Risk management in forage production of cow-calf systems of Appalachia.

摘要

Variation in production of cool-season forages over a typical grazing period increases the risk of failing to meet livestock nutrient needs. The objective of this study was to evaluate the risk-buffering capacity of warm-season forages to fill the summer slump in production of cool-season grasses in the Appalachian region. Small-plot experiments were initiated in the summer of 2008 at three sites in Virginia. Treatments included three tall fescue [Schedonorus phoenix (Scop.) Hulub] types (endophyte-infected [KY31 E+], endophyte free [KY31 E-], and novel endophyte [Max Q]), Teff [Eragrotis tef (Zucc.) Trotter], bermudagrass [Cynodon dactylon (L.) Pers.] (BG), and Caucasian bluestem [Bothriochloa bladhii (Retz) S.T. Blake] (CB). Plots were harvested May through October of 2009 and 2010 at the late boot stage at a cutting height of 10 cm. Subsamples were analyzed for dry matter and nutritive value. To assess risk, bootstrap distributions of biomass and quality data were generated by Monte Carlo simulation and compared against an objective function defined as 59 kg ha-1 d-1 forage yield; 100 g kg-1 crude protein (CP); 600 g kg-1 total digestible nutrients (TDN). The warm-season grasses produced biomass yields and nutritional values adequate to fill the summer slump from cool-season forages and demonstrated a higher probability of meeting the minimum requirements in July, August, and September. Teff was most consistent in meeting the minimum requirements in mid-summer. However, both BG and CB can help to fill the gap in summer months when compared to cool-season tall fescue. Bootstrap distributions provide producers with a tool that links their production goals with a measurable value of production risk.Digital Object Identifier http://dx.doi.org/10.2134/agronj2011.0236