Utilization of Starea, Urea, or Soybean Meal in Complete Rations for Lactating Dairy Cows

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Abstract
Three complete rations containing 15.8% of the dry matter as crude protein were compared to a 14.5% crude protein basal ration (dry matter basis) through eight Holstein cows in a replicated 4 times 4 Latin square design. The high protein rations contained supplemental nitrogen totally from soybean meal, urea, or Starea, the latter two providing 16 and 22% of total ration nitrogen, respectively. Concentrations were mixed with wilted alfalfa-bromegrass silage and complete rations fed ad libitum. Data were collected during the last week of each 28 days. Ration had no effect on milk yield, composition of fat or protein, or apparent digestibility of dry matter, crude protein, or acid detergent fiber. Weight gains and dry matter intake were greatest with the soybean meal ration. Intake of the low protein ration was depressed. There were no significant differences between the high protein rations for efficiency of nitrogen utilization.