Data sheets: Rapeseed meal

Introduction

Rapeseed is a plant belonging to the cruciferous family. It stands one and a half meters high and produces spherical seeds which are 2 to 2.5mm in diameter and are reddish brown or black in color when mature. These seeds have an oil content of 45%, which is of high nutritional quality and is used in the agro-industrial sector. However, rapeseed has considerable levels of erucic acid (35%) and glucosinolates. The former is a long chain fatty acid that is very difficult to oxidize and metabolize and that it is caried away with the oil but can stay in the small remaining fat fraction. Glucosinolates are glycosides that act as anti-nutritional factors; they are present in the rapeseed meal used as a protein source in pig feeding. However, the improved varieties used today called -00- or Canola (Canadian term meaning "Canadian Oil Low Acid") are already low in erucic acid (< 1% of the fat fraction) and glucosinolates (< 15 micromoles/g). Another anti-nutritional factor of rapeseed is synapine (0.6-1.8%), which is an ester of sinapic acid and choline. It has a bitter taste which can generate palatability problems in pigs (especially with early ages). The products of oil extraction are differentiated according to the extraction method used and are classified according to the remaining fat content of the meal. With cold pressing the fat content can vary between 5 and 14% while with other methods it is lower (<2.5%). Also, the fiber content can determine the final protein content. Rapeseed meal has a low, almost negligible starch content, but has a high content of soluble fiber (NDF >25%) and a high content of pectins. It is a good source of protein and sulphur-containing amino acids for pigs, especially for finishing pigs and breeding sows. Depending on the quality and variety used (guaranteed low concentration of anti-nutritional factors) it can also be a good ingredient for starter and pre-growing pig diets.

Comparative study of nutritional values

The systems used in the comparison are: FEDNA (Spain), CVB (the Netherlands), INRA (France), NRC (United States) and Brasil (Brazil).

¹For the FEDNA, CVB, and NRC evaluation systems, a range of values is given (minimum and maximum) derived from integrating the different classifications that these evaluation systems consider, mainly depending on protein content, which differs basically by the type of processing, the fat extraction system, and the amount of residual fat in the meal. FEDNA presents the greatest number of product categories.
²The evaluation systems INRA and BRASIL only give the average value. The French system considers only one quality as an average value.

The range of qualities considered by most evaluation systems for vegetable protein concentrates derived from extraction is very wide, with the exception of soy products. The ranges depend on the extraction system and its ability to extract the oil, which is the primary interest of this crop. Most evaluation systems, with the exception of INRA and BRAZIL which only consider a single quality, consider at least two categories depending on the extraction system (physical or by solvent). This is the case for CVB and NRC which give two clearly differentiated qualities or categories according to the extraction system. By contrast, FEDNA classifies rapeseed meals by protein content and clearly highlights the residual fat level of the extraction as a secondary classification parameter, presenting 4 categories.

For the present review, the maximum and minimum values have been chosen to coincide with the extremes used at the commercial level, as provided in the table of the evaluation systems. Unlike other vegetable protein concentrates from extraction processes, the protein content is not directly determined by the level of fiber (since its seed is processed whole because of its properties), so the final fiber content between products is not very variable (CV~5%). However, the type of processing and the efficiency of the extraction system determine the residual fat content that acts as a dilution factor and is the main determinant of the final protein content in the commercialized meal (R² = -0.58). With the exception of BRASIL, which gives a protein digestibility coefficient lower than the average (-3%), the rest of the systems present very similar digestibility coefficients. While the protein digestibility coefficients are similar between FEDNA, INRA and NRC, the digestibility coefficients CVB assigns to the different categories are lower. It is important to note that, in terms of net energy (NE), while INRA gives a lower value (between 350 kcal/kg lower than the average, and 840 lower than the more extreme values), the NE value for the rest of the systems FEDNA, BRASIL, NRC and CVB is very similar and is clearly dependent on the extraction system and its efficiency, indicating a clear positive relationship between the fat content of the products and the NE value (R² >0.80). It should be noted that the difference between those meals obtained from very efficient extraction systems with residual fat levels <3.5% clearly presents a differential of almost 500kcal EN/kg with respect to the rest. In general terms, and just as for the protein content, the estimation of the NE value is basically determined by the fat content, since the fiber is constant. Starch content (which is considered null by FEDNA and INRA and almost negligible by CVB (<1%) but >5% for NRC and BRASIL) presents a negligible influence on energy content as well as sugar content.

In terms of total amino acids, taking lysine as a reference, one can observe that there are no great differences between FEDNA, CVB and BRASIL (<2%) although INRA estimates values almost 7% lower than the average, and NRC 15% lower for low protein meal (~ 35%CP). However, it should be noted that rapeseed flour has a high concentration of sulphur-containing amino acids compared to the rest of the vegetable protein concentrates. With the exception of NRC, which gives lower values (<15%) for the same meal, the rest of evaluation systems show very stable values with an average >2% of the CP content (FEDNA, INRA, CVB and BRASIL). The values for the remaining total amino acids are quite proportional to the lysine for the different meal qualities. The lysine digestibility coefficient ranges between 74% and 75% (FEDNA, INRA, CVB and NRC) with an upper extreme of 96.2% for BRASIL and two lower extremes of 71% for FEDNA and NRC for those meals with a low protein content <35%CP.

Recent findings

1. A meta-analysis of the effects of dietary canola / double low rapeseed meal on growth performance of weanling and growing-finishing pigs.

A meta-analysis was conducted to quantify the effect of dietary inclusion rate of canola/rapeseed meal (CRM) on average daily gain (ADG), average daily feed intake (ADFI), and feed conversion in weanling and growing-finishing pigs. The dietary inclusion of low glucosinolate CRM reduced ADFI for weanling pigs, but not for growing-finishing pigs, and had minor or no effect on ADG and feed conversion. It is concluded that CRM can be included as a protein source in nutritionally balanced diets for growing-finishing pigs without adverse effects on growth performance.

2. Replacing soybean meal with rapeseed meal and faba beans in a growing-finishing pig diet: Effect on growth performance, meat quality and metabolite changes.

Rapeseed meal and faba beans (RSM/FB) can serve as an alternative to imported soybean meal (SBM). The inclusion of RSM/FB changed amounts of individual fatty acids, but not of total SFA, MUFA and PUFA. It reduced the glucose level in meat and pyroglutamic acid indicating lower oxidative stress in pre-rigor muscle cells. RSM/FB inclusion increased the abundance of free amino acids, sweet tasting metabolites, reduced warmed-over flavor and flavor attributes indicated desirable properties of meat. To conclude, RSM/FB in pig diet supported growth performance and carcass quality comparable to SBM and had a positive effect on meat quality.

3. Rapeseed-based diet modulates the imputed functions of gut microbiome in growing-finishing pigs.

Rapeseed meal is a sustainable feed ingredient that can be used as an alternative to imported soybean meal in European pig production. The gut microbiota plays an important role on pig physiology and health but the impact on microbiota of using rapeseed in diets is still not well known. A control diet containing soybean meal (CON) or a high-fiber experimental diet where 20% rapeseed meal (RSF) was included as an alternative to soybean meal in CON. The composition and function of microbiome in gut digesta samples were analyzed by performing 16S rRNA gene sequencing and culturing of bacteria. In comparison with the CON group, the gut microbiome of RSF group possessed an enhanced potential for carbohydrate and energy metabolism and a reduced potential for bacterial pathogenicity-related pathways.

4. Excessive heating of 00-rapeseed meal reduces not only amino acid digestibility but also metabolizable energy when fed to growing pigs.

The present work tested the hypothesis that both the degree of heating and the time that heat is applied will affect the concentration of DE and ME, and the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of amino acids (AA) in 00-rapeseed meal (00-RSM) fed to growing pigs. It was observed that there were no effects of autoclaving at 110 °C on DE and ME or on AID and SID of AA in 00-RSM, but DE and ME, and AID and SID of AA were less if 00-RSM was autoclaved at 150 °C compared with 110 °C. At 150 °C, there were decreases in DE and ME, and in AID and SID of AA as heating time increased. In conclusion, autoclaving at 110 °C did not affect ME or SID of AA in 00-RSM, but autoclaving at 150 °C had negative effects on ME and SID of AA and the negative effects increased as heating time increased.

5. Prediction of net energy values in expeller-pressed and solvent-extracted rapeseed meal for growing pigs.

The present study was conducted to determine net energy (NE) of expeller-press (EP-RSM) and solvent-extracted rapeseed meal (SE-RSM) and to establish equations for predicting the NE in rapeseed meal fed to growing pigs. The NE values were 10.80 and 8.45 MJ/kg DM for EP-RSM and SE-RSM, respectively. The NE value was positively correlated with gross energy (GE), digestible energy (DE), metabolizable energy (ME), and ether extract (EE) and this may be utilized to quickly determine the NE in rapeseed meal when DE or ME values are unavailable. The NE value of rapeseed meal can be well predicted based on energy content (GE, DE and ME) and proximate analysis.

References

FEDNA: http://www.fundacionfedna.org/
FND. CVB Feed Table 2016. http://www.cvbdiervoeding.nl
INRA. Sauvant D, Perez, J, y Tran G, 2004, Tables de composition et de valeur nutritive des matières premières destinées aux animaux d'élevage.
NRC 1982. United States-Canadian Tables of Feed Composition: Nutritional Data for United States and Canadian Feeds, Third Revision.
Rostagno, H,S, 2017, Tablas Brasileñas para aves y cerdos, Composición de Alimentos y Requerimientos Nutricionales, 4° Ed.