Potential of warm-season annual forages and Brassica crops for grazing: A Canadian Review

Abstract

. 2009. Potential of warm-season annual forages and Brassica crops for grazing: A Canadian Review. Can. J. Anim. Sci. 89: 431Á440. Extension of the grazing season beyond the normal perennial grazing season has been identified as a potential mechanism to reduce the cost of production on Canadian cow-calf operations. This review will provide an overview of the potential use of warm-season and Brassica crops including corn (Zea mays), Golden German foxtail millet (Setaria italica L. Beauv.), kale (Brassica oleracea L.), forage rape (B. napus ssp. biennis L.) and turnip (B. rapa L.). These crops have a high yield potential, but the cost for grazing these crops has not been adequately compared with the cost of grazing oat (Avena sativa L.), barley (Hordeum vulgare L.), and fall rye (Secale cereale L.). There are very few actual animal grazing trials evaluating the economics of using these crops in grazing systems in Canada, and this requires further research. Since the early 1900s, cow-calf producers have grazed annual crops as an alternative to deal with drought and perennial pasture shortage as a means of lowering their annual costs. Extension of the grazing season beyond the normal perennial grazing season is an alternative low-cost method. A previous review (McCartney et al. 2008) summarized the potential of annual cool season cereal crops for grazing. There has been considerable interest in evaluating the grazing potential of warmseason annual crops for their suitability in extending the grazing season in Canada because warm-season annuals tend to be seeded later and vary in days to maturity (May et al. 2007). This could be advantageous in a grazing system for extending the grazing season. This review summarizes warm-season and Brassica crops that show promise in grazing systems that are applicable to Canadian conditions. As limited published research on this grazing method can be found, historical information from other types of research summaries will be included as the information still has value.

Forage Brassicas Stockpiled for Fall Grazing: Yield and Nutritive Value

“…Forage brassicas are sometimes equated to concentrate feeds due to their relatively low aNDF and high CP and digestibility. Although grazing forage brassicas can affect rumen function unless roughage (e.g., hay) is provided (McCartney et al, 2009), mixtures with warm‐season (e.g., sorghum [ Sorghum bicolor (L.) Moench], sudangrass [ Sorghum bicolor (L.) Moench], or millets) and cool‐season grasses (e.g., small grains) have also been evaluated as a means of increasing DM and fiber content provided to beef cattle (Sedivec et al, 2011). Even though our study did not include grazing evaluations, previous evidence suggests that strip grazing should be used as a means to avoid trampling of the stand and to decrease waste, especially when soils are wet (Sedivec et al, 2011).…”

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Certain negative effects on animal health associated with grazing legume green manures, cereals, or brassicas have been observed (Gardner and Faulkner 1991;Johnson et al 1992;Panciera et al 1992;Hannaway and Larson 2004;Rao et al 2005;McCartney et al 2008McCartney et al , 2009McCartney and Fraser 2010); however, animal health risks posed by grazing can generally be minimized through crop cultivar selection and grazing management.…”

“…Grazing green manures and annual forages, rather than soilincorporating them or harvesting them as green feed or silage, may offer some economic benefits as well as the ecological benefits of integrating livestock directly into annual cropping systems (Thiessen Martens and Entz 2011), though only limited research has been conducted in this region (McCartney et al 2009;McCartney and Fraser 2010).…”

“…(1 and can provide mid-to late-season grazing, either as a standing crop or in swath McCartney et al 2008McCartney et al , 2009Lenssen et al 2010). Mixtures of annual cereals and legumes can produce large amounts of high-quality forage biomass (Carr et al 1998(Carr et al , 2004Strydhorst et al 2008).…”

Influence of Seeding Date and Growing Season Conditions on Forage Yield and Quality of Four Annual Crops in Northeastern Saskatchewan

“…The concern with this early seeding date is weed control. Millets do not compete well with weeds until they are 6 to 8 inches tall (Alberta Agriculture 2004;Reimer and Gaudiel 1984, 1986: McCartney, Fraser, and Ohama 2009. May et al (2007) found that seeding Golden German millet earlier than 10 June may be advantageous in the long term if weed control can be maintained.…”