Estimation of pasture herbage intake by beef cattle based on n-alkanes as markers

The aim of the study was to evaluate herbage dry matter intake in 16 beef cows which grazed continuously on permanent pastures within the “The Warta Estuary” National Park (Poland), using the minimally invasive method based on n-alkanes as markers (C29, C31, C33). Significant differences were observed in the nutritive value of herbage collected for analyses by cutting or nipping. The calculated content of energy and protein in the nipped herbage was higher: UFL by 58.1% and PDI by 50%, with a higher digestibility of nutrients. The values obtained for DM intake in pasture herbage by cows were closest to the standards when calculations were based on the C29/C32 pair of n-alkanes. However, the best prediction of DM intake estimation from creeping bentgrass (Agrostis stolonifera) pasture, in agreement with the accepted energy and protein standards, was based on the proportions between alkanes C31/C32