Thesis (MScAgric) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: The ruminant has the ability to utilize forages more efficiently than any other
production animal. The utilization of forage fibre is an important aspect of ruminant
production systems, as this is the main source of energy available to the animal. The
availability of high-fibre forage nutrients is, however, restricted by cell wall
degradability, and since low quality forages contribute a great deal to ruminant
production systems worldwide, the improvement of this degradation process is of
major economic importance.
The use of exogenous fibre degrading enzymes has been proposed as a means of
enhancing this process, with positive results being obtained from in vitro studies
incorporating exogenous enzyme preparations. Positive in vivo results with regard to
forage digestibility and other animal production parameters have consequently also
been obtained following the addition of exogenous fibre-degrading enzyme
preparations to the ruminant diet.
Two initial screening experiments were undertaken in order to identify fungal enzyme
preparations that may have a positive effect on in vitro fibre degradability. The initial
screening employed an in vitro organic matter digestibility technique, and was
successful in identifying at least six enzyme preparations displaying enhanced
digestibility results that were statistically significant. A second in vitro gas
production procedure was used to confirm results obtained from organic matter digestibility assays, as well as to increase screening capacity in order to evaluate new
enzyme preparations more time-efficiently. Statistical analysis of results obtained
from the secondary screening identified various enzyme candidates producing
promising results. Only one of these, Abo 374, proved to be statistically superior to
the control and other enzyme preparations.
A growth trial was subsequently conducted to assess the performance of this enzyme
in vivo. The trial involved individual feeding of 32 Dohne Merino ram lambs grouped
according to weights into four groups consisting of 8 lambs each. Each group
represented a specific application level of enzyme to the wheat straw component of a
high fibre diet, amounting to 10, 5, or 1 ml enzyme supematant/kg straw. The
enzyme was diluted with water at appropriate rates to obtain an application rate of
300ml/kg straw. The fourth (control) group was treated with water at the same
application rate. The trial was conducted over a period of six weeks, during which
feed intakes, weekly weight gains, as well as feed conversion efficiencies were
recorded. Results suggested significant weight gains in the high (10ml/kg) and
medium (5ml/kg) treatment groups, indicated by a P-value of 0.04. Similarly, feed
conversion efficiencies were improved for above-mentioned groups (P=0.05), while
feed intakes did not differ significantly between the four experimental groups. / AFRIKAANSE OPSOMMING: Die herkouer besit die vermoee om ruvoere beter as enige ander produksiedier te kan
benut. Die gebruik van ruvoervesel is 'n belangrike aspek van herkouer
produksiesisteme, aangesien ruvoere die hoof bron van energie aan die herkouer
verskaf. Die beskikbaarheid van hoe-vesel ruvoer nutriente word egter beperk deur
die degradeerbaarheid van die selwand, en aangesien lae kwaliteit ruvoere 'n groot
bydrae tot wereldwye herkouer-produksiesisteme maak, is die moontlike verbetering
van hierdie degraderingsproses van groot ekonomiese belang.
In 'n poging om hierdie verteringsproses te help bevoordeel, is die gebruik van
eksogene veselverterende ensieme ondersoek, en positiewe resultate is verkry
wanneer hierdie ensieme in in vitro studies gebruik is. Goeie verbeterings ten opsigte
van ruvoer verteerbaarheid en ander diereproduksie parameters is ook verkry deur
middel van in vivo studies waar eksogene ensieme by die ruvoer van herkouers
gevoeg IS.
Twee eksperimente is ondemeem in 'n poging om ensiempreparate wat 'n moontlike
positiewe effek op in vitro veselvertering mag he, te identifiseer. Die eerste, 'n in
vitro organiese materiaal verteerbaarheid tegniek, was suksesvol in die identifisering
van minstens ses ensiem preparate wat statisties betekenisvolle verbeterings ten
opsigte van verteringsresultate geproduseer het. 'n Tweede in vitro gasproduksie prosedure is vervolgens gebruik om resultate verkry vanaf die eerste tegniek, te
bevestig, asook om evalueringskapasiteit te vergroot en sodoende, nuwe
ensiempreparate meer tydseffektief te evalueer. Statistiese evaluering van resultate
verkry uit die tweede in vitro tegniek het 'n reeks ensieme met positiewe resultate
opgelewer. Een van hierdie, Ab0374, het statisties betekenisvolle resultate ten opsigte
van die kontrole, sowel as ander ensieme getoon.
In 'n volgende eksperiment is 'n groeiproef gedoen om die effektiwiteit van hierdie
ensiem in vivo te toets. In die proef is 32 Dohne Merino ramlammers op grond van
hul gewig in vier groepe van agt skape elk verdeel, en individueel gevoer. Die groepe
het verskillende toedieningsvlakke van die toetsensiem, toegedien tot die koringstrooi
komponent van 'n hoe-vesel dieet, ontvang. Toedieningsvlakke was 10, 5, of lml
ensiemkonsentraat/kg strooi. Elke groep se ensiemkonsentraat is verdun met die
toepaslike hoeveelheid water om 'n toedieningsvlak van 300ml ensiemoplossing/kg
koringstrooi te verkry. 'n Vierde groep is behandel slegs met water teen dieselfde
toedieningsvlak, en het gedien as 'n kontrole. Die eksperiment is oor 'n periode van 6
weke uitgevoer. Tydens die proeftydperk is voerinnames, weeklikse gewigstoenames,
sowel as voeromsetverhoudings, gedokumenteer. Resultate het betekenisvolle
gewigstoenames in die hoe (lOml/kg) en medium (5ml/kg) groepe opgelewer,
aangedui deur 'n P-waarde van 0.04. Voeromsetverhoudinge het ook verbeteringe
getoon vir bogenoemde twee groepe (P=0.05), terwyl voerinnames nie merkbaar
tussen die vier groepe verskil het nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50141 |
| Date | 12 1900 |
| Creators | Goosen, Liezel |
| Contributors | Cruywagen, C. W., Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xi, 91 leaves : ill. |
| Rights | Stellenbosch University |
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