Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2009
Publication Date: 7/1/2010
Citation: Coblentz, W.K. 2010. Effects of Wrapping Method and Soil Contact on Hay Stored in Large Round Bales in Central Wisconsin. Applied Engineering in Agriculture. 25:835-850.
Interpretive Summary: Traditionally, hay has not been stored as large-round bales within dairy operations in central Wisconsin, but the limited availability of labor and its escalating cost for making hay are forcing some producers to consider this option. To evaluate the effects of outdoor weathering on the nutritive value of hay in large-round bales, we conducted a study over two years. Two hay types (alfalfa or orchardgrass) were packaged as large-round bales, tied with net wrap or sisal twine, and then stored outside over winter – either directly on the ground or elevated onto wooden pallets. A control group was stored indoors. The nutritive value within the surface layer of bales wintered outdoors differed only marginally from control bales stored indoors. Recoveries of dry matter always were optimized with indoor storage, but this storage option can be cost-prohibitive for many livestock operations. For bales wintered outdoors, recoveries of dry matter were improved by 3.1 percentage units when bales were elevated off the ground. However, net wrap offered only limited advantages over conventional sisal-twine binding in this respect. In northern climates, deterioration of nutritive value is limited in bales stored outdoors, but recoveries of dry matter can be improved by breaking soil contact. This information will help hay and livestock producers decide how to best store large bales.
Technical Abstract: 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 (Dactylis glomerata L.) or alfalfa (Medicago sativa L.)] and storage treatments. Bales were wrapped with either sisal twine or net, and 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 < 0.001). 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 on 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 the 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 < 0.001). 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 from 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.