Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2011
Publication Date: 1/24/2012
Citation: Coblentz, W.K., Bertram, M.G., Martin, N.P., Berzaghi, P. 2012. Planting date effects on the nutritive value of fall-grown oat cultivars. Agronomy Journal. 104:312-323. Interpretive Summary: For the dairy industry within north-central USA, options for producing emergency forage are limited when late-summer or fall inventories are inadequate, primarily because of the relatively short growing season. Recently, fall-grown oats have been evaluated and show promise for filling this forage niche. When compared to oat cultivars, established traditionally during spring, additional benefits of fall growth include: i) reduced concentrations of forage fiber; ii) greater in-vitro dry matter or fiber digestibilities; and iii) increased concentrations of water-soluble carbohydrates. The objectives for this project were to evaluate the effects of planting and harvest dates on the nutritive value and energy density of forages harvested from three grain-type oat cultivars (Dane, Ogle, and Vista) and one forage-type oat cultivar (ForagePlus) that typically exhibit maturation characteristics ranging from early (Dane) to very late (ForagePlus). Considering both agronomic and nutritional characteristics, our results show that ForagePlus is likely to maximize both yield and nutritive value throughout central Wisconsin when planting dates are extended as late as the first week of August. When planting dates are delayed beyond the first week of August, the slower maturation rate of ForagePlus becomes an increasing liability. With late establishment dates, it is likely that more rapidly maturing grain-type cultivars will exhibit greater yields of DM before winter than forage-type cultivars. In addition, differences in nutritive value between grain and forage-type cultivars become less distinct following a delayed, mid-August establishment. Therefore, under these circumstances, selection of a grain-type cultivar may be a more solid recommendation to producers.
Technical Abstract: Fall-grown oat (Avena sativa L.) shows potential to fill an important niche as emergency fall forage 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 about 15 September. Cultivar by harvest date interactions (P = 0.041) were observed consistently within individual planting dates. Concentrations of in-vitro true digestibility declined throughout the fall for all cultivars. These concentrations ranged from 607 to 712, 712 to 852, and 868 to 958 g kg-1 following the 15 July, 1 August, and 15 August planting dates, respectively. Within planting date, these changes were explained by linear, quadratic, and cubic (P < 0.001) trends over time. Although these estimates represent extensive ruminal availability, overall means for ForagePlus were numerically greater by 97, 99, and 27 g kg-1 than grain-type cultivars following the 15 July, 1 August, and 15 August planting dates, respectively. Generally, similar trends were observed for estimates of TDN 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 advantages for both yield and nutritive value for planting dates as late as the first week of August. Thereafter, more rapidly maturing grain-type cultivars may be better management choices.