Planting Date Effects on the Nutritive Value of Fall‐Grown Oat Cultivars

Abstract

Fall‐grown oat ( Avena sativa L.) shows potential to fill an important niche as a fall forage option throughout central Wisconsin. Our objectives were to assess the effects of planting date on the nutritive value of fall‐grown oat from four cultivars exhibiting diverse maturation characteristics. During a 3‐yr trial, three grain‐ and one forage‐type cultivar were established on 15 July, 1 August, or 15 August, and subsequently harvested at 15‐d intervals beginning 15 September. Cultivar × harvest date interactions ( P ≤ 0.041) were observed consistently within individual planting dates. Estimates of 48‐h in vitro neutral detergent fiber digestibility (NDFD) declined throughout the fall for all cultivars, and ranged from 416 to 548, 529 to 704, and 665 to 798 g kg −1 neutral detergent fiber (NDF) following the 15 July, 1 August, and 15 August planting dates, respectively. Within planting date, these changes generally were explained by linear, quadratic, and cubic ( P < 0.001) trends over time. Overall, means for ForagePlus were greater by 127, 102, and 32 g kg −1 NDF than grain‐type cultivars following the 15 July, 1 August, and 15 August planting dates, respectively. Generally, similar trends were observed for estimates of total digestible nutrients with respective ranges of 503 to 592, 581 to 687, 685 to 747 g kg −1 across the three establishment dates. Selection of a forage‐type cultivar likely will result in superior yield and nutritive value for planting dates as late as the first week of August. Thereafter, these advantages become less distinct, and grain‐type cultivars often may be better management choices.