The effect of maize vitreousness and a starch binder on in vitro fermentation parameters and starch digestibility in dairy cows
| dc.contributor.advisor | Cruywagen, C. W. | en_ZA |
| dc.contributor.author | Van Zyl, Johan Hendrik Combrink | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences. | en_ZA |
| dc.date.accessioned | 2017-10-25T09:27:03Z | |
| dc.date.accessioned | 2017-12-11T10:46:33Z | |
| dc.date.available | 2017-10-25T09:27:03Z | |
| dc.date.available | 2017-12-11T10:46:33Z | |
| dc.date.issued | 2017-12 | |
| dc.description | Thesis (PhD)--Stellenbosch University, 2017. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Maize kernels consist of hard vitreous endosperm and soft floury endosperm, and the ratio of the vitreous to floury endosperm determines the vitreousness of the kernel. As ruminal fermentation and animal performance are higher for low vitreous maize, lower vitreous maize is favoured for inclusion in animal feeds. Very high ruminal starch degradability may, however, lead to metabolic disorder risks such as acidosis. The objective of this study was to evaluate various techniques for routine analysis to determine a rapid, simple, inexpensive method to predict maize vitreousness accurately. Secondly, the usability of Near-infrared spectroscopy (NIR) technology in the anmal feed industry to predict the fractional rate and extent of ruminal starch degradability in maize differing in vitreousness was investigated by means of in vitro starch disappearance. Thirdly, the effect of the treatment of maize with a commercial starch binder on rumen kinetics of lactating dairy cows was investigated by means of in vitro gas production and in vitro starch disappearance studies. For this part of the study, it was attempted to bind some of the maize starch (1 mm grind) in vitro with the treatment of a commercial starch binder. The fourth objective was to investigate the effect of particle size (1mm vs 4 mm grind) and a starch binder on in vitro disappearance of starch in low vitreous maize. The final objective was to determine the effect of starch binder treatment of low vitreous maize on the apparent total tract digestibility and production responses in lactating dairy cows. Ninety maize samples of different vitreousness were collected and subjected to NIR at a single absorbance of 2230 nm and PSI trough a single 106 μm screen. Samples were subsequently ranked according to vitreousness. The ten hardest and ten softest samples were selected to evaluate NIR, particle size index (PSI), and Rapid visco analyzer (RVA) rheological analyses as potential methods for the determination of maize vitreousness against X-ray micro-computed tomography (XCT). Significant relationships were found between NIR and PSI regarding hardness predictions, while the study with the smaller sample set (n = 10) showed significant relationships between PSI, NIR, RVA peak time (corresponding time required for a sample subjected to rheological analysis to reach peak viscosity) and RVA peak viscosity (the process of gelatinization and occurs at the equilibrium point between swelling and polymer leaching) in relation to XCT regarding maize vitreousness determination. All other rheological information data were not accurate to predict maize hardness. As NIR technology is already available and meets the requirements of speed, simplicity and inexpensiveness, it was concluded that NIR at a single absorbance of 2230 nm is the most accurate and practical method to determine maize vitreousness in the animal feed industry. Thereafter, six maize samples of decreasing vitreousness were selected from ninety samples with known vitreousness and subjected to in vitro starch disappearance at 0, 3, 6, 12, 24 and 48 h of incubation. The subsequently determined fractional rate of disappearance and predicted ruminal starch disappearance decreased significantly as maize vitreousness increased. Hardness indexes calculated from NIR analyses at a single absorbance of 2230 nm showed inverse linear and quadratic relationships for both fractional rate and extent of starch disappearance. It was concluded that NIR technology could be used to predict fractional rate and extent of starch disappearance from the rumen based on maize vitreousness. In a further study one low and one high vitreous maize sample were selected from the ninety samples with known vitreousness. Both samples were treated with equal amounts of a commercial starch binder (Bioprotect) and distilled water to determine the effect of the treatment on in vitro gas production and in vitro starch disappearance. The rate of in vitro gas produced from low vitreous maize was higher than that of high vitreous maize, irrespective of treatment. All other in vitro gas production parameters did not differ between treatments. In vitro starch disappearance values at 6, 12 and 24 h time intervals were, irrespective of binder treatment, higher with low vitreous maize compared to high vitreous maize. Starch binder treatment, however, did not affect in vitro starch disappearance. In a further in vitro study, maize samples of known low vitreousness were milled through 1 mm and 4 mm sieves, respectively. The milled samples were then thereafter treated with equal amounts of a starch binder (Bioprotect) and distilled water to determine the effect of particle size and treatment on in vitro starch disappearance after 0, 3, 6, 12, 24 and 48 h of incubation. Particle size reduction increased (P < 0.05) both fractional rate and extent of starch disappearance, while binder treatment showed a tendency (P < 0.10) towards decreased fractional rate and extent of starch disappearance. Despite no differences in ruminal kinetics with the binder treatment of 1 mm milled maize, treatment of 0.4 mm milled maize, however, indicated lower (P < 0.05) fractional rate and extent of starch disappearance. It was concluded that a reduction in particle size of maize with hammer mill processing changes rumen starch fermentation characteristics and that the treatment of 4 mm milled maize with a commercial starch binder may alter rumen fermentation kinetics. In the final trial, six primiparous Holstein dairy cows were used to investigate the effect of a starch binder (Bioprotect) treatment of low vitreous maize on total tract nutrient digestibility and production parameters of lactating dairy cows. Starch binder (10/L/tonne grain) or water treated maize were used in two TMR’s. No differences in dry matter intake, milk yield, 4% fat corrected milk yield, energy corrected milk yield, milk fat concentration, milk fat yield, milk protein concentration, milk protein yield, milk urea nitrogen concentration or somatic cell count were found between binder treated or water treated maize. Apparent estimated ruminal pH and the ratio of milk protein (%) to milk fat (%) also did not differ between treatments. Although total tract dry matter and nitrogen digestibilities did not differ between treatments, total tract starch digestibility decreased (P < 0.05) when maize was treated with a starch binder compared to the water treatment. It was concluded that the commercial starch binder might not be an effective tool to manipulate total tract maize starch digestion in dairy cows, as is apparently the case with wheat and barley. However, when the prevention of acidosis in dairy cows that receive high amounts of low vitreous maize is the objective, then a starch binder may prove to be effective. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Mieliepitte bestaan uit beide harde- en sagte endosperm en die verhouding van harde tot sagte endosperm, bepaal mielie-hardheid. Weens verhoogde ruminale verteerbaarheid en diereprestasie met sagte- teenoor harde mielies, word sagte mielies in herkouerdiëte verkies. ‘n Baie hoë ruminale stysel-fermentasietempo kan egter tot metaboliese steurnisse, soos assidose, lei. Die doelwit van hierdie studie was om verskillende tegnieke te ondersoek om ‘n vinnige, eenvoudige en koste-effektiewe metode te vind om mielie-hardheid akkuraat, te bepaal. ‘n Tweede doelwit was om die doeltreffendheid van die gebruik van NIR (Near-infrared spectroscopy) skandering vir vinnige, akurate voorspellings van die tempo- en hoeveelheid van ruminale styselverdwyning in mielies met te ondersoek. ‘n Derde doelwit was om die invloed van die behandeling van mielies met ‘n styselbinder op rumenwerking in lakterende melkkoeie deur middel van in vitro gasproduksie en in vitro styselverteerbaarheid te ondersoek. ‘n Poging om van die mieliestysel deur die behandeling met ‘n kommersiële styselbinder te bewerstellig is dus ondersoek. Hierna is die in vitro styselverteerbaarheid van mieliestyselbinder-behandeling tesame met verkleining van partikelgroote deur maal met ‘n hammermeul (1 mm vs. 4 mm) van sagte mielies ondersoek. ‘n Finale doelwit van hierdie studie was om in vivo te bepaal of die behandeling van sagte mielies met ‘n styselbinder ‘n invloed op totale nutriënt-verteerbaarhede en diereproduksie het. Negentig mieliemonsters met verskillende grade van hardheid is versamel en deur ‘n NIR met ‘n enkele absorpsie van 2230 nm geskandeer. Siffraksie-ontledings deur ‘n enkele 106 μm sif is ook gebruik om mielie-hardheid te bepaal. Vanuit hierdie data is tien harde en tien sagte monsters geselekteer vir verdere NIR-, sif (particle size index (PSI))- en RVA (Rapid visco analyzer)-analises om akkuraatheid van mielie-hardheid toetsmetodes teenoor XCT (X-straal analisse) te bepaal. Betekenisvolle korrelasies om mielie-hardheid te bepaal is tussen die siffraksie, NIR, XCT, RVA piektyd en RVA piekviskositeit met beide datastelle bevind. Alle ander reologiese data kon nie mielie-hardheid akkuraat beskryf nie. Gesien in die lig daarvan dat NIR tegnologie nie net voldoen aan die behoeftes van die veevoerbedryf ten opsigte van tempo van ontleding, eenvoud en lae koste nie, maar ook aan die beskikbarheid van die tegniek, maak NIR die gewenste metode in die praktyk. Ses mieliemonsters van dalende en bekende hardheid is geselekteer en vir 0, 3, 6, 12, 14 en 48 uur in vitro verteer. Berekende tempo- en mate van styselverdwyning was betekenisvol stadiger (P <0.05) en minder namate mieliehardheid verhoog het. Betekenisvolle inverse liniêre en kwadratiese verwantskappe is tussen NIR skandering en beide die tempo- en mate van runimale styselverdwyning waargeneem. Die gevolgtrekking is gemaak dat NIR skandering effektief binne die veevoerbedryf gebruik kan word om die tempo- en mate van styselverdwyning in mielies met verskillende hardhede te voorspel. Een harde- en een sagte mieliemonster, geselekteer uit die negentig monsters met bekende hardheid, is vir verdere studies geselekteer. Beide monsters is (na maal deur 1 mm sif) afsonderlik met gelyke dele van ‘n kommersïele styselbinder (Bioprotect) en gedistilleerde water behandel om die invloed van behandeling op in vitro gasproduksie en in vitro styselverteerbaarheid te bepaal. Die tempo van gasproduksie van sagte mielies, ongeag behandeling, was hoër teenoor die van harde mielies. Geen ander gasproduksieparameters het tussen behandelings verskil nie. Die 6, 12 en 24 uur in vitro styselverteerbaarhede van sagte mielies was, ongeag behandeling, hoër vir al drie tye teenoor harde mielies. ‘n Enkele sagte mieliemonster is deur 1 mm en 4 mm siwwe gemaal en daarna met gelyke dele styselbinder (Bioprotect) of gedistilleerde water behandel. Die verkleining van mieliepartikelgroote het die 0, 3, 6, 12, 24 en 48 uur in vitro tempo- en mate van styselverdyning betekeninsvol verhoog, terwyl ‘n neiging (P < 0.10) van verlaagde tempo en hoeveelheid van styselvertering met styselbinder-behandeling waargeneem is. Ten spyte van geen verskille in tempo- en hoeveelheid van styselverdwyning met styselbinder-behandelde mielies nie, het behandelde mielies ‘n betekenisvol laer tempo- en mate van styselverdyning getoon. ‘n Verlaging in mieliepartikelgroote met ‘n hammermeul verander dus ruminale parameters, terwyl 4 mm styselbinder-behandeling van sagte mielies ruminale fermentasieparameters kan verander. Die invloed van die behandeling van sagte mielies met ‘n styselbinder (Bioprotect) op totale spysverteringskanaalverteerbaarhede en produksieparameters van ses eerstekalf lakterende Holsteinkoeie is bepaal. Beide styselbinder-behandelde (10L/ton graan), sowel as onbehandelde mielies, is in ‘n volvoerrantsoen aan die diere voorsien. Geen verskille tussen behandelings is in droëmaterialinname, melkproduksie, 4% vetgekorrigeerde melkproduksie, energiegekorrigeerde melkproduksie, bottervetinhoud en -opbrengs, melkproteïenkonsentrasie en -opbrengs, melk ureumstikstof en somatiese seltelling waargeneem nie. Daar is verder ook geen verskille in voorspelde rumen pH of die verhouding tussen melkproteïen- en bottervetinhoud tussen behandelings waargeneem nie. Ten spyte van geen verskille in totale spysverteringskanaal droëmateriaal- en stikstof verteerbaarhede nie, was totale spysverteringskanaal styselverteerbaarheid met styselbinder-behandelde 4 mm mielies betekenisvol laer (P < 0.05) teenoor die van onbehandelde mielies. Die gevolgtrekking is gemaak dat die kommersiële styselbinder waarskynlik nie ‘n doeltreffende hulpmiddel is om styselverteerbaarheid in melkkoeie te manipuleer, soos wat skynbaar die geval met koring en gars is nie. Indien die voorkoming van asidose by melkkoeie wat baie hoë vlakke van sagte mielies inneem egter die doelwit is, kan die behandeling van sulke mielies met ‘n styselbinder moontlik doeltreffend wees. | af_ZA |
| dc.format.extent | 260 pages : illustrations, map | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/102726 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Dairy cattle -- Effect of maize vitreousness on | en_ZA |
| dc.subject | Dairy cattle -- Breeding | en_ZA |
| dc.subject | Dairy cattle -- Feeding and feeds | en_ZA |
| dc.subject | Dairy cows -- Starch digestibility | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | The effect of maize vitreousness and a starch binder on in vitro fermentation parameters and starch digestibility in dairy cows | en_ZA |
| dc.type | Thesis | en_ZA |