Fermentation of fall-oat balage over winter in northern climates

Authors: Coblentz, Wayne; Muck, Richard; CAVADINI, JASON - University Of Wisconsin

Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2015
Publication Date: 1/8/2016
Publication URL: http://handle.nal.usda.gov/10113/61792
Citation: Coblentz, W.K., Muck, R.E., Cavadini, J.S. 2016. Fermentation of fall-oat balage over winter in northern climates. Crop, Forage & Turfgrass Management. doi: 10.2134/cftm2014.0110.

Interpretive Summary: Since forage usually is ensiled in summer or early fall, the effect of below-freezing temperatures on silage fermentation has not been of concern or studied scientifically. But recently, fall-grown oat has been identified as a potential emergency forage crop which can be planted, harvested and ensiled late in the season; this crop is attractive because the yield potential is good and because it may accumulate significant amounts of sugar (energy source for livestock) following frost events. So we conducted a study to determine how freezing temperatures do affect the fermentation of this silage crop. Generally, fermentation of silages is delayed or suspended by below freezing temperatures within the silage mass, but fermentation will begin again when temperatures warm in the spring. Furthermore, the high sugar concentrations within fall-grown oat forages can encourage the activity of anaerobic yeasts, resulting in losses of silage quantity and quality when fermentation restarts in the spring. These results show producers that losses of silage quantity and quality during fermentation by yeasts can be avoided by feeding fall-grown oat silages before temperatures warm in the spring.

Technical Abstract: The effects of below-freezing temperatures on silage fermentation are poorly understood. Recently, several studies have evaluated the efficacy of producing fall-grown oat as an emergency silage crop within central Wisconsin; this late-season forage option is attractive because the yield potential is good, and because these forages may accumulate significant amounts of sugar following frost events. ‘Vista’ oat from two field sites was harvested at the boot (Experiment 1) or early-heading (Experiment 2) stages of growth, and then baled and ensiled in plastic film on 15 November 2013. Bales were sampled over the winter and spring, concluding with a final sampling date of 15 May. Generally, there was little evidence of silage fermentation prior to internal bale temperatures exceeding 32oF, which occurred on 15 and 13 April for Experiments 1 and 2, respectively. During the final month of sampling, the pH of silages declined to 4.61 and 5.71 for Experiments 1 and 2, respectively. Substantial amounts of ethanol were produced from these respective silages (5.82 and 4.85%), but lactic acid production was much greater for Experiment 1 (4.82%) than for Experiment 2 (1.63%). Silage fermentation within both experiments likely included significant activity by anaerobic yeasts, which metabolize sugars, thereby yielding ethanol, as well as CO2 and H2O. These results suggest that silage fermentation can be delayed until spring by below-freezing temperatures within the ensiled forage mass, and the high sugar content of these oat forages (= 21.0%) can encourage the production of ethanol, likely through activity of anaerobic yeasts.