Evaluating whole flaxseed and flaxseed meals as energy and protein sources for high-producing dairy cows

点击翻译按钮获取中文摘要

Canada produces about 40% of world flaxseed production, with Saskatchewan accounting for 60% of this production. About 80% of flaxseed that is produced in Canada is exported, with the remainder being processed locally. Flaxseed is traditionally processed using solvent extraction to extract the oil, with flaxseed meal being produced as a byproduct. A small proportion of flaxseed is processed by using expeller processing (also termed cold-pressing), with cold-pressed flaxseed meal being produced as a byproduct. The primary market for disposal of these byproducts will be dairy herds in western Canada. Typically, whole flaxseed contains 42-46% oil and 21% protein, making it a good supplement for dairy cows because of its high contents of energy (oil) and protein. Flaxseed meal contains greater levels of protein (31-33%) than whole flaxseed, making it a rich source of essential amino acids for dairy cows. Cold-pressed flaxseed meal contains greater amounts of residual oil (7-14%) than solvent-extracted flaxseed meal (<1%), so the higher residual oil would increase energy density when cold-pressed flaxseed meal is included in the diet. Flaxseed oil is high in polyunsaturated fatty acids (PUFA) such as linoleic and linolenic acids. These PUFA yield desirable intermediates during rumen biohydrogenation, known as conjugated linoleic acids (CLA). These CLA have numerous health benefits in humans, including reduced inflammatory response, improved immune function, and prevention of cardiovascular diseases and cancer. Milk products from dairy cows that are fed flaxseed or flaxseed meals can be enriched in CLA, thus making these value-added milk products more appealing to health-conscious consumers. Also, flaxseed is a rich source of lignans, which are converted to bioactive compounds (primarily enterolactone) in the digestive tract that can be transferred into milk after absorption. When consumed in milk, these bioactive compounds can reduce the risk of cardiovascular disease. The proposed research will investigate how inclusion of whole flaxseed, and solvent-extracted and cold-pressed flaxseed meals in dairy cow diets influence milk production, and milk fatty acid and enterolactone profiles.