EFFECTS OF WRAPPING METHOD AND SOIL CONTACT ON HAY STORED IN LARGE ROUND BALES IN CENTRAL WISCONSIN

A 2-yr study was conducted during 2006-2007 and 2007-2008 to evaluate the effects of outdoor weathering on the nutritive value, ruminal disappearance kinetics of dry matter (DM), and recoveries of DM from 1.4- x 1.2-m large-round bales. The study consisted of (n = 90) bales that were allocated within a 2 x 5 factorial arrangement of hay types [orchardgrass (Dactyl is glomerata L.) or alfalfa (Medicago sativa L.)] and storage treatments. Bales were wrapped with either sisal twine or net, and they were positioned outdoors either elevated on wooden pallets or directly on the ground. For both hay types, positive controls were wrapped with net and stored indoors. Generally, the main effects of hay type and storage treatment did not interact, but both main effects interacted with year During 2006-2007, wrapping with net did not improve recovery of DM compared to bales wrapped with twine (93.7% vs. 93.4%; P = 0.781), but recovery was improved by elevating bales on wooden pallets (95.0% vs. 92.1%; P < 0.00.1). However, control hays surpassed by 4.6 percentage units the overall recovery mean for all bales wintered outdoors (98.1% vs. 93.5%; P < 0.001). Precipitation was above normal during 2007-2008; this resulted in a 7.3-percentage-unit recovery advantage for indoor storage compared to all bales stored outdoors. Unlike the previous year, bales wrapped with twine and placed directly oil the ground were especially vulnerable to weathering, recovering only 85.2% of initial DM, while recoveries for other treatments stored outdoors ranged from 89.6% to 91.1%. During tire relatively dry conditions observed during 2006-2007, the energy density (total digestible nutrients; TDN) of the 0.15-m surface layer for all bales wintered outdoors was depressed, but by only 1.4 percentage units (60.8% vs. 59.4%; P = 0.017) relative to indoor controls. With much greater precipitation during 2007-2008, this differential increased only marginally (57.3% vs. 54.1%; P < 0.00.1). Generally, kinetic estimates obtained from in situ evaluations of ruminal disappearance of DM were consistent with responses observed for TDN. In summary, recoveries of DM front large-round bales always were greatest with indoor storage. The results of these studies suggest that elevating bales off of the soil surface and wrapping with net offer the highest probability of maximizing recovery of DM following outdoor winter storage in northern climates.