Canola As A Forage Crop

When cattle producers are faced with forage shortages they must explore atypical feed options. Surprisingly, canola can make nutritious and palatable hay or silage. If canola is hayed, sufficient drying time is essential to prevent molding. Typically, canola plants take four to six days to dry down to acceptable moisture levels (16 to 18% moisture content) for baling. As canola cures, it has a tendency to darken in color however this should not affect palatability. When cut in the late-bloom to mid-podded stage, canola hay is similar to good quality alfalfa grass with crude protein content averaging 15%, total digestible nutrients (TDN) 60.4% and acid detergent fiber (ADF) 35.8%. If cut at a later stage of development when plants are fully-podded and stemmy with little or no leaf, canola hay is similar in quality to slough hay. Crude protein averages 10%, TDN 49.8% and ADF 45.9%. Producers have reported that cattle tend to refuse stemmy canola hay.

If canola is ensiled, wilting to 65% moisture content is critical to prevent seepage and other ensiling problems. This process may take several days since canola is naturally high in moisture (75-80%). Some producers have had success filling silage pits with alternating layers of canola and cereal crops cut for silage. This helps reduce seepage and provides the option to combine the layers when feeding. Canola cut for silage at the early to mid-podded stage of development averages 16% crude protein, 56.3% TDN and 36.8% ADF.

Producers supplying their cattle with forage-canola should have their feed analyzed to determine nutrient content. They should also have the forage analyzed for mycotoxins, nitrates and sulfur which can be harmful to cattle's health. Canola can accumulate high levels of nitrates. Crops that have been stressed or had high applications of top-dressed nitrogen fertilizer commonly have elevated nitrate concentrations. Ensiling can reduce nitrate content of forages by 30 to 50%, making it safer to feed.

Canola naturally contains high levels of sulfur (0.5 to 1.3%). The National Research Council recommends that total dietary intake of sulfur should not exceed 0.4% of dry-matter intake. Prolonged feeding of canola may hinder cattle's use of trace minerals particularly copper and selenium whose absorption is inhibited by sulfur. Producers using canola in their feeding strategy need to pay particular attention to providing sufficient quantities of these trace minerals. Cattle consuming excessive amounts of sulfur may also experience suppressed appetite and reduced rate of gain. As sulfur concentrations increase in the rumen, thiamine (vitamin B1) production becomes impaired which may cause scouring and ultimately thiamine deficiency. This may instigate polioencephalomalacia (PEM), a dietary disease, which causes lesions to form in the brain.

Canola hay or silage can be a good feed, but producers should be cautious, limiting its inclusion to 50-60% of the total ration on a dry-matter basis. Forage-canola should be introduced slowly into cattle's diets over a period of days to prevent animals from going off-feed and to reduce the incidence of digestive upset and bloat.

Works cited

Contact

Kristen Bouchard
Animal Nutritionist
Manitoba Agriculture, Food and Rural Initatives