Comparing Individual Grass Intake of Dairy Cows in 3 Grass‐Based Systems Using 3 Methods: Automated Weighing Bins, Net Energy Evaluation, and n‐Alkanes

ABSTRACT Estimating fresh grass intake of grazing cows is important for effective management, but direct measurements are inherently difficult in grazing systems. Therefore, this study compared 3 methods to estimate fresh grass intake of dairy cows: automated weighing bins (Roughage Intake Control; RIC), net energy evaluation (VEM), and n‐alkanes. A grazing trial was performed in 3 periods with 3 different grass‐based systems: restricted zero‐grazing (ZG), restricted grazing (RG), and unrestricted grazing (UG). For the VEM method, energy requirements and intake and VEM content of grass were used. For the n‐alkane method, C32 and C36 were supplied to the cows, and faecal samples were collected. For ZG cows, RIC indicated a higher fresh grass DMI (9.6 kg cow −1 day −1 ) compared with VEM (9.3 kg cow −1 day −1 ) and n‐alkanes (8.4 kg cow −1 day −1 ). For all groups and periods, VEM resulted in a higher DMI (11.2 kg cow −1 day −1 ) compared with n‐alkanes (9.6 kg cow −1 day −1 ). Methods did not show high correlations, but differences in the estimation of DMI were relatively small. With the n‐alkane method, intake is estimated via natural markers, reflecting environmental and behavioural factors for grazing cows, possibly giving a better reflection of individual variation in grazing behaviour among cows compared with VEM. Concluding, either the VEM method or the n‐alkanes method may be used to estimate fresh grass DMI of individual dairy cows grazing in groups, depending on the study context.