Flaxseed, also known as linseed, is an excellent source of the essential omega-3 fatty acid, linolenic acid. Information is limited on feeding flaxseed to lactating dairy cattle, but generally the amount of seed should be limited to provide less than a pound of added vegetable oil per cow per day. Flaxseeds contain about 42% fat. Most studies fed diets that contained 7 to 10% flaxseed, which is greater than the upper oil limit of 1 lb. The seed should be cracked to increase digestibility and to minimize the passage of whole flaxseed from the digestive tract into the manure.