Genetically-modified canola seeds
Many genetically-modified canola cultivars have been developed and are widely used in Canada (95% of the crop) and in the USA (82%) (GMO Compass, 2010). In the European Union, GM rapeseed crops are banned but rapeseeds, rapeseed oil and rapeseed oil meal resulting from the cultivation of certain cultivars (GT73 and T45) can be imported and used as feed and food (EFSA, 2009; European Commission, 2003). Harmonisation of GM rapeseed labelling has been recommended so that livestock farmers can make an informed choice. However, no compulsory labelling is required for livestock products resulting from feeding GM oilseed rape products (European Commission, 2003).
Cover crop, mulch and stubbles
Winter oilseed rape covers the soil for 10-11 months. It has high nutritional demands in autumn and is able to scavenge soil nutrients (especially N), thus reducing N nutrient losses. Plant cover also reduces soil erosion in winter and the taproots alleviate soil compaction (SARE, 2008; Snowdon, 2006). Oilseed rape plants are known to reduce root nematodes (SARE, 2008). During winter, crop residues left on the soil after harvest help to trap snow and subsequently reduce snow melt run-off, wind and water erosion. Oilseed rape is increasingly recommended for soil conservation as well as for minimal or no-till practices, provided it is combined with adequate weed control (Snowdon, 2006).