Chemical drying agents for alfalfa hay: effect on nutrient digestibility and lactational performance

Effects of chemical drying agents for hay on plasma profile, lactational performance, and nutrient digestibility by cows were studied. First-cutting alfalfa (late bud) was harvested as hay and treated when cut by applying untreated control, a commercial drying agent (7.64 kg/ha), or a mixture of active ingredients, potassium carbonate and sodium carbonate (7.47 kg/ha). Six multiparous Holstein cows (120 to 150 d postpartum) were fed diets (two cows per treatment) containing 55% hay and 45% concentrate (DM basis) in a balanced two period changeover design. Plasma profiles were similar for all cows, regardless of hay treatment. There were no differences in milk yield, milk fat, or milk protein percentages for control, drying agent, or mixture. Intake of DM was not different among treatments. Apparent digestibilities of DM, OM, CP, NDF, and ADF were not different among treatments. Treatment of alfalfa hay with chemical drying agents did not alter plasma profile, milk production, or nutrient digestibility in midlactation cows.