Comparison of faecal crude protein and n-alkanes techniques to estimate herbage intake by grazing sheep

This paper has the following objectives: i) evaluate which of the two techniques, n-alkanes or faecal crude protein (fCP), and their equations had the highest accuracy in estimating DM intake by sheep; and ii) evaluate which ratio option of n-alkanes (C31:C32 or C33:C32) was most accurate in estimating sheep DM intake. The experimental design was a randomised complete block with three replicates (paddocks) and repeated measures on time (periods), arranged in a two-level factorial design, with two stocking methods (continuous and rotational) and two grazing intensities (moderate and low). In general, both the fCP and n-alkanes techniques and equations tested are potential to estimate DM intake by sheep grazing Italian ryegrass, however, the equation proposed by Azevedo et al. (2014) and De-Stefani Aguiar et al. (2013) are the most accurate (lower CV), respectively. The n-alkanes ratio C31:C32 is the more accurate predictor of DM intake by sheep grazing Italian ryegrass pastures.