Hybrid, Maturity, and Cutting Height Interactions on Corn Forage Yield and Quality
2004
Lewis, Andrew L. | Cox, William J. | Cherney, Jerome H.
Corn (Zea mays L.) hybrids may show different silage quality responses to harvest date and cutting height because hybrids differ in neutral detergent fiber (NDF) digestibility. A brown midrib, leafy, and dual-purpose hybrid were harvested at early [≈280 g kg⁻¹ dry matter (DM) content], medium (≈350 g kg⁻¹), and late (≈420 g kg⁻¹) harvest dates at 15-, 30-, and 46-cm cutting heights in 2001 and 2002 to determine optimum harvest management for each hybrid type. Most forage quality characteristics had hybrid × harvest date interactions as indicated by the 73 g kg⁻¹ decrease in NDF digestibility of the brown midrib compared with 20 g kg⁻¹ decreases of the other hybrids between the early and late harvest date. Milk per megagram, a forage quality index, declined (1523, 1487, and 1417 kg Mg⁻¹), but DM yields increased (13.2, 13.6, and 14.1 Mg ha⁻¹), so calculated milk yields were similar (20333, 20200, and 20233 kg ha⁻¹) at early, medium, and late harvest dates, respectively, suggesting a broad optimum DM content for harvest. The sharp decline in NDF digestibility, however, raises concern about harvesting the brown midrib hybrid above 350 g kg⁻¹ DM content. Calculated milk yield had a hybrid × cutting height interaction, as indicated by no change in the leafy hybrid and a 13% decrease in the brown midrib hybrid as cutting height increased from 15 to 46 cm. This suggests that an increase in cutting height may be a good management practice for the leafy hybrid but not for the brown midrib hybrid.
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