AANWENDING VAN SOJABONE VIR DIEREVOER

Transcription

1 AANWENDING VAN SOJABONE VIR DIEREVOER

2 PNS Posbus 1564 Rivonia 2128 Telefoon Faks E-pos Webtuiste

3 Inhoud 1. Voeding van enkelmaagdiere 1 Varke 2 2. Ander enkelmaagdiere 2 Visse 2 Konyne 3 Honde en katte 3 3. Voeding van herkouers 3 Melkbeeste 3

4 Voeding van enkelmaagdiere Gedurende 2010/2011 was die totale veevoerverbruik in Suid-Afrika 10,6 miljoen ton voer. Die pluimveebedryf het 4,3 miljoen ton of 40,6% van hierdie verbruik uitgemaak. Soja-oliekoek, met sy goeie aminosuursamestelling, is n baie belangrike grondstof in pluimveerantsoene. Groot volumes word verbruik, wat die pluimveebedryf by verre die grootste verbruiker van soja-oliekoek in Suid-Afrika maak. Om optimale groei en voeromsettingsverhoudings by braaikuikens te verseker, word braaikuikenvoere hoofsaaklik in pilvorm aangebied. Grondstowwe met n hoë olieinhoud, soos volvetsoja, het dikwels n onbevredigende pilkwaliteit tot gevolg. Dit is om hierdie rede dat veevoervervaardigers eerder ontvette sojaboonmeel in braaikuikenvoere gebruik as volvetsojas. Ontvette sojaboonmeel lewer goeie kwaliteit pille en word die nodige energie eers na verpilling aangevul deur vette of olies op die pille te sproei. Wanneer pluimveerantsoene in meelvorm aangebied word, kan ontvette of volvet-sojaboonmeel of n kombinasie van die twee gebruik word. Soos reeds vroeër genoem, is dit belangrik om te verseker dat tripsien-inhibeerders en antigroei-faktore in beide ontvette en volvetsojabeenmeel deur hittebehandeling geïnaktiveer is. Dit is ook belangrik om seker te maak dat die kwaliteit van die proteïen nie benadeel is deur oor- of onderverhitting tydens prosessering nie. Vir verdere inligting oor sojaboonprosessering word lesers verwys na die dokument op PNS se webblad ( Soybean meal use in the South African poultry industry: formulation and quality considerations by Brett Roosendaal. In die geval van volvetsojameel moet daar ook gekyk word na die olie-inhoud van sojabone en die verteerbaarheid daarvan. Dit is voor die handliggend dat sojabone met n hoër olie-inhoud n hoër energie-inhoud sal hê. Die verteerbaarheid van die olie sal egter afhang van die prosesseringsmetode wat gebruik word. Die redes vir die verskille in verteerbaarheid is nog nie bewys nie, maar dit wil voorkom asof dit verband hou met die maal van die produk of die graad van vetselbeskadiging tydens prosessering. Dit wil ook voorkom asof ekstrahering een van die beter prosesse is om die beskikbaarheid van olie in sojabone te verhoog veral by enkelmaagdiere. Tydens hierdie proses wat maal, hoë druk, hitte, wrywing en swelling as gevolg van skielike daling in druk wanneer die produk die drukbuis verlaat, insluit is die fisiese beskadiging van vetselle waarskynlik meer drasties as in ander prosesse. In Tabel 1 word die resultate van dr Julian Wiseman, een van die vroeëre navorsers op volvetsojabone, aangetoon. 1 Proteïennavorsingstigting

5 Tabel 1: Klaarblyklike (Apparent) metaboliseerbare energie (AME) en stikstofretensie (NR) van geprosesseerde heel sojabone vir twee en n half week oue hoenders. AME PROSES (MJ/KG) NR % * Nat ekstrusie 17,9 54 * Droë ekstrusie 17,4 59 * Mikroniseer 15,4 48 * Jet-sploded 14,7 61 * Geroosterde 15,6 57 * Rou sojabone 13,5 30 ** Hitte-behandelde sojaboonsaad 13,8 - * Wiseman, 1994 ** NRC Poultry, 1994 Tabel 1 toon duidelik dat ekstrusie van sojabone n produk lewer met n hoër metaboliseerbare energie-inhoud vir pluimvee as die ander prosesse. Varke Naas die pluimveebedryf is varkboerdery die tweede grootste verbruiker van sojaoliekoek. Varke is net soos hoenders sensitief vir die anti-voedingsfaktore wat in rou sojabone voorkom, omdat hulle ook enkelmaagdiere is. Daarom moet daar ook hier gelet word op die twee fundamentele doelwitte van prosessering, naamlik dat antivoedingsfaktore deur hittebehandeling vernietig word en dat sojavetselle fisies sodanig beskadig word, dat dit oliebeskikbaarheid bevorder. ANDER ENKELMAAGDIERE Visse Om ekonomies lewensvatbaar te wees, moet visboerdery kompeterend wees en moet daar noukeurig gekyk word na die voerkoste wat tot 50% van die produksiekoste kan uitmaak. Visrantsoene stel egter baie hoë proteïenvereistes en is dit dus belangrik om te probeer om n gedeelte van die duur grondstowwe, soos vismeel en olie, te vervang met goedkoper alternatiewe. Heelwat navorsing in hierdie verband word gedoen en daar is gevind dat: Volvetsojas, wat behoorlik verhit is, vismeel gedeeltelik kan vervang. In ander gevalle is vismeel algeheel vervang in beide vars- en seewatervisrantsoene. Moontlike tekorte aan essensiële aminosure kan reggestel word deur dit aan te vul met addisionele proteïenbronne of sintetiese aminosure. 2

6 Waar tripsien-inhibeerders van volvetsojas deur hittebehandeling geïnaktiveer is, word n produk van hoër voedingswaarde as geëkstraheerde soja-oliekoek geproduseer. Die hoë olie-inhoud van volvetsojas voorsien nie alleen essensiële vetsure nie, maar verminder die nodigheid om proteïene te kataboliseer vir energiedoeleindes. Konyne Rascon et al (1985) het, in vitro, die tripsien en chimotripsien-aktiwiteit van elf verskillende dierespesies in die teenwoordigheid van tripsien-inhibeerders bepaal. Hulle kom tot die gevolgtrekking dat konyne die sensitiefste spesie vir tripsien-inhibeerders is. Dit is dus voor die handliggend dat die prosessering van sojabone van besondere belang is in die voeding van konyne. Cheeke (1988) het getoon dat die groeitempo van konyne ietwat beter was op geëkstrueerde volvetsojabone as op soja-oliekoekmeel. Die doeltreffendheid van voerverbruik was ook beter op volvetsojas as gevolg van die hoër energie-inhoud daarvan. Verskeie ander studies op teelkonyne het getoon dat die reproduktiewe vermoë aansienlik verbeter wanneer daar kort na geboorte gepaar word, mits hoë energie en proteïenlakterende rantsoene gevoer word. Partridge et al (1984) het getoon dat daar op hierdie wyse tot 80 kleintjies per wyfie per jaar geproduseer kan word. Hittebehandelde volvetsojabone is n nuttige grondstof om te gebruik wanneer laktasierantsoene vir konyne geformuleer word. Hierdie grondstof is ook van besondere belang in die formulering van konyn-afrondingsrantsoene. Dié rantsoene benodig n hoë proteïen- en energie-inhoud, maar terselfdertyd voldoende vesel om spysverteringstoornisse te voorkom. Wanneer volvetsoja-oliekoek met sy hoë energie- en proteïeninhoud in die formulering van sulke rantsoene gebruik word, is daar genoeg spasie om ander hoë veselgrondstowwe in te sluit. Honde en katte In honde- en katvoeding word soja-oliekoek suksesvol as proteïenbron gebruik. Voeding van herkouers Melkbeeste Daar is twee belangrike redes waarom hittebehandelde volvetsojabone aan hoë produserende melkkoeie gevoer behoort te word. Die eerste is die groot voordeel wat verkry word wanneer n hoë kwaliteit deurvloeiproteïen aan hoë produserende melkkoeie gevoer word. Tweedens, sojabone is ekonomies en n gerieflike manier om olie (energie) aan hoë produserende diere te voorsien. 3 Proteïennavorsingstigting

7 Hittebehandeling verhoog die hoeveelheid proteïen wat degradering in die rumen vryspring. Wanneer hittebehandeling onvoldoende is, is die beskerming van proteïene swak. Oormatige hitte aan die ander kant veroorsaak dat Maillard-verbindings ontwikkel, wat nie in die dunderm benut kan word nie. Hittebeskadigde proteïen beweeg onbenut deur die spysverteringskanaal. Dit is dus belangrik om toe te sien dat toepaslike hitte aangewend word om n hoë kwaliteit deurvloeiproteïen te verseker. Die werk van Faldet en Satter (1991) van die Universiteit Wisconsin in die VSA in dié verband is insiggewend. Hulle wys daarop dat die tipiese lugtemperature waaraan sojabone in n dromrooster blootgestel word, gewoonlik tussen 200 ºC en 300 ºC varieer. Die blootstelling aan hierdie hoë temperatuur van ongeveer een minuut is ook nie voldoende om eenvormige hitte van al die boontjies te verseker nie. Die buitenste gedeelte sal warmer wees as die binneste gedeelte. Om n egalige temperatuur in al die boontjies te verseker moet dit ná verhitting vir n sekere periode in n houer geplaas word. Daar word na die proses verwys as steeping. Om die optimale roostertemperatuur en steeping tydsduur te bepaal, is sojabone by verskillende temperature gerooster en steeping van 15 minute en 30 minute toegelaat. Die temperatuurbehandeling wat in Tabel 2 aangetoon word, is die temperatuur van die sojabone toe dit uit die dromrooster gehaal is. Tabel 2: Ondegradeerbare proteïen, lisien, beskikbare lisien en post-ruminale beskikbare lisien van sojaboonmonsters. SOJABOON- BEHANDELING ONDEGRADEER- BARE PROTEïEN LISIEN BESKIKBARE LISIEN % van Ru-proteïen mg/g N Onverhit 33 a a 123 ºC 30 minute 44 bc bc 135 ºC 0 minute 46 cd bcd 135 ºC 30 minute 55 de de 146 ºC 0 minute 57 ef de 146 ºC 15 minute 63 g de 146 ºC 30 minute 61 g e 153 ºC 30 minute 65 g de 160 ºC 30 minute 66 g cd Standaardfout 2,9 21,1 19,1 9,6 POST-RUMINALE BESKIKBARE LISIEN* a, b, c, d, e, f, g, h getalle met verskillende alfabetiese letters in dieselfde kolom verskil betekenisvol (P< 0,05). * Verkry deur ondegradeerbare proteiïenfraksie te vermenigvuldig met beskikbare lisien. 4

8 Uit Tabel 2 is dit duidelik dat die maksimum post-ruminale beskikbare lisien verkry is toe sojabone tot 146 ºC verhit is en vir 30 minute gesteep is. Hierdie temperatuur en tydsduur kan dus beskou word as die optimale hittebehandeling vir herkouers. Dit is ook duidelik dat 160 ºC oormatig was, omdat die post-ruminale beskikbare lisien in hierdie geval heelwat laer was, ten spyte van n hoër ondegradeerbare proteïen. Faldet en Satter (1991) het toe n laktasiestudie onderneem op hierdie optimale geroosterde sojabone. Holstein-koeie is gevoer op een van die volledige voere vanaf 15 dae na kalwing tot 119 dae na kalwing lusernkuilvoer was die enigste bron van ruvoer. Elke rantsoen het op n droë-materiaal-basis 50% lusernkuilvoer en 50% konsentraat bevat. Die drie konsentrate het of rou sojabone of vetgeëkstraheerde sojameel of optimaal geroosterde sojaboonmeel bevat. Die drie rantsoene het dieselfde proteïeninhoud gehad, wat verkry is deur mielies en sojaboonmeel (vetgeëkstraheerde meel) met rou sojabone of die geroosterde sojaboonmeel te verplaas. Die verhouding van die proteïensupplement in die rantsoene op n droëmateriaal-basis was 10% sojaboonmeel, 13% rou sojabone of 13% geroosterde sojabone. Die invloed van die drie sojaboonbehandelings op voerinname, liggaamsgewig, melkproduksie en melksamestelling word in Tabel 3 aangetoon. Tabel 3: Die invloed van proteïensupplement op voerinname, liggaamsgewig, melkproduksie en melksamestelling. ITEM SOJABOON- MEEL ROU SOJABONE GEROOSTERDE SOJABONE Aantal koeie Inname Droëmateriaal (kg/dag) 23,4 22,3 23,6 Droëmateriaal (% van liggaamsgewig) 4,06 3,76 3,84 Ru-proteïen (kg/dag) 4,11 3,91 4,11 Liggaamsgewig Begingewig Eindgewig Verandering 26 a 2 b 31 a Opbrengs (kg/dag) Melk 34,5 b 34,2 b 38,9 a Vetgekorrigeerde melk (3,5%) 33,4 b 34,7 b 38,0 a Vet 1,16 b 1,22 ab 1,31 a Proteïen 1,01 b 1,01 b 1,10 a Melksamestelling % Vet 3,41 3,50 3,41 Proteïen 2,99 a 2,89 ab 2,85 b a, b Gemiddeldes in dieselfde ry met verskillende opskrifte verskil (P<0,05) 5 Proteïennavorsingstigting

9 Dit is interessant om daarop te let dat alhoewel die voerinname van die rou sojabonegroep ietwat laer was as dié van die soja-oliekoek- en geroosterde sojaboongroep, dit nie statisties betekenisvol was nie. Verder kan daar uit die gegewens in Tabel 3 bereken word dat melkkoeie op die rou sojaboonrantsoen daagliks 2,9 kg rou sojabone ingeneem het. Ten spyte hiervan, was die melkproduksie van hierdie groep (34,2 kg/koei/ dag) nie betekenisvol laer as dié van die vetgeëkstraheerde sojameelgroep nie. Toename in liggaamsgewig gedurende laktasie op die rou sojaboonbehandeling was egter betekenisvol laer as dié van die ander twee behandelings. Sojabone wat egter gerooster is om die maksimum beskikbare lisien aan die dunderm beskikbaar te stel, het respektiewelik 4,7 kg en 4,4 kg meer melk per koei per dag gelewer as die rou sojaboon- en soja-oliekoekbehandelings. Faldet en Satter (1991) wys daarop dat die respons wat hulle gekry het, aansienlik beter is as die gemiddeld van vyf ander studies waar kommersieel geroosterde sojabone slegs 1,5 kg en 2,2 kg beter presteer het as rou sojabone en sojaboonmeel. Hulle is van mening dat hul beter resultate waarskynlik toegeskryf kan word aan verskille in temperatuur en tydsduur van verhitting. Hulle wys verder daarop dat 13 kommersiële bronne geroosterde sojabone getoets is en die ondegradeerbare proteïeninhoud gewissel het van 36% tot 58% met n gemiddeld van 48%. Klem word gelê op die belangrikheid van steeping. Wanneer sojabone vir 30 minute na rooster by roostertemperatuur gehou word, is die ondegradeerbare proteïen 66%, teenoor die 48% van sojabone wat toegelaat is om af te koel direk na prosessering. Wanneer n oorsig gedoen word van verskeie proewe waar rou sojabone aan herkouers gevoer is, kan die volgende algemene gevolgtrekkings gemaak word: Bevredigende resultate kan behaal word waar rou sojabone 10% - 12% van die dieet op n droë-materiaal-basis uitmaak. Mikro-organismes in die rumen degradeer die tripsien-inhibeerders. Indien groter hoeveelhede rou sojabone gevoer word, word die tripsien-inhibeerders nie genoegsaam in die rumen geïnaktiveer nie, soveel so dat sommige daarvan deurbeweeg en spysverteringstoornisse laer af in die spysverteringskanaal kan veroorsaak. Menige in vitro-verteerbaarheidstudies het aangetoon dat wanneer die dieet 10% -12% rou sojabone bevat, die verteerbaarheid van vesel in die rumen nie onderdruk word nie. Ureum moet nie in rantsoene ingesluit word wanneer rou sojabone gebruik word nie. Die urease aktiwiteit in die rou sojabone stel die ammonia in die ureum vry en n vinnige styging van ammonia in die grootpens vind plaas. Dit kan dan lei tot ureumvergiftiging. 6

10 Gemaalde rou sojabone kan nie vir lang periodes gestoor word nie veral nie gedurende warm weersomstandighede nie. Wanneer sojabone dus gemaal word, moet slegs hoeveelhede wat binne n paar dae gebruik sal word, gemaal word. Wanneer sojabone aan jong herkouers soos jong vervangingsverse en gespeende kalwers gevoer word, moet dit hittebehandelde sojabone wees. Tripsien-inhibeerders word nie in die grootpens van jong diere degradeer nie en die teenwoordigheid hiervan kan die voerinname en verteerbaarheid verlaag. Lammers moet nie onverhitte volvetsoja ontvang nie, as gevolg van die tripsieninhibeerders wat daarin teenwoordig is. Volwasse skape kan egter soja sowel as soja-oesreste goed benut. Teks saamgestel in Augustus 2011 deur dr M Griessel. VERWYSINGS Cheeke, PR (1988) Rabbit Feeding. The utilization of protein. In Feed Intern 3, Faldet, MA, and Satter, LD (1991) Feeding Heat Treated Full Fat Soybeans to Cows in early Lactation. J Dairy Sci. Vol 74: National Research Council, Nutrient requirements of Poultry. 9th Rev. Ed. Acad. Sci., Washington, DC. Partridge, GC, Allan, SJ, Findlay, M and Corrigall, W (1984). The effects of reducing the remating interval after parturition on the reproductive performance of the commercial rabbit doe. Animal Production, 39, Rascon, A, Siedi, DS, Jaffe, WG and Aizman, A (1985). Inhibition of trypsin and chymotripsins from different animal species, A Comparitive Study, Comp. Biochem. Phys., 82B, Wiseman, J, (1994) Full Fat Soya, Oils and Fats in Poultry Nutrition. American Soybean Association Brussels, Belgium, page 7. 7 Proteïennavorsingstigting

11 REFERENCES Cheeke, PR (1988) Rabbit Feeding. The utilization of protein. In Feed Intern 3, Faldet, MA, and Satter, LD (1991) Feeding Heat Treated Full-fat Soybeans to Cows in early Lactation. J Dairy Sci. Vol 74: National Research Council, Nutrient requirements of Poulty. 9th Rev. Ed. Acad. Sci., Washington, DC. Partridge, GC, Allan, SJ, Findlay, M and Corrigall, W (1984). The effects of reducing the remating interval after parturition on the reproductive performance of the commercial rabbit doe. Animal Production, 39, Rascon, A, Siedi, DS, Jaffe, WG and Aizman, A (1985). Inhibition of trypsin and chymotripsins from different animal species, A Comparitive Study, Comp. Biochem. Phys., 82B, Wiseman, J, (1994) Full Fat Soya, Oils and Fats in Poultry Nutrition. American Soybean Association Brussels, Belgium, page 7. 7 Protein research foundation

12 soybeans per day their milk production (34,2 kg/cow/day) was the same as that of the group fed fat-extracted soybean meal. However, the increase in body weight during lactation of cows on the raw soybean treatment was significantly lower than that of the other two treatments. Soybeans roasted to provide the maximum available lysine in the small intestine resulted in, respectively, 4,7 kg and 4,4 kg more milk per cow per day, compared to the raw soybean and soya oilcake treatments. Faldet and Satter (1991) showed that the response obtained was significantly better than the average of five other studies involving commercially roasted soybeans, where only 1,5 kg and 2,2 kg better milk yield resulted than with raw soybeans and soybean meal. They ascribe these significantly better results to differences relating to temperature and period of heating. In addition, they tested 13 commercial sources of roasted soybeans and showed that the non-degradable protein content differed from 36% to 58%, at an average difference of 48%. In an overview of various trials involving the use of raw soybeans for ruminants, the following deductions seem valid: Satisfactory results may be obtained if raw soybeans comprise 10% to 12% of the diet on a dry matter basis. Micro-organisms in the rumen degrade trypsin inhibitors. If more raw soybeans are included, the trypsin inhibitors are not deactivated sufficiently in the rumen. This means that some pass through and may cause problems lower in the digestive system. Many in vitro digestibility studies have shown that a diet containing 10% to 12% raw soybeans, does not suppress the digestibility of fibre in the rumen. Urea should not be included in rations if raw soybeans are included. The urease activity in the raw soybeans releases ammonia in the urea and this leads to a rapid increase of ammonia in the rumen. This may cause urea poisoning. Ground raw soybeans cannot be stored for long periods. This is particularly true in warm climates. If soybeans are ground, one should only grind sufficient quantities to be used within a few days. If soybeans are used for young ruminants, such as young replacement heifers and weaned calves, the soybeans must have been heat-treated. It is important to remember that trypsin inhibitors are not degraded in the rumen of young animals and that these may decrease the intake of nutrients and digestibility. Lambs must not be fed raw full-fat soya, because it contains trypsin inhibitors. Adult sheep may use soya and soya harvest stubble efficiently. Text prepared by dr M Griessel in August

13 Faldet and Satter (1991) then undertook a lactation study related to the optimally roasted soybeans. Holstein cows were fed, using one of the complete feeds, from 15 days to 119 days after calving, where lucerne was the only source of roughage. On a dry matter basis each ration contained 50% lucerne silage and 50% concentrate. The three concentrates contained raw soybean or fat-extracted soybean meal or the optimal roasted soybean meal. The three rations had the same protein content, obtained by replacing maize and soybean meal (fat extracted meal) with raw soybeans or the roasted soybean meal. The protein supplement ratio in the rations, on a dry material basis, was 10% soybean meal, 13% raw soybeans or 13% roasted soybeans. The effects of the three soybean treatments on feed intake, body weight, milk production and milk composition are shown in Table 3. Table 3: The effects of protein supplement on feed intake, body weight, milk production and milk composition. ITEM SOYBEAN MEAL RAW SOY- BEANS Number of cows Intake Dry matter (kg/day) 23,4 22,3 23,6 Dry matter (% of body weight) 4,06 3,76 3,84 Crude protein (kg/day) 4,11 3,91 4,11 Body weight Starting weight End weight Change 26 a 2 b 31 a Yields (kg/day) Milk 34,5 b 34,2 b 38,9 a Fat corrected milk (3,5 %) 33,4 b 34,7 b 38,0 a Fat 1,16 b 1,22 ab 1,31 a Protein 1,01 b 1,01 b 1,10 a Milk composition % Fat 3,41 3,50 3,41 Protein 2,99 a 2,89 ab 2,85 b a, b averages in the same row but under different headings differ (P<0,05) ROASTED SOYBEANS It is interesting to note that, although the feed intake of the raw soybean group was somewhat lower than that of the groups fed soy oilcake and roasted soybean, the difference was not statistically significant. In spite of this group consuming 2,9 kg raw 10 5 Protein research foundation

14 be utilised in the small intestine. It is therefore important to ensure that the appropriate amount of heat is applied to ensure a high quality bypass protein. The work done on this subject by Faldet and Satter (1991) at the University of Wisconsin in the USA is insightful. They showed that soybeans in a drum roaster are exposed typically to air temperatures varying between 200 ºC and 300 ºC. Exposure to such high temperatures for about one minute is insufficient in producing a uniform heat for all the beans. The outer sections will be warmer than the inner sections. To ensure a uniform temperature for all the beans, it should be steeped in a container for a given period after heating. In determining the optimal roast temperature and the duration of steeping, soybeans were roasted at different temperatures and steeped for periods of 15 minutes to 30 minutes. The temperature treatments shown in Table 2 are the temperatures of the soybeans when they were removed from the drum roaster. Table 2: Non-degradable protein, lysine, available lysine and post-ruminal available lysine in soybean samples. SOYBEAN TREATMENT NON-DEGRADABLE PROTEIN LYSINE AVAILABLE LYSINE POST-RUMINAL AVAILABLE LYSINE* Standard error 2,9 21,1 19,1 9,6 a, b, c, d, e, f, g, h numbers with various alphabetical letters in the same column differ meaningfully (P < 0,05). * Obtained by multplying non-degradable protein fraction with available lysine. This work shows clearly that the maximum post-ruminal available lysine was obtained where soybeans were heated to 146 ºC and steeped for 30 minutes. This temperature and period may therefore be considered the optimal heat treatment required when feeding soya to ruminants. It is also clear that 160 ºC was too high, because the post-ruminal available lysine was much lower at that temperature, in spite of a higher undegradability of the protein. % of raw protein mg/g N Unheated 33 a a 123 ºC 30 minutes 44 bc bc 135 ºC 0 minutes 46 cd bcd 135 ºC 30 minutes 55 de de 146 ºC 0 minutes 57 ef de 146 ºC 15 minutes 63 g de 146 ºC 30 minutes 61 g e 153 ºC 30 minutes 65 g de 160 ºC 30 minutes 66 g cd

15 If trypsin inhibitors in full-fat soy have been deactivated by heat treatment, the resultant product has a higher nutritional value than extracted soybean oilcake. The high oil content of full-fat soya does not only provide essential fatty acids, it also reduces the need to catabolise proteins for energy purposes. Rabbits Rascon et al (1985) determined, in vitro, the trypsin and chymotrypsin activity of eleven different animal species in the presence of trypsin inhibitors. They determined that rabbit species are the most sensitive to trypsin inhibitors. This means that the processing of soybeans is of particular importance if these are to be used in rabbit feeds. Cheeke (1988) showed that the growth rate of rabbits is somewhat improved using extruded full-fat soybeans compared to soybean oilcake meal. Feed efficiency using full-fat soya was better, due to its higher energy content. Various studies involving breeding rabbits, have shown that reproduction significantly improved in cases where mating occurred shortly after giving birth if high energy and protein lactation rations are fed. Partridge et al (1984) showed that this could lead to the production of up to 80 babies per female per year. Heat-treated full-fat soybeans are useful in lactation feeds for rabbits. This ingredient is also of particular importance in rabbit finishing feeds. These feeds require a high protein and energy content, but also sufficient fibre to prevent digestive problems. In using full-fat soya with its high energy and protein content in formulating such feeds, there is sufficient room for including other high fibre raw materials. Dogs and cats Soybean oilcake is a successful protein source for dog and cat food. RUMINANT FEEDS Milk cows There are two important reasons for using heat-treated full-fat soybeans in feeds for high-producing milk cows. The first is the significant benefit of using a high quality bypass protein and the second is that soybeans are an economical and easy way to include oil (energy) in high producing animal feeds. Heat treatment increases the amount of protein that remains undegraded in the rumen. If heat treatment is insufficient, protein protection is poor. On the other hand, too much heat damages the protein by causing the formation of Maillard complexes that cannot 12 3 Protein research foundation

16 Table 1: Apparent metabolisable energy (AME) and nitrogen retention (NR) of processed whole soybeans for 2,5 week old chickens. AME PROCESS (MJ/KG) NR % * Wet extrusion 17,9 54 * Dry extrusion 17,4 59 * Micronized 15,4 48 * Jet-sploded 14,7 61 * Toasted 15,6 57 * Raw soybeans 13,5 30 ** Soybean seed heat processed 13,8 - * Wiseman, 1994 ** NRC Poultry, 1994 Table 1 clearly shows that the extrusion process produces a product with higher metabolisable energy content for poultry, compared to other processes. Pigs Pigs are the second largest consumers of soybean oilcake (poultry being the biggest). Being monogastrics they are, just like chickens, sensitive to anti-nutritional factors present in raw soybeans. It is therefore important to note the two fundamental objectives of processing, namely that anti-nutrition factors are destroyed by heat treatment and that the fat cells are damaged in such a way that the availability of oil is increased. OTHER MONOGASTRIC ANIMALS Fish To be economically viable, fish farming should be competitive. Be sure to look into the feed cost, that makes out 50% of the production cost. Fish require very high protein levels in their feed. In order to reduce the cost of fish feed some of the expensive raw materials like fishmeal and oil should be replaced where possible with less expensive alternatives. Much research has been conducted on this subject. The results of which are: Full-fat soya that has been properly heat treated may be used as a partial replacement of fishmeal. In some cases, fishmeal was replaced entirely in both fresh and sea water fish feeds. Deficiencies of essential amino acids resulting from this substitution may be rectified by adding additional protein sources or synthetic amino acids

17 Feed for monogastric animals During 2010/2011 the total feed consumption by livestock in South Africa was 10,6 million tonnes. The poultry industry consumed 4,3 million tonnes or 40,6 % of the total. Soya oilcake, with its favourable amino acid composition, is such an important raw material in poultry feeds that significant volumes of this commodity are used by the poultry industry, making it by far the largest consumer of soya oilcake in South Africa. To ensure optimal growth and feed conversion, broiler chickens are invariably fed pelleted feed. Raw materials with a high oil content, like full-fat soya, often lead to an unsatisfactory pellet quality, so animal feed producers place an upper limit on the amount of full-fat soya that is included in broiler feed. The advantage of using defatted soybean meal (soya oilcake) is that it produces good quality pellets. The energy content of such feed can then be increased by spraying fats or oils onto the pellets (post-pellet treatment). Where poultry feed is manufactured in meal form, soybeans can be used in the full-fat or oilcake form or in combination. As mentioned earlier, irrespective of whether the oil has been extracted from the soya, it is important to ensure that trypsin inhibitors and other anti-nutritional factors in the ingredient are deactivated using heat treatment. It is also essential that protein quality is not damaged due to overheating during processing. Refer to the document on the PRF website ( for more information on soybean processing Soybean meal use in the South African poultry industry: formulation and quality considerations by Brett Roosendaal. In the case of full-fat soya, both the content and digestibility of the oil vary between samples. It is self-evident that oil content and energy content are correlated. However, the digestibility or availability of the oil depends on the processing method used. The reasons for these differences have not been proven, but appear to be related to the extent to which the product has been ground, which is in turn related to the degree of fat cell damage that occurs during processing. Where the soybeans have been subjected to grinding, high pressure, heat, friction and swelling, due to a sudden drop in pressure when the product leaves the pressure tube, the physical damage to fat cells is greater than in other processes. As a result, extrusion appears to be one of the better processes for increasing the digestibility of soybean oil in animal feeds, especially for monogastric animals. Table 1 shows the results reported by dr Julian Wiseman, one of the early researchers working with full-fat soybeans Protein research foundation

18 Index 1. Feed for monogastric animals 1 Pigs 2 2. Other monogastric animals 2 Fish 2 Rabbits 3 Dogs and cats 3 3. Ruminant feeds 3 Milk cows 3

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20 APPLICATION OF SOYBEANS FOR ANIMAL FEED