent milk oxidation: A "cardboardy" or "metallic" flavor is produced when the milk gets oxidized. Common causes are lack of vitamin E, especially in winter; copper or iron in the water used for pipeline cleaning; chlorine sanitizers; or feeding too much vegetable fat, such as soybean.
7) Prevent rancidity: Rancidity occurs when milkfat globule membranes are weakened or broken, allowing enzymes to react with the fat and form free fatty acids. Common causes are too little protein in the diet, too little energy in the diet, air leaks in pipeline milkers, over-agitating the milk at any point, or turbulence from sharp turns in the pipeline. This milk will taste "cheesey".
8) Eliminate ketosis: Ketones in the milk produce a highly objectionable, chemical odor and flavor. Manage the protein content of the diet, especially in the spring and after calving.
9) Use the right breed of cow: With protein being a big factor in sweetness, the different protein structures that different breeds have can change the flavor. For instance, Normandes have been bred for superb cheese, making the protein structure of their milk quite different from Jerseys, which have been bred for butter. I would call my Jersey milk "clean sweet" and my Normande milk "candy sweet".
Even when doing everything right, some cows just have milk that is a lot more prone to tasting "cheesey", especially when on hay or late summer grass. This milk often makes really good yogurt, though!