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Oligosaccharides in Canola Meal and Their Effect on Nonstarch Polysaccharide Digestibility and True Metabolizable Energy in Poultry
Oligosaccharides in Canola Meal and Their Effect on Nonstarch Polysaccharide Digestibility and True Metabolizable Energy in Poultry B. A. SLOMINSKI, L. D. CAMPBELL, and W. GUENTER Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2 ABSTRACT Balance studies utilizing laying hens and adult cockerels were conducted to determine the influence of oligosaccharides (raffinose and stachyose) present in canola meal (CM) on the digestibility of nonstarch polysaccharides (NSP) and on the TMEn of the meal. Ethanol extraction was used to produce oligosaccharide-free meal, and exogenous dietary enzymes (agalactosidase and invertase) were employed to bring about oligosaccharide hydrolysis in the intestinal tract of the birds. In each of two balance trials, six hens individually housed were randomly allotted to each of the experimental diets in completely randomized design. Experiment 1 consisted of a factorial arrangement of treatments (two sources of protein with or without enzyme supplementation), whereas Experiment 2 consisted of five diets: semipurified CM control, semipurified ethanol-extracted CM; semipurified ethanolextracted CM plus raffinose; conventional CM; and conventional ethanolextracted CM. Elimination of oligosaccharides by the use of exogenous dietary enzymes had no effect on NSP digestion. Removal of oligosaccharides by ethanol extraction increased NSP digestibility from 4 to 8%. A more pronounced effect (17% NSP digestion) was noted in hens fed a wheat-based diet containing 30% oligosaccharide-free CM. This latter effect may have been due to the relatively high content of water-soluble polysaccharides contributed by the wheat portion of the diet. The TMEn content of ethanol-extracted CM was 2,302 kcal/kg as compared with 2,426 kcal/kg for untreated CM. The data indicate no advantage of oligosaccharide removal with regard to the nutritive worth of canola meal. (Key words: oligosaccharides, canola meal, true metabolizable energy, hen, enzymes) 1994 Poultry Science 73:156-162
pectic substances (Slominski and Campbell, 1990). The digestibility of nonstarch Canola meal (CM) contains high quality polysaccharides (NSP), the major compoprotein but its use in the diets of monogas- nent of dietary fiber in CM, has been tric animals, particularly broiler chickens, reported to be very low (3%) in poultry has been limited by the relatively high (Slominski and Campbell, 1991). The content of fiber in the meal (Bell, 1982). oligosaccharides raffinose and stachyose, The fiber components in canola meal which account for 2.5% of canola meal include lignin (8%), cellulose (4 to 6%), (Slominski and Campbell, 1991), have and the noncellulosic polysaccharides (13 been indicated to have a depressing effect to 16%), which consist predominantly of on utilization of energy from soybean meal (SBM) in poultry (Coon et al, 1990). Removal of oligosaccharides by ethanol extraction increased NSP digestibility and Received for publication May 3, 1993. TME of SBM for poultry by 50 and 20%, Accepted for publication September 16, 1993. INTRODUCTION
156
OLIGOSACCHARIDES IN CANOLA MEAL
respectively. The objective of the current study was to evaluate the effect of CM oligosaccharides on NSP digestibility and energy utilization in poultry. Exogenous enzymes and ethanol extraction were employed to produce dietary treatments with and without oligosaccharides. MATERIALS AND METHODS Two balance trials were conducted with Shaver 288 hens to determine the effect of oligosaccharides in SBM or CM on NSP digestibility. In each trial, six hens individually housed in cages (25 x 40 cm) were randomly allotted to each of the experimental treatments. The diets containing .3% chromic oxide as an internal marker were fed for 7 d and excreta collections were made on Days 3, 5, and 7 as described by Slominski et al. (1987). The daily samples were freeze-dried,1 ground with a Cyclotec 1093 sample mill equipped with a 1-mm screen,2 and pooled for the 3-d collections prior to analysis for NSP and chromium. Nonstarch polysaccharide digestibility was calculated by the indicator method (Crampton and Harris, 1969). Data were subjected to ANOVA (SAS Institute, 1985) and treatment means separated using Tukey's multiple comparison test (Snedecor and Cochran, 1980). Experiment 1
157
invertase (.1%) were added to a standard wheat-soybean diet containing 1.3% oligosaccharides. The same a-galactosidase preparation, used in this study, was a crude enzyme obtained from the mycelial pellet of Mortirella vinacea. An activity of 4.3 nkat agalactosidase/mg was determined with melibiose as a substrate. Invertase, having an activity of 56 and 16 nkat/mg as determined with raffinose and stachyose substrates, respectively, was derived from Baker's yeast.3 Both enzymes were added to the diets in a dry form using wheat as a carrier. Experiment 2 Oligosaccharides and other ethanolsoluble components were removed from CM following vigorous mixing of 2 kg CM with 10 L of 80% ethanol. The extraction was performed for 4 h and was repeated four times. The ethanol-extracted meal (EtOH CM) was dried under a fume hood for 2 d. Canola meal and EtOH CM were both subjected to oligosaccharide, sucrose, NSP, protein, fat and ethanol-soluble analysis (Table 2). Isocaloric and isonitrogenous diets containing CM and EtOH CM were prepared as semipurified or conventional diets and contained similar levels of dietary
TABLE 1. Composition of canola meal and soybean meal diets used in Experiment 1
Two diets consisting of CM or SBM Canola Soybean (Table 1) were prepared with and without a Ingredients and analysis meal1 meal1 combination of a-galactosidase and inver(%) tase enzymes to produce four dietary treatments in a factorial arrangement. The Wheat 64.7 56.7 28.0 enzymes used in this experiment have Canola meal meal 20.0 previously been shown, in our laboratory, Soybean .3 Chromic oxide .3 2 to bring about the hydrolysis of oligosacch- Standard ingredients 15.0 15.0 arides in the digestive tract of poultry. In Calculated analyses this regard, the hydrolysis of raffinose and CP 18 18 stachyose in the gastrointestinal tract of ME, kcal/kg 2,809 2,940 ! cecectomized laying hens averaged 88% Each diet was prepared with and without supwhen a-galactosidase (.2%) in concert with plemental enzyme (.2% a-galactosidase and .1%
1
Labconco freeze drier Model Number 75150, Labconco Corp., Kansas City, MO 64132. 2 Tecator AB, S-26321, Hoganos, Sweden. sSigma Chemical Co., St. Louis, MO 68178-9916.
invertase) added in place of wheat. Contained vegetable oil (5.0%), calcium carbonate (6.0%), calcium phosphate (2.5%), vitamin premix (1.0%), and mineral premix (.5%) to meet or exceed the nutrient requirements of laying hens as specified by NRC (1984) and described in detail by Slominski et at (1987).
158
SLOMINSKI ET AL. TABLE 2. Chemical composition of canola meal (CM) and ethanol-extracted canola meal (EtOH CM)
Component
CM
Protein Fat Oligosaccharides2 Sucrose Nonstarch polysaccharides Total ethanol solubles Unidentified ethanol solubles
39.7 ± .131 3.1 ± .10 2.6 ± .04 7.5 ± .12 22.7 ± .14 19.5 ± .13 6.33
EtOH CM — (% DM) 47.4 ± .21 .3 ± .01 .1 ± .00 .1 ± .01 29.0 ± .26 .9 ±.04 .43
'Mean of duplicate determination ± SD. 2 Includes raffinose and stachyose. Calculated by difference [total ethanol solubles - (oligosaccharides + sucrose + fat)] and assumed to consist of free glucose and fructose, free amino acids, peptides, glucosinolates, sinapine, phenolic acids, phytate, and a variety of other components.
fiber [i.e., neutral detergent fiber (NDF), total and soluble NSP] but different levels of oligosaccharides and other ethanolsoluble components of CM (Table 3). Due to the presence of substantial amounts of ethanol solubles other than sucrose or oligosaccharides in CM, a semipurified diet containing EtOH CM with added pure oligosaccharide (raffinose) was also prepared (Table 3). The data from the semipurified and conventional diets were analyzed statistically by one-way analysis of variance (SAS Institute, 1985). The TME,, contents of CM and EtOH CM were determined according to the procedure described by Sibbald (1986). The digestibility of NSP by adult roosters was also determined for CM and EtOH CM using the same procedure as for TMEn. Analytical Procedures Nonstarch polysaccharides were determined by gas-liquid chromatography4 (component neutral sugars) and by colorimetry5 (uronic acids). The procedure for neutral sugars was as described by Englyst and Curnmings (1984) with minor
4 Vista 6000 Gas Chromatograph, Varian, Palo Alto, CA 94303. 5 2400 Spectrophotometer, Gilford Instrument Co., Oberlin, OH 44074. 6 1241 Adiabatic Calorimeter, Parr Instrument Co., Moline, IL 61265.
modifications (Slominski and Campbell, 1990). Uronic acids were determined by the method of Scott (1979). Soluble NSP analysis was done utilizing the procedure for total NSP as recommended by Graham et al. (1988). The clear hydrolysate obtained following starch hydrolysis and centrifugation was transferred to a separate test tube. Ethanol was then added to a final alcohol concentration of 80%, and the resulting precipitate was analyzed for component neutral sugars and uronic acids as described above. The oligosaccharides, raffinose and stachyose, were determined by gas-liquid chromatography (Slominski and Campbell, 1991), and NDF content was analyzed by the method described by Goering and Van Soest (1970). The NDF procedure was modified to exclude the use of decalin and sodium sulfite (Mascharenhas Ferreira et al, 1983). Chromic oxide analysis was done by atomic absorption spectrometry (Williams et al, 1963), and crude protein and gross energy were determined with the aid of a Kjeltec Auto 1030 Protein Analyzer,2 and an adiabatic, oxygen-bomb calorimeter,6 respectively. Ethanol solubles were determined gravimetrically following an extensive, 5-h extraction of .4 g of canola meal with 10 mL of 80% ethanol, centrifugation, and subsequent measurement of the dry residue after evaporation of ethanol from the 1 mL of supernatant.
159
OLIGOSACCHARIDES IN CANOLA MEAL TABLE 3. Composition of experimental diets used in Experiment 2 Semipurified diet Item
CM
Diet composition CMi EtOH CM! Cornstarch Wheat Casein Sunflower oil Sucrose Raffinose Chromic oxide Other2 Chemical analyses Total NSP3 Soluble NSP NDF4 Oligosaccharides Calculated nutrient content CP ME, kcal/kg
Conventional diet
EtOH CM EtOH CM
40.0 31.9 47.3
3.7 5.0
4.2 2.0 2.8
.3 10.0
.3 10.0
4.2 2.5 2.8 1.0 .3 10.0
9.3 .7 11.2 .9
9.4 .6 11.1 .0
9.2 .7 10.9 1.0
18 2,909
EtOH CM
30.0 31.9 48.8
41.0
CM
18 2,876
18 2,869
54.4 .3 5.0
24.6 4.3 54.4 .8 3.4 2.2
.3 10.0
.3 10.0
12.9 1.3 14.2 1.0
13.2 1.3 14.0 .2
18 2,787
18 2,766
*CM = canola meal; EtOH CM = ethanol-extracted canola meal. Contained calcium carbonate (6.0%), calcium phosphate (2.5%), vitamin premix (1.0%), and mineral premix (.5%) to meet or exceed the nutrient requirements of laying hens as specified by NRC (1984) and described in detail by Slominski et al. (1987). 3 Nonstarch polysaccharides. 4 Neutral detergent fiber. 2
which represent the normal level of oligosaccharides present in CM and SBM. The The digestibility of NSP in laying hens removal of oligosaccharides utilizing the fed CM and SBM with and without added dietary enzyme treatment did not inenzymes (a-galactosidase and invertase) is fluence NSP digestibility. The low level for shown in Table 4. The enzyme mixture used in the current study was shown in a NSP digestibility was similar to that previous study to be effective in bringing observed in a previous study (Slominski about the hydrolysis of oligosaccharides in and Campbell, 1990). The data, however, the gastrointestinal tract of the laying hen. do not agree with the enhanced fiber Thus, the enzyme treatments represent a digestibility reported by Coon et al. (1990) low oligosaccharide level in comparison to for diets in which the oligosaccharides the positive controls without enzyme, were removed by ethanol extraction. RESULTS AND DISCUSSION
TABLE 4. Digestibility Of ± SD) of nonstarch polysaccharides in laying hens fed canola meal (CM) and soybean meal (SBM) diets with and without enzyme supplementation, Experiment 1 Treatment
Digestibility
CM CM + a-galactosidase (.2%) + invertase (.1%) SBM SBM + a-galactosidase (.2%) + invertase (.1%)
3.4 3.7 3.6 3.7
(%) ± ± ± ±
2.1 3.2 1.3 1.4
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SLOMINSKI ET AL.
TABLE 5. Digestibility (x ± SD) of nonstarch polysaccharides in laying hens fed semipurified diets containing canola meal (CM), ethanol-extracted canola meal (EtOH CM) and EtOH CM plus raffinose for 3, 5, and 7 d, Experiment 2 Day of experiment Treatment CM EtOH CM EtOH CM + raffinose
5.4 ± 2.3 4.4 ± 3.3 4.3 ± 3.7
In Experiment 2, the digestibility of NSP from EtOH CM did not differ from that for CM when the meals were fed as semipurified diets to laying hens (Table 5). The digestibility of NSP from EtOH CM with added raffinose was similar to that for the CM control. In contrast, but similar to the response noted by Coon et al. (1990), ethanol extraction resulted in twofold higher NSP digestibility when EtOH CM was fed as a conventional diet (Figure 1). However, the increase in NSP digestibility observed in the current study was lower than that reported for hemicellulose (62%) and cellulose (35%) by Coon et al. (1990). The reason for this discrepancy is not clear, but it would appear that the observed difference between semipurified and conventional diets in the current study may be related to the water-soluble NSP contents of the respective diets. Wheat has a higher content of watersoluble NSP than canola meal, and this
-> 30 r-
Co nolo meal EtOH conolo meal
E
20
1.0
(%) 4.2 ± 3.1 7.3 ± 2.4 5.3 ± 2.9
may have contributed to the improvement in NSP digestibility between CM and EtOH CM. The digestibilities of the soluble component of NSP from CM and EtOH CM for the semipurified and conventional diets are shown in Table 6. Irrespective of the presence or absence of oligosaccharides in the diets, the wheatbased conventional diets resulted in higher (P < .05) soluble NSP digestibilities than the semipurified diets. The lack of effect of oligosaccharides indicates that the effect of removal of oligosaccharides on NSP digestibility was a consequence of a change in the nonsoluble as opposed to the soluble NSP fraction. Coon et al. (1990) reported a high (77.9%) apparent digestibility by adult rooster for the total water soluble carbohydrates in SBM. The values for soluble NSP digestibilities obtained in the current study, ranging from 41.5 to 50.6 and 63.8 to 70.1% for semipurified and conven-
TABLE 6. Digestibility (x ± SD) of soluble nonstarch polysaccharide in laying hens fed semipurified and conventional diets containing canola meal (CM) or ethanol-extracted CM (EtOH CM), Experiment 2 Treatment
CL
FIGURE 1. Percentage nonstarch polysaccharide (NSP) digestibilities in laying hens fed wheat-based diets containing canola meal and ethanol-extracted (EtOH) meal. Values are expressed as mean ± SD. 'Values significantly different from the control (P < .05).
4.7 ± 3.0 8.6 ± 3.0 5.0 ± 2.1
Digestibility
(%) Semipurified CM diets CM EtOH CM EtOH CM + raffinose Conventional diets CM EtOH CM
41.5 ± 6.7>>b 50.6 ± 8.2 44.6 ± 9.3b 63.8 ± 4.0* 70.1 ± 6.3a
ab ' Means with no common superscript differ significantly (P < .05).
161
OLIGOSACCHARIDES IN CANOLA MEAL
TABLE 7. Gross energy, nitrogen-corrected true metabolizable energy, and nonstarch polysaccharide (NSP) digestibility of the canola meal (CM) and ethanol-extracted CM (EtOH CM) used in Experiment 2 Variable
CM
EtOH CM
Gross energy, kcal/kg TMEn, kcal/kg NSP digestibility, %
4,446 ± 12ia 2,426 ± 10" 11.6 ± 0.4t>
4,326 ± 17b 2,302 ± 39b 15.1 ± 0.2"
ab
' Means within a row with no common superscript differ significantly (P < .05).
tional diets, respectively, are in agreement with this finding. However, in contrast to the data of Coon et al. (1990), in which the total soluble carbohydrates in EtOH SBM were essentially indigestible, the digestibility of soluble NSP in EtOH CM was high and similar to that for CM. The reason for this discrepancy is not clear. The digestibilities of oligosaccharides in the CM and EtOH CM plus raffinose diets were 68.5 ± 6.7 and 70.4 ± 5.1%, respectively (not shown in tables), and agree with the high (90.5 and 83.5%) apparent digestibilities reported by Coon et al. (1990) for adult roosters. The TMEn and NSP digestibility values for the CM and EtOH CM in Experiment 2 and determined with adult roosters are shown in Table 7. Ethanol extraction resulted in a decrease in gross energy and TME„ of CM, which is in disagreement with the marked improvement reported for SBM by Coon et al. (1990). There was, however, a slight improvement in NSP digestibility with ethanol extraction, and the values obtained with adult roosters were higher than those for laying hens, particularly those determined for the semipurified diets (Table 5). Coon et al. (1990) suggested that a slow rate of passage and the acidic cecal conditions of roosters fed EtOH SBM are possible factors contributing to the enhancement of the TMEn of EtOH SBM. The fact that the removal of oligosaccharides from CM with the aid of dietary enzymes did not alter NSP digestibility, whereas some improvement was noted for EtOH CM in comparison to CM, indicates that ethanol-soluble components other than oligosaccharides were involved in the response. In this regard, the ethanolsoluble content of CM was 19.5% (includ-
ing 7.5% sucrose and 2.6% oligosaccharides) and that of EtOH CM was .9% DM. The SBM used in the study by Coon et al. (1990) contained 12.0% total soluble carbohydrates (including 6.0% sucrose and 5.3% oligosaccharides), whereas EtOH SBM contained .3% total water-soluble carbohydrates. Canola meal contained more ethanol-soluble material but less of the oligosaccharides than SBM, which might have contributed to the differences observed between the two studies. Further work is needed to clarify the different effects noted for ethanol extraction of CM and SBM. Nevertheless, the addition of agalactosidase and invertase to CM diets would appear to be of limited practical value. ACKNOWLEDGMENTS
Partial funding provided by the Canola Utilization Assistance Program of the Canola Council of Canada and by the Natural Sciences and Engineering Research Council of Canada is gratefully acknowledged. REFERENCES Bell, J. M., 1982. From rapeseed to canola: A brief history of research for superior meal and edible oil. Poultry Sci. 61:613-622. Coon, C. N., K. L. Leske, O. Akavanichan, and T. K. Cheng, 1990. Effect of oligosaccharide-free soybean meal on true metabolizable energy and fiber digestion in adult roosters. Poultry Sci. 69: 787-793. Crampton, E. W., and L. E. Harris, 1969. Applied Animal Nutrition. 2nd ed. W. H. Freeman and Co., San Francisco, CA. Englyst, H., and J. H. Cummings, 1984. Simplified method for the measurement of total non-starch polysaccharides by gas-liquid chromatography of constituent sugars as alditol acetates. Analyst 109:937-942.
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Goering, H. K., and P. J. Van Soest, 1970. Forage fibre analyses (apparatus, reagents, procedures and some applications). Agriculture Handbook, Number 379, USDA, Washington, DC. Graham, H., M-B. Gron Rydberg, and P. Aman, 1988. Extraction of soluble dietary fibre. J. Agric. Food Chem. 36:494-497. Mascharenhas Ferreira, A., J. Kersten, and C. H. Cast, 1983. The study of several modifications of the neutral detergent fiber procedure. Anim. Feed Sri. Technol. 9:19-28. National Research Council, 1984. Nutrient Requirements of Poultry. 8th rev. ed. National Academy Press, Washington, DC. SAS Institute, 1985. SAS® User's Guide: Statistics. Version 5 Edition. SAS Institute Inc., Cary, NC. Scott, R. W., 1979. Colorimetric determination of hexuronic acids in plant materials. Anal. Chem. 51:936-941. Sibbald, I. R., 1986. The TME system of feed evaluation: methodology, feed composition data and bibliography. Agric. Can. Tech. Bull. 1986-4E, Ottawa, ON, Canada.
Slominski, B. A., and L. D. Campbell, 1990. Nonstarch polysaccharides of canola meal: quantification, digestibility in poultry and potential benefit of dietary enzyme supplementation. J. Sci. Food Agric. 53:175-184. Slominski, B. A, and L. D. Campbell, 1991. The carbohydrate content of yellow-seeded canola. Pages 1402-1407 in: Proceedings of the 8th International Rapeseed Conference, Saskatoon, SK, Canada. Slominski, B. A., L. D. Campbell, and N. E. Stanger, 1987. Influence of cecectomy and dietary antibiotics on the fate of ingested intact glucosinolates in poultry. Can. J. Anim. Sci. 67:1117-1124. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 7th ed. Iowa State University Press, Ames, LA. Williams, C. H., D. J. David, and O. Yisamaa, 1963. The determination of chromic oxide in feces samples by atomic absorption spectrometry. J. Agric. Sci. (Camb.) 59:381-385.
pectic substances (Slominski and Campbell, 1990). The digestibility of nonstarch Canola meal (CM) contains high quality polysaccharides (NSP), the major compoprotein but its use in the diets of monogas- nent of dietary fiber in CM, has been tric animals, particularly broiler chickens, reported to be very low (3%) in poultry has been limited by the relatively high (Slominski and Campbell, 1991). The content of fiber in the meal (Bell, 1982). oligosaccharides raffinose and stachyose, The fiber components in canola meal which account for 2.5% of canola meal include lignin (8%), cellulose (4 to 6%), (Slominski and Campbell, 1991), have and the noncellulosic polysaccharides (13 been indicated to have a depressing effect to 16%), which consist predominantly of on utilization of energy from soybean meal (SBM) in poultry (Coon et al, 1990). Removal of oligosaccharides by ethanol extraction increased NSP digestibility and Received for publication May 3, 1993. TME of SBM for poultry by 50 and 20%, Accepted for publication September 16, 1993. INTRODUCTION
156
OLIGOSACCHARIDES IN CANOLA MEAL
respectively. The objective of the current study was to evaluate the effect of CM oligosaccharides on NSP digestibility and energy utilization in poultry. Exogenous enzymes and ethanol extraction were employed to produce dietary treatments with and without oligosaccharides. MATERIALS AND METHODS Two balance trials were conducted with Shaver 288 hens to determine the effect of oligosaccharides in SBM or CM on NSP digestibility. In each trial, six hens individually housed in cages (25 x 40 cm) were randomly allotted to each of the experimental treatments. The diets containing .3% chromic oxide as an internal marker were fed for 7 d and excreta collections were made on Days 3, 5, and 7 as described by Slominski et al. (1987). The daily samples were freeze-dried,1 ground with a Cyclotec 1093 sample mill equipped with a 1-mm screen,2 and pooled for the 3-d collections prior to analysis for NSP and chromium. Nonstarch polysaccharide digestibility was calculated by the indicator method (Crampton and Harris, 1969). Data were subjected to ANOVA (SAS Institute, 1985) and treatment means separated using Tukey's multiple comparison test (Snedecor and Cochran, 1980). Experiment 1
157
invertase (.1%) were added to a standard wheat-soybean diet containing 1.3% oligosaccharides. The same a-galactosidase preparation, used in this study, was a crude enzyme obtained from the mycelial pellet of Mortirella vinacea. An activity of 4.3 nkat agalactosidase/mg was determined with melibiose as a substrate. Invertase, having an activity of 56 and 16 nkat/mg as determined with raffinose and stachyose substrates, respectively, was derived from Baker's yeast.3 Both enzymes were added to the diets in a dry form using wheat as a carrier. Experiment 2 Oligosaccharides and other ethanolsoluble components were removed from CM following vigorous mixing of 2 kg CM with 10 L of 80% ethanol. The extraction was performed for 4 h and was repeated four times. The ethanol-extracted meal (EtOH CM) was dried under a fume hood for 2 d. Canola meal and EtOH CM were both subjected to oligosaccharide, sucrose, NSP, protein, fat and ethanol-soluble analysis (Table 2). Isocaloric and isonitrogenous diets containing CM and EtOH CM were prepared as semipurified or conventional diets and contained similar levels of dietary
TABLE 1. Composition of canola meal and soybean meal diets used in Experiment 1
Two diets consisting of CM or SBM Canola Soybean (Table 1) were prepared with and without a Ingredients and analysis meal1 meal1 combination of a-galactosidase and inver(%) tase enzymes to produce four dietary treatments in a factorial arrangement. The Wheat 64.7 56.7 28.0 enzymes used in this experiment have Canola meal meal 20.0 previously been shown, in our laboratory, Soybean .3 Chromic oxide .3 2 to bring about the hydrolysis of oligosacch- Standard ingredients 15.0 15.0 arides in the digestive tract of poultry. In Calculated analyses this regard, the hydrolysis of raffinose and CP 18 18 stachyose in the gastrointestinal tract of ME, kcal/kg 2,809 2,940 ! cecectomized laying hens averaged 88% Each diet was prepared with and without supwhen a-galactosidase (.2%) in concert with plemental enzyme (.2% a-galactosidase and .1%
1
Labconco freeze drier Model Number 75150, Labconco Corp., Kansas City, MO 64132. 2 Tecator AB, S-26321, Hoganos, Sweden. sSigma Chemical Co., St. Louis, MO 68178-9916.
invertase) added in place of wheat. Contained vegetable oil (5.0%), calcium carbonate (6.0%), calcium phosphate (2.5%), vitamin premix (1.0%), and mineral premix (.5%) to meet or exceed the nutrient requirements of laying hens as specified by NRC (1984) and described in detail by Slominski et at (1987).
158
SLOMINSKI ET AL. TABLE 2. Chemical composition of canola meal (CM) and ethanol-extracted canola meal (EtOH CM)
Component
CM
Protein Fat Oligosaccharides2 Sucrose Nonstarch polysaccharides Total ethanol solubles Unidentified ethanol solubles
39.7 ± .131 3.1 ± .10 2.6 ± .04 7.5 ± .12 22.7 ± .14 19.5 ± .13 6.33
EtOH CM — (% DM) 47.4 ± .21 .3 ± .01 .1 ± .00 .1 ± .01 29.0 ± .26 .9 ±.04 .43
'Mean of duplicate determination ± SD. 2 Includes raffinose and stachyose. Calculated by difference [total ethanol solubles - (oligosaccharides + sucrose + fat)] and assumed to consist of free glucose and fructose, free amino acids, peptides, glucosinolates, sinapine, phenolic acids, phytate, and a variety of other components.
fiber [i.e., neutral detergent fiber (NDF), total and soluble NSP] but different levels of oligosaccharides and other ethanolsoluble components of CM (Table 3). Due to the presence of substantial amounts of ethanol solubles other than sucrose or oligosaccharides in CM, a semipurified diet containing EtOH CM with added pure oligosaccharide (raffinose) was also prepared (Table 3). The data from the semipurified and conventional diets were analyzed statistically by one-way analysis of variance (SAS Institute, 1985). The TME,, contents of CM and EtOH CM were determined according to the procedure described by Sibbald (1986). The digestibility of NSP by adult roosters was also determined for CM and EtOH CM using the same procedure as for TMEn. Analytical Procedures Nonstarch polysaccharides were determined by gas-liquid chromatography4 (component neutral sugars) and by colorimetry5 (uronic acids). The procedure for neutral sugars was as described by Englyst and Curnmings (1984) with minor
4 Vista 6000 Gas Chromatograph, Varian, Palo Alto, CA 94303. 5 2400 Spectrophotometer, Gilford Instrument Co., Oberlin, OH 44074. 6 1241 Adiabatic Calorimeter, Parr Instrument Co., Moline, IL 61265.
modifications (Slominski and Campbell, 1990). Uronic acids were determined by the method of Scott (1979). Soluble NSP analysis was done utilizing the procedure for total NSP as recommended by Graham et al. (1988). The clear hydrolysate obtained following starch hydrolysis and centrifugation was transferred to a separate test tube. Ethanol was then added to a final alcohol concentration of 80%, and the resulting precipitate was analyzed for component neutral sugars and uronic acids as described above. The oligosaccharides, raffinose and stachyose, were determined by gas-liquid chromatography (Slominski and Campbell, 1991), and NDF content was analyzed by the method described by Goering and Van Soest (1970). The NDF procedure was modified to exclude the use of decalin and sodium sulfite (Mascharenhas Ferreira et al, 1983). Chromic oxide analysis was done by atomic absorption spectrometry (Williams et al, 1963), and crude protein and gross energy were determined with the aid of a Kjeltec Auto 1030 Protein Analyzer,2 and an adiabatic, oxygen-bomb calorimeter,6 respectively. Ethanol solubles were determined gravimetrically following an extensive, 5-h extraction of .4 g of canola meal with 10 mL of 80% ethanol, centrifugation, and subsequent measurement of the dry residue after evaporation of ethanol from the 1 mL of supernatant.
159
OLIGOSACCHARIDES IN CANOLA MEAL TABLE 3. Composition of experimental diets used in Experiment 2 Semipurified diet Item
CM
Diet composition CMi EtOH CM! Cornstarch Wheat Casein Sunflower oil Sucrose Raffinose Chromic oxide Other2 Chemical analyses Total NSP3 Soluble NSP NDF4 Oligosaccharides Calculated nutrient content CP ME, kcal/kg
Conventional diet
EtOH CM EtOH CM
40.0 31.9 47.3
3.7 5.0
4.2 2.0 2.8
.3 10.0
.3 10.0
4.2 2.5 2.8 1.0 .3 10.0
9.3 .7 11.2 .9
9.4 .6 11.1 .0
9.2 .7 10.9 1.0
18 2,909
EtOH CM
30.0 31.9 48.8
41.0
CM
18 2,876
18 2,869
54.4 .3 5.0
24.6 4.3 54.4 .8 3.4 2.2
.3 10.0
.3 10.0
12.9 1.3 14.2 1.0
13.2 1.3 14.0 .2
18 2,787
18 2,766
*CM = canola meal; EtOH CM = ethanol-extracted canola meal. Contained calcium carbonate (6.0%), calcium phosphate (2.5%), vitamin premix (1.0%), and mineral premix (.5%) to meet or exceed the nutrient requirements of laying hens as specified by NRC (1984) and described in detail by Slominski et al. (1987). 3 Nonstarch polysaccharides. 4 Neutral detergent fiber. 2
which represent the normal level of oligosaccharides present in CM and SBM. The The digestibility of NSP in laying hens removal of oligosaccharides utilizing the fed CM and SBM with and without added dietary enzyme treatment did not inenzymes (a-galactosidase and invertase) is fluence NSP digestibility. The low level for shown in Table 4. The enzyme mixture used in the current study was shown in a NSP digestibility was similar to that previous study to be effective in bringing observed in a previous study (Slominski about the hydrolysis of oligosaccharides in and Campbell, 1990). The data, however, the gastrointestinal tract of the laying hen. do not agree with the enhanced fiber Thus, the enzyme treatments represent a digestibility reported by Coon et al. (1990) low oligosaccharide level in comparison to for diets in which the oligosaccharides the positive controls without enzyme, were removed by ethanol extraction. RESULTS AND DISCUSSION
TABLE 4. Digestibility Of ± SD) of nonstarch polysaccharides in laying hens fed canola meal (CM) and soybean meal (SBM) diets with and without enzyme supplementation, Experiment 1 Treatment
Digestibility
CM CM + a-galactosidase (.2%) + invertase (.1%) SBM SBM + a-galactosidase (.2%) + invertase (.1%)
3.4 3.7 3.6 3.7
(%) ± ± ± ±
2.1 3.2 1.3 1.4
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SLOMINSKI ET AL.
TABLE 5. Digestibility (x ± SD) of nonstarch polysaccharides in laying hens fed semipurified diets containing canola meal (CM), ethanol-extracted canola meal (EtOH CM) and EtOH CM plus raffinose for 3, 5, and 7 d, Experiment 2 Day of experiment Treatment CM EtOH CM EtOH CM + raffinose
5.4 ± 2.3 4.4 ± 3.3 4.3 ± 3.7
In Experiment 2, the digestibility of NSP from EtOH CM did not differ from that for CM when the meals were fed as semipurified diets to laying hens (Table 5). The digestibility of NSP from EtOH CM with added raffinose was similar to that for the CM control. In contrast, but similar to the response noted by Coon et al. (1990), ethanol extraction resulted in twofold higher NSP digestibility when EtOH CM was fed as a conventional diet (Figure 1). However, the increase in NSP digestibility observed in the current study was lower than that reported for hemicellulose (62%) and cellulose (35%) by Coon et al. (1990). The reason for this discrepancy is not clear, but it would appear that the observed difference between semipurified and conventional diets in the current study may be related to the water-soluble NSP contents of the respective diets. Wheat has a higher content of watersoluble NSP than canola meal, and this
-> 30 r-
Co nolo meal EtOH conolo meal
E
20
1.0
(%) 4.2 ± 3.1 7.3 ± 2.4 5.3 ± 2.9
may have contributed to the improvement in NSP digestibility between CM and EtOH CM. The digestibilities of the soluble component of NSP from CM and EtOH CM for the semipurified and conventional diets are shown in Table 6. Irrespective of the presence or absence of oligosaccharides in the diets, the wheatbased conventional diets resulted in higher (P < .05) soluble NSP digestibilities than the semipurified diets. The lack of effect of oligosaccharides indicates that the effect of removal of oligosaccharides on NSP digestibility was a consequence of a change in the nonsoluble as opposed to the soluble NSP fraction. Coon et al. (1990) reported a high (77.9%) apparent digestibility by adult rooster for the total water soluble carbohydrates in SBM. The values for soluble NSP digestibilities obtained in the current study, ranging from 41.5 to 50.6 and 63.8 to 70.1% for semipurified and conven-
TABLE 6. Digestibility (x ± SD) of soluble nonstarch polysaccharide in laying hens fed semipurified and conventional diets containing canola meal (CM) or ethanol-extracted CM (EtOH CM), Experiment 2 Treatment
CL
FIGURE 1. Percentage nonstarch polysaccharide (NSP) digestibilities in laying hens fed wheat-based diets containing canola meal and ethanol-extracted (EtOH) meal. Values are expressed as mean ± SD. 'Values significantly different from the control (P < .05).
4.7 ± 3.0 8.6 ± 3.0 5.0 ± 2.1
Digestibility
(%) Semipurified CM diets CM EtOH CM EtOH CM + raffinose Conventional diets CM EtOH CM
41.5 ± 6.7>>b 50.6 ± 8.2 44.6 ± 9.3b 63.8 ± 4.0* 70.1 ± 6.3a
ab ' Means with no common superscript differ significantly (P < .05).
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OLIGOSACCHARIDES IN CANOLA MEAL
TABLE 7. Gross energy, nitrogen-corrected true metabolizable energy, and nonstarch polysaccharide (NSP) digestibility of the canola meal (CM) and ethanol-extracted CM (EtOH CM) used in Experiment 2 Variable
CM
EtOH CM
Gross energy, kcal/kg TMEn, kcal/kg NSP digestibility, %
4,446 ± 12ia 2,426 ± 10" 11.6 ± 0.4t>
4,326 ± 17b 2,302 ± 39b 15.1 ± 0.2"
ab
' Means within a row with no common superscript differ significantly (P < .05).
tional diets, respectively, are in agreement with this finding. However, in contrast to the data of Coon et al. (1990), in which the total soluble carbohydrates in EtOH SBM were essentially indigestible, the digestibility of soluble NSP in EtOH CM was high and similar to that for CM. The reason for this discrepancy is not clear. The digestibilities of oligosaccharides in the CM and EtOH CM plus raffinose diets were 68.5 ± 6.7 and 70.4 ± 5.1%, respectively (not shown in tables), and agree with the high (90.5 and 83.5%) apparent digestibilities reported by Coon et al. (1990) for adult roosters. The TMEn and NSP digestibility values for the CM and EtOH CM in Experiment 2 and determined with adult roosters are shown in Table 7. Ethanol extraction resulted in a decrease in gross energy and TME„ of CM, which is in disagreement with the marked improvement reported for SBM by Coon et al. (1990). There was, however, a slight improvement in NSP digestibility with ethanol extraction, and the values obtained with adult roosters were higher than those for laying hens, particularly those determined for the semipurified diets (Table 5). Coon et al. (1990) suggested that a slow rate of passage and the acidic cecal conditions of roosters fed EtOH SBM are possible factors contributing to the enhancement of the TMEn of EtOH SBM. The fact that the removal of oligosaccharides from CM with the aid of dietary enzymes did not alter NSP digestibility, whereas some improvement was noted for EtOH CM in comparison to CM, indicates that ethanol-soluble components other than oligosaccharides were involved in the response. In this regard, the ethanolsoluble content of CM was 19.5% (includ-
ing 7.5% sucrose and 2.6% oligosaccharides) and that of EtOH CM was .9% DM. The SBM used in the study by Coon et al. (1990) contained 12.0% total soluble carbohydrates (including 6.0% sucrose and 5.3% oligosaccharides), whereas EtOH SBM contained .3% total water-soluble carbohydrates. Canola meal contained more ethanol-soluble material but less of the oligosaccharides than SBM, which might have contributed to the differences observed between the two studies. Further work is needed to clarify the different effects noted for ethanol extraction of CM and SBM. Nevertheless, the addition of agalactosidase and invertase to CM diets would appear to be of limited practical value. ACKNOWLEDGMENTS
Partial funding provided by the Canola Utilization Assistance Program of the Canola Council of Canada and by the Natural Sciences and Engineering Research Council of Canada is gratefully acknowledged. REFERENCES Bell, J. M., 1982. From rapeseed to canola: A brief history of research for superior meal and edible oil. Poultry Sci. 61:613-622. Coon, C. N., K. L. Leske, O. Akavanichan, and T. K. Cheng, 1990. Effect of oligosaccharide-free soybean meal on true metabolizable energy and fiber digestion in adult roosters. Poultry Sci. 69: 787-793. Crampton, E. W., and L. E. Harris, 1969. Applied Animal Nutrition. 2nd ed. W. H. Freeman and Co., San Francisco, CA. Englyst, H., and J. H. Cummings, 1984. Simplified method for the measurement of total non-starch polysaccharides by gas-liquid chromatography of constituent sugars as alditol acetates. Analyst 109:937-942.
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Goering, H. K., and P. J. Van Soest, 1970. Forage fibre analyses (apparatus, reagents, procedures and some applications). Agriculture Handbook, Number 379, USDA, Washington, DC. Graham, H., M-B. Gron Rydberg, and P. Aman, 1988. Extraction of soluble dietary fibre. J. Agric. Food Chem. 36:494-497. Mascharenhas Ferreira, A., J. Kersten, and C. H. Cast, 1983. The study of several modifications of the neutral detergent fiber procedure. Anim. Feed Sri. Technol. 9:19-28. National Research Council, 1984. Nutrient Requirements of Poultry. 8th rev. ed. National Academy Press, Washington, DC. SAS Institute, 1985. SAS® User's Guide: Statistics. Version 5 Edition. SAS Institute Inc., Cary, NC. Scott, R. W., 1979. Colorimetric determination of hexuronic acids in plant materials. Anal. Chem. 51:936-941. Sibbald, I. R., 1986. The TME system of feed evaluation: methodology, feed composition data and bibliography. Agric. Can. Tech. Bull. 1986-4E, Ottawa, ON, Canada.
Slominski, B. A., and L. D. Campbell, 1990. Nonstarch polysaccharides of canola meal: quantification, digestibility in poultry and potential benefit of dietary enzyme supplementation. J. Sci. Food Agric. 53:175-184. Slominski, B. A, and L. D. Campbell, 1991. The carbohydrate content of yellow-seeded canola. Pages 1402-1407 in: Proceedings of the 8th International Rapeseed Conference, Saskatoon, SK, Canada. Slominski, B. A., L. D. Campbell, and N. E. Stanger, 1987. Influence of cecectomy and dietary antibiotics on the fate of ingested intact glucosinolates in poultry. Can. J. Anim. Sci. 67:1117-1124. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 7th ed. Iowa State University Press, Ames, LA. Williams, C. H., D. J. David, and O. Yisamaa, 1963. The determination of chromic oxide in feces samples by atomic absorption spectrometry. J. Agric. Sci. (Camb.) 59:381-385.