Canola meal
Canola meal is a by-product of oil extraction from canola seeds. New varieties were developed with reduced concentrations of glucosinolates and referred as canola in Canada and United States, and double-low rapeseed or 00-rapeseed in Europe. Glucosinolates are goitrogenic compounds that affect the thyroid function and iodine metabolism, impairing feed intake and growth performance of pigs fed diets with high concentration of glucosinolates (Parr et al., 2015). The concentration of glucosinolates in new varieties is generally less than 30 μmol/g and it varies depending on the extent of degradation during toasting in canola meal (Mejicanos et al., 2016).
Canola meal contains between 35-40% crude protein (NRC, 2012). Compared to soybean meal, canola meal contains lower crude protein, lower concentration of lysine but greater concentration of sulfur-containing amino acids than soybean meal. The fiber content of canola meal is 20-25% neutral detergent fiber and 3 times greater than soybean meal due to the use of hulled canola seeds, which reduces the energy value in canola meal (NRC, 2012). Recently, new varieties of high-protein canola meal were developed that contain approximately 45% crude protein (Liu et al., 2014). Although the crude protein value is closer to that of soybean meal, concentration of amino acids and energy in high-protein canola meal is less than in soybean meal.