Rumen function and grazing behavior of early-lactation dairy cows supplemented with fodder beet

Fodder beet (FB) is a source of readily fermentable carbohydrate that can mitigate early spring herbage deficits and correct the negative energy balance experienced during lactation in pastoral dairy systems New Zealand. However, low-fiber high-soluble content both FB bulb are factors promote subacute ruminal acidosis, impairing rumen function limiting marginal milk production response to supplement. In crossover experiment, 8 Holstein Friesian × Jersey early-lactation cows were used test effect supplementing 16 kg dry matter (DM) grazed perennial ryegrass with 6 DM/d (FBH) versus only (HO) on changes grazing behavior. Following 20 d adaptation diets, DM disappearance (%) (FBH only) measured sacco, separately. Cows fasted overnight, contents bailed following morning (~0930 h) again determine pool size volatile fatty acids, ammonia, particle digesta, as well estimate rate outflow degradation neutral detergent fiber. The FBH diet did not alter intake, yield, or solid (fat + protein) compared HO. Supplementation reduced pH HO between ~0800 h 1300 each day. During period, 1 cow severe acidosis (pH <5.6 for >180 min/d) final target allocation. acetate but increased butyrate lactate When fed FB, rumination time intensity declined Despite rumination, comminution large particles 28% first second bailing when sacco 18% These results indicate supplemented (40% daily intake) increase mastication counteract due low fluid pH.