Methane Emission and Metabolic Status in Peak Lactating Dairy Cows and Their Assessment Via Methane Concentration Profile | Emisija metana i metabolički status mlečnih krava u piku laktacije i njihova procena putem profila koncentracije metana

Abstract Ruminant husbandry contributes to global methane (CH 4 ) emissions and beside its negative impact on the environment, enteric CH 4 emissions cause a loss of gross energy intake in cows. The study is aimed to estimate CH 4 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 CH 4 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 CH 4 enteric emissions, cows were divided into two groups (n=6, respectively): HM (average CH 4 concentration: 5430.08 ± 365.92 ppm) and LM (average CH 4 concentration: 1351.85 ± 205.20 ppm). Following CH 4 measurement, on day 3, venous blood was sampled to determine the indicators of the metabolic status. HM cows had significantly higher average CH 4 concentrations, maximum and average CH4 peak amplitude than LM cows in all measuring periods (P1-P3), while the number of CH 4 peaks tended to be higher in HM than in LM cows in P2. There were no differences in the maximum and average CH 4 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 CH 4 per eructation than LM cows, hence the differences in metabolic status are most likely related to the differences in their liver function.