EVALUATION OF CORN AND BARLEY AS ENERGY-SOURCES FOR COWS IN EARLY LACTATION FED ALFALFA-BASED DIETS

Twenty-four multiparous, lactating Holstein cows were used in an experiment to determine the value of corn or Steptoe barleys of one of three densities (.66, .73, or .79 kg/L) on production in early lactation. The corn diet also contained 11.8% beet pulp. Each cow was assigned to a sequence of three diets that were fed during three 21-d periods. Cows were fed TMR containing 56% concentrate and 44% mixed alfalfa forage (DM basis). The corn and .73-kg/L barley diets were formulated to be isonitrogenous and isocaloric. Other barleys were included in their respective diets on an equal weight basis with the .73-kg/L barley diet. The corn diet contained a greater amount of beet pulp than the barley diets to equalize NDF content. There was no effect of diet on milk production, milk composition, or DMI for cows in early lactation. Diets were quite palatable; DMI averaged more than 4% of BW. Results of an in situ study showed that the corn used in these diets contained DM, CP, and starch that was less degradable than the barleys, yet this did not affect intake or milk production. Results of this trial indicate that barley can be used effectively in rations of high producing cows. Energy values listed by the NRC for barley appear to be accurate for Steptoe barley and can be used to develop an alfalfa-barley ration of feeding value equal to an alfalfa, corn, and beet pulp ration.