Vol. 4:3-9. Nutritive value of wet distillers' solubles for pigs Jarmo Valaja and Matti Näsi Department ofAnimal Science, P.O. Box 28, FIN-00014 University ofHelsinki, Finland Digestibility and nitrogen (N) metabolism were studied to evaluate the nutritive value of wet barley distillers’ solubles (DSB) from an integrated starch-ethanol process for pigs. Eight castrated male pigs (live weight 72-103 kg) were used in a 8 x 3 cyclic change-over design, where the diets were arranged factorially 2x2. The corresponding factors were the protein source (DSB or soya bean meal (SBM)) and the protein level (131 or 162 g crude protein (CP)/kg dry matter (DM)). Faeces and urine were collected in total. The four diets comprised barley, barley starch, minerals and vitamins with either DSB or SBM as the main source of protein. The digestibility of CP(p<0.001) and organic matter (pcO.Ol) was higher in SBM than in DSB-based diets, but the digestibility of ash (pcO.Ol) and ether extract (pcO.OOl) was higher in DSB than in SBM-based diets. The digestibility coefficients of the nutrients calculated by regression were gener- ally higher in SBM than in DSB. The digestibility of CP was 0.865 in DSB and 0.902 in SBM, The pigs on SBM-based diets retained more (pcO.OOl) and excreted less N in urine (p<0.001) than the pigs on DSB-based diets. The nitrogen balance parameters were closely related to lysine supplies, which were higher in SBM-based diets. Key words: swine, digestibility, protein metabolism, distillery by-product, soya bean meal ntroduction Wet distillers’ solubles (DSB) are a proteinous feed fraction derived from an integrated starch- ethanol process using barley as a raw material. They mainly consist of the water-solublepart of the distilling residue. The proximate crude pro- tein (CP) content of DSB is 360 g/kg dry matter (DM) and theiramino acid composition reflects that of barley (Huhtanen and Näsi 1992). Because of the suspicion that their high ash content may be harmful to pigs, DSB are prima- rily used as a protein supplement in the diets of dairy cows and growing cattle. Moreover, most of the nutritional research into DSB has been conducted on dairy cows (Huhtanen and Miet- tinen 1992) or growing cattle (Huhtanen et al. 1991). The reported digestibilities of the nutri- ents in dried DSB from a similar process in pigs were quite high, ranging from 0.740 to 0.876 (Näsi 1989), whereas those of the nutrients in © Agricultural Science inFinland Manuscript received August 1994 3 AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=lTp5aqzHdo_T1Bpd.J62GmlStm6_DQZQuHDyHaQ.N2Uc9IwiUMecf8s9ZfEWD7SQfVlsC_5NUb7VltmwL3nhKKFqLLpIUmxdJ7JOgG-4nSH6xmjPHQx-O2NmYeIYKIp5IwO55n8Tngqw6hejPdFfkDkKZE0dYfx5081ZBRtD7UcDc_eKCEwaxznCVIBQwGF3TIn3wQz6Y_Ie9ZCm-8zF0qTWZ4UgasiuZkUMMTFw8rBsgtk6kzlPzdsippHR7rEn-k2_67tLN9m2yLmbyXa8edAPubdwM8cLjNp_BIoKQv2VIwaGiTt_WgPa-2_E5xWTqD8oxjw Valaja, J. & Näsi, M.: Nutritive value of wet distillers’ solublesfor pigs semi-solid DSB (DM 550 g/kg) from dehulled barley were clearly lower, especially for crude protein (Näsi 1985). Owing to the inconsistency in the digestibil- ity coefficients of the above experiments and to the lack ofknowledge about the digestibility and protein utilization of the wet form of DSB, we set out to determine and compare the nutritive value of wet distillers’ solubles and soya bean meal for pigs. Chemical composition, digestibil- ity and protein balance responses were used as comparable parameters. Material and methods The digestibility and protein utilization experi- ment was conducted with eight castrated Lan- drace x Yorkshire male pigs to evaluate and com- pare the nutritive value of DSB and soya bean meal (SBM). The average initial weight of the pigs was 72.4 (SE 1.84)kg and the final weight 102.9(SE 1.83) kg. The experimental design was an 8 x 3 cyclic change-over, and the diets were arranged 2x2 factorially, with protein source (DSB or SBM) and protein level (131 or 162 g crude protein (CP)/kg dry matter (DM)) as fac- tors. The pigs were kept in metabolism cages througout the trial, which allowed separate total collection of faeces and urine. Each experimen- tal period lasted ten days: five days of adjust- ment and five days of collection.The daily feed- ing scale was from 2.4 to 2.5 kg DM. The daily allowance was fed in two equal portions at 8.00 and 15.00 hours and was mixed with water be- fore feeding. The pigs had ad libitum access to water. The four experimental diets consisted of bar- ley, barley starch and DSB or SBM as a protein supplement (Table 1). Minerals and vitamins were added to the diets to meet the requirements of growing pigs (Salo et al. 1990). All the diets contained a constant amount of barley (757 g/ kg DM) and eitherDSB or SBM at two levels to provide 131 or 162 g CP/kg DM. Barley starch Table 1. Dietary ingredients and calculated chemical com- position of the diets. I 3 23 3 4Diet Content in dry matter, g/kg 757 757 757 757Barley Distillers’solubles 119 218 Soya bean meal 78 142 Barley starch 96 - 134 71 Minerals and vitamins' - - 25 2525 25 Trace elements2 14 13 Limestone 8 12 Dicalcium phosphate 6-65 Chemical composition: Content in dry matter, g/kg Crude protein 131.3 162.1 131.7 162.9 Lysine 4.7 5.9 5.6 7.6 Methionine + cystine 8.9 11.1 8.1 9.5 Threonine 5.9 6.8 5.5 7.05.9 6.8 5.5 7.0 Calcium 8.3 8.3 8.3 8.2 Phosphorus 5.3 5.5 5.8 6.1 1. Provided the following per kg diet DM: Fe 80 mg, Zn 100 mg, Mn 40 mg, Cu 6 mg, Se 0.1 mg and vitamin A 5000 lU, vitamin D 1500IU and vitamin E25 mg. 2. Provided the following per kg diet DM: Fe 80 mg, Zn 100 mg, Mn 40 mg, Cu 6 mg, Se 0.1 mg. 3. Diets 1 and 2 were supplemented with vitamin mixture to provide the following per kg diet DM; vitamin A 5000 lU, vitamin D 1500 IU and vitamin E 25 mg. served as a balancer. DSB were manufactured from barley at the Alko Ltd. Koskenkorva fac- tory, which employs an integrated starch-etha- nol process as described in detail by Näsi (1988). After the distilling process, DSB were separat- ed by centrifugation from distillers’ solids and evaporated to a DM content of 360 g/kg. To en- sure quality during the trial, it was delivered fro- zen from the factory and thawed in the experi- mental stall. The proximate composition of the feeds and faeces was analysed by standard methods (AOAC 1984). The amino acid composition of barley, SBM and DSB was determined by high performance liquid chromatography (HPLC) af- ter hydrolysis with 6 N HCI at 110°C for 23 h. The fatty acid composition of DSB was analysed by gas chromatography (AOAC 1984). 4 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 3-9. The apparent digestibility coefficients of the nutrients in the experimental feeds (DSB and SBM) were calculated by multiple regression equation (Schneider and Flatt 1975): Y = aX, + bX2 In the equation, Y stands for the total amount of digested nutrient from the diet (g/d), and X, and X 2 for the amounts of diet nutrients from the basic feed (barley, barley starch and miner- als and vitamins) and protein supplement (DSB or SBM), respectively, and a and b for the di- gestibility coefficients of the nutrients from the basic feed or protein supplement, respectively. In the calculations, barley starch was assumed to be totally digested (Graham et al. 1989). The regression method was preferred to the differ- ence method, because it is more suitable for es- timating digestibility coefficients when the amount of experimental feed in a diet is low (Fan and Sauer 1994). The feeding value of the ex- perimental feeds was calculated as feed units (FU) according to Salo et al. (1990) or as net energy (NE) according to CVB (1991). The data were subjected to analysis of variance using the general linear model (GLM) procedure of SAS (1985). The model included the effect of period, animal and diet. The diet effect was further sep- arated into the three orthogonal contrast: Cl = DSB vs. SBM-based diets, C 2 = low protein di- ets vs. high protein diets and C 3 = interaction Cl x C2. Table 2. Analysed chemical compositions of barley and protein supplements. Feed Barley Soya bean Wet distillers’ meal solubles Dry matter, g/kg 859 869 358 Ash, g/kgDM 21 64 135 Crude protein, ” 123 494 319 Ether extract, ” 33 71 89 Crude fibre, ” 54 71 17 N-free extracts, ” 769 300 440 Amino acids, g/160 g N Lysine 34 64 39 Threonine 40 48 44 Methionine 26 23 20 Cystine 42 29 48 Histidine 20 25 26 Leucine 68 78 53 Isoleucine 40 51 33 Phenylalanine 36 53 41 Arginine 51 77 52 Fatty acids, g/100 g ether extract CI4:0 0.4 C 15:0 0.1 CI6:0 26.4 C 17:0 0.1 C18:0 2.4 C18:lw9 11.6 C18:2w6 47.6 C18:3w3 6.1 C20:0 0.2 C20:1w9 0.8 C22:0 0.2 C22:1w1l 0.1 C24:0 0.1 Results DSB contained DM 358 and SBM 869 g/kg (Table 2). The CP content of SBM was higher than thatof DSB (494 and 319 g/kg DM, respec- tively), but DSB contained twice as much ash as SBM (135 and 64 g/kg DM, respectively). The amino acid profile of SBM was better than that of DSB, the lysine contents being 64 and 39 g/ 160 g N, respectively. The ether extract of DSB mainly contained Cl6:0, Cl 8:1 w 9 and C18:2w6 fatty acids (26.4, 11.6 and 47.6 g/100 g ether extract, respectively). One pig was excluded from the experiment because of leg injury, and another one was ex- cluded from periods 1 and 2 because of poor appetite. This resulted in fewer observations for diets 2 (n=4), 3 (n=4) and 4 (n=s). Otherwise the pigs completed the experiment successfully. Palatability problems could not be related to the protein sources, because diet rejections occurred for both protein supplements. The average DM 5 AGRICULTURAL SCIENCE IN FINLAND Valaja, J. & Näsi, M.: Nutritive value ofwet distillers’ solubles for pigs Table 3. Apparent faecal digestibility of experimental diets and nitrogen (N) metabolism and utilization in the pigs (LS means). Diet 12 3 4 SEM Cl C 2 C3 Protein source DSB DSB SBM SBM “ level, g/kg DM 131 162 131 162 Dry matter 0.839 0.822 0.844 0.841 0.0024 ** * * Organic matter 0.861 0.843 0.865 0,860 0.0023 ** ** o Ash 0.480 0.528 0.435 0.493 0.0077 ** *** NS Crude protein 0.795 0.804 0.830 0.844 0.0051 *** NS NS Ether extract 0.587 0.627 0.497 0.539 0.0077 *** ** NS Crude carbohydrates 0.884 0.866 0.885 0.878 0.0023 o ** o N intake, g/day 50.6 61.2 51.5 63.9 0.32 ** *** o Faecal N, “ 10.3 11.9 8.7 10.0 0.21 *** *** NS N absorbed, “ 40.3 49.3 42.8 53.9 0.46 *** *** NS N digestibility 0.795 0.804 0.830 0.844 0.0051 *** NS NS N in urine, g/day 23.1 29.0 21.9 25.0 0.16 *** *** *** Urea-N in urine, “ 17.5 22.6 17.6 19.2 0.44 * *** * N retained, g/day 17.2 20.3 20.9 28.9 0.51 *** *** **17.2 20.3 20.9 28.9 0.51 *** *** ** of intake 0.340 0.332 0.406 0.452 0.0074 *** o * ofabsorbed 0.428 0.413 0.489 0.537 0.0071 *** NS ** DSB = wet distillers’ solubles, SBM = soya bean meal, SEM = standard error of the means. Cl = protein source (DSB diets vs. SBM diets), C 2 = protein level (131 vs. 162 g CP kg ' DM) and C 3 = interaction Cl * C2. intake of the experimental diets was 2406 g/day, being higher for the pigs on SBM diets than for those on DSB diets (pcO.OI; 2435 and 2377 g/ day, respectively), because the number ofobser- vations on the diets was unequal. The diets composed ofdifferent protein sup- plements were highly digestible (Table 3). The apparent digestibility of DM (p<0.01), organic matter (OM) (p<0.01) and CP (p<0.00l) was higher in the diets composed of SBM than in those composed of DSB, but ash (p<0.01) and ether extracts (p<0.001) were better digested in DSB than in SBM-based diets. The digestibilities of the nutrients calculat- ed by regression were higher for SBM than for DSB (Table 4). DM, OM. ash, CP and crude car- bohydrates were digested better in SBM than in DSB. The calculated energy values for DSB and SBM were 1.067 and 1.165 FU/kg DM, respec- tively according to Salo et al. (1990) or 10.27 and 10.64 MJ NE/kg DM, respectively accord- ing to CVB (1991). There was a marked difference in N utiliza- tion between the pigs on the diets composed of DSB and SBM (Table 3). N retention (pcO.001) was higher and N excretion (p<0.001) lower for the pigs on SBM than on DSB-based diets.Also the proportion of N retained per intake or per absorption differed between the pigs fed the di- ets composed ofSBM or DSB (p<0.001). A high- er protein level improved daily N retention (p<0.001). Protein source and level interacted with each other in most of the protein utilization parameters, because the enhancement in the pro- tein utilization was higher when the amount of SBM was increased in the diets. Increased pro- tein supplementation improved the proportion of N retained per intake or absorption for the pigs on SBM-based diets (p<0.05) but not for those on DSB-based diets. 6 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 3-9. Table 4. Apparent faecal digestibility calculated by regression and feed value of wet distillers’ solubles and soya bean meal. Feeds DSB SE SBM SE Digestibility: Organic matter 0.850 0.0453 0.901 0.0859 Ash 0.674 0.0561 0.999 0.2238 Crude protein 0.865 0.0654 0.902 0.0676 Ether extracts 0.774 0.0497 0.753 0.1578 Crude carbohydrates 0.844 0.0527 0.915 0.0859 Feed value: FU'/kg DM 1.067 1.165 NE2 , MJ/kg DM 10.27 10.64 DCP, g/kg DM 288 445 DCP, g/FU 270 382 DSB = wet distillers’ solubles, SBM = soya bean meal. DCP =digestible crude protein. SE = standard error of the estimate. 1, Feed unit = 0.7 starch equivalent. 2. NE calculated according to CVB (1991). Discussion The present experiment showed clearly that DSB are highly digestible for pigs. The apparent di- gestibility coefficients obtained from this trial were consistent with the results of Näsi (1989). In contrast to our results. Näsi (1985) obtained much lower digestibility coefficients of CP in DSB (0.626). The process, however, was differ- ent in that experiment because barley was only dehulled before distilling. The digestibility of CP in wet distillers’ solids from the same process is very similar to that of CP in DSB (Näsi and Ai- monen 1992, Valaja and Näsi, manuscript Vala- ja, unpublished), because the feed fractions orig- inate from the same process. Conventional distillerfeeds have very varia- ble and usually rather low digestibility of CP, ranging from 0.469 to 0.775 in the former ex- periments (Salo 1978,Peers et al. 1978, Zoiopou- los et al. 1983a, 1983b, Näsi, manuscript 1984). Cromwell et al. (1993) stated that overheating during drying is the main reason for the varia- tion in nutritive value. Further, the high fibre content reduces the nutritive value of distiller feeds for monogastrics (Cromwell et al. 1993, Näsi 1984). The N balance parameters were closely re- lated to dietary lysine supplies, which were lower in DSB-based diets. Lysine is the first limiting amino acid in DSB, as it occurs in its raw mate- rial, barley (Fuller et al. 1979). N retention per intake or per absorption increased by 0.05 units, when more SBM was added to the diets; the ad- dition of DSB had, however, no effect on the parameters. The bulk of the increased protein supply from DSB was excreted in urine. The most efficient way to improve the protein utili- zation ofdistiller feeds is by supplementing syn- thetic amino acids (Valaja 1992). The content ofsulphur-containing amino ac- ids (methionine + cystine) was very high in both protein supplements. This resulted in an imbal- ance of methionine + cystine per lysine in all diets. The analysed content of methionine and cystine in the protein supplements was higher than thatof the feeds in the former analyses (Salo et al. 1990, Huhtanen and Näsi 1992). Since amino acid analysis is a complex procedure and oxidation prior acid hydrolysis is needed for the sulphur-containing amino acids, the possibility of analytical error cannot be totally ruled out. DSB have mainly been used in the diets of ruminants, as the high ash content of DSB is believed to be harmful to pigs. DSB have high 7 AGRICULTURAL SCIENCE IN FINLAND Valaja, J. & Näsi, M.: Nutritive value ofwet distillers’ solubles for pigs phosphorus, potassium and sodium contents (Näsi 1985). However, the content of these min- erals in the diets is well under the toxious levels reported in ARC (1980). According to this trial, DSB are highly di- gestible for pigs. However, its use as the only protein supplement is limited, because the lysine content is low with respect to the requirement of the pigs. Further, the production experiments are needed to establish the full nutritive value of DSB. References ARC 1981. The nutrient requirements ot pigs. Agricultur- al Reseach Council, Commonwealth Agricultural Bureaux, Slough. 304 p. AOAC 1984. Official methods of analysis. 14th edn. Association of Official Analytical Chemist, Arlington, Vir- ginia. Cromwell, G.L., Herkelman, K.L. & Stahly, T.S. 1993. Physical, chemical, and nutritional characteristics of dis- tillers dried grains with solubles for chicks and pigs. Jour- nal of Animal Science 71: 679-686. CVB 1991. Veevoedertabel. Centraal Veevoederbureau. The Netherlands. ISBN 90-72839-13-7. Fan, M.Z. & Sauer, W.C. 1994. Determination of appar- ent ileal amino acid digestibility in low-protein feedstuffs with the direct, difference, and regression method. In: Souffrant, W.-B. & Hagemeister, H, (eds.). Proceedings of the 6th International Seminar on Digestive Physiology in Pigs, Bad Doberan, Germany. EAAP-publicalion n:o 80, vol. 1. p. 103-106. Fuller, M.F., Livingstone, R.M., Baird, B.A. & Atkin- son, T. 1979. The optimal amino acid supplementation of barley for growing pig, 1. Response of nitrogen me- tabolism to progressive supplementation. British Journal of Nutrition 41: 321-331. Graham, H., Fadel, J.G., Newman, C.W. & Newman, R.K. 1989. Effect of pelleting and 13-glucanase supple- mentation on the ileal and faecal digestibility of a barley- based diet in the pig. Journal of AnimalScience 67:1293- 1298. Huhtanen, P., Khalili, H. & Nasi, M. 1991. A compari- son of untreated and formaldehyde-treated barley distill- er’s solubles and rapeseed meal as protein supplements in dairy cows given grass silage ad libitum. Journal of Agricultural Science in Finland 63: 455-463. - & Miettinen, H. 1992. Milk production and concentra- tions of blood metabolites as influenced by the level of wet distiller’s solubles in daily cows receiving grass si- lage-based diet. Agricultural Science in Finland 1; 279- 290. - & Näsi, M. 1992. Evaluation ot feed fractions from in- tegrated starch-ethanol production from barley in diets of cattle, pigs and poultry. Proceedings of Distillers Feed Conference, Cincinnati, Ohio. Vol. 47: 67-86. Näsi, M. 1984. Evaluation ot barley distillers dried grains with soluble, and condensed distillers solubles in the diet of growing pigs. Journal of Agricultural Science in Fin- land 56: 221-226. - 1985. Distillers feeds from various grains as protein sources for pigs. Journal of Agricultural Science in Fin- land 57: 255-262. - 1988. Evaluating barley feed fractions from integrated ethanol-starch production in the diets of ruminants. Jour- nal of Agricultural Science in Finland 60: 701-709. - 1989. Barley feed fractions from integrated ethanol- starch process in diets of pigs. Journal of Agricultural Science in Finland 61: 441-450. - & 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: 291-301. Peers, D.G., Hillyer, G.M. & MacAndrew, A. 1978. The evaluation of grain distillers evaporated spent wash in diets for growing pigs. Animal Production 26: 396-397. Salo, M.-L. 1978. Vehnärankkijauhon rehuarvo lihasiko- jen ruokinnassa. Journal of the Scientific Agricultural Society of Finland 42: 291-295. -, Tuori, M. & Kiiskinen, T. 1990. Rehutaulukot ja ruok- intanormit. Helsinki. 70 p. SAS 1985. SAS User’s Guide: Statistics. 956 p. 5 th Ed. SAS Institute Inc, Cary, NC, USA. Schneider, B.H. & Flatt, P.W. 1975. The evaluation of feeds through digestibility evaluation. 423 p. University of Georgia Press, Athens, Georgia. Valaja, J. 1992. The effect of supplementation of liquid and crystalline lysine to barley-distillers solids diet on the performance and carcass quality of pigs. Agricultural Science in Finland 1: 559-567. Zoiopoulos, P.E., English, P.R. & Topps, J.H. 1983a. Fibrous agro-industrial by-products as protein sources for bacon pigs. 1. Assessment of performance, digesti- bility and carcass quality, Zeitschrift fur Tierphysiologie, Tierernährung und Futtermittelkunde 49: 210-218. - , Topps, J.H. & English, P.R. 1983b. Fibrous agro- industrial by-products as protein sources for bacon pigs. 2. Study of digestion with pigs cannulated at the ileum. Zeitschrift fur Tierphysiologie, Tierernährung und Futter- mittelkunde 49: 219-228. 8 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 3-9. SELOSTUS Tiivistetyn tärkkelysrankin ravintoarvo lihasikojen rehuna Jarmo Valaja ja Matti Näsi Helsingin yliopisto Tutkimuksessa selvitettiin tärkkelys-etanolituotan- nosta saatavan kuivaamattoman tiivistetyn tärkkelys- rankin rehuarvoa lihasikojen ruokinnassa. Kokeessa verrattiin tiivistetyn tärkkelysrankin ja soijarouheen ravintoaineiden sulavuutta ja valkuaisen hyväksikäyt- töä. Koe-eläiminä oli kahdeksan leikkosikaa (maati- ainen x yorkshire), jotka painoivat kokeen alussa 72 ja lopussa 105 kg. Neljä koedieettiä sisälsivät tut- kittavia valkuaisrehuja kahdella tasolla sekä lisäksi ohraa, ohratärkkelystä sekä kivennäisiä ja vitamiineja. Sekä tiivistetty tärkkelysrankki- että soijarouhe- pohjaisten dieettien ravintoaineet sulivat hyvin. Soi- jarouheen ravintoaineet sulivat kuitenkin hiukan pa- remmin kuin tiivistetyn tärkkelysrankin. Tiivistetyn tärkkelysrankin valkuaisen sulavuus oli 0,865 ja soi- jarouheen 0,902. Soijarouhepohjaista dieettiä saaneet siat pidättivät typpeä paremmin elimistöönsä ja erit- tivät vähemmän typpeä virtsan mukana kuin tiivis- tettyä tärkkelysrankkia syöneet siat, koska soijarou- heen valkuaisen aminohappokoostumus oli parempi kuin tiivistetyn tärkkelysrankin. Soijarouhe ja tiivis- tetty tärkkelysrankki sisälsivät lysiiniä 64 ja 39 g/kg raakavalkuaista. Kokeen perusteella tiivistetty tärkkelysrankki on hyvin sulavaa. Alhainen lysiinipitoisuus kuitenkin rajoittaa sen käyttöä pelkkänä valkuaisrehuna. 9 AGRICULTURAL SCIENCE IN FINLAND