Comparison of faecal pigments and faecal nitrogen as digestibility indicators in grazing cattle studies

Summary Digestibility data and faecal pigment andnitrogen concentrations are reported for 37 consecutive weekly trials with cows fed cut pasture herbage. The formula of Reid et al. (1952) was in general not satisfactory for predicting dry‐matter digestibility from faecal pigment concentrations. For estimating the feed/faeces (organic matter) ratio, faecal nitrogen, with a prediction error of 8%, provided a more reliable index than faecal pigments (error 11%), the prediction relationship in both cases being curvilinear. However the use of faecal pigments in addition to faecal nitrogen led to a small but significant reduction (to 7%) in the error of prediction.