Effects of Replacing Alfalfa Hay With Barley Silage in High‐Concentrate Diets: Chewing Behavior, Ruminal Fermentation, Total‐Tract Digestibility, and Milk Production of Dairy Cows in Mid‐Lactation Phase

ABSTRACT Limited land or water resources, climate variability, and price fluctuations challenge the consistent availability of alfalfa forage. Barley forage, with high energy and low agronomic costs, shows promise as an alternative in dairy diets. Our objective was to examine the effects of replacing alfalfa hay with whole‐plant barley silage on behavioral patterns, ruminal fermentation, nutrient digestibility, and lactation productivity. A 3 × 3 Latin square design was employed, involving 12 multiparous Holstein cows (days in milk = 122 ± 6; milk production = 49.3 ± 2.0 kg; mean ± standard deviation). Alfalfa hay was partially or completely substituted with barley silage as (1) a control diet without barley silage (BS0; 23.2% corn silage + 15.6% alfalfa hay), (2) 23.2% corn silage + 7.8% alfalfa hay + 7.9% barley silage (BS50), and (3) 23.2% corn silage + 15.7% barley silage + 0% alfalfa hay (BS100). Dry matter intake was the greatest in BS50‐fed cows (27.3 kg/day) and lowest with BS100‐fed cows (24.4 kg/day). Time spent eating, ruminating, and chewing was not different across treatments. BS50‐fed cows had the highest propionate concentration and the lowest acetate and valerate concentrations. Cows fed BS50 and BS100 had lower starch digestibility than BS0. Milk production was not different between diets, but feed efficiency was the greatest with BS100‐fed cows, resulting in the highest income over feed cost estimated in this group. Overall, barley silage can replace alfalfa hay in high‐concentrate diets fed to mid‐lactation cows, as its total replacement improved the efficiency of feed conversion into milk.