Defoliation management effects on nutritive value of ‘performer’ switchgrass

Abstract

Forage species with greater nutritive value have the potential to positively affect animal responses. 'Performer' switchgrass (Panicum virgatum L.) was released because of greater digestibility and lower lignin concentrations as compared to 'Alamo' and 'Cave-in-Rock.' However, the relationship between nutritive value, canopy characteristics, and dry matter yield for this species has not yet been established. The goal of this study was to determine in vitro true digestibility (IVTD), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) as a function of a wide range of defoliation management strategies to aim optimize production of nutritious forage. Treatments were the factorial combination (4 × 4) of defoliation height (DH; clipped to 10, 20, 30, and 40 cm) and defoliation frequency (DF; clipped every 3, 6, 9, and 12 wk). The range of digestibility values was greater due to DF (from 590-779 g kg −1 when averaged across DH treatments) than DH treatments (from 675-692 g kg −1 when averaged across DF treatments). In general, frequent defoliation resulted in greater IVTD and CP but lower yields; however, there were interaction effects of DF × DH for all response variables. With the exception of NDF, all response variables had strong correlations with dry matter yield, canopy height, and leaf/stem ratio. Although there are tradeoffs when managing for productivity and nutritive value, there is a wide range of defoliation management options for 'Performer' switchgrass that provide flexibility in terms of harvesting schedules to optimize productivity and persistence of nutritious forage.

Tree species effects on understory forage productivity and microclimate in a silvopasture of the Southeastern USA

“…Lower TDN and CP values, concomitant with greater fiber concentration values, have been previously reported in the literature numerous times for warm-season grasses when the forage is harvested at greater maturity stages (Griffin and Jung, 1983;Perry and Baltensperger, 1979;Richner et al, 2014). This includes specific reports for switchgrass in NC (Bekewe et al, 2019b;Burns et al, 1997), which Temperature mitigation was not different due to species of trees and it was strongly dependent on month-of-the-year and time-of-day (Fig. 6-B).…”

Evaluation of five bermudagrass cultivars fertigated with swine lagoon effluent

“…Samples were scanned with a Foss NIRS Model 6500 (Foss North America) and NIRS model development was performed using a data analysis pipeline written in R environment (R Core Team, 2016). The pipeline was previously used in the successful development of NIRS models to determine forage nutritive value of native warm‐season grasses and bermudagrass (Bekewe et al., 2019; Castillo et al., 2020), and to compare predictions among benchtop and handheld NIRS devices (Acosta et al., 2020). To obtain a calibration for CP and ADF, a total of 147 samples (72 samples selected from this trial + 75 samples from bermudagrass trials previously conducted across North Carolina) were assembled into a library, in which both laboratory analyses and NIRS scans were available.…”

Comparison of benchtop and handheld near‐infrared spectroscopy devices to determine forage nutritive value

“…Model development was performed using a data analysis pipeline written in R environment (R Core Team, 2016). The pipeline was previously used in the successful development of NIR models to determine chemical properties of wood (Hodge, Acosta, Unda, Woodbridge, & Mansfield, 2018) and nutritive value of switchgrass (Bekewe, Castillo, Acosta, & Rivera, 2019) and a mixture of native warm‐season grasses (Castillo, Tiezzi, & Franzluebbers, 2020). The pipeline has two separate phases: (a) transformations and outlier detection and (b) model training, cross‐validation, and prediction of new observations.…”