Changes in nutritive value of tall fescue hay as affected by natural rainfall and moisture concentration at baling

Relatively little is known about the combined effects of rain damage and spontaneous heating on the storage characteristics and nutritive value of tall fescue (Festuca arundinacea Schreb.) hay. Objectives were to assess effects of these variables in five management situations. ‘Kentucky 31’ tall fescue infested with the fungal endophyte (Neotyphodium coenophialum [Morgan-Jones & Glenn, Bacon, and Hamlin comb. nov.]) was packaged in conventional rectangular bales at 99 g/kg (low, L), 164 g/kg (ideal, I), and 225 g/kg (high, H) of moisture prior to rainfall, and at 246 g/kg of moisture after a 23 mm rainfall event (H–R) and at 93 g/kg of moisture after a total accumulation of 72 mm of rain (L–R). Concentrations of neutral-detergent fiber (NDF), acid-detergent fiber (ADF), and lignin immediately after baling increased (P≤0.017) with rain damage, but concentrations of total N and fiber-associated N components were little affected. Immediately after baling, the in situ dry matter (DM) disappearance for L–R hay was 32–44 g/kg lower (P=0.0001) than observed for hays baled without rain damage. After a 40–45-day storage period, L and I hays had a 31–36 g/kg advantage for in situ DM disappearance over hays damaged by spontaneous heating (H), rainfall (L–R), or both (H–R). Generally, the effects of a single 23 mm rainfall event on the nutritive value of tall fescue hay was relatively small, but damage increased substantially with multiple rainfall events.