Timing Corn Forage Harvest for Bunker Silos

Abstract

Dairy producers with large operations have switched from upright to bunker silos so they begin corn (Zea mays L.) forage harvest at 300 g kg−1 instead of 350 g kg−1 dry matter (DM) content. Three hybrids were harvested at average DM contents of 295, 310, and 350 g kg−1 to compare DM yield and forage quality of corn forage typical of bunker and upright silos. Hybrid and DM content did not have interactions for DM yield and forage quality characteristics. The DM content at harvest did not affect DM yield (14.6, 15.0, and 15.1 Mg ha−1 at 295, 310, and 350 g kg−1, respectively). As DM content increased, neutral detergent fiber (NDF) declined (469, 447, and 417 g kg−1, respectively), but NDF digestibility (657, 632, and 631 g kg−1) and crude protein (78, 73, and 72 g kg−1) declined only from 295 to 310 g kg−1 As DM content increased, milk per megagram, a forage quality index, increased (1622, 1699, and 1764 kg Mg−1 respectively), but in vitro true digestibility (IVTD) increased (839, 835, and 847 g kg−1), only from 310 to 350 g kg−1 Calculated milk yields differed at DM contents of 295 (24380 kg ha−1) vs. 350 g kg−1 (26947 kg ha−1) but not at 310 g kg−1 (25727 kg ha−1). Results from this study indicate that dairy producers with bunker silos do not compromise DM and calculated milk yields, despite somewhat lower forage quality, if they begin harvest at 310 g kg−1 DM content.