As summer approaches, forage managers look to summer forage availability and needs, but it also time to consider winter forage programs.
In temperate environments of the U.S., winter forage management has traditionally necessitated either feeding conserved forages — i.e., baled hays and silages — or stockpiling grazeable perennial forage, according to S. Leanne Dillard with Auburn University and Eric D. Billman and Kathy J. Soder with the U.S. Department of Agriculture-Agricultural Research Service's Pasture Systems & Watershed Management Research Unit, in an article published in Applied Animal Science.
Dillard et al. suggested that forage brassicas might offer a low-cost alternative to these strategies, explaining that forage brassicas are characterized by relatively greater leaf-to-stem ratios and nutritive values that are maintained longer into the plant life cycle compared to other forages.
Historically, brassicas have served an agricultural function as oilseeds (canola and rapeseed) or as cover and horticultural crops (turnips), Dillard et al. noted. However, they explained that forage brassicas grow rapidly post-germination and tolerate higher temperatures than annual ryegrass (28-30°C), which allows for earlier establishment as well as late-season grazing.
On the other hand, knowledge of brassica management for forage compared with annual ryegrass is lacking, which has inhibited producer adoption, Dillard et al. said. Therefore, they conducted a study to quantify and compare yield potential and forage quality among three forage brassica species with those of annual ryegrass.
Dillard et al. compared three brassicas — Barsica forage rape (Brassica napus L.), Inspiration canola (B. napus L.) and Appin turnip (B. rapa L.) — against KB Supreme annual ryegrass (Lolium multiflorum Lam.) for dry matter yield and nutritive value over two fall seasons. Plot sizes were 5.5 x 9.1 m and seeded in August of 2015 and 2016 in a randomized complete block design with four replications. Harvests occurred at two-week intervals in 2015 and 2016, the researchers said.
Brassica dry matter yields (734-861 kg of dry matter per hectare) were greater (P < 0.001) than annual ryegrass (344 kg of dry matter per hectare), Dillard et al. reported.
Net energy concentrations in the forage canola and forage rape — lactation, 1.73-1.79 Mcal/kg; gain, 1.04-1.11 Mcal/kg and maintenance, 1.65-1.72 Mcal/kg — were greater than annual ryegrass (P < 0.001), Dillard et al. said.
Furthermore, the researchers pointed out that total nutrient yields of crude protein (176-204 kg of dry matter per hectare) and net energy of lactation (1,200-1,500 Mcal/ha) were greater (P < 0.001) for brassicas than annual ryegrass (crude protein, 88 kg of dry matter per hectare; net energy of lactation, 555 Mcal/ha).
Dillard et al. concluded that forage brassicas had greater dry matter and nutrient yields, allowing for twice as many potential grazing days as annual ryegrass, thereby conceivably extending the grazing season with high-quality forage and reducing feeding costs.