Quality of Orchardgrass Hay Ammoniated at Different Rates, Moisture Concentrations, and Treatment Durations1
- K. J. Moore,
- V. L. Lechtenberg and
- K. S. Hendrix2
Mature grass hays are generally characterized by low fiber digestibility and low protein concentration. Research is needed to determine how various treatment conditions influence changes in nutritive value obtained by amntoniating mature grass hay. The objectives of this study were to determine the effects of NH3 application rate, hay moisture concentration, and treatment duration on the chemical composition and digestibility of a mature orchardgrass (Dactylis glomerata L.) hay. Hays reconstituted to moisture concentrations of 100, 300, and 500 g kg−1 wet weight (WW) were treated with NH3 at rates of 12, 24, or 36 g kg−1 dry weight (DW) in 2-L enclosed containers. The containers were aerated after treatment durations of 7, 21, or 63 days. All treatments were in factorial combination. In another experiment conducted similarly, hay with a moisture concentration of 200 g kg−1 WW was treated with NH3 at rates up to 144 g kg−1 DW for 21 days. Increases in the in vitro digestibility of all constituents were largest for hay with a moisture concentration of 300 g kg−1 WW. Treatment of this hay with NH3 at 36 g kg−1 DW increased (P <0.01) the in vitro digestibility of neutral detergent fiber (NDF) by 227 g kg−1, acid detergent fiber by 265 g kg−1, cellulose by 293 g kg−1, and hemicellulose by 186 g kg−1. No further increase in NDF digestibility occurred when NH3 was applied at rates greater than 36 g kg−1 DW (P >0.01). The proportion of the total increase in NDF digestibility after 7 and 21 days was 75.0 and 96.3%, respectively, for hay with a moisture concentration of 300 g kg−1 WW treated with NH3 at 36 g kg−1 DW. Ammoniation at 36 g kg−1 of hay with moisture concentration of 500 g kg−1 WW increased (P <0.01) the concentrations of total N, ammonium N, and acid detergent insoluble N by 29.9, 15.1, and 1.8 g kg−1 DW. The proportion of the total N added that was retained by the hay 63 days after treatment averaged 65.0, 85.2, and 99.4% for hay with moisture concentrations of 100, 300, and 500 g kg−1 WW, respectively. The proportion of the added N retained in the ammonium form for these hays averaged 39.1, 51.6, and 59.3%. Ammoniation at 36 g kg−1 DW decreased (P <0.01) the concentration of hemicellulose by as much as 70 g kg−1 DW in hay with a moisture concentration of 500 g kg−1 WW. The concentrations of other fiber constituents were not affected by ammoniation. These results indicate that the fiber digestibility of low quality orchardgrass hay can be greatly increased by treatment with NH3 at 36 g kg−1 DM. The increase in digestibility occurs over a wide range of hay moisture concentrations and can be obtained using relatively short treatment durations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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