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The effects of cutting height and plant maturity on yield and nutritional value of brome forage
It is well known that quality of forage decreases as plants matures. Although some forage quality must be sacrificed to achieve sustainable yields, the purpose of this study is to determine the combination of cutting height and stage of plant maturity that optimizes both quality and forage 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 brome yield and nutritional value. A strip of forage (0.91 m × 3.05 m) was harvested from each plot. One grab sample from each strip was weighed in the field, oven dried (49° C for 24-48 h), reweighed to determine percent dry matter and then calculate plot yield (kg.ha-1). A second grab sample from each harvested strip was collected and analyzed for DM, Ash, N, NDF, and ADF. Forage yield was greater (P < 0.0002) when brome was cut at 2.54 cm compared to 7.62 cm and 12.7 cm cutting heights. Brome cut at 7.62 cm and 12.7 cm produced similar yields. Cutting height had no effect on any of the nutritional parameters measured. Forage yield was greatest (P < 0.0001) for brome that was in the seed stage of maturity, followed by bloom then boot which produced the lowest forage yield. Dry matter content was greatest (P = 0.0001) in the seed stage brome but lower and similar between bloom and boot stage brome. Ash content was also similar between boot and bloom stage brome with both having a greater (P = 0.002) ash content than seed stage brome. Both NDF and ADF increased with plant maturity, with seed and bloom stage brome having a greater (P = 0.0001) fiber content than boot stage brome. Crude protein, estimated from N content, was greatest (P = 0.0001) in boot, followed by bloom, then seed stage brome which contained the lowest CP content. Reducing cutting height produced a greater forage yield without negatively impacting nutritional value. 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 without sacrificing nutritional value.
Keywords:
brome, plant maturity, cutting height