Evaluation of Urea and Anhydrous Ammonia as Preservatives and Quality Enhancers for Ryegrass Hay

A distributor was designed to apply granular urea on ryegrass during cutting or during baling of the forage. The drying rate of annual ryegrass (Lolium multiflorum Lam.) was not affected by urea application when urea was applied at 5.6% (d.m. basis) in a lab study and at 5.8% (d.m. basis) in a field study. Application of urea during cutting or baling in the field resulted in urea-nitrogen retention of 5 to 24%. The rates of urea application were 5.8% at cutting and 6.4% and 19.8% at baling (d.m. basis). Treated and untreated windrows were baled at 29% moisture (w.b.) and 11% moisture (w.b.). Half of the untreated bales were ammoniated at the rate of 3% (d.m. basis). Crude protein contents were significantly higher for urea and ammonia treated bales than for the control bales. In vitro dry matter digestibility was increased by ammoniation. Urea application did not result in a greater digestibility. Higher digestibilities were observed for all high moisture treatments compared with the respective low moisture hays. Extensive fungal growth was observed after 60 days storage in the high moisture control bales and in the high moisture bales treated with urea during baling. In contrast, high moisture bales treated with anhydrous ammonia and urea during cutting had little surface mold after 60 days.