Reduction of Methane Production from Dairy Cows by Decreasing Ruminal Degradability of Concentrated Ingredients

Abstract

Enteric fermentation by the global population of ruminant livestock is the largest single contributor to anthropogenic methane (CH4) emissions. CH4 gas produced in the rumen represents a significant loss of gross energy of 2-15 % from feed. To clarify the effects of ruminal degradability of protein (soybean meal or extruded soybean meal) and carbohydrate (whole steam-rolled corn or whole steam-rolled barley) sources on CH4 production, three lactating Holstein cows were fed four different treatments in a 3 x 4 Youden square experiment. Each cow was assigned one of four dietary treatments (2 x 2 factorial). The effect of the dietary treatments was not significant for milk yield, the mean for which was 22.9 kg/day. CH4 production was highest for cows fed on soybean meal and barley, which was 22.3 g/kg-Dry matter intake. It was lowest, 19.4 g/kg-Dry matter intake, for cows fed on extruded soybean meal and corn. Cows fed on extruded soybean meal tended to produce 0.9 g/kg-Dry matter intake, or 5% less CH4 gas than those fed on soybean meal (p<0.1). Cows fed on corn produced 1.9 g/kg-Dry matter intake, or 9 % less CH4 gas than those fed on barley (p<0.05). The degradability of Italian ryegrass hay in the rumen of cows fed on soybean meal tended to be higher than that of cows fed on extruded soybean meal. The results suggest that CH4 production from lactating dairy cows is associated with ruminal degradability of protein and carbohydrate sources.