Rapeseed meal is a common feed ingredient for all classes of ruminant livestock, used as a source of protein and energy (see CCC, 2015 for an exhaustive literature review). Due to its lower protein content, higher fibre and higher protein degradability, rapeseed meal is often considered of significantly lower value than soybean meal. However, several meta-analysis of dairy cattle studies (Huhtanen et al., 2011; Martineau et al., 2013; Martineau et al., 2014) tend to conclude that both the energy value and the protein value of rapeseed meal are higher than previously thought (Evans et al., 2016).
Rapeseed meal is a highly palatable source of protein for ruminant animals. In dairy cows, replacing soybean meal with rapeseed meal maintained intake (20% rapeseed meal; Maxin et al., 2013) or increased intake (9% rapeseed meal; Broderick et al., 2014). Substituting rapeseed meal for high-protein maize distillers grains maintained intake (20% rapeseed meal; Swanepoel et al., 2014). In beef cattle, diets with 10% rapeseed meal resulted in higher intake than diets based on maize distillers grains or wheat distillers grains (Li et al., 2013). In finishing cattle, diets containing 30% expeller or solvent-extracted rapeseed meal did not cause intake issues (He et al., 2013). In calves, feed intake was similar for diets containing 00 rapeseed meal and diets containing soybean meal. However, intake was reduced for calves fed a diet with a high-glucosinolate rapeseed meal (> 100 µmol/g) (Ravichandiran et al., 2008). In dairy calves, using flavouring agents was found unnecessary when feeding a diet containing rapeseed meal (Terré et al., 2014). Preweaning calves offered low-protein starter pellets and either rapeseed meal or soybean meal chose to consume more soybean pellets than rapeseed pellets (Miller-Cushon et al., 2014).
Digestibility and energy value
Rapeseed meal is a good source of energy for ruminants. For solvent-extracted rapeseed meal, The Net Energy values for lactation cited in feed tables range from 6.8 to 7.45 MJ/kg DM (NRC, 2001; Sauvant et al., 2004; NorFor, 2016) and correspond roughly to 80% of the Net Energy value for a soybean meal. OM digestibility is about 74-77%. However, it has been suggested that fibre digestibility of rapeseed meal may be undervalued (CCC, 2015) and some experiments have shown than rapeseed meal can result in dairy performance similar to that obtained with soybean meal (Brito et al., 2007b). Further research is needed to determine the correct energy value of rapeseed meal (CCC, 2015). Expeller and cold-pressed rapeseed meal have a higher energy value due to the higher amount of residual oil.
Rapeseed meal is a common source of protein for ruminants. Its protein has long been considered as more degradable than that of soybean, but estimates of rumen-undegraded protein (RUP) made using newer methods taking into account the contribution of the soluble-protein fraction to the RUP available to the animal suggest that the RUP (expressed in % of protein) of rapeseed meal is in the 40-56% range, compared to 27-45% for soybean meal (CCC, 2015).
Amino acid value
Rapeseed meal has a good amino acid profile for ruminants, and contributes a significant amount of methionine to diets, which is often the first limiting amino acid in production. In addition, the amino acid profile of the RUP fraction more closely matches requirements for maintenance and milk than other vegetable proteins (CCC, 2015).
Solvent-extracted rapeseed meal
Rapeseed meal is an excellent protein supplement for lactating dairy cows and can be included in relatively large amounts in diets for lactating dairy cows. Inclusion rates as high as 20% have been reported with no negative effect on intake and production (Brito et al., 2007b; Swanepoel et al., 2014). A meta-analysis of 122 studies comparing rapeseed meal to soybean meal found that for each additional kilogram of protein supplied in the diet, milk production increased by 3.4 kg with rapeseed meal, and 2.4 kg with soybean meal, showing a 1 kg advantage to rapeseed meal (Huhtanen et al., 2011). Another meta-analysis of 49 studies comparing rapeseed meal with other protein sources found that at the average level of inclusion, rapeseed meal increased milk yield by 1.4 kg when all the other ingredients were considered, but only by 0.7 kg when rapeseed meal was substituted for soybean meal (Martineau et al., 2013). A follow-up of the latter study focused on plasma amino acids suggests that feeding rapeseed meal increases the absorption of essential amino acids, resulting in the higher milk protein secretion and higher protein efficiency (Martineau et al., 2014). Rapeseed meal can be effectively used in combination with maize distillers grains to restore amino acid balance and maximise animal performance (Mulrooney et al., 2009; Swanepoel et al., 2014). Blends of rapeseed meal and wheat distillers grains have also been shown to support high levels of milk production (Chibisa et al., 2012; Chibisa et al., 2013). A comparison between rapeseed meal with wheat distillers grain resulted in similar dairy performances (Mutsvangwa, 2014a; Mutsvangwa, 2014b).
Expeller and cold-pressed rapeseed meal
Expeller or cold-pressed rapeseed meal is a suitable ingredient for dairy cattle. When compared to solvent-extracted rapeseed meal, expeller rapeseed meal resulted in similar or higher milk yield (Beaulieu et al., 1990; Hristov et al., 2011; Jones et al., 2001). Cold-pressed rapeseed meal is a valuable energy and protein source in organic diets (where solvent-extracted meals are forbidden) and could increase milk production when replacing a commercial protein supplement (Johansson et al., 2006). Due to its high oil content, the feeding of expeller rapeseed meal tends to modify the fatty acid profile of milk by reducing saturated fat, increasing the level of oleic acid (C18:1) and decreasing the level of palmitic acid (C16:0) (Jones et al., 2001; Hristov et al., 2011).
Rapeseed meal is a suitable protein source for growing and finishing cattle. In post-weaning beef calves, a comparison of rapeseed meal and legume seeds (field peas, chickpeas and lentils) showed that the rapeseed meal diet resulted in a lower daily gain and in higher feed:gain ratio (Anderson et al., 2004). In dairy calves, rapeseed meal and soybean meal resulted in similar DM intake and daily gain (Terré et al., 2014). In heifers, a comparison of rapeseed meal and several types of wheat or maize distillers grains showed that all ingredients improved performance and increased DM intake while total tract digestibility for OM and NDF was highest with rapeseed meal (Li et al., 2013). In dairy heifers fed diets containing either soybean meal or rapeseed meal, pregnancy rates were higher for the heifers given rapeseed meal during prepubertal development, than for those fed soybean meal (Gordon et al., 2012). In steers, a similar study found that rapeseed meal improved intake and weight gain and resulted in higher average daily gains than in steers fed distillers grain (Yang et al., 2013). Supplementing grass silage with rapeseed meal increased weight gains in growing beef steers, and increased daily gains and reduced days on feed in finishing steers (Petit et al., 1994). In finishing cattle, 15 or 30% expeller or solvent-extracted rapeseed meal gave similar average daily gain but the 30% rapeseed diet reduced feed efficiency (He et al., 2013).
In grazing beef cows, protein supplementation with either rapeseed meal, sunflower meal or cull beans (Phaseolus vulgaris) resulted in similar calf birth weight, calf weaning weight and cow body condition change, whereas weight loss during gestation was lowest with rapeseed meal (Patterson et al., 1999). Grazing beef cows produced more milk when rapeseed meal was partially substituted for wheat (Auldist et al., 2014).
Rapeseed meal has been shown to support growth in sheep. In growing lambs, rapeseed meal was found superior to lupins for weight gain and feed efficiency (Wiese et al., 2003; Malau-Aduli et al., 2009). In lambs fed high-roughage diets, supplementation of hay or silage diets with rapeseed meal or fish meal improved daily gains and feed efficiency, and rapeseed meal appeared to be as effective as fish meal (Agbossamey et al., 1998). In lambs fed diets containing up to 30% rapeseed meal, there were no effects on weight gain or feed intake, despite the fact that thyroid hormone production was lower at the higher inclusion levels of rapeseed meal (Mandiki et al., 1999).
Due to its methionine content, rapeseed meal is an ideal supplement for the production of wool and mohair (Reis et al., 1990).