– Dietary changes can negatively affect digestive processes, particularly at ruminal level and mainly when rapid and associated with an increase of fermentable carbohydrates (Owens et al., 1998). Milk quality can also be affected by digestive functionality (Bertoni et al., 1992). Excesses of degradable N boost blood and milk urea levels but these latter parameters are also influenced by the amount of escape protein fed, the aminoacid profile of absorbed protein and the energy availability (Westwood et al., 1998). Some field experiences indicated increases of milk urea after reformulation of diets to change some ingredients,......