Effects of Incremental Dietary Levels of Ground Flaxseed on Milk Production, Ruminal Metabolism, and Enteric Methane Emissions in Organic Dairy Cows

Ground Flaxseed (Linum uitatissimum) is a lipid supplement that is commonly fed to dairy cows. It is believed that supplemental lipid can change the Fatty Acid (FA) composition in the milk, and decrease methane production. Twenty lactating organic Jersey cows, housed at the UNH Organic Dairy Research Farm (ODRF), were randomly assigned to five replicated 4 × 4 Latin squares to investigate the effects of increasing dietary levels of ground flaxseed (0, 5, 10, or 15% of the diet dry matter) on animal fperformance (e.g., dry matter intake, milk production, milk composition), ruminal metabolism, and enteric methane emissions. Each period lasted 21 days with 14 days for diet adaptation and seven days for data and samples collection. Cows were fed twice daily (a.m. and p.m.) a total mixed ration containing 65% grass-legume baleage, and one of the following supplemental mixturess: • 0% ground flaxseed, 27% corn meal, and 8% soybean meal • 5% ground flaxeed, 24% corn meal, and 6% soybean meal • 10% ground flaxseed, 21% corn meal, and 4% soybean meal • 15% ground flaxseed, 17.5 corn meal, and 2.5% soybean meal. Feeding incremental dietary levels of ground flaxseed resulted in linear decreases of dry matter intake, yields of milk and milk components, ruminal molar proportion of acetate and butyrate, and enteric methane emissions. However, the molar proportion of propionate increased linearly with feeding incremental dietary levels of ground flaxseed. Further research is needed to investigate the long-term effects of ground flaxseed on milk yield and animal health.