Methane from Lactating Dairy Cattle: Studies for Mitigation, Diurnal Variation, and Role in Energy Metabolism

Reducing methane production in dairy cattle has received an increased interest due to environmental concerns associated with its potency as a greenhouse gas. Methane represents lost energy in cattle and reduction may increase animal efficiency and productivity. Experiment 1 evaluated strategies of mitigating methane production in lactating dairy cattle with inclusion of dried distillers grains and solubles (DDGS), DDGS with added corn oil, and DDGS with added calcium sulfate and effects on energy and nitrogen balance. Inclusion of DDGS, corn oil, and calcium sulfate, increased DMI and milk yield. Methane production was reduced with addition of corn oil and calcium sulfate to diets containing DDGS and these factors did not negatively affect production. When methane production was reduced, more energy was partitioned to milk production. Compared to zero control, cattle consuming DDGS had greater energy balance while nitrogen balance was not affected. Experiment 2 evaluated effects of increasing linolenic acid on methane production in lactating dairy cattle. Dry matter intake, digestibility, milk production and composition were not affected by increased linolenic acid. Increased linolenic acid did not reduce methane production as hypothesized. Results suggest that altering fatty acid profile has little if any influence on methane production. Furthermore, results suggest that previous observations reporting reductions in methane production were a result of fat content not fatty acid profile. Experiment 3 evaluated effects of feeding frequency (once versus twice daily) on diurnal methane production and energy balance in lactating dairy cattle. Dry matter intake, nutrient digestibility, milk yield and composition were not affected by feeding frequency. Feeding twice daily did not affect total methane production; however, pattern of diurnal methane production was affected with greater methane production observed in the hours following the second feeding. Energy balance was not affected by feeding frequency with observed energy maintenance requirements near 146 kcal/kg BW0.75 and k1 of 0.76. Results emphasize the importance of sampling methane throughout the day to ensure accurate methane production values are obtained. Methane production can be affected by diet and ration-balancing strategies may be a powerful tool to reduce greenhouse gas production in the dairy industry. Advisor: Paul J. Kononof