Effect of Fat and Fiber on Methane Production and Energy Utilization in Lactating Dairy Cows

Due to rising concerns of greenhouse gases and that ruminants are the largest livestock methane producers, an emphasis has been put on developing methane mitigation strategies to reduce methane emissions in ruminants. Other than reducing methane, maximizing the energy utilization of cattle is also important for producer’s overall productivity and profitability. In the first experiment, fat or cellulose was added to fiber isolated from dried distiller’s grains and solubles. Isolated NDF residue from an in vitro setting was fermented 1) alone (control); 2) with feed grade corn oil at 20%; or 3) with cellulose powder microcrystalline at 20% using the in vitro gas production technique. Results suggested that the addition of oil or cellulose to NDF residue resulted in a decrease or no effect on methane production and total gas production, respectively. These observations further suggest that diets may be manipulated to mitigate methane from ruminant livestock. A second experiment was conducted using, eight multiparous, lactating Jersey cows in a twice replicated 4 × 4 Latin square using a headbox type indirect calorimetry to determine the effects of feeding different concentrations of fat and hemicellulose on energy utilization and methane production. For fat concentration manipulation, tallow was included at either approximately 0 or 2 % of the diet DM. For hemicellulose concentration manipulation, the inclusion rates of corn silage, alfalfa hay, and soybean hulls were changed and resulted in diets containing either 11.3 % or 12.7 % hemicellulose (DM basis). The factorial arrangement of the treatments were both high and low fat and hemicellulose (LFLH, LFHH, HFLH, and HFHH). Results suggest that methane production was not affected by treatment however methane produced per unit of DMI tended to decrease with inclusion of fat. Fiber digestibility improved with increasing concentration of hemicellulose. Methane per unit of digested NDF tended to decrease with increasing concentration of hemicellulose. Energy utilization overall was improved as net energy of lactation was improved with increasing hemicellulose in low fat diets. Advisor: Paul J. Kononof