Planting Date Effects on the Nutritive Valueof Fall-Grown Oat Cultivars

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.