Feed intake, milk production, and nutrient use efficiency with early lactating Norwegian Red dairy cows fed concentrates with varying levels of local ingredients

• Alkalised barley is a valid non-protein nitrogen alternative to soya protein. • Alkalised barley improves feed use efficiency compared with urea-treated barley. • Ingredient pre-pelleting structure affects starch digestibility of concentrates. We evaluated the effects of replacing imported soya protein and carbohydrate ingredients in concentrate feeds with alkalised barley in dairy cow diets with grass silage as a basal diet. Eight multiparous early lactation Norwegian Red dairy (NRF) cows with an initial daily milk yield (MY±SD) of 30.5 ± 5.94 kg were used in a 4 × 4 replicated Latin square design experiment of four 35-day experimental periods. Four roughly isonitrogenous and isoenergetic diets were included: a positive control with a higher share of imported ingredients, including soya as a protein source (Soya-F), two concentrates including alkalised barley (Alka-diets), differing in pre-pelleting particle size (i.e., Alka fine = Alka-F, and Alka coarse = Alka-C), and a negative control with the same basal ingredients as the Alka-diets but with untreated barley and added feed-grade urea replacing the alkalised barley (Urea-F). Grass silage was offered ad libitum and concentrate requirement for individual cows was calculated based on Soya-F. The Soya-F was then quantitatively replaced by the other three concentrate feeds. Feed intake, nutrient digestibility, milk production, nutrient use efficiency, and serum metabolites were measured. Replacing Soya-F with Alka-diets did not affect feed intake, digestibility, and milk production. However, Alka-diets supported a greater milk yield than Urea-F, which in turn improved feed utilisation efficiency for Alka-diets without altered N efficiency. A coarser pre-pelleting structure of Alka-C resulted in a lower starch digestibility compared to Alka-F. In conclusion, alkaline-treated barley has the potential to replace soya in concentrates for NRF dairy cows without compromising production efficiency.