Annual warm‐season forages have been used to fill productivity and nutritional gaps during summer months throughout the southeastern United States. However, their performance and nutritive value in cooler, short‐season temperate climates above 40 °N has been less well studied. This study evaluated the forage mass and nutritive value of four warm‐season annual forages {brown midrib [BMR] sudangrass [Sorghum bicolor ssp. Drummondii (L.) Moench], buckwheat (Fagopyrum esculentum Moench), Japanese millet [Echniochloa esculenta (A. Braun) H. Scholz], and teff [Eragrostis tef (Zuccagni) Trotter]} compared with a cool‐season small grain forage, oat (Avena sativa L.), and a cool‐season annual forage legume, chickling vetch (Lathyrus sativus L.). Monocultures of the six annual forage species, along with a mixture of all six species, were evaluated over 2 years in southeastern New Hampshire. Forage mass and nutritive value were assessed at weekly intervals over 3 weeks in July–August, approximately 4‐to‐5 weeks post‐germination. Across all three harvests, buckwheat, Japanese millet, and the summer mix produced greater forage mass than oat, while chickling vetch and teff produced the least. Conversely, chickling vetch had greater crude protein (CP), acid detergent fiber, and neutral detergent fiber compared with oat, while buckwheat had the lowest CP, in vitro true dry matter digestibility, and in vitro neutral detergent fiber digestibility of all the species assessed. Japanese millet produced greater forage mass while providing similar nutritive value as oat, making it a good alternative warm‐season annual forage for use under cool, short growing seasons.

Annual cool‐season forage crops could fill the gaps in spring forage availability that are typical in perennial pastures in the northeastern United States. Despite their potential as supplemental forages, few studies have examined the productivity–quality tradeoffs of annual forages grown as monocultures or mixtures. This study compared five species of winter annual forages grown as monocultures and mixtures for forage mass production and nutritive value across three harvest timepoints. Beginning in fall 2015, plots were planted in monocultures of cereal rye (Secale cereale L.), barley (Hordeum vulgare L.), triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)], wheat (Triticum aestivum L.), and hairy vetch (Vicia villosa Roth), as well as a mix of all five species. Samples were taken on 1, 7, and 14 June 2016, and on 3, 10, and 17 May 2017 to determine forage mass, nutritive value in the second year, and tradeoffs between biomass and nutritive value. The mixture's forage mass always ranked similarly to the best performing monoculture treatments. All monocultures except hairy vetch had increased forage mass at later harvests. In vitro digestibility of neutral detergent fiber was lower in later harvests. Triticale consistently had the greatest forage mass. Barley had greater energy and lower fiber concentrations than the other species. The results of this study suggest that triticale and barley have the most potential for supplementing spring perennial forage production.