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The effects of cutting height and plant maturity on yield and nutritional value of smooth brome forage over a two year period
Some forage quality must be sacrificed to achieve sustainable yields. The purpose of this study was to determine the combination of cutting height and stage of plant maturity that optimizes quality and yield. A brome pasture was divided into 27 plots (3.05 m × 4.57 m) in a completely randomized block design with a 3 x 3 factorial treatment arrangement to determine the effect of cutting height (2.54 cm, 7.62 cm, or 12.7 cm) and plant maturity (boot, bloom, seed) on yield and nutritional value. A strip of forage (0.91 m × 3.05 m) was harvested from each plot and weighed to determine yield. A grab sample from each harvested strip was collected and dried. Ground grab samples were analyzed for DM, Ash, NDF, ADF, and N. Treatments were applied to the same pasture over a two year period. In both years, yield was greater (P ≤ 0.01) when brome was cut at 2.54 cm compared to the 7.62 cm and 12.7 cm. In year 1, cutting height had no effect on any of the nutritional parameters measured. In year 2, NDF content tended (P = 0.06) to increase as cutting height was reduced. Yield was greatest (P < 0.05) for brome that was in the seed stage of maturity, followed by bloom then boot which produced the lowest yield. In both years, dry matter content was greatest (P ≤ 0.01) in the seed stage, but lower in bloom and boot stages. In year 1, ash content was similar between the boot and bloom stages with both having a greater (P = 0.002) ash content than seed stage. In year 2, ash content was higher in seed and boot while being lower in bloom stage. In both years, NDF and ADF increased with plant maturity, with seed and bloom stages having a greater (P < 0.01) fiber content than boot stage. Crude protein, estimated from N content, was greatest (P < 0.01) in boot, followed by bloom, than seed stage which contained the lowest CP content. Reducing cutting height produced a greater yield; however, NDF tended to increase in year 2. More mature brome produced greater yields; however nutritional value was decreased with increasing maturity. Cutting brome at a reduced cutting height in a younger stage of maturity can lead to better yields, but may lead to an increase in fiber content with consecutive years of reduced cutting height.
Keywords: Plant Maturity, Cutting Height, Forage Yield