Methane Emission and Metabolic Status in Peak Lactating Dairy Cows and Their Assessment Via Methane Concentration Profile

Ruminant husbandry contributes to global methane (CH₄) emissions and beside its negative impact on the environment, enteric CH₄ emissions cause a loss of gross energy intake in cows. The study is aimed to estimate CH₄ emission and metabolic status in dairy cows via the methane concentration profile as a tool for analyzing the CH4 production pattern. The study included eighteen cows whose enteric CH₄ emission was measured during three consecutive days in three periods: 2 hours before (P1), 2–4 hours (P2) and 6–8 hours (P3) after the morning feeding. Based on CH₄ enteric emissions, cows were divided into two groups (n=6, respectively): HM (average CH₄ concentration: 5430.08 ± 365.92 ppm) and LM (average CH₄ concentration: 1351.85 ± 205.20 ppm). Following CH₄ measurement, on day 3, venous blood was sampled to determine the indicators of the metabolic status. HM cows had significantly higher average CH₄ concentrations, maximum and average CH4 peak amplitude than LM cows in all measuring periods (P1-P3), while the number of CH₄ peaks tended to be higher in HM than in LM cows in P2. There were no differences in the maximum and average CH₄ peak width and average distance among two CH4 peaks between examined groups of cows. HM cows had significantly higher total protein concentrations and significantly lower total bilirubin and NEFA concentrations than LM cows. In conclusion, HM cows have a greater number of eructations and release more CH₄ per eructation than LM cows, hence the differences in metabolic status are most likely related to the differences in their liver function.