Maataloustieteellinen A ikakauskirja Vol. 63: 465—474, 1991 Digestibility and protein utilization responses of soybean and rape seed meal to physical and enzymatic treatments in diets for growing pigs MATTI NASI University of Helsinki Department of Animal Husbandry SF-00710 Helsinki, Finland Abstract. The effects of extrusion, hydrothermal processing and enzyme pretreatment of soybean meals (SBM) and rapeseed meals (RSM) and the multienzyme supplementation of diets on nutrient digestibility, protein utilization and performance were investigated in growing pigs. The study was comprised of two separate total-collection digestibility and balance trials with 6x6 Latin square designs and a production trial with 140 growing pigs. The processes em- ployed had only minor effects on the chemical composition of the treated oilseed meals. Ex- trusion and addition of enzyme premix improved the organic matter (OM) and protein (CP) digestibilities of SBM (P<0.05). These processes also tended to have a positive effect on the nitrogen retention and protein utilization in the pigs. The hydrothermal process had no effect on the nutritive value of SBM, but improved the OM and CP digestibility in RSM (Pc0.05). Energy values of the treated SBM and RSM tended to increase compared with the untreated meals. There were no significant differences in growth rate, feed conversion or carcase quality between pigs fed diets supplemented with differently treated SBM, relative to untreated con- trol. Partial hydrolysis of the polysaccharides present in SBM and RSM with hydrothermal or enzymatic processing may have resulted in the release of intracellular nutrients in the intes- tine and improved their absorption and utilization. More consistent responses to these thermal and enzymatic treatments could be expected with younger pigs with less microbial activity in the alimentary canal. Index words: soybean meal, rapeseed meal, processing, enzymes, digestibility, pig Introduction Protein supplementation in pig diets is mainly based on oilseed meals while the use of fish meal is avoided due to its negative ef- fects on meat quality. Proper processing is of great importance in order to ensure the nutri- tional value of soybean meal (SBM) and rape seed meal (RSM) for pig diets. Heat treatment is necessary to inactivate antinutritional fac- tors present in oilseeds. In soybeans those fac- tors are primarily protease inhibitors and in 465 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=rrR9CzcwwRs5dWOE.TO2ie3NiUayiSoHKeMTpMw.o6xbY_HhzdoeYCEZkGcR-Q6vjl3yk5Tgg63KpR3iAiIU4mfTjtAOCEnRrg4eQ-om_KR2inol4ML8-mGytlIMxVdzJzwUElAWdsHgFRx_ouxSb1Ar6tp_tZWqz6PHHmpGn9HY_ZZy67IXfD6yUpgrALG_KWCZfJIa76B5URhXkWXFcH1s4-fg1F9Qv0JYEEweDCs1QvvqT68nMBYYdxlg0LFp rape seeds glucosinolates, tannins, myrosinase, rapeseed gumsand phytic acid. Other process- ing methods can also enhance the nutritive val- ue of these oil seed meals as an ingredient in pig diets. Heat treatment and hydrothermal process- ing rupture the cell wall matrix and modify the chemical structure of plant constituents. These processes render nutrients more suscep- tible to enzyme degradation in the small in- testine, thus improving the digestibility and utilization, especially of amino acids. The con- tent of structural polysaccharides in the soy- bean is rather low compared with rapeseed, and is mostly present in the hulls, which com- pose only 7 °7o of the soybean. The hull frac- tion in RSM comprises 25—28 °7o of the dry matter. The different types of polysaccharides in defatted SBM hulls are galactomannans (9— 11 %), acidic polysaccharides (10 —12 %), xylan hemicellulose (9 —10 %) and cellulose (40 %) (Aspinall et al. 1967). The lignin con- tent is low in soybean hulls (1.3 %), while in rapeseed hulls it is 28.9 % (Mitaru et al. 1984). Polysaccharides compose 26 % of hulled SBM and the major components are arabino-galactan and acidic polysaccharides belonging to the pectic group of substances (Aspinall et al. 1967). The polysaccharides present in the greatest amounts in dehulled rapeseed are pectins (14.5 %), cellulose residues (7 %), and fuco-amyloid, arabinan and arabinogalactan (together 5 to 6 °7o) (Bell 1984). Insoluble fibre tends to increase pas- sage rate and to form an insulating coat on the digestible nutrients, thus reducing the nu- trient supply. Soluble fibres slow down the transit time, but their gelling, ion-exchange and absorbing characteristics retard digestion and absorption. The cellulolytic or hemicellulolytic enzymes are potent agents of degradation of poorly digestible or viscous polysaccharides and thus a dietary addition of suitable enzymes (cellu- lase, 3-glucanase, xylanase, mannase and pec- tinase) may be of practical importance in im- proving the feeding value of some low-energy feed components for monogastrics. Enzyme supplementation could also be used to break down anti-nutritional substances found in feed raw materials, thus augmenting the diges- tive capacity of the animal, improving avail- ability of the nutrients in the feed, and increas- ing release of nutrients in the upper part of the gastrointestinal tract (Chesson 1987, Die- rick 1989). In dry feeding systems, enzymes can be ad- ded directly to the complete feed or used in the pretreatment of feeds and feed raw materi- als. With the former application, the sup- plementary enzymes will act in the gastroin- testinal tract of thepigs. In pretreatment, the enzymes act on specific poorly-digestible sub- stances in the raw material, thus improving its feed value. In wet feeding systems, enzymes can be added directly, and during the soak- ing they will break down poorly digestible sub- stances. The enzyme mixtures, their compo- sitionand the level of activity used depend on the feed composition and the enzymes’ stabil- ity under feed-processing conditions. The objective of this study was to elucidate the effect of thermal processing and addition of enzymes or enzymatic pretreatment on the nutritive valueof soybean meals. In one of the experiments, rapeseed meals also were pro- cessed in the same way as SBM. In addition, a growth trial was performed to investigate the effect of soybean processing and enzyme sup- plementation on theperformance of the pigs. Preliminary results of the present study have been published previously by Nasi (1988). Materials and methods The animal response to physical and en- zymatic treatments of soybean meal and rapeseed meal was evaluated in two digesti- bility and balance trials and in one perform- ance trial with growing pigs. The treatments of the soybean meals used in Exp. I. were: 1.) normal solvent-extracted SBM, 2.) SBM extruded with a single-screw extruder, exit temperature ca. 100°C, 3) heat- treated, low-degradable SBM for ruminants 466 467 (Opex-process, Oljynpuristamo Oy, Helsinki), 4.) treatment with multienzyme premix (cel- lulase, protease and P-glucanase, Suomen Rehu Oy, Helsinki) addition of 0.1 %, in dry solvent-extracted SBM diet, 5.) multienzyme premix added at the level of 0.1 % to a wet SBM diet 8 hours before feeding and 6.)SBM conditioned at 60°C and 30 % moisture con- tent, sprayed with enzyme premix 2 h prior to drying. The chemical composition of the experimental feeds is shown in Table 1. The treatments of the SBM’s and RSM’s in Exp. 11. were: 1.) normal SBM, 2.) SBM con- ditioned at 60°C and at 30 % moisture for 30 min followed by drying, 3.) SBM treated as above (2.) followed by addition of 0.1% en- zyme (Multienzyme premix, containing cellu- lase and protease-activities, Suomen Rehu Oy, Helsinki), which was allowed to act for 30 min prior to drying, 4.) normal RSM, 5.) RSM treated as SBM in 2.), and 6.) RSM treated as SBM in 3), but with an enzyme premix in- cluding xylanase and cellobiase as well. The chemical composition of the experimental feeds is presented in Table 2. In the first digestibility and balance trial, the variously processed SBM’s were used as protein supplements in six isonitrogenous, 150 g crude protein (CP)/kg, barley-based diets. The supplements were fed to growing pigs (30—75 kg) at the inclusion level of 165 —lB5 g/kg diet. In the second experiment, threeprocessed SBM’s and three RSM’s were used as protein supplements in barley-based diets (160 g CP/kg diet). SBM supplementa- tion was 122—129g/kg diet and that of RSM 185—209 g/kg. Both experiments had a 6 x 6 Latin square design. The basal diet was evaluated separately. Each period was com- prised of 6 days of adjustment and 6 days of faeces and urine total collection. Assay proce- dures were similar to those reported by Nasi (1984). The various SBM’s were also evaluated in a performance trial, in which the four diets used had processed SBM as the sole protein supplement. SBM supplementation was 170 g and the diets contained 130 g DCP and 8.7 g lysine per kg feed. As a positive control diet a mixture was used in which the protein supplement was 120 g SBM and in addition 40 g/kg fishmeal (140 g DCP and 9.7 g/kg ly- sine). Pure lysine and methionine were added to adjust the amino acid levels in the rations. The composition of the feeds and their nutri- ent contents are given in Table 3. The ex- Table 1. Chemical composition and calculated feed values of the experimental feeds (Experiment. 1). g/kg DM Soybean meals Barley Normal Ex- Rumen Enzyme Enzyme Enzyme truded escape added added pre- treated dry wet treated Crude protein 482 497 508 492 493 493 97 Ether extract 33 40 31 29 28 28 31 Crude fibre 75 73 70 65 65 65 46 Nitrogen free extract 347 325 325 352 352 351 804 Neutr. deterg. fibre 131 134 134 120 120 123 286 Acid deterg. fibre 93 92 91 81 86 89 64 Lysine, g/160 g N 62 61 59 62 61 62 41 Threonine » 40 39 40 41 41 41 35 Methionine » 15 15 16 17 16 20 19 Cystine » 17 16 15 17 16 17 24 Available lysine » 60 58 56 59 58 58 40 FU/kg DM 1.01 1.09 1.03 1.08 1.07 1.07 1.14 Kg/FU 1.13 1.03 1.08 1.06 1.10 1.11 1.03 DCP, g/kg DM 394 427 417 426 433 438 68 ME, MJ/kg DM 14.77 16.01 15.14 15.86 15.75 15.79 14.71 468 Table 2. Chemical composition and calculated feed values of the experimental feeds (Experiment. 2). g/kg DM Soybean meals Rapeseed meals Barley Normal Hydro- Enzyme Normal Hydro- Enzyme thermal treat. thermal treat, proces. proces. Crude protein 471 487 494 361 352 349 138 Ether extract 53 34 32 102 100 98 36 Crude fibre 63 77 70 134 123 125 45 Nitrogen free extract 303 331 338 329 351 352 758 Neutr. deterg. fibre 111 121 101 247 237 235 172 Acid deterg. fibre 57 72 62 182 171 170 41 Acid deterg. lignin 78 73 77 Lysine, g/160 g N 59 60 61 59 57 55 35 Threonine » 38 39 39 43 45 44 33 Methionine » 19 15 14 25 24 24 20 Cystine » 15 16 15 27 25 25 27 Available lysine » 56 57 59 56 54 52 34 FU/kg DM 1.00 0.91 1.06 0.80 0.92 0.88 Kg/FU 1.13 1.25 1.12 1.40 1.17 1.31 DCP, g/kg DM 359 398 368 288 268 272 ME, MJ/kg DM 14.8 13.6 15.7 12.0 13.7 13.0 perimental animals numbered 140, seven repli- cates of four pigs being used in each treat- ment. The pigs were assigned at random to the different feeds, with the variation in starting weight between the groups kept as small as possible. The pigs were weighed every two weeks and and the feed consumption was de- termined for each pen. Feeding was made ac- cording to the weight-based schedule of Salo et al. (1982). The individual pigs were slaugh- tered at an average weight of 100kg, at which time the carcase weight was recorded and the carcase classified. Results and discussion Only small differences were found in the proximate composition of the processed SBM’s. Enzyme-treated SBM had slightly lower crude fibre, NDF and ADF than nor- mal or extruded SBM. However the differ- ences were quite small. The different SBM’s were similar in their amino acid composition except that the SBM treated for ruminants had a lower lysine and available lysine content. Small reductions in lysine were also evident in other processed SBM’s (Table 1). Excessive heat treatment during processing can lead to the destruction of amino acids and the forma- tion of biologically unavailable amino acid carbohydrate complexes such as Maillard reaction products (Mauron 1981). Total ly- sine may be lost during heating but available lysine is depressed even more (Roach et al. 1967). Veltman et al. (1986) have shown that increased cooking temperature reduces CP content of a SBM treated for rumen escape and decreases amino acids such as lysine, methionine and threonine. In Expt. II processing did not have any ef- fect on the fibre composition of SBM’s and only a small reduction was noticed in the NDF and ADF content of treated RSM’s (Table 2). Processing reduced the lysine content and availability in RSM’s. According to the data of Inborr et al. (1988), hydrothermal and en- zymatic processing decreased the content of lysine and available lysine in barley meal. The same observation was made for processed oats by Nasi (1988, unpublished data) when methods of processing similar to the present experiments were applied. The processing con- ditions should be optimal for the action of the enzymes, but at the same time care has to be 469 Table 3. Chemical composition and calculated feed values of the experimental feeds (Experiment. 3). g/kg DM Contr. Soybean meals posit. Normal Rumen Extruded Extruded escape Enzyme- treated pretreated Ingredients, g/kg Barley 717 707 701 699 690 Oats 50 50 50 50 50 Molasses 20 20 20 20 20 Soybean meal normal 117 161 rumen escape (Opex) 167 extruded 169 extruded, enzyme pret. 178 Fishmeal 40 Skimmilk powder 10 Fat mixture 10 20 20 20 20 L-Iysine 1.0 1.2 1.2 1.2 1.2 DL-methionine 0.3 0.3 0.3 0.3 0.3 Mineral + vitamin prem. 35 35 35 35 35 Calculated nurtients Digestible CP, g/kg 140 129 129 129 129 FU/kg feed 1.00 1.00 1.00 1.00 1.00 Lysine, g/kg 9.7 8.7 8.7 8.7 8.7 Meth. + cyst., g/kg 6.2 5.6 5.6 5.6 5.6 Threonine, g/kg 6.3 5.8 5.8 5.8 5.8 Calcium, g/kg 9.0 9.0 9.0 9.0 9.0 Analysed composition, g/kg DM Dry matter 886 892 886 890 889 Ash 57 57 57 56 57 Crude protein 186 171 170 169 170 Ether extract 37 45 44 46 45 Crude fibre 53 52 56 57 57 Nitrogen free extract 666 675 673 671 671 Table 4. Digestibilities of processed soybean meals and protein utilization of the diets (Experiment 1). Soybean meals SEM Statis. Normal Ex- Rumen Enzyme Enzyme Enzyme- signif. truded escape added added pretreat, treated dry wet Organic matter 0.795 0.851 0.801 0.851 0.837 0.864 0.027 NS Crude protein 0.817 0.860 0.821 0.865 0.879 0.887 0.017 » Ether extract 0.497 0.708 0.642 0.649 0.704 0.735 0.103 NS Crude fibre 0.415 0.522 0.425 0.393 0.422 0.355 0.072 NS Nitrogen free extract 0.876 0.927 0.891 0.930 0.874 0.875 0.037 NS N intake, g/d 47.1 48.3 47.6 47.9 47.9 48.8 0.321 NS N excr. in faeces, g/d 10.9 10.1 10.9 10.1 9.7 9.7 0.408 � N excr. in urine, g/d 16.2 17.2 16.8 17.1 17.6 17.6 0.492 NS N retained, g/d 20.0 20.9 19.9 19.9 20.5 21.5 0.713 NS of intake 0.425 0.437 0.423 0.423 0.430 0.448 0.022 NS of absorbed 0.561 0.559 0.558 0.538 0.542 0.561 0.022 NS UreaN excr. in urine, g/d 17.2 14.8 14.8 20.3 17.6 17.3 0.637 NS Biological value 0.643 0.638 0.639 0.618 0.621 0.637 0.013 NS SEM = standard error of the means; significance: NS (non-significant), * (P<0.05), ** (P<0.01). taken to avoid destruction of amino acids and their availability. The digestibility of CP in the different SBM’s varied from 0.817 to 0.887, and differed significantly between untreated and enzyme-pretreated SBM (P<0.05). Addition of enzyme to the diet or extrusion of SBM tended to improve both OM and CP digesti- bility (Table 4). Enzymatic processing also im- proved the OM and ether extract digestibility of SBM (P < 0.05) in Exp. 11, but not ofRSM, while hydrothermal processing of RSM in- creased OM and CP digestibility (P<0.05, Table 5). SBM treated for ruminants in order to decrease protein degradability had the same digestibility as normal SBM. This has practi- cal importance, since the same lots of oil seed meals can be used for both ruminants and monogastrics. Addition of enzyme, wet feed- ing and pretreatment of SBM resulted in higher mean nitrogen retention than diets with other SBM but differences were not signifi- cant (P > 0.05, Table 4). It is also possible that the addition of enzyme to SBM in wet feed- ing can have an effect on thebarley in the diet and that this is partly responsible for the im- proved nutrient utilization. A small improve- ment is achieved by enzyme, mainly (3-gluca- nase, supplements in barley-based diets (Gra- ham et al. 1986, Inborr et al. 1988, Thacker et al. 1988). Acid resistance of the enzyme sup- plements in applying direct addition in diet is of great importance because in pig stomach there is very low pH. It has been well established that the nutri- tive value of vegetable protein is improved by heat treatment. Industrial applications of heat treatment for feeds are extrusion, toasting, pressure cooking and infrared radiation. With some exceptions heat treatment may result in an increased accessibility of protein to en- zymatic attack (Van Der Pol 1990). Heating primarily inactivates the proteinaceous an- tinutritive factors in oilseed meals. Improved energy values of the processed oilseed meals found in present study are in agreement with previous studies, in that extrusion has been found to improve organic matter and energy digestibility of grain or grain, SBM and wheat middlings diets (Noland et al. 1976, Skoch et al. 1983, Fadel et al. 1988, Herkelman et al. 1990). No affect on the utilization of protein or lysine at the terminal ileum was observed in the study of Herkelman et al. (1990), while Noland et al. (1976) reported improved pro- tein digestibility following by extrusion in agreement with the present observations. Pres- ent finding that enzyme pretreatment of meals and hydrothermal processing of RSM im- proved ADF and NDF digestibilities is sup- ported by the higher NDF digestibility noticed after pressure cooking (Van Der Pol et al. 1989). Extrusion or other hydrothermal pro- cesses have also resulted in 0.19 more ileal digestion of soluble non-starch polysaccha- rides (NSP) and 0.13 more lower tract diges- tion of insoluble NSP (Fadel et al. 1988). In this study a mixture of enzymes having several activities was used, while the response of pigs to supplementation of diets with pro- teolytic enzymes alone has been very poor (re- view of Dierick (1989). Only in baby pigs did proteolytic enzymes improve live weight gain and feed conversion (Lewis et al. 1955, Baker et al. 1956). However, Zamora and Veum (1979) found that growing pigs have a greater growth rate and net nitrogen utilization due to improved amino acid availability when heated whole soybeans fermented with some fungi were fed compared with heated unfer- mented whole soybeans. Pigs do not secrete endogenous enzymes which break down NSP found in most raw materials of plant origin. Degradation of the cell wall matrix and the structural polysaccha- rides in rapeseed fibre by physical or other means promotes the release of intracellular nutrients in the small intestine for digestion and absorption. The addition of enzyme pre- parations withcellulolytic and hemicellulolytic activities has improved feed utilization in pigs, but the results have not always been consis- tent (review of Dierick 1989). Recently im- provements in performance were noted when diets for early-weaned pigs were supplement- 470 471 Table 5. Digestibilities of processed soybean meals and rape seed meals and protein utilization of the diets (Experiment 2). Soybean meals Rapeseed meals SEM Significance of effect Normal Hydro- Enzyme Normal Hydro- Enzyme SBM Soybean meals Rapeseed meals thermal treat. thermal treat. vs.~~ ~ “ next Compar. Compar. Compar. Compar. proces. proces. RSM A „ B Organic matter 0.815 0.754 0.847 0.609 0.694 0.667 0.0228 *•* NS * * NS Crude protein 0.762 0.742 0.790 0.642 0.701 0.684 0.0153 *** NS NS * NS Ether extract 0.757 0.517 0.725 0.639 0.766 0.700 0.0669 NS NS * NS NS Crude fibre 0.485 0.465 0.639 0.322 0.410 0.382 0.0962 NS NS NS NS NS Nitrogen free extract 0.977 0.807 0.984 0.679 0.766 0.743 0.0453 *** * NS NS NS Neutr. deterg. fibre 0.523 0.288 0.607 0.206 0.343 0.306 0.1403 NS NS NS NS NS Acid deterg. fibre 0.527 0.403 0.669 0.177 0.292 0.258 0.1214 ** NS NS NS NS Hemicellulose 0.542 0.152 0.539 0.297 0.488 0.445 0.1738 NS NS NS NS NS Cellulose 0.553 0.454 0.671 0.376 0.490 0.425 0.1006 NS NS NS NS NS N intake, g/d 53.1 53.0 53.2 53.2 53.3 53.3 0.03 *** NS * NS NS N excr.in faeces, g/d 10.0 10.5 9.6 12.9 11.5 12.1 0.29 *** NS NS ** NS N excr.in urine, g/d 20.9 20.7 20.9 18.4 20.2 19.0 0.73 * NS NS NS NS N retained, g/d 22.2 21.8 22.8 22.0 21.6 22.2 0.67 NS NS NS NS NS of intake 0.418 0.414 0.426 0.411 0.405 0.423 0.0135 NS NS NS •• NS of absorbed 0.520 0.519 0.524 0.544 0.522 0.552 0.0185 NS NS NS NS NS UreaN excr.in urine, g/d 15.3 14.8 14.4 23.4 14.5 14.3 0.86 NS NS NS NS NS Biological value 0.593 0.592 0.596 0.619 0.597 0.625 0.0174 NS NS NS NS NS ed with enzyme preparations containing amy- lase, proteases, P-glucanase and cellulases (Hogeberg et al. 1983, Collier and Hardy 1986a, b), indicating that the animals’ own digestive enzyme system seems to be limiting in some way. Some antinutritive factors as glucosinolates in rapeseed meal could be elimi- nated with enzymatic treatments followed by fermentation as reported by Staron (1984). Dense populations of cellulolytic and pectino- lytic anaerobes have been measured in the in- testines of pigs fed different diets (Chesson et al. 1985). This suggests that bacterial fibre- degrading capacity in growing pigs may be sufficient to degrade reasonable NSP enabling proper digestion. A component of the re- sponse to the treatments may be affected by the age of the experimental pigs. Probably treatment responses would have been greater in piglets as indicated by Inborr and Ogle (1988). In the performance trial there were no sig- nificant effects of dietary treatments on the average daily gain or the feed conversion ra- tio (P>0.05, Table 6). In this experiment the positive control group was fed a diet contain- ing fish mealprotein supplement and a higher protein content. Fish meal is now avoided in the diets of growing pig due to offflavor which are detected in the meat followed by lower eat- ing quality. Formulas have been made using only oilseed meals to supplement protein. The aim of this study was to elucidate which processing methods can improve the value of oilseed meal in pig diets. Extrusion of SBM tended to improve the performance as com- pared with the group on the normal SBM and gave the same daily gain and FCR as the posi- tive control having a greater protein supply. This observation is in agreement with the results obtained in the balance trial. In this performance test the enzymatic process had a rather small effect, in contrast to the results obtained in the digestibility trial, but it is pos- sible that during preparation of the feed in- activation of the enzymes occurred. Hydro- thermal or enzymatic treatments of barley fibre, a by-product with a high hemicellulose content from intergraded starch-ethanol proc- ess, containing diets for growing pigs did not result in improved performance in an earlier study (Nasi 1989). Hydrolysis of structural plant polysaccha- rides is generally of nutritional benefit. The Table 6. Performance of pigs on diets supplementedwith soybean meals processed with different methods (Experi- ment. 3). Contr. posit. Soybean meals Statist. signif. Normal Rumen Extruded Extruded escape Enzyme- treated pretreated No. pigs in test 28 27 25 28 28 NS Initial liveweight, kg 29.5 29.2 29.5 29.5 29.5 NS Final liveweight, kg 99.6 97.4 98.7 100.3 98.5 NS Days in test 86.8 90.0 90.5 88.2 88.8 NS Daily gain, g 815 762 766 807 781 NS Feed intake, kg/d 2.32 2.26 2.26 2.29 2.25 NS Feed/gain, kg/kg LWG 2.87 2.99 2.95 2.85 2.90 NS Carcase weight, kg 71.1 69.4 70.0 71.4 70.1 NS Dressing 0.714 0.712 0.710 0.712 0.711 NS Carcase grading, % E+ glass 22.2 18.5 16.0 21.4 21.4 E 25.9 29.6 32.0 21.4 28.6 I 51.9 48.2 52.0 57.2 46.4 I— 3.6 Withdrawal 3.6 See footnote Table 4. 472 breakdown of the cell walls makes nutrients available which would otherwise be protect- ed from digestive processes. Legume seeds contain specific gel-forming polysaccharides and the destruction of these polysaccharides by hydrothermal processing or the application of enzymes tended to give better performance than feeding untreated material in this study. Endo-enzymes produce random hydrolysis of linkages within a polysaccharide chain. Cleavage of relatively few linkages rapidly leads to chain shortening and subsequent loss of gel-forming properties (Chesson 1987). Fekete (1984) has suggested that the greatest benefit from the addition of cellulase to pig diets is an improvement in nitrogen utilization rather than enhanced utilization of fibre. When only one enzyme activity is added to the diet, the structural polysaccharides in the plant cell wall may remain intact. A multienzyme additive with cellulolytic and proteolytic ac- tivities can degrade the polysaccharides more effectively, promoting release of intracellular nutrients in the small intestine for digestion and absorption. This may be more important in younger pigs than those used in the pres- ent experiment, since the oligosaccharides, es- pecially raffinose and stachyose of SBM have been reported to cause diarrhea in young pigs. 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Tutkimus kasitti kaksi sulavuus- ja tasekoetta (6x6 latinalaiset nelidt) seka tuo- tantokokeen, jossa oli 140 lihasikaa. Rouheiden proses- sointeina oli ekstrudointi, kostea lampokasittely ja ent- symaattinen kasittely. Entsyymiseosta lisattiin myOs ka- sittelemattomaan soijarouheeseen sikojen ruokinnan yh- teydessa jokokuivaan rehuun tai 12 tuntia ennen ruokin- taa kostutettuun soijarouheeseen. Ekstrudointi ja entsyy- mikasittely paransivat soijarouheen orgaanisen aineen ja raakavalkuaisen sulavuutta. Lampokasittely lisasi rypsi- rouheen sulavuutta. Kasittelyt lisasivat myos hieman val- kuaisen hyvaksikayttoa seka laskennallista energia-arvoa. Tuotantokokeessa eri tavoin kasitellyt soijarouheet eivat poikenneet merkitsevasti kasittelemattomasta, ekstrudoin- nin ollessa kuitenkin toisia parempi. Saatujen tulosten pe- rusteella seka fysikaalisilla etta entsymaattisilla kasitte- lyilla oli rouheiden kayttokelpoisuuttaparantava vaiku- tus sikojen ruokinnassa. Vaikutus perustui ilmeisesti kui- tuaineksen ja solunseinamien pilkkoutumiseen ja sita kautta ravintoaineiden parantuneeseen sulavuuteen ja imeytymiseen. 474