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< PreviousINFORMATION RUMINANTS SWINEPOULTRYAQUACULTURE 8 | CANOLA COUNCIL OF CANADA | CANOLAMAZING.COM Table 6. Vitamin content of canola meal 1 . VITAMIN 12% MOISTURE BASIS DRY MATTER BASIS Biotin, mg/kg1.081.22 Choline, g/kg6.7 7.6 Folic acid, mg/kg1.551.76 Niacin, mg/kg160182 Pantothenic acid, mg/kg9.410.6 Pyridoxine, mg/kg7.108.10 Riboflavin, mg/kg5.806.5 Thiamine, mg/kg5.205.9 Vitamin E, mg/kg18.521.0 1 Wickramasuriya et al., 2015. Anti-nutritional Factors Rapeseed meal, the parent of canola meal, is recognized as an ingredient that may need to be limited in diets for livestock and fish due to certain anti-nutritional factors, primarily glucosinolates. These factors have been reduced in Canadian canola meal to levels that do not pose threats to performance and feeding for most species. Glucosinolates Glucosinolates are a large group of secondary plant metabolites common to all cruciferous plants. While nontoxic on their own, breakdown products of glucosinolates can adversely affect animal performance. Canola glucosinolates are composed of two main types, aliphatic and indolyl (or indole) glucosinolates. Aliphatic glucosinolates make up approximately 85% of the glucosinolates present in canola meal, while indolyl glucosinolates account for the other 15% (Adewole et al., 2016). The low glucosinolate content of canola, compared to previous cultivars of rapeseed, constitutes the major improvement in meal quality achieved by plant breeders. The average total glucosinolate content of Canadian canola meal, based on seven years of data, is 3.6 μmol/g (Slominski and Rogiewicz, unpublished). By comparison, traditional rapeseed meal contains levels as high as 120 μmol/g of total glucosinolates. The reason that glucosinolates are expressed on a molecular (μmol/g) basis rather than on a weight (mg/ kg) basis is that glucosinolates have significantly different molecular weights, depending on the size of their aliphatic side chain. Since the negative effect on the animal is at the molecular level, the most accurate estimate of this effect must be gauged by expressing glucosinolate concentration on a molecular basis. According to the most recent data provided by The Canadian Grains Commission (2023) (https://www. grainscanada.gc.ca/en/grain-research/export-quality/ oilseeds/canola/2021/08-glucosinolate.html) the content of glucosinolate compounds in canola seed is low and has not changed noticeably since 2000. The level of glucosinolates in Canadian canola seed prior to processing has averages around 10 μmol/g. Glucosinolate content is then concentrated in the meal; after that, the glucosinolates are reduced during processing to values averaging 3.6 μmol/g. Erucic acid Consumption of this fatty acid has been associated with myocardial lesions. However, Canadian plant breeders successfully reduced the amount of erucic acid in canola oil to very near zero levels (Figure 2). Erucic acid is no longer considered a problem for either the meal or the oil. Tannins Tannins are present in canola meal at a range of 1.5–3.0%, with brown-seeded varieties having higher levels than yellow-seeded varieties. The tannins in canola meal are associated with the hull and are primarily insoluble. These tannins do not appear to have the same negative effects on palatability and protein digestibility that they do in other edible plants (Khajali and Slominski, 2012). INFORMATION RUMINANTS SWINE POULTRY AQUACULTURE CANOLA MEAL FEEDING GUIDE | INTRODUCTION | 9 Figure 2. Erucic acid levels in canola oil from 2000 to 2022. (https://www.grainscanada.gc.ca/en/ grain-research/export-quality/oilseeds/ canola/2021/10-fatty-acid-composition.html). NUTRITIONAL COMPOSITION OF EXPELLER CANOLA MEAL Several terms are used interchangeably to differentiate solvent extracted versus expeller-extracted meals. Terms commonly used to describe the meal include expeller meal, double-press meal and presscake. Currently in Canada, a small percentage of seed is processed using the expeller method. Smaller oilseed plants as well as those associated with some biodiesel plants use double-press expeller processing rather than solvent extraction. Since the oil is extracted simply by mechanical means, the resulting meal contains significantly more oil than that of standard solvent-extracted canola meal. The nutritional profile of the meal is like that of canola meal, except that it contains 8–12% fat and therefore has much higher energy values. The nutritional composition of expeller meal is provided in Table 7. Fat content can vary widely, so it is important that the expeller meal is analyzed for fat, and the energy value adjusted accordingly. High levels of fat will also dilute other nutrients in the resultant meal, relative to solvent-extracted canola meal. Table 7. Typical composition of expeller canola meal 1 . COMPONENT 12% MOISTURE BASIS DRY MATTER BASIS Moisture (as measured), %4.020.00 Crude protein (N*6.25), %34.2838.95 Rumen escape protein, % of protein (NRC method) 2 48.5048.50 Rumen escape protein, % of protein (CNCPS method) 3 59.1059.10 Ether extract, %10.9612.44 Oleic acid, %6.857.75 Linoleic acid, %2.202.50 Linolenic acid, %0.911.03 Ash, %6.967.90 Calcium, %0.620.71 Phosphorus, %0.961.09 Total dietary fibre37.0742.12 Acid detergent fibre, %16.7219.00 Neutral detergent fibre, %26.8330.49 Glucosinolates, μmol/g 8.8510.06 Methionine, % of crude protein1.931.93 Lysine, % of crude protein5.935.93 Threonine, % of crude protein3.693.69 1 Adewole et al., 2016; 2 Broderick et al., 2016; 3 Ross et al., 2013. 20002005201020152020 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 Erucic acid, % of oil YearINFORMATION RUMINANTS SWINEPOULTRYAQUACULTURE 10 | CANOLA COUNCIL OF CANADA | CANOLAMAZING.COM NUTRIENT COMPOSITION OF CANOLA SEED The key nutrient values for canola seed are shown in Table 8. These values were obtained from recent publications (Assadi et al., 2011; Leterme et al., 2008). Most nutrient values for canola seed can be calculated from the nutrient values in canola meal and oil, considering that approximately 56% of the seed is meal and 44% is oil. The exception is energy content, because the energy value of canola seed cannot be estimated reliably from the addition of the energy values for canola oil and meal. For swine and poultry, the seed has less energy than the sum of its oil and meal components. This is likely because whole canola seed is not processed to the same degree as canola oil and meal; and therefore, not as well digested. Heat treatment and particle size reduction of canola seed by micronization, extrusion or expansion is often used to increase its energy digestibility. Table 8. Reported chemical composition of canola seed (12% moisture basis). REFERENCE ComponentsFeedipedia, 2018Assadi et al., 2011 Montoya and Leterme, 2008 DairyOne, 2023 Moisture, %6.85.05.75.8 Crude protein, %18.420.020.721.5 Ether extract,%40.543.838.634.5 Linoleic acid, %8.38.57.9– Linolenic acid, %4.14.23.9– Ash, %3.83.74.14.7 Crude fibre, %8.9––8.9 ADF, %12.7–10.615.9 NDF, %17.916.612.922.5 Calcium, %0.43––0.39 Phosphorus, %0.64––0.65 INFORMATION RUMINANTS SWINE POULTRY AQUACULTURE CH. 3 – CANOLA MEAL FOR RUMINANTS Canola meal is widely used in diets for dairy and beef cattle. It is considered to be a premium ingredient for both dairy and beef animals as well as small ruminants due to the exceptionally high quality of protein to support milk production and growth. INFORMATION RUMINANTS SWINEPOULTRYAQUACULTURE 12 | CANOLA COUNCIL OF CANADA | CANOLAMAZING.COM Practical Inclusion Levels of Canola Meal in Diets for Ruminants DIET TYPEINCLUSION LEVELS Starter preweaning20% with no flavoring agent Starter preweaningUp to 35% with flavoring agents Weaning transitionNo Limit Heifer development and growth No Limit Dairy transitionNo Limit Dairy lactationNo Limit Beef backgroundingNo Limit Beef finishingNo Limit Goat lactationNo Limit Lambs and Kids, growingNo Limit DAIRY CATTLE Canola Meal Use In a 2021 anonymous survey conducted by the marketing agency broadhead and executed by Farm Journal on behalf of the Canola Council of Canada, the primary concern expressed by nutritionists regarding feed formulation was ensuring profitability. The second-greatest concern was environmental sustainability. Canola meal has become a common feed ingredient for dairy cows. Nutritionists find it easy to balance diets for amino acids and to reduce protein use when canola meal is present. Recent research demonstrates that canola meal and canola oil reduce greenhouse gas (GHG) emissions when fed to dairy cows, compared to feeding other vegetable proteins. Canola Meal and Profitability While not frequently measured in university trials, several field trials have shown canola meal can help improve profitability. A trial conducted in Wisconsin involving 1,295 mid-lactation cows showed a significant improvement in income over feed costs (Faldet, 2018). The ration, formulated to contain 3.4 kg of dry matter from canola meal/cow/day, reduced ration costs while increasing milk production. In an early-lactation study conducted in California involving 566 cows that were three to 23 weeks into lactation, canola meal supported greater milk yield at a lower feed cost (Swanepoel et al., 2020). In this feeding trial, the control diet contained canola, the primary vegetable protein used in California. For both of the two test diets, half of the added protein was provided by soybean meal as a replacement for canola meal. One of the soybean meal diets also contained added methionine (Table 2). Table 1. Findings for cows involved in a Wisconsin field trial. PARAMETER CONTROL PERIODTEST PERIOD Number of cows1,2951,295 Ration cost/day, $6.256.22 Milk, kg41.9143.95 Fat %3.863.92 Protein %3.193.29 Fat, kg1.671.79 Protein, kg1.431.49 3.5% FCM, kg46.3249.45 ECM, kg46.4149.27 Table 2 shows that substituting part of the canola meal with soybean meal resulted in lost production, even with elevated levels of rumen-protected methionine. There were no differences in rate of involuntary culling or health events. The daily ration cost at the time the trial was conducted was approximately $US 0.05 and $US 0.08/cow/day less expensive for the canola meal treatment compared to the treatments containing soybean meal or soybean meal with added methionine. INFORMATION RUMINANTS SWINE POULTRY AQUACULTURE CANOLA MEAL FEEDING GUIDE | RUMINANTS | 13 Table 2. On-farm results for cows participating in a feeding trial in California. DIET Item Canola meal Soybean meal Soybean meal + methionine Canola meal, % of DM 1 14.36.66.6 Soybean meal, % of DM 1 06.66.6 Milk, kg51.3149.5549.93 Fat, kg1.781.711.75 Protein, kg1.451.381.44 Dry matter intake, kg28.528.228.3 First service conception, % 48.944.748.5 1st + 2nd service conception, % 68.964.267.4 1 Cost for canola meal was $US 405/ton, and cost for soybean meal was $US 496/ton, equivalent to $US 440 and $US 550/metric tonne, respectively. Using Canola Meal to Reduce Greenhouse Gas Emissions Canola meal has been repeatedly shown to contribute to reducing methane emissions in lactating Holstein dairy cows. It can provide an economical way to lower enteric methane and nitrous oxide output, the two greenhouse gases of greatest importance in livestock production. Enteric methane production can be expressed in several ways. The first is amount/animal/day. This is influenced by the size (Jersey vs. Holstein as an example), maturity of the animal, and the level of milk production. Another measurement used is methane/ unit of feed consumed. This metric is useful for analyzing the portion of the total gross energy lost under defined conditions. It is referred to as methane yield. Methane intensity is a measure of methane output/unit of meat or milk produced. Table 3 provides results from recent studies in which canola meal was used to replace soybean meal as a protein source in experimental rations. Only one trial was available with Jersey cows. The inclusion of 10.1% canola meal in that study did not reduce methane output, as determined using the indirect calorimetry method (Reynolds et al., 2019). The results showed that, on average, energy- corrected milk (ECM) was increased by 1.0 kg/cow/day, while methane was reduced by 5.0, 7.5 and 8.6% when expressed as grams/day, yield or intensity, respectively. Many factors influence the extent to which enteric methane output is reduced by the inclusion of canola meal in the diet. Some examples are the forage sources and the forage-to-concentrate ratio. The level of canola meal inclusion appears to be a factor, as well. In a recent experiment (Benchaar et al., 2021), cows received 16% crude protein diets that varied from 0–24% canola meal. As Table 4 shows, methane output was reduced as the level of inclusion increased. Less information is available for dry cows and heifers, but some inferences can be gathered from studies with beef cattle as well as in-vitro trials. Substitution of canola meal for soybean meal in one growth study reduced methane yield by 27% (Elshareef et al., 2020). Likewise, in-vitro fermentation results have demonstrated reduced methane production under a variety of feeding situations (Paula, et al., 2017; Ramirez-Bribiesca et al., 2018; Soliva et al., 2008). Table 3. Comparison of methane output for diets in which canola meal replaced soybean meal as the primary source of protein. MEAL 1 METHANE OUTPUT Ref 2 SRC % Of DM ECM, kg 3 g/ day g/kg DMI g/kg ECM 3 1 SBM17.044.048919.011.1 CM24.046.246116.610.0 2 SBM15.029.446124.117.8 CM20.830.745622.515.8 3 SBM10.232.044217.613.8 CM13.033.140415.712.2 4 SBM13.640.341417.010.4 CM17.141.139615.09.5INFORMATION RUMINANTS SWINEPOULTRYAQUACULTURE 14 | CANOLA COUNCIL OF CANADA | CANOLAMAZING.COM MEAL 1 METHANE OUTPUT 5 SBM14.555.453820.39.7 CM19.455.446618.08.4 6 SBM13.731.033519.110.8 CM10.131.736020.511.4 1 SBM = solvent-extracted soybean meal. CM = solvent-extracted canola meal; 2 1-Benchaar et al., 2021; 2-Gidlund et al., 2015; 3-Holtshausen et al., 2021; 4-Lage et al., 2021; 5-Moore et al., 2016; 6-Reynolds et al., 2019 3 ECM = energy-corrected milk. Table 4. Relationship between the level of inclusion of canola meal in the diet and methane output as determined in one study 1 . CANOLA MEAL INCLUSION LEVEL, % OF DM Variable081624 Production Dry matter intake (DMI), kg25.826.927.327.7 Energy corrected milk (ECM), kg44.045.045.646.2 Methane g/day489475463461 g/kg DMI18.917.817.116.8 g/kg ECM12.512.011.611.3 1 Benchaar et al., 2021. Part of the methane reduction value of canola meal can be associated with the lipid profile, which is rich in the mono-unsaturated fatty acid oleic acid. Lipids can reduce enteric methane in three ways: by directly targeting methanogens and protozoa, by acting as a reservoir for H+, and by providing a concentrated source of energy. Unsaturated fatty acids can bind to protozoa cell membranes and inhibit the transport of H+ by protozoa to methanogens (Kobayashi, 2010). The biohydrogenation of unsaturated fatty acids likewise provides a hydrogen sink, resulting in less H+ available in the rumen to produce methane. A meta-analysis (Eugene et al., 2008) revealed that methane was reduced by 2.2% for each 1% addition of lipid to the diet of dairy cows. Similarly, Beauchemin, et al. (2008) found that dietary lipids reduced methane by 5.6% for each 1% lipid added to diets for beef cattle. The reduction in methane that occurs with the feeding of canola meal is only partially related to the contribution of the lipid fraction. Beauchemin et al. (2009) determined that when canola oil, flax oil or sunflower oil were added to diets already containing canola meal, all supported reduced methane output, demonstrating additivity between the meal and oil fractions. Furthermore, Ramirez-Bribiesca et al. (2018) found that the fermentation of canola meal increases propionate, resulting in one less carbon moiety available to contribute to gas production. These researchers were able to identify a high negative correlation between the slowly degraded protein fraction of CM (-0.99) and methane. They additionally correlated reduced methane with fat content of the meal (-0.80). Williams et al. (2020) determined that tannins can likewise reduce methane, with the effect being additive to the effects of fat. The seed hull of canola is a notable source of tannins. Canola meal additionally has been shown to reduce nitrous oxide. Many research papers, as described in two recent meta-analyses (Martineau et al., 2013; Martineau et al., 2019), have shown that the efficient use of absorbed protein from canola results in lower blood urea nitrogen when compared to other vegetable protein meals. Excreted urea nitrogen is rapidly converted to ammonia gas, which can thereby indirectly contribute to atmospheric nitrous oxide. As Table 5 illustrates, urine nitrogen excretion is reduced, and milk nitrogen (protein) is elevated as canola meal in the diet is increased. Hristov et al. (2011) found that modifying the level of canola oil in diets containing canola meal did not alter nitrous oxide production. Table 5. Effect of increasing canola meal on the diet on urinary nitrogen excretion 1 . CANOLA MEAL INCLUSION LEVEL, % OF DM 081624 Nitrogen intake, g/day679700707718 Milk nitrogen, g/day210213218222 Urine nitrogen, g/day35.133.431.731.4 Urine nitrogen, % of total intake 5.14.84.54.3 1 Hassanat et al., 2020. INFORMATION RUMINANTS SWINE POULTRY AQUACULTURE CANOLA MEAL FEEDING GUIDE | RUMINANTS | 15 Canola Meal Palatability Canola meal is a highly palatable ingredient for adult ruminant animals. Many recent studies have revealed that intakes in dairy cows can be maintained or enhanced when canola meal replaces soybean meal or distillers’ grains. In a Latin Square designed study, Benchaar et al. (2021) provided dairy cows with diets containing 0, 8, 16 or 24% canola meal, replacing soybean meal. Dry-matter intakes increased linearly with canola meal inclusion, contributing to greater milk yield (Table 6). Broderick and Faciola (2014) replaced 8.7% of soybean meal with 11.7% canola meal. Cows consumed 0.5 kg more DM with the canola meal diet. Maxin et al. (2013a) substituted 20.8% canola meal in replacement of 13.7% soybean meal, with cows consuming 23.6 and 24.0 kg of DM for the two diets, respectively. Swanepoel et al. (2014) fed up to 20% of DM as canola meal to high-producing cows in exchange for high-protein distillers’ grains, with no reduction in DMI. Three early-lactation trials (Moore and Kalscheur, 2016; Gauthier et al., 2019; Kuehnl and Kalscheur, 2021) noted a 1-kilogram increase in intake when canola meal replaced soybean meal in the diet. Heim and Krebs (2020) suggested that solvent-extracted canola meal may be more palatable than expeller canola meal. Solvent-extracted meal is more readily available on the North American market. Table 6. Effect of increasing dietary canola meal on dry matter intake 1 . DIET Canola meal inclusion, %07.8915.823.7 Soybean meal inclusion, %17.011.35.650 Dry matter intake, kg/day25.826.927.327.7 Energy corrected milk, kg/ day 44.045.045.646.2 1 Benchaar et al., 2021. Growing cattle likewise have been shown to find canola meal to be a palatable feed ingredient. Nair et al. (2014) found that when barley grain was replaced by canola meal at either 15 or 30% of the total dry matter (DM) during backgrounding, cattle consumed greater amounts of feed with the addition of the canola meal. In a continuation of that study (Nair et al., 2015) with finishing cattle, intakes were improved when canola meal was included in the diet at concentrations of 10 or 20% of the DM. For beef cattle, intakes were higher in backgrounded beef cattle given diets with 10% canola meal than diets containing corn distillers’ grains or wheat distillers’ grains (Li et al., 2013). He et al. (2013) determined that there was no reduction in dry matter intake (DMI) when canola meal replaced barley grain at 30% of the diet DM during the growing or finishing phase with beef cattle in feedlot. Both solvent-extracted and expeller canola meal treatments were tested in that experiment, with the same result. Using Canola Meal as a Protein Source Amino acid composition Canola meal has been recognized as the star of all vegetable proteins due to the meal’s superior amino acid profile. A quarter century ago, Shingoethe (1996) demonstrated that the amino acid profile of canola meal matched the needs of dairy cows for milk yield (Table 7), and complemented rumen microbial protein to a greater degree than other vegetable proteins. This was recently underscored by Kuehnl and Kalscheur (2022), who continue to examine the effect of amino acids in early lactation, and showed that the efficiency of amino acid utilization was superior for canola meal. The determined amino acid composition of the intact meal and the rumen undegraded protein (RUP) fraction of the meal are provided in Table 8. These values were determined by Ross (2015), based on the RUP method developed by Cornell University (Ross et al., 2013). The samples were a subset of a survey of samples obtained from 2011 through 2014 from processing plants across Canada.INFORMATION RUMINANTS SWINEPOULTRYAQUACULTURE 16 | CANOLA COUNCIL OF CANADA | CANOLAMAZING.COM Table 7. Milk protein score system used to compare proteins (1.00 = perfect) 1 . LIMITING AMINO ACID ProteinScore1st2nd3rd Rumen microbial protein0.78HistidineLeucineValine Fish meal0.75LeucineTryptophanIsoleucine Canola meal0.68IsoleucineLeucineLysine Cottonseed meal0.46MethionineIsoleucineLysine Soybean meal0.46MethionineValineIsoleucine Sunflower meal0.46LysineLeucineMethionine Meat and bone meal0.43TryptophanIsoleucineMethionine Brewers’ grains0.40LysineMethionineHistidine Corn distillers’ grains0.32LysineTryptophanMethionine Corn gluten meal0.21LysineTryptophanIsoleucine Feather meal0.19HistidineMethionineLysine 1 Shingoethe, 1996. The determined amino acid composition of the intact meal and the rumen undegraded protein (RUP) fraction of the meal are provided in Table 8. These values were determined by Ross (2015), based on the RUP method developed by Cornell University (Ross et al., 2013). The samples were a subset of a survey of samples obtained from 2011 through 2014 from processing plants across Canada. Table 8. Essential amino acid composition of canola meal and canola meal RUP fraction, as determined by Cornell University using the Ross method 1 . % DM BASIS% OF PROTEIN Intact mealRUP fractionIntact mealRUP fraction Arginine2.172.236.036.19 Histidine 0.930.912.562.53 Isoleucine1.241.283.443.56 Leucine2.522.687.007.44 Lysine1.841.765.114.89 Methionine1.271.553.534.31 Phenylalanine1.441.494.004.14 Threonine1.471.514.094.19 Tryptophan0.480.511.331.42 Valine1.441.544.004.28 1 Ross et al., 2015 Rumen undegraded protein in canola meal. Rumen undegraded protein in canola meal While the amino acid profile contributes greatly to the importance of canola meal in ruminant feeds systems, equally so does the RUP component of the meal. Approximately half of the protein in canola meal is in the form of RUP (Table 9). The RUP, expressed as a percentage of total protein, has consistently been demonstrated to be greater than that found for solvent extracted soybean meal. Many feed libraries have incorrect values for the RUP content of canola meal. In the past, the in-situ nylon bag method has been used to partition feed protein into RUP and rumen degraded protein (RDP) fractions. The error in this method resides in the fact that soluble protein and protein that becomes soluble and leaves the porous bags are assumed to be degraded by the microbes in the rumen, and, therefore, unavailable as an amino acid source for the host animal. Indeed, so entrenched is the notion that solubility and degradation are equal, that the recently released NASEM (2021) did not update the acceptance of this notion since the last publication (NRC, 2001). Errors in estimating how feed proteins are partitioned have hampered the ability of feed formulators to support optimum rumen microbial growth, as well as the calculation of the amounts of amino acids entering the intestine from microbial and feed ingredient sources. INFORMATION RUMINANTS SWINE POULTRY AQUACULTURE CANOLA MEAL FEEDING GUIDE | RUMINANTS | 17 Table 9. The RUP value for canola meal and soybean meal, as determined by several newer methods of analysis (% of total protein). REFERENCE CANOLA MEAL SOYBEAN MEAL CANOLA/ SOY RATIO Broderick et al., 201646.330.51.51 Hedqvist and Uden, 2006 56.327.02.07 Jayasinghe et al., 201442.831.01.38 Maxin et al., 201352.541.51.27 Ross, 201553.245.21.18 Tylutki et al., 200841.838.31.09 The actual rumen degradability of soluble protein is variable and has long been known to be variable. The breakdown of protein results in the release of ammonia nitrogen in the rumen. Broderick et al. (1991) evaluated the amount of ammonia generated under in vitro conditions, and clearly indicate that peptides and amino acids can accumulate. The authors stated “a portion of the soluble protein may require some disruption of secondary and tertiary structure for proteolysis to proceed. Proteins with extensive disulfide bonding, such as albumins or immunoglobulins, or those containing artificial cross-links caused by chemical treatment, are more slowly degraded than less ordered proteins.” Proteins that are rich in disulfide bonds are soluble, but resistant to degradation in the rumen (Wallace, 1983; McNabb et al., 1994). The two major storage proteins in canola meal are napin, an albumin protein, and cruciferin, a globulin protein (Perera et al., 2016). Under a range of conditions, both proteins can become soluble (Chmielewska et al., 2020), with napin highly likely to become soluble in the rumen environment. In the case of canola meal, with napin rich in disulfide bonds, the degradability of soluble protein is less than some other common vegetable proteins. Table 10 provides an example of true degradation rates for the soluble fraction of proteins (Hedqvist and Udén, 2008). The soluble protein in canola meal is broken down much more slowly than the soluble protein in soybean meal or wheat distillers’ grains. This means that there is considerable opportunity for the soluble fraction from canola meal to reach the intestine. Add to that the fact that soluble protein will exit the rumen with the liquid outflow, which is at least twice as fast as the solid turnover rate (Seo et al., 2006). This would likewise apply to the misrepresented portion of protein that becomes solubilized while suspended in the rumen during the in-situ analyses. Table 10. Rates of digestion of the soluble fraction of protein in the rumen for selected ingredients 1 . VEGETABLE PROTEIN SOLUBLE PROTEIN, % OF TOTAL PROTEIN RATE % DEGRADED/HOUR Canola meal (rapeseed meal) 20.419 Flax (linseed meal)58.618 Lupins80.234 Peas77.839 Soybean meal16.946 Wheat distillers’ grains24.362 1 Hedqvist and Udén, 2008. Rumen microbial protein production Studies have confirmed that diets containing canola meal support similar levels of microbial production when compared to soybean meal. Using the direct measurement abomasal nitrogen flow, Brito et al. (2007) and Paula et al. (2018) both determined that there were no differences in microbial protein yield when canola meal was used to replace soybean meal as a source of protein. Results from two feeding trials (Lage et al., 2021; Pereira et al., 2020) using urinary purine derivatives to estimate microbial protein yield found no differences in the two sources of protein, while Swanepoel et al. (2021) using the same methodology found that the canola meal diet promoted rumen conditions to improve microbial growth. Paula et al. (2017) determined that there were no differences in microbial protein yield for soybean meal or canola meal diets in a dual flow fermentation study. Next >