Published online by Cambridge University Press: 23 November 2017
NRC (2001) recommended 250 g/kg dietary neutral detergent fibre (NDF) with a minimum of 190 g/kg dietary forage NDF to prevent milk fat depression. This recommendation does not account for the differences in forage particle size. The forage particle size requirements of dairy cows fed barley grain-based diets can differ from those fed maize grain-based diets (Yang and Beauchemin, 2006). The objective of this experiment was to evaluate the effects of lucerne hay and barley grain particle sizes on chewing activity, rumen pH, milk yield and milk composition using barley grain-based diets.