In an attempt to reduce the costs and turn around times experienced with outsourcing starch analysis in finished feed products, the company decided to invest in a NIR instrument to carry out such analyses in house. The particular instrument purchased by the company comes with a build in calibration for specific finished feed products and the main objective of this investigation was to evaluate whether the instrumentation and build in calibration gives reliable analyses of a finished poultry feed. The results obtained showed that : - The NIR results obtained have a positive bias compared to the theoretical (formulation specified value) and also to the value obtained by enzymatic starch analysis. - Despite the positive bias, the starch values were well within the allowable limits - Repeatability measurements on the data generated by two different analysts showed that while the percentage relative standard deviations obtained (< 1.0 percent) were well within the company specifications of percentage RSD < 5.0 percent, the inter sample repeatability showed small, but significant variation. - The results for intermediate precision showed that there is no statistically significant difference between the results obtained by two different analysts, nor was there any difference in the results of the same samples analysed at different time periods. - Reproducibility could not be evaluated due to the lack of another instrument within the company that were similarly set up as the instrument used for the investigation. This investigation has shown that, given the restrictions enforced by the build incalibration of the NIR instrument, the use of NIR for the analyses of the finished feed product is valid, but will require that careful attention be paid to data collection procedures.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The use of fungal enzymes as ruminant feed digestibility enhancers was investigated. Currently, ruminants may not digest 38 to 80 % of fibrous forages' content. A renewed interest in the potential of feed enzymes for ruminants was prompted by the high costs of livestock production, together with the availability of newer enzyme preparations. Direct application of enzyme preparations can improve in vitro dry matter (DM) and neutral detergent fibre (NDF) degradation, indicating that direct-fed fibrolytic enzymes may be effective in enhancing in vivo digestion of forages. Two commercial enzyme products, Fibrozyme and Celluclast, and fungal extracellular enzyme extracts from Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, and Thermomyces lanuginosus were evaluated for enhancing in vitro feed digestibility. Fibrozyme addition to both wheat straw and lucerne hay did not improve their in vitro digestibilities, even after a two hour pre-incubation period. The four fungal enzyme extracts did not enhance wheat straw's digestibility, but marginal increases were evident for lucerne hay. Celluclast addition resulted in marginal increases in the digestibility of both oat hay and oat silage, with no enhanced effect on lucerne hay and NaOH-treated wheat straw. No relationship could be found between the level of enzyme activity and the degree of feed digestion in the in vitro assay. Enzyme hydrolysis with Celluclast, in the absence of rumen fluid, gave more conclusive results. All the feed samples tested showed a positive response to Celluclast addition, even the less digestible feeds, namely sugarcane bagasse and wheat straw. In vitro results show that the assays were unsuccessful, because almost all of the experiments conducted showed inconclusive results. Alternative feed evaluation assays, which include the in vivo, in sacco and in situ methods of analysis, as well as gas production measurement and in vitro analysis with the DAISyII system, should be evaluated. A more detailed study of feed digestibility should be motivated by determining which feeds are hydrolysable, their chemical composition, i.e. how accessible the feeds are, and also evaluation of feed mixtures. The enzyme supplements also need to be evaluated for optimum temperature and pH, as well as the compilation of enzyme cocktails. / AFRIKAANSE OPSOMMING: Die gebruik van swamensieme om die verteerbaarheid van herkouervoere te verhoog, is ondersoek. Tussen 38 en 80 % van veselagtige voere se inhoud is tans onverteerbaar. 'n Hernieude belangstelling in die potensiaal van voerensieme vir herkouers word deur die hoë koste van veeproduksie, asook die beskikbaarheid van nuwe ensiempreparate gedryf Direkte byvoeging van ensiempreparate kan die in vitro droëmateriaal (DM) en neutrale onoplosbare vesel (NOV) vertering verbeter, wat daarop dui dat fibrolitiese ensieme wat direk gevoer word, effektief mag wees tydens die in vivo vertering van voer. Twee kommersiële ensiemprodukte, Fibrozyme en Celluclast, en die vier ekstrasellulêre ensieme van vier swamme, naamlik Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, en Thermomyces lanuginosus is vir hul vermoë om die in vitro verteerbaarheid van voere te verbeter getoets. Byvoeging van Fibrozyme by beide koringstrooi en lusernhooi het geen verbetering in hulonderskeie in vitro verteerbaarheid tot gevolg gehad nie, selfs nie eens na 'n twee uur vooraf inkubasieperiode nie. Koringstrooi se verteerbaarheid is nie verbeter deur die byvoeging van die vier swam-ensiempreparate nie, maar 'n minimale verbetering is wel waargeneem in die verteerbaarheid van lusernhooi. Byvoeging van Celluclast het 'n minimale verbetering in beide hawerhooi en hawerkuilvoer se verteerbaarheid tot gevolg gehad, maar geen effek op lusernhooi of NaOH-behandelde koringstrooi se verteerbaarheid nie. Geen verwantskap is tussen die vlak van ensiemaktiwiteit en die mate van vertering tydens die in vitro toets gevind nie. Ensiematiese afbraak met Celluclast, in die afwesigheid van rumenvloeistof, het meer konkrete resultate gelewer. Al die voermonsters het 'n positiewe respons op die byvoeging van Celluclast getoon, selfs ook die minder verteerbare voere, nl. suikerrietbagasse en koringstrooi. In die wyer konteks was die resulate van die in vitro verteringstoetse egter onbeduidend as gevolg van groot variasie in die metings. Alternatiewe voerontledingstoetse, wat moontlik beter resultate mag lewer, sluit in in vivo, in sacco en in situ analises, asook die meting van gasproduksie en in vitro analise met die DAISyII sisteem. 'n Meer uitgebreide studie van voerverteerbaarheid wat die bepaling van die afbraak van voere, hul chemiese samestelling, met ander woorde toeganklikheid van voere, en die ondersoek van voermengsels behels, behoort aandag te geniet. Die ensiemmengsels behoort ook ten opsigte van samestelling, optimum temperatuur en pH ondersoek teword.

Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Two in vitro experiments were conducted to evaluate the effect of exogenous fibrolytic enzyme application on dry matter (DM) and neutral detergent fibre (NDF) degradation and gas production (GP) of mature forages and forage-concentrate mixtures. The forages used in the first experiment were lucerne hay (LH), oat hay (OH) and wheat straw (WS). The same forages were used in the second experiment, but they were mixed with a concentrate feed to make three mixtures consisting of 80% (HC), 50% (MC) or 20% (LC) concentrate. The extracellular enzyme fraction (supernatant) of a fungal strain, ABO 374, was used as feed additive. The supernatant was used in a fresh (SU-ABO374) or lyophilized (CSIR-ABO374) form, the latter being reconstituted with water immediately before application. The liquid supernatants were applied to the incubation medium and not directly to the substrate, at a rate equivalent to 7.5 ml/kg feed DM. In the control treatments of both experiments, water was used instead of the liquid supernatants. For the DM and NDF degradability trials in both experiments, 500 mg forage samples were weighed into 50 x 50 mm dacron bags which were incubated anaerobically at 39ºC in 1.4L of a rumen liquid inoculated buffered medium in 2L fermentation jars. Bags from all treatments were removed after 2, 4, 8, 12, 24, 48, 72 and 96 h of incubation. For the gas production determinations, 500 mg of the respective substrate samples were weighed into 120 ml glass vials which were incubated for 96 h in 40 ml inoculated medium to which 0.5 ml of the respective enzyme solutions were added. Gas pressure was recorded manually with a digital pressure gauge after 2, 4, 8, 12, 24, 48, 72 and 96 h and pressure was converted to volume with a predetermined regression. The 96 h substrate residues were washed, dried, weighed and analyzed for NDF and OM. In both experiments the substrates differed in terms of DM and NDF degradability and gas production rates, but the enzyme treatments had no effect. The lack of response to enzyme application was ascribed to a number of factors, including the fact that enzyme application was into the incubation medium and not directly onto the substrates and also that no significant pre-incubation interaction time was allowed. The same preparations gave positive results in previous trials where they were applied directly onto the substrates and where a pre-incubation interaction time of 16 hours was allowed. (Key words: Exogenous enzymes, forages, concentrate based diets, DM and NDF degradation, gas production ) / AFRIKAANSE OPSOMMING: Die invloed van eksogene fibrolitiese ensieme op in vitro fermentasiekinetika van ruvoer- en gemengde voersubstrate. Twee in vitro-experimente is uitgevoer om die invloed van eksogene fibrolitiese ensieme op droëmateriaal (DM) en neutraal-onoplosbare vesel (NDF) degradering en gasproduksie (GP) van volwasse ruvoersubstrate en ruvoer-kragvoermengsels te bepaal. Ruvoere in die eerste eksperiment was lusernhooi (LH), hawerhooi (HH) en koringstrooi (KS). Dieselfde ruvoere is in die tweede eksperiment gebruik, maar hulle is met ‘n kragvoer gemeng om drie mengsels te maak, bestaande uit 80% (HK), 50% (MK) of 20% (LK) kragvoer. Die ekstrasellulêre ensiemfraksie (supernatant) van ‘n fungiale stam, ABO 374, is as ‘n voertoedieningsmiddel gebruik. Die supernatant is is in ‘n vars (SU-ABO374) of gevriesdroogde (WNNR-ABO374) vorm gebruik, waar laasgenoemde onmiddellik voor toediening gerekonstitueer is. Die vloeistof-supernatante is nie direk op die substrate gevoeg nie, maar tot die inkubasiemedium gevoeg, teen ‘n hoeveelheid ekwivalent aan 7.5 ml/kg voer DM. In die kontrolebehandeling van beide eksperimente, is water in plaas van die vloeistofsupernatante gebruik. Vir die DM- en NDF-degraderingsproewe in beide eksperimente, is 500 mg van die onderskeie ruvoere in 50 x 50 mm dacronsakkies geweeg wat anaerobies by 39ºC geïnkubeer is in 1.4L van ‘n rumenvloeistof-geïnokkuleerde medium in 2L fermentasieflesse. Vir alle behandelings is sakkies na 2, 4, 8, 12, 24, 48, 72 en 96 h inkubasie verwyder. Vir gasproduksiebepalings is 500 mg van die onderskeie substraatmonsters in 120 ml glasbotteltjies geweeg en vir 96 h in 40 ml geïnokkuleerde medium geïnkubeer waarin 0.5 ml van die onderskeie ensiemoplossings gevoeg is. Gasdruk is na 2, 4, 8, 12, 24, 48, 72 en 96 h bepaal met behulp van ‘n digitale drukmeter en druk is met behulp van ‘n voorafbepaalde regressie na volume omgeskakel. Die 96 h substraatresidue is gewas, gedroog, geweeg en ontleed vir NDF en OM. In beide eksperimente het die substrate verskil ten opsigte van DM- en NDF-degradeerbaarheid en gasproduksietempo’s, maar die ensiembehandelings het geen invloed gehad nie. Die gebrek aan respons is aan verskeie faktore toegeskryf, insluitend die feit dat ensiemtoediening in die inkubasiemedium toegedien is en nie direk op die substrate nie, asook die feit dat daar nie ‘n noemenswaardige pre-inkubasie interaksietyd toegalaat is nie. Dieselfde ensiempreparate het positiewe resultate gelewer in vorige proewe waar dit direk op die substraat toegedien is en waar ‘n pre-inkubasie interaksietyd van 16 ure toegelaat is. (Sleutelwoorde: Eksogene ensieme, ruvoere, kragvoerdiëte, DM- en NDF-degradering, gasproduksie)

MSCAGR / Department of Animal Science