Assessment of forage brassica species for dairy and beef-cattle fall grazing systems

Abstract

In temperate environments of the United States, winter forage management has traditionally necessitated either (a) feeding conserved forages or (b) stockpiling grazeable perennial forage. Forage brassicas might offer a low-cost alternative to these strategies. This project evaluated different annual forage brassicas in a temperate forage fall production system. Three brassicas, Barsica forage rape (Brassica napus L.), Inspiration canola (B. napus L.), and Appin turnip (B. rapa L.) were compared against KB Supreme annual ryegrass [(Lolium multiflorum Lam.) ARG] for DM yield and nutritive value over 2 fall seasons. Plot sizes were 5.5 × 9.1 m and seeded in August of 2015 and 2016 in a randomized complete block design with 4 replications. Harvests occurred at 2-wk intervals in 2015 and 2016. Brassica DM yields (734 to 861 kg of DM/ha) were greater (P < 0.001) than ARG (344 kg of DM/ha), and NEl (1.73 to 1.79 Mcal/kg), NEg (1.04 to 1.11 Mcal/kg), and NEm (1.65 to 1.72 Mcal/kg) concentrations in Inspiration canola and Barsica forage rape were greater than ARG (P < 0.001). Additionally, total nutrient yields (kg of DM/ha) of CP (176 to 204 kg of DM/ha) and NEl (1,200 to 1,500 Mcal/ha) were greater (P < 0.001) for brassicas than ARG (CP = 88 kg of DM/ha; NEl = 555 Mcal/ha). Brassicas had greater DM and nutrient yields, allowing for twice as many potential grazing days as ARG, thereby conceivably extending the grazing season with high-quality forage and reducing feeding costs.