Apparent ileal digestibility of amino acids in wet wheat protein and soya bean meal for growing pigs Markku Mäkinen Agricultural Research Centre of Finland, Institute ofAnimal Production, FIN-31600 Jokioinen, Finland Hilkka Siljander-Rasi Agricultural Research Centre ofFinland, Swine Research Station, Tervamäentie 179, FIN-05840 Hyvinkää, Finland, e-mail: hilkka.siljander-rasi@mtt.fi, (corresponding author). A study was conducted on four castrated male pigs to determine the apparent ileal digestibility (AID) of crude protein (CP) and amino acids in wheat protein (WP), a wet by-product of the starch and gluten industry, and in soya bean meal (SBM). The pigs were fitted with a steered ileo-caecal valve cannula at a liveweight of 35 kg. They were assigned to two semi-purified wheat starch based diets, with either WP or SBM as a sole protein source, and fed according to a three-period reversal design. The diets were formulated to contain 140 g CP/kg DM, 11.3 MJ net energy/kg DM and similar amounts of lysine, methionine and threonine. The CP content and the lysine and threonine contents in CP were lower in WP than in SBM. Nearly half of the DM in WP was starch, and the crude fibre content of the product was very low. The apparent ileal and total tract digestibilities of CP were very similar in both the WP and SBM diets. The AID of methionine was higher in WP (88.2%) than in SBM (84.6%) diets (P<0.01) but no differ- ences were found in the AID of the other amino acids. The results show that the AID values of CP and amino acids in WP in growing pigs are comparable to those in SBM. Key words: cannulation; proteinous by-products; chemical composition ntroduction The grain starch industry provides several pro- tein-richby-products useful for pig feeding, such as wheat or maize gluten feed (Knabe et al. 1989, Smits et al. 1992), and barley or oat protein (Näsi 1989, Näsi and Aimonen 1992). In the vicinity to starch plants they can easily be used in unde- hydrated form on farms with wet feeding sys- tems. Although the protein content and the ap- parent ileal digestibility (AID) of protein and amino acids in these by-products is usually much higher than that in the grain (Knabe et al. 1989, Buraczewska et al. 1996), the low lysine con- tent limits their use as a sole supplementary pro- tein source for pigs. Fortified with lysine, how- ever, grain protein can replace as much as two thirds of soya bean meal (SBM) in barley-based pig diets (Näsi 1989). © Agricultural and Food Science in Finland Manuscript received October 1996 547 Voi 5 (1996): 547-555. AGRICULTURAL AND FOOD SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=-TgZc_CcbAZDF1vA.VBjSA6XtgHJK08dWheruEw.pMvwCjEldNyQmwuXu383tt4RjeSG8_-z2WAns0Tr1STWIjIotvDKNfFt5tLD0QcqKg8sV6wRrzjMpiURy42uKxeDtzd6gT_EWUCreu0bMCuXcV74XCameOiN-c8ve0IvS57bLOwRwkOx6vrrZAF9BcRh84VANRX2BncDLDHFj4AaGFWmU5TImhZBT1p8b3C73H1iLc6P2AB-LXp1INtaPjgV_X7SNj59TAweUFysjK_Us9hxMSLPUnbt2sPeeSgrxcIg0YvxVGFkzCXe3TwGKxzJprh5_M1lp7WDlxDTRW4z Mäkinen, M. & Siljander-Rasi, H. Apparent ileal digestibility ofamino acids in wet wheatprotein... Wheat protein (WP) is a wet by-product of the grain starch industry of the Raisio Group’s Grain Starch Division (Raisio, Finland). During processing, the outer parts of the wheat kernel are first removed as bran and middlings by dry milling. The large A-starch granules of the en- dosperm are separated from a water-flour mix- ture by fractionation and the gluten proteins by a maturation process. The soluble proteins of the residual are coagulated by cooking at 104°C for a few minutes. Finally, after cooling, WP is sep- arated from the residual starch, which mainly consists of small B-type granules. The remain- ing starch is hydrolysed and, after evaporation, formed into wheat syrup. WP is a low-fibrous feedstuff, containing about 15% dry matter (DM) and 22% crude pro- tein in DM. Data on the apparent total tract di- gestibility (ATTD) of protein and amino acids in a dried by-product from a roughly similar wheat starch process have been published by Smits et al. (1992). However, it is accepted that ileal digestibility is the most reliable method for determining the amino acid digestibility of feed- stuffs for pigs (Sauer and Ozimek 1986, Moughan 1993), but no information on AID val- ues in the wet by-products of wheat starch in- dustry has so far been published. The objective of the present trial was, first, to evaluate the AID and ATTD of crude protein and the AID of amino acids in WP for growing pigs and, second, to compare the digestibility of the nutrients in WP with those in SBM. Material and methods Animals and experimental procedure Four castrated Finnish Yorkshire male pigs, at an average initial liveweight of 35 kg, were sur- gically fitted with steered ileo-caecal valve (SICV) cannulae under halothane anaesthesia. A schematic view of the cannulation and detailsof the surgical operation were presented by Mroz et al. (1996). The pigs were individually housed in metabolic pens (143 x 123 cm, slatted plastic floor), at a room temperature of +23°C during therecovery period and at +lB°C during the tri- al. The pigs weighed 44.4 (SE 3.2) kg at the be- ginning and 91 (SE 1.8) kg at the end of the tri- al. The pigs were randomly assigned to two semi- purified wheat starch-based diets containing ei- therWP or normal solvent-extracted SBM as the sole protein source. The trial consisted of three experimental periods, and the pigs were trans- ferred from one diet to the other after each peri- od. The duration of the period was 16 days, in- cluding 7 days of adaptation, 5 days of faeces collection and finally, on days 13 and 16, ileal digesta collection. The faeces were collected quantitatively into a plastic bag attached to the pig with a Velcro support system (Van Kleef et al. 1994), that was glued to the skin around the anus. The faeces were stored frozen at -20°C. Ileal digesta was collected for 12 hours on each of2 days, between 6.00 and 18.00h, into a plas- tic bag connected to the barrel of the cannula. The bags were replaced with new ones at least hourly and the digesta was quick-frozen at -30°C. Cumulative feed samples of both protein sources and the semi-purified parts of the diets were collected during the experiment. Feeds and feeding Before the operation and during the 3-week re- covery period, the pigs were fed a standard bar- ley-soya bean meal diet. During recovery, the feed allowance was gradually increased to the experimental level. Two experimental diets were formulated to be isonitrogenous and isoenerget- ic and to contain equal amounts of lysine, threo- nine and methionine (Table 1). The WP batch used was frozen in plastic containers and defrost- ed for a few days in a cold store before feeding. Chromium (Cr), ytterbium (Yb) and cobalt (Co) were used as indigestible markers in the trial. Chromium-mordanted straw (70 g/kg Cr) was prepared as described by Udén et al. (1980), and 3 g of the ground straw was mixed with each 548 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Table 1.Composition and calculated analyses of the exper- imental dietsbased on wet wheat protein or soya bean meal (g/kg DM). WP diet SBM diet Wheat protein 516 Soya bean meal - 278 Wheat starch 339 574 Cellulose 55 40 Sugar 50 50 Vegetable oil - 20.7 Dicalcium monophosphate 21.4 23.2 Calcium carbonate 7.3 5.6 Mineral+vitamin premix' 5.0 5.0 NaCI 3.0 3.0 L lysine HCI 2.7 DL methionine - 0.6 L threonine 0.8 Calculated analyses Crude protein 141 141 Crude fibre 46 47 Lysine 8.5 8.5 Methionine 2.7 2.5 Threonine 5.5 5.4 Phosphorus 6,0 6.0 Calcium 7.5 7.5 Energy value, NE, MJ/kg DM2 11.27 11.26 WP=wheat protein; SBM=soya bean meal I) Mineral+vitamin-premix provided the following vitamins and trace minerals per kilogram dry matterof diet: 25001U vitamin A, 500 IU vitamin D, 31.2 mg vitamin E, 1.5 mg thiamine, 3.0 mg riboflavin, 1.25 mg pyridoxine, 10 pg vitamin B |2, 50 mg choline, 7.5 mg pantothenic acid, 6.2 mg nicotinic acid, 1.1 mg folic acid, 48 mg Fe, 110 mg Zn, 19 mg Cu, 15.5 mg Mn, 0.34 mg I and 0.11 mg Se and barley as a carrier. 2) According to Tuori et al. (1996). meal. Ytterbium acetate (Yb(CH 3COO) 3 ) and lithium-Co-EDTA complex (LiCoEDTA) were dissolved in water in a ratio of 1:2.5:40,and 20 ml of the solution was first mixed with the liq- uid part of the diets (WP or water), providing 200 mg of Yb and Co for each meal. The dry and liquid feed ingredients were mixed directly prior to feeding. The water to feed ratio in the SBM diet was 2; 1. The pigs were fed twice dai- ly (at 6.00 and 18.00), at a feeding level of 90 g DM/kg liveweighta75 /day. Water was freely avail- able from low-pressure drinking nipples. Analytical procedure The faeces were defrosted before pooling, but the digesta was pooled in a frozen state. All the samples were freeze-dried and ground to pass a 1-mm sieve. Their proximate composition was analysed by the methods of AOAC (1984). Ether extract was determined after 4 N HCI hydroly- sis. The amino acid composition of WP, SBM and ileal digesta was assayed on an LKB Alfa plus II amino acid analyser after hydrolysis for 23 h in 6 N HCI. Methionine and cystine were determined after oxidation with performic acid before acid hydrolysis, whereas tryptophan was determined as barium hydroxide hydrolyzate. The starch in WP and SBM was measured as glu- cose after hydrolysis with thermamyl and amy- loglucosidase and the sugar composition with HPLC after ethanol extraction and Sep-Pak ClB purification. The lactic acid in WP was deter- mined with a colorimetric method ofBarker and Summerson (1941). The calcium in WP and SBM and the concentrations of Cr, Yb and Co in the chromium-mordanted straw, (Yb(CH 3 COO)3 ) - LiCoEDTA solution, faeces and digesta were analysed by atomic absorption spectroscopy. The phosphorus in WP and SBM was assayed by photometry after ammonium vanadate pretreat- ment. All analyses were made in duplicate, ex- cept those of the marker concentrations, which were determined with a single assay. TheAID values were calculated from the mark- er ratio of the feeds and digesta and the ATTD val- ues from the total collection offaeces. The digest- ibility coefficients calculated using Cr as the marker are presented here, since they showed the smallest variation (standard error of the mean). The results of a comparison of the different markers will be laterpublished by Valaja et al.. The digestibility data were subjected to a least-squares analysis of variance (Snedecor and Cochran 1989)according to the following model: Y,jk =H+A i+ Pj+D k +e,jk> where p = the overall mean, A.= the effect of animal i, P. = the effect of period j, D k = the ef- fect of diet k and e , = the residual term.■jk 549 Vol. 5 (1996): 547-555. AGRICULTURAL AND FOOD SCIENCE IN FINLAND Mäkinen, M. & Siljander-Rasi, H. Apparent ileal digestibility ofamino acids in wet wheatprotein... Table 2. Analysed chemical compositions of wet wheat protein, soya bean meal and diets based on wet wheat protein or soya bean meal. WP SBM WP SBM diet" diet" Dry matter, g/kg 153 906 250 910 Ash, g/kg DM 25 63 43 50 Crude protein, g/kg DM 240 478 135 144 Ether extract, g/kg DM 38 46 22 37 Crude fibre, g/kg DM 20 85 51 58 Nitrogen free extract, g/kg DM 677 328 749 711 Starch, g/kg DM 490 10 Total sugars, g/kg DM 86 18 Lactic acid, g/kg DM 18 ND Phosphorus, g/kg DM 4.5 7.5 Calcium 1.3 3.3 Amino acids2 ’ g/16gN g/kg DM Indispensable Arginine 6.5 7.6 8.5 10.5 Histidine 2.6 2.8 3.4 3.8 Isoleucine 3.8 4.7 4.9 6.5 Leucine 7.6 7.9 9.9 10.8 Lysine 4.5 6.5 8.1 9.0 Methionine 2.0 1.5 2.6 2.7 Phenylalanine 4.4 5.3 5.8 7.2 Threonine 3.5 4.2 5.5 5.8 Tryptophan 1.5 1.4 2.1 1.9 Valine 5.7 5.1 7.4 7.0 Dispensable Alanine 5.2 4.5 6.7 6.2 Aspartic acid 7.3 11.8 9.6 16.2 Cystine 2.5 1.5 3.3 2.0 Glutamic acid 18.8 17.5 24.7 24.3 Glycine 4.7 4.5 6.1 6.3 Proline 7.5 5.3 9.9 7.4 Serine 4.7 5.4 6.1 7.4 Tyrosine 3.6 3.8 4.7 5.2 WP=wheat protein; SBM=soya bean meal; ND=not determined. "Analysed chemical composition of the diets: sum of nutrients content in WP or in SBM and in the mixture of the other ingredients. "Amino acid composition in WP and SBM: n=2. Dprulfr HkflMinnncauiu aim uuv,uw Ul Chemical composition As compared with SBM, WP protein was rela- lively poor in lysine and threonine but rich in sulphur-containing amino acids (Table 2). The contents of indispensable amino acids, except phenylalanine, were somewhat higher (0.3-2.0% units) in WP protein than in whole wheat (Just et al - 1983’ Tuori et al - 19%)- By contrast, the protein in WP contained 4.2% units less glutamic acid and 2.8% units less proline than did CP in wheat grains, the gluten storage proteins having been separated from wheat endosperm after the 550 Vol. 5 (1996): 547-555. starch process. Up to 90% of CP in wheat is glu- ten, rich in both glutamic acid and proline (36% and 13% of total amino acids), but poor in lysine and threonine (Lookhart 1991). The essential to non-essential amino acids ratio in WP, 44/56, was slightly higher than that in wheat grains, 38/62 (Just et al. 1983,Tuori et al. 1996), which may also reflect a reduction in the gluten contentin WP. The content of lysine in WP (4.5 g/16 g N) was higher than that found by Smits et al. (1992) in a protein fraction (wheat gluten feed) derived from the wheat starch and gluten industry (3 g/ 16 g N), which may be caused by the different efficiency of the gluten process. Grain protein from the barley starch industry (Näsi and Aimo- nen 1992,Buraczewska et al. 1996) had a lower lysine content than the protein in WP, whereas oat protein (Näsi and Aimonen 1992) had a sim- ilar content. The CP content of these products ranged, however, from 158 (wheat gluten feed) to 408 g/kg DM (oat protein), resulting in large differences in the total content of lysine and other amino acids. The crude fat of the grain was enriched in WP, as it was in the protein fractions mentioned above. Separation of the residual starch and co- agulated proteins seemed to be rather incom- plete, as nearly half of the DM in WP was starch. The sugar fraction consisted of maltose (47 g/ kg DM), glucose (37 g/kg DM) and small amounts offructose and saccharose (2.5 and 0.6 g/kg DM). Comparable starch and sugar contents were found in barley protein by Näsi and Aimo- nen (1992). WP also contained a small amount of lactic acid and the average pH of the product was 5.6. The phosphorus content ofWP, 4.5 g/kg DM, was slightly higher than that of whole wheat, 3.8-4.0 g/kg DM (Just et al. 1983). Remarkably high phosphorus contents (10-13 g/kg DM) were found in wheat gluten feed by Smits et al. (1992), even though the phosphorus-rich aleurone was not present in the product. Barley protein also had a higher phosphorus content (7 g/kg DM) than did WP (Buraczewska et al. 1996). The cal- cium content of these protein fractions was, how- ever, rather similar (1-1.3 g/kg DM). The experimental diets (Table 2) contained nearly similar amounts of threonine and methio- nine but the analysed lysine content of the WP diet was lower than that of the SBM diet. The formulation of the WP diet was based on the analyses a sample removed from the process before the experiment, which had a higher lysine content than the sample collected during the trial. Nutrient digestibility One pig, which recovered slowly from the oper- ation, was excluded from the first experimental period but takenback to the trial for the last two periods. At the beginning of the second period, the cannula ofanother pig slipped out of the gut, and the pig was removed from the trial. There- fore, the final number of observations was five in WP and four in SBM diets. The pigs ate the experimental diets readily and their average daily weight gain was 1017 (SE 21) g in the course of the trial. Necropsy revealed that, as in the case of pigs with simple T or re-entrant cannulae, some adherences existed around of the terminal ileum of the pigs, but this had no impact on the digesta passage and quantitative collection. The AID coefficients of CP and individual amino acids in WP and SBM are presented in Table 3. Their calculation was based on the as- sumption that the supplemented synthetic ami- no acids were completely absorbed in the ileum (Leibholz et al. 1986). The AID of methionine was higher in WP than in SBM (3.6% units; P<0.01), but there was no difference in the AID of the other amino acids between these protein sources (P>o.l). The AID values of the essential amino acids, except methionine, in SBM were somewhat high- er than those reported by Sauer and Ozimek (1986), Furuya and Kaji (1989), Knabe et al. (1989), De Lange et al. (1990) and Marty et al. (1994), but lower than those presented by ITCF- Eurolysine (1993), which were determined with ileo-rectal anastomised pigs. The variation not- ed between individual experiments may have been caused by the quantity and quality of die- 551 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Mäkinen, M. & Siljander-Rasi, H. Apparent ileal digestibility ofamino acids in wet wheat protein... Table 3. Apparent ileal digestibility (%) of amino acids in pigs fed wet wheat protein or soya bean meal diets. WP SBM SEM Statistical diet diet significance Amino acids, indispensable Arginine 91.1 92.5 0.72 NS Histidine 88.6 89.4 1.18 NS Isoleucine 85.6 86.8 0.76 NS Leucine 88.4 87.1 0.95 NS Lysine 83.2 87.6 1.37 NS Methionine 88.2 84.6 0.26 ** Phenylalanine 88.3 87.7 0.91 NS Threonine 80.2 82.3 2.00 NS Tryptophan 86.1 84.4 1.37 NS Valine 87.0 84.8 1.11 NS Total indispensable amino acids 87.1 87.4 1.02 NS Amino acids, dispensable Alanine 84.8 82.2 1.32 NS Aspartic acid 81.6 87.2 2.10 NS Cystine 86.3 85.1 1.93 NS Glutamic acid 91.1 91.0 0.78 NS Glycine 80.4 79.6 1.45 NS Proline 90.6 87.4 1.30 NS Serine 85.5 86.7 1.65 NS Tyrosine 87.9 85.9 0.87 NS Total indispensable amino acids 87.3 87.2 1.27 NS WP=wet wheat protein; SBM=soya bean meal; SEM=standard error of the mean. Statistical significance: NS = non-significant (P>o.l), ** = PcO.Ol. SEM has been shown forWP diets. To obtain the corresponding values for SBM diets, the values for WP diets should be multiplied by 0.827. tary fibre, processing conditions and residual levels of trypsin inhibitors in SBM (Sauer and Ozimek 1986, Schulze et al. 1994). Threonine was the least digestible indispen- sable amino acid and glycine the least digesti- ble dispensable amino acid in both WP and SBM. The consistently low AID obtained for these amino acids is partly due to theirrelatively high concentrations in endogenous secretions (Sauer et al. 1977, Low 1979). Small intestinal secre- tion is very rich in threonine, and glycine ac- counts for more than 90% of all amino acids se- creted in porcine bile juice (Souffrant 1991). According to Low (1980), threonine has the shortest potential absorption time, because it appears last in the small intestine, after enzymic hydrolysis. The AID values of the indispensable amino acids, except phenylalanine, were higher in WP than in whole wheat (Sauer and Ozimek 1986, De Lange et al. 1990). The high AID of amino acids can partly be explained by the very low content of crude fibre in WP. Sauer et al. (1977) showed that the AID of lysine and threonine in wheat milling fractions was related to the fibre content and declined from wheat flour to whole wheat to wheat offal (a mixture of bran, shorts and middlings). The high AID of the amino acids in WP indi- cates that heat treatment at +IO4°C during the coagulation step was unlikely to have caused extensive damage to the proteins. Moreover, the AID of CP and amino acids in WP was closely similar to that in wet barley protein (Buracze- 552 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Table 4. Apparent ileal and total tract digestibilities of dietary proximate components in pigs fed wet wheat protein or soya bean meal diets. Apparent ileal digestibility, % Total tract digestibility, % WP diet SBM diet SEM Significance WP diet SBM diet SEM Significance Dry matter 83.3 83.3 2.12 NS 91.1 92.4 0.64 NS Organic matter 85.0 85.5 2.07 NS 92.6 94.2 0.65 NS Ash 46.3 40.9 3.46 NS 57.2 58.4 0.49 NS Crude protein 82.5 82.9 1.18 NS 89.2 89.6 1.17 NS Ether extract 77.8 81.3 2.59 NS 78.0 79.7 0.09 ** Crude fibre 1.7 12.6 15.0 NS 41.0 60.9 9.47 NS Nitrogen free extract 91.9 92.8 1.33 NS 97.3 98.8 0.21 * WP=wet wheat protein; SBM= soya been meal; SEM=standard error of the mean. Statistical significance: NS= non-significant (P>o.l), * = P<0.05, ** = Po.l). The ATTD val- ues of ether extract (P<0.01) and nitrogen-free extract (Pc0.05) were higher the SBM diet than in the WP diet. For nitrogen-free extract, the dif- ference is obviously caused by the greater pro- portion of fully digestible starch in the SBM diet than in the WP diet and, for ether extract, by the addition of vegetable oil to the SBM diet. Just et al. (1980) showed that the apparent digestibility of fat is improved by increasing the concentra- tion of crude fat in the diet. The ATTD of CP in the SBM batch used was comparable with that reported by Knabe et al. (1989). but clearly higher than that found in nor- mal and processed SBMs in the study of Näsi (1991). The ATTD of protein in WP was similar to that in wet barley protein in the study of Bu- raczewska et al. (1996), but higher than that found in dried wheat gluten feed (Smits et al. 1992). Nearly 90% ofCP in both protein sources was digested in the ileum, and disappearance of CP from the large intestine of pigs fed WP and SBM diets was rather low, 6.9% and 6.7% units, as expressed by CP intake. The protein absorbed from the large intestine is lost from the protein synthesis of the pig and excreted in the urine (Zebrowska 1973). In conclusion, our results show that the pro- tein content of WP from the wheat starch and gluten industry was lower than thatof SBM, and the protein in WP contained less lysine and thre- onine than did that of SBM. Starch was the main component in the DM of WP, and the crude fi- bre content of the product was very low. The apparent ileal digestibilities of protein and ami- no acids in WP were as high as in SBM and the digestibility of methionine was even higher 553 Vol. 5 (1996): 547-555. AGRICULTURAL AND FOOD SCIENCE IN FINLAND Mäkinen, M. & Siljander-Rasi, H. Apparent ileal digestibility of amino acids in wet wheat protein... (3.6 %-units). Although the number of observa- tions in the study was small, the digestibility values noted for WP and SBM agreed well with the data presented earlier for similar by-prod- ucts from the starch or oil industry. Acknowledgements. The authors wish to thank Dr. Z. Mroz for his valuable advice on the details of the SICV-cannula- tion method and Mrs. Aino Matilainen and the staff of the experimental stable for their technical assistance. The fi- nancial support ofRehuraisio Ltd. (Raisio, Finland) is grate- fully acknowledged. References AOAC. 1984. Official methods of analysis. Association of Official Analytical Chemists. Arlington, Virginia. 1141 p. Barker, S.B. & Summerson, W.H. 1941.The colorimet- ric determination of lactic acid in biological material. Jour- nal of Biological Chemistry 138: 535-554. Buraczewska, L., Valaja, J., Buraczewski, S., Näsi, M. & Gdala, J. 1996. Digestibility and availability of protein and phosphorus in pigs fed wet barley protein and wet distillers’ solids from integrated starch-ethanol produc- tion. Animal Feed Science and Technology 58: 201-212. De Lange, C.F.M., Souffrant, W.B. & Sauer, W.C. 1990. Real ileal protein and amino acid digestibilities in feed- stuffs tor growing pigs as determined with the 15N-iso- tope dilution technique. Journal of Animal Science 68: 409-418. Furuya, S. & Kaji, Y. 1989. Estimation of the true ileal digestibility of amino acids and nitrogen from their ap- parent values for growing pigs. AnimalFeed Science and Technology 26: 271-285. ITCF-Eurolysine. 1993. Ileal digestibility ofamino acids in feedstuffs for pigs. Institut Technique des Céréales et des Fourrages and Eurolysine. Project report. Paris, 45 p. Just, A., Andersen, J.O. & Jorgensen, H. 1980. The influence of diet composition on the apparent digestibili- ty of crude fat and fatty acids at the terminal ileum and overall in pigs. Zeitschrift fur Tierphysiologie, Tierernährung und Futtermittelkunde 44: 89-92. -, Jorgensen, H. & Fernandez, J.A. 1983. Feed value of spring barley, winter barley and winter wheat for pigs and the influence of type of soil and nitrogen fertilization on the feed value. 546. Beretning fra Statens Husdyr- brugsforsog. Kobenhavn. 80 p. Knabe, D.A., Laßue, D.C., Gregg, E.J., Martinez, G.M. & Tanskley, T.D., Jr. 1989. Apparent digestibility of ni- trogen and amino acids in protein feedstuffs by growing pigs. Journal of Animal Science 67: 441-458. Leibholz, J., Love, R.J., Mollah,Y. & Carter, R.R. 1986. The absorption of dietary L-lysine and extruded L-lysine in pigs. Animal Feed Science and Technology 15: 141- 148. Linko, R., Lapveteläinen, A., Laakso, P. & Kallio, H. 1989. Protein composition of a high- protein barley flour and barley grain. Cereal Chemistry 66: 478-482. Lookhart, G.L. 1991. Cereal proteins: composition of their major fractions and methods for identification. In: Lorenz, K. J. & Kulp, K. (eds.). Handbook of cereal sci- ence and technology, Marcel Dekker, New York. p. 441- 468. Low, A.G. 1979. Studies on digestion and absorption in the intestines of growing pigs. 6. Measurements of the flow of amino acids. British Journal of Nutrition 41:147- 156. - 1980. Nutrient absorption in pigs. Journal of Science of Food and Agriculture 31: 1087-1130. Marty, 8.J., Chavez, E.R. & de Lange, C.F.M. 1994. Recovery of amino acids at the distal ileum for determin- ing apparent and true ileal amino acid digestibilities in growing pigs fed various heat-processed full-fat soybean products. Journal of Animal Science 72: 2029-2037. Mosenthin, R., Sauer, W.C., Ahrens, F., de Lange. C.F.M. & Bornholdt, U. 1992. Effect of dietary supple- ments of propionic acid, siliceous earth or a combination of these on the energy, protein and amino acid digestibil- ities and concentrations of microbial metabolites in the digestive tract of growing pigs. Animal Feed Science and Technology 37: 245-255. Moughan, P.J. 1993. Towards an improved utilization of dietary amino acids by the growing pig. In: Cole, D.J.A. et al. (eds.). Recent developments in pig nutrition. Uni- versity of Nottingham, p. 117-136, Mroz, Z., Bakker, G.C.M., Jongbloed, A.W., Dekker. R.A., Jongbloed, R. & van Beers, A. 1996. Apparent digestibility of nutrients in diets with different energy den- sity, as estimated by direct and marker methods tor pigs with or without ileo-cecal cannulas. Journal of Animal Science 74: 403-412. Näsi, M. 1989. Barley feed fractions from integrated eth- anol-starch process in diets of pigs. Journal of Agricul- tural Science in Finland 61: 441-450. - 1991. Digestibility and protein utilization responses of soyabean and rape seed meal to physical and enzymat- ic treatments in diets for growing pigs. Journal of Agri- cultural Science in Finland 63: 465-482. - & Aimonen, E. 1992. Evaluation of undehydrated bar- ley feed fractions and dried oat feed fractions from inte- grated starch-ethanol process in diets of growing pigs. Agricultural Science in Finland 1; 291-302, Sauer, W.C. & Ozimek, L. 1986. Digestibility of amino acids in swine: results and their practical applications. A review. Livestock Production Science 15: 367-388. 554 AGRICULTURAL AND FOOD SCIENCE IN FINLAND - , Stothers, S.C. & Parker, R.J. 1977. Apparent and true availabilities of amino acids in wheat and milling by- products for growing pigs. Canadian Journal of Animal Science 57: 775-784. Schulze, H., Van Leeuwen, P., Verstegen, M.W.A., Huisman, J., Souffrant, W.B. & Ahrens, F. 1994. Effect of level of dietary neutral detergent fiber on ileal appar- ent digestibility and ileal nitrogen losses in pigs. Journal of Animal Science 72: 2362-2368. Smits, 8., Kappers, 1.E., Sebek, L.B.J. & Kroonsberg, C. 1992. Digestibility and feeding value of wheat gluten feed ‘Amyfeed’ for pigs. Rapport IVVO no. 235. ISSN 0922 3282. Lelystad, Netherlands. 10p. (in Dutch). Snedecor, G.W. & Cochran, W.G. 1989.Statistical meth- ods. Bth ed. lowa State University Press, Ames, lowa. 504 p. Souffrant, W.B. 1991. Endogenous nitrogen losses dur- ing digestion in pigs. In: Verstegen, M.W.A. et al. (eds.). Digestive physiology in pigs. EAAP Publication No 54. Pudoc Wageningen, The Netherlands, p. 147-166. Tuorl, M., Kaustell, K., Valaja, J., Aimonen, E., Saari- salo, E. & Huhtanen, P. 1996. Rehutaulukot ja Ruokin- tasuositukset. 2. painos. ISBN 951-45-7348-X. Yliopis- topaino, Helsinki. Finland. 102 p. Udén, P., Colucci, P.E. & Van Soest, P.J. 1980. Investi- gation of chromium, cerium and cobalt as markers in di- gests. Rate of passage studies. Journal of the Science of Food and Agriculture 31: 625-632. Van Kleef, D.J., Deuring, K. & Van Leeuwen, P. 1994. A new method of faeces collection in the pig. Laboratory Animals 28: 78-79. Zebrowska,T. 1973. Digestion and absorption of nitrog- enous compounds in the large intestine of pigs. Roczniki Nauk Rolniczych Series 895, 3: 85-89. SELOSTUS Kuivaamattoman vehnäproteiinin ja soijarouheen aminohappojen ohutsuolisulavuus sioilla Markku Mäkinen ja Hilkka Siljander-Rasi Maatalouden tutkimuskeskus Kokeessa määritettiin vehnätärkkelys- ja gluteenite- ollisuuden (Raision Yhtymä) sivutuotteena syntyvän kuivaamattoman vehnäproteiinin ja vertailurehuna soijarouheen valkuaisen ja aminohappojen ohutsuo- lisulavuus neljällä leikkosialla. Sioille asennettiin 35 kilon painoisina umpisuoleen SICV-kanyyli, jonka kautta voitiin kerätä ohutsuolen ruokasulaa. Siat ruo- kittiin vehnätärkkelyspohjaisella puolipuhdistetulla rehulla, jonka ainoana valkuaisen lähteenä oli joko vehnäproteiini tai soijarouhe. Rehuissa oli 140 g raa- kavalkuaista ja 11,3 MJ nettoenergiaa kuiva-aineki- lossa ja niiden lysiini-, metioniini- ja treoniinipitoi- suus oli samanlainen. Kokeessa oli kolme jaksoa, ja jakson vaihtuessa siat siirrettiin ruokinnalta toiselle. Tutkitun vehnäproteiinierän valkuaispitoisuus oli pienempi kuin soijarouheen (240 g/kg ka vs. 478 g kg/ka), ja sen valkuainen sisälsi vähemmän lysiiniä (4,5 vs. 6,5 g/16 g N) ja treoniinia (3,5 vs. 4,2 g/ 16 g N) kuin soijarouheen. Noin puolet vehnäproteiinin kuiva-aineesta oli tärkkelystä, ja raakakuitupitoisuus oli pieni (20 g/kg ka). Vehnäproteiinin valkuaisen ohutsuolisulavuus (82,5 vs. 82,9 %) ja kokonaissu- lavuus (89,4 vs. 89,6 %) olivat lähes samat kuin soi- jarouheen. Vehnäproteiinin aminohappojen ohutsuo- lisulavuus oli hyvä, metioniinin ohutsuolisulavuus (88,2 %) jopa parempi kuin soijarouheen (84,6 %). Kokeen tulosten perusteella vehnäproteiinin valkuai- sen ja aminohappojen ohutsuolisulavuus on hyvin verrattavissa soijarouheen sulavuusarvoihin. 555 Vol. 5 (1996): 547-555. AGRICULTURAL AND FOOD SCIENCE IN FINLAND