Mean background and peak concentrations of δ13C for individual n-alkanes in feces as a mean of four grass silage treatments.

Standard error of the mean given in parenthesis. C34: internal standard. δ13C refers to the relative atom% 13C in the sample relative to the atom% 13C of the international Vienna Pee Dee Belemnite standard.1Difference between δ13C background and peak concentration based on least square means.