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The evaluation of larvae of Musca Domestica (common house fly) as protein source for boiler productionPretorius, Quinton 03 1900 (has links)
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: The objective of this study was to evaluate the use of Musca domestica (common house fly) larvae meal, as
protein source, for broiler production. This was done by investigating the nutritive value of house fly larvae meal
together with its total tract digestibility, potential toxicity and carcass characteristics of the broilers supplemented
with house fly larvae meal. The proximate analysis of house fly larvae meal show that it contained, on a dry
matter basis, a gross energy value of 20.10 MJ/kg, 60.38% crude protein, 14.08% crude fat and 10.68% ash and
that the house fly pupae contained a gross energy of 20.42 MJ/kg, 76.23% crude protein, 14.39% crude fat and
7.73% ash. House fly pupae meal had the closest match of amino acid profile when compared with the ideal
amino acid profile required by broilers and it has arginine relative to the lysine content closer to the ideal amino
acid profile than the house fly larvae meal. The essential fatty acid, linoleic acid, was found at levels of 26.25
and 36.27% of the total fats for the house fly larvae and pupae meal respectively. House fly larvae meal
supplementation did not induce gizzard erosion or showed toxicity (regarding the gastro intestinal tract, immune
system and organ stress) in broilers.
Results revealed that house fly pupae meal had higher total tract digestibilities for most nutrients than of the
house fly larvae meal. House fly larvae meal had a crude protein total tract digestibility of 69% and that of pupae
meal was 79%. Both larvae and pupae meal had high amino acid total tract digestibilities of all the amino acids
analysed. The house fly larvae and pupae meal had an apparent metabolizable energy (AME) value of
14.23MJ/kg and 15.15MJ/kg respectively. The larvae meal total tract crude fat and crude fibre digestibilities
were 94% and 62% respectively. The pupae meal total tract crude fat and crude fibre digestibilities were 98%
and 58% respectively.
House fly larvae meal supplementation in a three phase feeding system significantly increased average broiler
live weights at slaughter, total feed intake, cumulative feed intake as well as average daily gain (ADG) when
compared to commercial maize: soya oil cake meal diet. In direct comparison of larvae inclusion levels with
fishmeal in isonitrogenous and isoenergetic diet, no significant differences were observed between a 10% house
fly larvae and a 10% fish meal diets regarding performance characteristic. The 25% house fly larvae meal diet
yielded significantly better average broiler live weights at slaughter, total feed intake, cumulative feed intake
(from the second week until slaughter) as well as average daily gain when compared to the 25% fish meal diet in
the growth phases.
Carcass characteristics of the 10% larvae, 10% fishmeal and commercial diets were compared. Chicks that
received either the 10% house fly larvae meal or 10% fish meal supplementation produced significantly heavier carcasses and breast muscle portions than the chicks that received the commercial maize: soya oil cake meal.
No treatment differences were found regarding breast and thigh muscle colour or pH.
This study showed that house fly larvae meal can be regarded as a safe protein source that can be used to
replace other protein sources and that has the ability to promote broiler performance without having any
detrimental effects on carcass characteristics. / AFRIKAANSE OPSOMMING: Die doel van die studie was om die effek van Musca domestica (gewone huisvlieg) larwe meel, as ‘n protein
bron, in braaikuikens te evalueer. Dit was gedoen deur die nutrient waarde van huisvlieg larwe meel saam met
die totale spysvertering verteerbaarheid, moontlike toksiesiteit en karkas-eienskappe van braai kuikens te
evalueer. Laboratoruim analiese toon dat huisvlieg larwe meel 20.10 MJ/kg bruto energie, 60.38% ru- protein,
14.08% ru- vet en 10.68% as bevat en huisvlieg papie meel 20.42 MJ/kg bruto energie, 76.23% ru- protein,
14.39% ru- vet en 7.73% as bevat. Huisvlieg papie meel stem die meeste ooreen met die idiale amino suur
profiel soos wat benodig word deur braaikuikens en dit het ‘n arginien tot lisien verhouding wat die meeste
ooreenstem met die idiale amino suur profiel in vergelyking met huis vlieg larwe meel. Die essensiele vet suur,
linolien suur, was geanaliseer teen vlakke van 26.25- en 36.27% van die totale vette onderskeidelik vir huisvlieg
larwe- en papie meel. Huisvlieg larwe meel vervanging het nie spiermaag erosie of enige ander toksiese effekte
te veroorsaak nie.
Resultate het getoon dat huisvlieg papie meel, in vergelyking met larwe meel, het ‘n hoër totale spysvertering
verteerbaarheid vir meeste van die nutrient. Die huisvlieg larwe meel het ‘n totale ru- protein spysvertering
verteerbaarheid van 69% en die van papie meel van 79%. Beide larwe en papie meel het hoë amino suur
spysvertering verteerbaarheid. Larwe meel en papie meel het skynbare metaboliseerbare energie waardes van
14.23MJ/kg en 15.15%MJ/kg onderskeidelik. Die larwe meel het ‘n ru-vet en ru- vesel spysvertering
verteerbaarheid van 94% en 62% onderskeidelik, waar die papies ‘n ru-vet en ru- vesel spysvertering
verteerbaarheid van onderskeidelik 98% en 58% het.
Huisvlieg larwe meel vervanging in ‘n drie fase voer stelsel het getoon om die gemiddelde braaikuiken lewende
gewigte by slag, totale voer iname, sowel as die gemiddelde daaglikse toename te verhoog waneer dit vergelyk
word met ‘n kommersiele mielie- soya olie koek dieet. Geen mekwaardige verskille was waargeneem toe die
10% larwe meel dieet direk met die 10% vismeel diet vergelyk was rakende enige produksie einskappe gemeet
nie. Die 25% larwe meel dieet het merkwaardig beter gemiddelde braaikuiken lewende gewigte by slag, totale
voer iname, sowel as die gemiddelde daaglikse toename getoon wanneer vergelyk word met die 25% vismeel
dieet gedurende die verskeie groei fases.
Karkas eienskappe van die 10% larwe meel, 10% vismeel en die kommersiele diete was gevergelyk. Kuikens
wat 10% larwe meel en 10% vismeel in die diete ontvang het, het swaarder karkasse gelewer met swaarder
borsie massas wanneer vergelyk word met die kommersiele mielie- soya olie koek dieet. Geen behandelings
verskille was gevind rakende die borsie- en dy spier kleure of pH nie. Die studie toon dat huisvlieg larwe meel as ‘n veillige protein bron kan beskou word, wat gebruik kan word om
ander protein bronne te vervang. Huisvlieg larwe meel het ook die vermoë om braaikuiken produksie te verhoog
sonder om enige negitiewe effekte rakende die karkas eienskappe te toon nie.
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Effect of exogenous fibrolytic enzymes on fibre and protein digestion in ruminant animalsUseni, Bilungi Alain 03 1900 (has links)
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Forages are the main feed components in ruminant production systems for the reason that they are often the major
source of energy available to the animal. However, only 10 to 35% of energy intake is available as net energy because
the digestion of plant cell walls is not complete. This can significantly affect livestock performance and profits in
production systems that use forages as a major source of nutrients of the diet. As a result of low and variable nutritive
values of forage feedstuffs, attempts to improve ruminal fibre degradability have been an ongoing research topic. The use
of exogenous fibrolytic enzymes (EFE) has been proposed as means to improve forage digestibility. Positive results with
regard to rumen forage digestibility and other animal production traits have consequently been obtained due to increased
rumen microbial activity following EFE addition in ruminant diets.
Two EFE (Abo 374 and EFE 2) and one commercial yeast preparation were firstly identified and selected for their
potential to improve the cumulative gas production (GP) at 24 hours of a range of feed substrates using the in vitro GP
system as a screening step to identify the superior EFE products. The different feed substrates were lucerne hay, wheat
straw, wheat straw treated with urea and a commercial concentrate diet. An in vitro experiment was undertaken on these
four different substrates in order to evaluate the two EFE and the yeast preparation. This was to identify the most
promising EFE capable of producing a significant effect on feed digestibility using organic matter digestibility (in vitro true
digestibility) and fermentation characteristics (in vitro GP system). Results from the in vitro evaluation showed that EFE
significantly enhanced in vitro DM degradability and GP profiles (P < 0.05). Abo 374 enzyme showed potential to increase
in vitro microbial protein synthesis (MPS) of GP residues of the concentrate diet. In addition, no correlation was found
between the in vitro MPS and the 48 hours cumulative GP of all the tested substrates (P < 0.05; R2 < 0.30). Treatments
were found to increase in vitro MPS, feed degradability and the cumulative GP of different quality forages and the
concentrate diet, with Abo 374 being the best treatment (P < 0.05). However in vitro responses of EFE were variable
depending on the energy concentration and chemical composition of different substrates. Variation in MPS was mostly
due to the low recovery of purine derivates with the purine laboratory analysis.
On the basis of these results, Abo 374 was selected and consequently further tested in another in vitro and in situ trial
using a mixed substrate of lucerne hay and wheat straw. Abo 374 significantly improved the cumulative GP, in vitro DM
and NDF disappearance of the mixed substrate (P < 0.05). In addition, no correlation was found between the in vitro MPS
and the cumulative GP at 48 hours (P = 0.68; R2 < 0.25). The in situ disappearance of feed nutrients (DM, NDF and CP)
with Abo 374 was similar to the control. The lack of significance of disappearance was probably due to the small number
of sheep used in the study and the relatively high coefficient of variation associated with measuring ruminal digestion. Abo 374 significantly increased the in situ MPS (P = 0.0088) of the mixed substrate of lucerne hay and wheat straw. Evidence
of the increased MPS and both in vitro and in situ disappearance of DM and NDF resulted from the Abo 374 activity
during either the pre-treatment or the digestion process. The addition of Abo 374 to the mixed substrate of lucerne hay
and wheat straw appeared to have been beneficial for microbial colonization of feed particles as a result of the increased
rumen activity. It could be speculated that the primary microbial colonization was thus initiated, leading to the release of
digestion products that attract in return additional bacteria to the site of digestion. This EFE may be efficient to produce
some beneficial depolymerisations of the surface structure of the plant material and the hydrolytic capacity of the rumen
to improve microbial attachment and the feed digestibility thereafter. Therefore, the mechanism of action by which Abo
374 improved the feed digestion can be attributed to the increased microbial attachment, stimulation of the rumen
microbial population and synergistic effects with hydrolases of ruminal micro-organisms. With regard to these findings, the
addition of EFE in ruminant systems can improve the ruminal digestion of DM, NDF and CP to subsequently enhance the
supply of the metabolizable protein to the small intestine.
Key words: crude protein (CP), exogenous fibrolytic enzymes (EFE), dry matter (DM), gas production (GP), neutral
detergent fibre (NDF), microbial protein synthesis (MPS). / AFRIKAANSE OPSOMMING: Ruvoere is die hoof-voerkomponent in herkouer produksiesisteme aangesien dit dikwels die vernaamstebron van energie
aan herkouer is. Slegs 10 tot 35% van die energie-inname is beskikbaar as netto-enrgie, omdat die vertering van
selwande onvolledig is. Dit kan die prestasie en profyt in produksiesisteme drasties beïnvloed waar ruvoere as ’n
hoofbron van nutriënte in die dieet gebruik word. Aangesien die nutriëntwaarde van ruvoere laag is en baie varieer, is
navorsing vir verbeterde ruminale veselvertering steeds ’n voorgesette onderwerp. Dit is voorgestel dat eksogeniese
fibrolitese ensieme (EFE) gebruik kan word vir verbeterde ruvoervertering. Positiewe resultate in ruminale ruvoerverterig
en ander diereproduksie-eienskappe, is verkry as gevolg van toenemende rumen mikrobiese aktiwiteit na EFE aanvulling
in herkouerdiëte.
Twee EFE’s (Abo 374 en EFE 2) en `n gisproduk is geïdentifiseer en geselekteer vir hul potensiaal om die kumulatiewe
gasproduksie (GP) na 24 uur met ’n reeks voersubstrate te verbeter met die gebruik van die in vitro GP sisteem as
seleksiemetode om die superieure EFE produkte te identifiseer. Die verskillende ruvoersubstrate was lusernhooi,
koringstrooi, ureumbehandelde koringstrooi en ’n kommersiële konsentraatdieet. ’n In vitro eksperiment was onderneem
om die vier verskillende substrate te gebruik om die twee EFE’s en gisproduk te evalueer. Hierdeur sou die belowendste
EFE’s identifiseer kon word wat ’n betekenisvolle effek op ruvoervertering het. Die vertering van ruvoer sal bepaal word
deur organiese materiaal vertering (in vitro ware vertering), asook fermentasie-eienskappe (in vitro GP sisteem).
Resultate van die in vitro evaluering het getoon dat EFE’s in vitro DM degradering en GP profiele verbeter. Dit blyk dat
die Abo 374 ensiem ’n potensiële toemame in in vitro mikrobiese proteïensintese (MPS), soos bepaal deur die GP
oorblyfsels van konsentraat diëte, tot gevolg gehad het. Daar was geen korrelasie tussen die in vitro GP en MPS van al
die proefsubstrate nie. Dit blyk dat die behandelings ’n toename in in vitro GP, MPS en ruvoerdegradeerbaarheid van lae
kwaliteit ruvoer- en konsentraatdiëte gehad het, waar Abo 374 die beste behandeling was. Die in vitro reaksies van die
EFE’s was egter wisselend, afhangende van die energiekonsentrasie en die chemiese samestelling van die verskillende
substrate. Variasie van MPS was meestal as gevolg van die lae herwinning van purienderivate tydens die purienanalise.
Op grond van dié resultate, is Abo 374 geselekteer om verdere toetse in ander in vitro en in situ proewe te doen. Die
substraat wat gebruik is, was ’n 1:1 mengsel van lusernhooi en koringstrooi. Abo 374 het die kumulatiewe RP, in vitro DM
en NBV verdwyning van die gemengde substraat verbeter. Boonop is geen korrelasie tussen die MPS en in vitro GP
gevind nie. In situ verdwyning van DM, NBV en RP was hoër vir Abo 374, maar nie betekenisvol nie. Die gebrek aan
betekenisvolle verdwynings mag die gevolg wees van die klein hoeveelheid skape wat in die proef gebruik is, asook die
relatiewe hoë koëffisient van variasie wat gepaard gaan met die bepaling van ruminale vertering. Abo 374 het die in situ MPS betekenisvol verhoog. Verhoogde MPS en in vitro en in situ verdwyning van DM en NBV is waargeneemwaarskynlik
as gevolg van die aktiwiteit van Abo 374 gedurende die voorafbehandeling óf die verterings proses. Die byvoeging van
Abo 374 tot die gemengde substraat van lusernhooi en koringstrooi blyk om voordelig te wees vir mikrobiese kolonisering
van voerpartikels as gevolg van ’n toename in rumenaktiwiteit. Die primêre mikrobiese kolonisering het waaarskynlik gelei
tot die vrystelling van verteringsprodukte wat addisionele bakterieë na die plek van vertering lok. Die EFE mag geskik
wees vir voordelige depolimerisasie op die oppervlakstruktuur van die plantmateriaal, asook verbeterde hidrolitiese
kapasiteit van die rumen om sodoende mikrobiese aanhegting, asook ruvoervertering te verbeter. Dus, Abo 374 se
meganisme van aksie wat verbeterde ruvoervertering tot gevolg het, kan toegeskryf word aan `n verhoogde mikrobiese
aanhegting, stimulering van die rumen mikrobiese populasie en die sinergistiese effek met hidrolases van rumen
mikroörganismes. Ten opsigte van die bevindings, kan die byvoeging van EFE in herkouersisteme ruminale vertering van
DM, NBV en RP verbeter, wat dan daaropvolgend die dunderm met meer metaboliseerbare proteïn sal voorsien.
Sleutelwoorde: eksogene fibrolitiese ensieme (EFE), droëmaterial (DM), ruproteïen (RP), neutraal bestande vesel (NBV),
mikrobiese proteïensintese (MPS), gasproduksie (GP).
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The effect of transport on live weight loss, meat quality and blood haematology in slaughter ostrichesWolmarans, Wilhelm J. 03 1900 (has links)
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The production and export of ostrich meat from southern Africa, to especially the European Union, are
increasing rapidly due to the healthy nature of ostrich meat. The European Union has very high standards
when importing food products, and it is inevitable that more emphasis is being placed on the production of
high quality ostrich meat. Another aspect also of concern to consumers, is the welfare of animals prior to
slaughter, and this forces producers to look at ways to decrease stress of animals during the ante-mortem
period. Research regarding the effect of stress during the ante-mortem period, and as a result, on meat
quality, haematology and weight loss in ostriches, is lacking and thus the purpose of this study was to
investigate the effect of various transport distances, travel conditions and different birds on these factors.
Ante-mortem stress was measured using serum corticosterone levels (ng/ml), heterophil: lymphocyte (H:L)
ratio, white blood cell (WBC) count, aspartate aminotransferase (AST) and creatine kinase (CK), as well as
the rate and extent of pH decline in the M. gastrocnemius. Special emphasis was also placed on the meat
quality parameters drip loss, cooking loss, colour and Warner-Bratzler shear force (kg/1.27 cm diameter).
Live weight losses, as well as carcass weight and weight of bruises cut off from each bird were also recorded
during various stages of the trials.
The effect of transport distance on the meat quality of ostriches was investigated. Ultimate pHu
measurements were taken at 24 hours post-mortem. The muscles of the ostriches from the control group
(i.e. birds that were not transported prior to slaughter) had a lower mean pHu (5.77 ± 0.053) than birds that
travelled 60 (5.93 ± 0.053) and 600 km (6.11 ± 0.053), respectively. Differences in meat drip loss percentage
were also observed between the three treatments. The birds in the control group (0.40 ± 0.07 %) had the
lowest meat drip loss percentage compared to the birds that travelled 60 km (treatment C) (1.36 ± 0.07 %)
and 600 km (treatment B) (0.97 ± 0.07 %), respectively, to a commcerical ostrich abattoir. Ostriches that
were transported for 600 km (8.13 ± 1.16 %) had a greater percentage live weight loss during the antemortem period than birds that travelled a distance of 60 km (2.4 ± 2.185 %) to the abattoir, although both
groups were deprived of feed for the same period. When the haematology of the groups that travelled
different distances was compared at various time intervals in the ante-mortem period, both groups of birds
experienced significant increases in WBC, s-AST and s-CK. An increased H:L ratio from pre-transport to
post-transport was only evident in the birds that travelled 600 km (treatment B). However, the birds that
travelled 60 km were the only group of birds that had significant elevated serum corticosterone levels during
the ante-mortem period. The increase in the various blood parameters indicates severe physical stress,
which negatively affected meat quality.
Another trial also investigated the effect of various farming systems and transport on meat quality and
bruising of ostrich carcasses. Ostriches were raised in three different farming systems, i.e. feedlot -, semiintensive - and free range conditions. Other factors that could maybe impact on stress susceptibility, such as
road conditions, floorspace and floor type were also investigated. A significant difference in meat pHu was
found between ostriches that were raised in a feedlot (5.95 ± 0.018) and semi-intensive (6.04 ± 0.033) environment. The feedlot birds also had the greatest percentage of carcass weight removed due to bruising.
The free range birds were the birds that had the lowest floor density per birds and also had the least amount
of bruising on their carcasses. Incidently the other two groups (feedlot and semi intensive) were the birds
that travelled on the same type of road (mountain pass) in a truck with rubber flooring whilst the free range
birds travelled on a straight road in trucks with metal grid floors.The results indicate that the type of farming
system didn’t have a significant influence on meat quality of ostriches, but that factors such as road
conditions, flooring and bird density did play a significant role in the incidence of bruises and injuries
obtained during transport. / AFRIKAANSE OPSOMMING: Die produksie en uitvoer van volstruisvleis vanuit suidelike Afrika, na veral die Europese Unie, is gedurig aan
die toeneem as gevolg van die gesonde aard van volstruisvleis. Die Europese Unie het baie hoë standaarde
wanneer dit kom by die invoer van voedselprodukte en dit is onvermydelik dat meer klem op die produksie
van hoë gehalte volstruisvleis gelê word. ʼn Ander aspek wat ook kommer wek by verbruikers is die welstand
van diere voor slagting en hierdie aspek noodsaak produsente om te kyk na maniere om stres te beperk
tydens die periode voor slagting. Navorsing rakende die effek van stres tydens die ante-mortem periode,
asook vleiskwaliteit, hematologie en gewigsverlies in volstruise as gevolg van vervoer, ontbreek. Die doel
van die studie was dus om die invloed van verskillende vervoerafstande, vervoersomstandighede en tipe
produksiesisteme op volstruise se stresrespons te ondersoek. Die omvang van ante-mortem stres is bepaal
deur die serum-kortikosteroon vlakke (ng/ml), heterofiel: limfosiet (H:L) ratio, witbloedsel (WBS) telling,
aspartaat aminotransferase AST en creatien kinase CK, asook die tempo en vlak van pH-daling in die M.
gastrocnemius, te meet. Spesiale klem is gelê op die vleisgehalte parameters kookverlies, drupverlies, kleur
en Warner-Bratzler-skeurwaardes (kg/1.27 cm deursnee). Gewigsverlies is aangeteken op verskillende
stadiums tydens die proewe. Karkasgewigte en die hoeveelheid gewig afgesny van elke volstruiskarkas
a.g.v. kneusings is ook bepaal.
Die eerste studie het die invloed van vervoerafstand op vleiskwaliteit van slagvolstruise ondersoek. Vleis
kwaliteit parameters soos pH, drip verlies, kook verlies, taaiheid en kleur is ondersoek. Die pHu metings is op
24 uur post-mortem geneem. Slagvolstruise in die kontrole groep (d.i. -volstruise wat nie voor slagting
vervoer is nie) het ’n laer vleis pHu (5.77 ± 0.05) gehad as voëls wat onderskeidelik 60 km (5.93 ± 0.05) en
600 km (6.11 ± 0.05) ver vervoer is. Verskille in persentasie dripverlies is gesien tussen die vleis van die
voëls wat nie vervoer is nie (0.40 ± 0.07 %) en die voëls wat 60 km (1.36 ± 0.07 %) en 600 km ver (0.97 ±
0.07 %) onderskeidelik vervoer is. Volstruise wat vir 600 km (8.13 ± 1.16 %) vervoer is, het ‘n groter
persentasie lewende gewig tydens die ante-mortem periode as voëls wat 60 km (2.4 ± 2.19 %) ver vervoer is
na die abattoir, verloor, al was beide groepe weerhou van voer vir dieselfde tydperk. Beide groepe wat
vervoer is (60 en 600 km) het merkbare toenames in witbloedsel (WBS) tellings, s-AST’s en s-CK’s getoon
tydens die ante-mortem periode. Daar is slegs ʼn toename in H:L ratio (ʼn indikator van stres) van voor
vervoer tot na vervoer gesien in die voëls wat 600 km vervoer is. Daarteenoor was die voëls wat slegs 60 km
vervoer is die enigste voëls wat ʼn toename in korticosteroon vlakke getoon het gedurende die ante-mortem
periode. Die toenames is heel moontlik ‘n aanduiding van erge fisiese stres wat ‘n negatiewe effek op
vleiskwaliteit het.
Die tweede studie het die effek van verskillende produksiesisteme en die stress respons van die verskillende
groepe slagvolstuise op vervoer ondersoek. Vleis kwaliteit parameters soos pH, drip verlies, kook verlies en
taaiheid is ondersoek. Die hoeveelheid kneusings per volstruis is ook gemeet. Daar was ‘n beduidende
verskil (P = 0.009) tussen die pHu van die voerkraal (5.95 ± 0.018) en semi- intensiewe (6.04 ± 0.033) volstruise. Die voerkraal volstruise se vleis het die grootste drip- en kookverliese gehad in vergelyking met
die ander twee groepe (semi-intensiewe en ekstensiewe) terwyl die ekstensiewe volstruise die taaiste vleis
gehad het. Die voerkraalvoëls het ook die grootste persentasie karkasgewig verloor a.g.v. kneusings wat
afgesny is. Die ekstensiewe voëls het die laagste vloer digtheid per volstruis gehad asook die minste
kneusings. Die ander twee groepe (voerkraal en semi intensief) was die groepe wat op dieselfde pad vervoer
is (bergpas) in vragmotors wat rubber vloere gehad het terwyl die ekstensiewe voêls op ‘n reguit pad vervoer
is in ‘n vragmotor met ‘n metaal oppervlakte. Die resultate van die studie is ‘n aanduiding dat die tipe
plaassisteem nie ‘n groot impak op die hoeveelheid akute stres ervaar deur die voëls tydens vervoer gehad
het of gevolglik op die vleiskwaliteit van die volstruise nie, maar dat faktore soos pad toestand, tipe vloer en
voëldigtheid wel ‘n wesenlike rol speel in die voorkoms van kneusings en beserings opgedoen tydens
vervoer.
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Fibrolytic enzymes in ruminant nutrition and their effect on forage cell wall integrityVan de Vyver, Wilhelmus Francois Joubert 03 1900 (has links)
Thesis (PhD(Agric))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Exogenous fibrolytic enzymes (EFE) as additives in ruminant feeds are being researched
worldwide. Promising effects on dry matter intake (DMI), digestibility and production in
especially dairy cows, but also feedlot steers and even sheep have been observed.
However, lack of or negative effects are also reported and the need arises for clarity on the
mode-of-action of EFE. Forages are characterised as being highly heterogenic and contain
varying concentrations of fibre. The fibre, in turn, varies greatly in digestibility, due to the
chemical as well as anatomical build-up of this complex carbohydrate. Fibre, however,
presents a major source of potential energy for ruminant animals and EFE is a viable option
to increase the digestibility of forages. Therefore, a study with the aim of establishing
whether EFE can affect the digestibility of forages, how it affects the digestibility and the
clarification of the mode-of-action was drafted. From the literature, the first objective was
readily attained and clear indications exist that EFE can indeed improve animal performance
when their diets are treated with such enzymes. From the current study, it was shown that
EFE can alter the rate and extent of gas production of certain forages (lucerne, kikuyu and
weeping love grass) and also improve the in vitro digestibility thereof (P < 0.05). This is in
agreement with other research findings and it was concluded that these effects were likely
exerted during the early stages of digestion. A complete feed for sheep, when treated with
the EFE, showed positive effects on the in sacco digestibility, as well as on the digestion
kinetics of the feed (P < 0.05). The in vitro digestibility of the complete feed was also
improved due to EFE treatment (P < 0.05). The observations on in vitro digestibility were
less marked when a purified xylanase, obtained from the partial purification of the EFE
cocktail, was used as the sole fibrolytic enzyme treatment. It is apparent, therefore, that
enzyme specificity plays a major role in obtaining positive effects on digestibility of forages and feeds. In agreement with the literature, it is proposed that the approach to improve the
digestibility of forages should be to use EFE cocktails containing various enzymes, matching
the complexity of the substrate. The major aim of the study was, however, an in depth
investigation of the mode-of-action of EFE. This aim was approached by observing changes
in plant tissue material at the histological level upon treatment with EFE and incubation in
buffered rumen fluid. Results showed that EFE had subtle, yet significant effects on cell wall
material for the various tissues studied (P < 0.05). The major effect observed here was that
EFE had a thinning effect on the cell wall thickness (P < 0.05). It was deduced that as EFE
affected the cell wall of the plant material, earlier access by microorganisms could be
achieved. Also, nutrients caught in the cell wall matrix could then be released for digestion.
Therefore, observations that EFE increases the rate of digestion, as well as the extent of
digestion of not only fibre, but also protein, were explained by the enzyme’s action on cell
wall material. It was concluded that there is definite merit in the use of EFE to improve the
digestibility of ruminant feeds and that this is partly related to effects on the cell walls of the
forages. The effects can be expected to occur during the early stages of digestion, thereby
potentially increasing the passage rate of digesta from the rumen. Additionally, the effect of
the EFE is not limited to fibre and increased digestibility of all nutrients can be expected,
thereby increasing the overall digestibility of the feed. Future research should further
elucidate the mode-of-action of EFE using advanced technologies routinely employed in the
plant sciences. Additionally, the main potential advantage of EFE treatment lies in improving
the digestibility of poor quality roughages. Unfortunately, this is an area where limited
positive effects are observed and in depth investigations should be undertaken to classify
the specificity and optimum conditions of EFE to better match the complexity of the substrate
being treated. / AFRIKAANSE OPSOMMING: Eksogene fibrolitiese ensieme (EFE) word tans wêreldwyd ondersoek vir die gebruik
daarvan as voerbymiddels vir herkouers. Belowende effekte op DMI, verteerbaarheid en
produksie van vernaam melkbeeste, maar ook voerkraalbeeste en selfs skape is al
gerapporteer. Swak en selfs negatiewe effekte word egter ook waargeneem en daarom is ʼn
deeglike ondersoek na die metode van werking van EFE van belang. Ruvoere word
gekenmerk deurdat dit heterogeen van aard is en bevat variërende vlakke van vesel. Vesel
maak op sy beurt ʼn wesenlike deel uit van die ruvoer, maar varieer baie in verteerbaarheid
weens die chemiese sowel as anatomiese samestelling van hierdie komplekse koolhidraat.
Ruvoer verteenwoordig egter ʼn goeie bron van potensiële energie vir herkouers en EFE
word voorgestel as ʼn haalbare behandeling om die verteerbaarheid daarvan te verhoog.
Dus is ʼn studie beplan met die doelwit om die effekte van EFE te definieer, hoe dit
verteerbaarheid beïnvloed en die metode van werking daarvan te ondersoek. Vanuit die
literatuur is dit duidelik dat daar wel baie positiewe effekte is waar ruvoere met EFE
behandel is en dat diereproduksie wel bevoordeel word daardeur. Vanuit die studie is dit
getoon dat die tempo en hoeveelheid gasproduksie van sekere ruvoere (lusern, kikuyu en
oulandsgras) verbeter word deur EFE behandeling (P < 0.05). Hierdie bevinding was
ondersteun deur verbeterde in vitro verteerbaarheid van die ruvoere (P < 0.05). Dit is in
ooreenstemming met literatuur en die gevolgtrekking is gemaak dat hierdie effekte tydens
die vroeëre stadia van vertering verwag kan word. ʼn Volledige skaapvoer wat met EFE
behandel is, het positiewe effekte op in sacco verteerbaarheid en verterings kinetika data
gehad (P < 0.05). Weereens is die in vitro verteerbaarheid van die voer verbeter (P < 0.05).
Waarnemings op in vitro verteerbaarheid was veel minder opvallend wanneer ʼn gesuiwerde
xylanase as enigste fibrolitiese ensiem behandeling gebruik is. Dit is dus duidelik dat ensiem spesifisiteit ʼn belangrike rol speel in die verkryging van positiewe resultate in die
verteerbaarheid van ruvoere en veevoere. In ooreenstemming met literatuur word dit
voorgestel dat ensiemmengsels wat verskeie ensieme bevat as EFE gebruik behoort te word
ten einde aan die kompleksiteit van die substraat te voldoen. Die hoof doelwit van die studie
was egter ʼn indiepte ondersoek na die metode van werking van EFE. Hierdie doelwit is
benader deur die effekte van EFE op selwand strukture van plantmateriaal op ʼn histologiese
vlak te ondersoek. Die ruvoere was vooraf met EFE behandel en in vitro geïnkubeer in
rumen vloeistof. Die resultate het getoon dat EFE ʼn matige, dog betekenisvolle effek op die
selwand materiaal van die onderskeie weefsels gehad het (P < 0.05). Die belangrikste
waargeneemde effek was dat EFE ʼn verdunningseffek op die selwande gehad het. Dit is
afgelei dat as EFE die selwand kan beïnvloed, mikro-organismes vroeër toegang tot die
inhoud kan kry. Verder, nutriënte vasgevang in die selwand matriks raak ook beskikbaar vir
vertering. Hierdie afleiding en die effek van EFE op selwande verklaar waarnemings dat
EFE die tempo van vertering sowel as die vlak van vertering van nie net vesel, maar ook
proteïen kan bevoordeel. Die gevolgtrekking is gemaak dat daar definitiewe meriete is in die
gebruik van EFE om die verteerbaarheid van herkouervoere te verbeter en dat dit verband
hou met die ensiem se werking op selwande van die ruvoere. Die effekte kan verwag word
tydens die vroeë stadia van vertering om dus deurvloeitempo van digesta te verbeter. Die
effek van die EFE is verder nie beperk tot vesel nie, maar positiewe effekte op ander
nutriënte kan verwag word en vervolgens ʼn algehele verhoging in die verteerbaarheid van
die voer. Navorsing behoort in die toekoms verder die metode van werking van EFE te
ondersoek deur gebruik te maak van gevorderde tegnologie wat alledaags gebruik word in
die Plantwetenskappe. Die belowendste aanwending van EFE lê in die verbetering in
vertering van swak kwaliteit ruvoere. Dit is ongelukkig juis hier waar min positiewe resultate
gerapporteer word en indiepte navorsing moet onderneem word om ensiem spesifisiteit en
optimum kondisies te definieer sodat EFE beter opgewasse is teen die kompleksiteit van die
substraat.
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Studies on the hatching, growth and energy metabolism of ostrich chicks : Struthio Camelus var. DomesticusSwart, Derick 03 1900 (has links)
Thesis (PhD(Agric) Animal Sciences))--University of Stellenbosch, 1988. / Farming with ostriches became established as a new stock-farming activity in South Africa around 1863. Ostrich feathers were then the only commercial product of that activity and fifty years later still held fourth place on the list of exports from South Africa - after gold, diamonds and wool (Smit, 1963). However during the world depression of 1914 - 1945 the appeal of ostrich feathers vanished and the industry collapsed.
Today commercial farming with domesticated ostriches (Struthi0 camelus var. domesticus), originating from a cross (Duerden, 1910; Smit, 1963, 1984) between the South African (Struthio camelus australis) and the North African ostriches (Struthio camelus camel us), is again a rapidly expanding activity in South Africa's Little Karoo. This is the only region in the world where farming with ostriches is still encountered at a commercial scale, and although relatively small in the general stock-farming scenario, it provides a livelihood for about 400 farmers who run some 150 000 ostriches. Feathers, together with ostrich leather and meat are all prominent export products that account for foreign exchange earnings of more than R30 million.
In terms of monetary value the ostrich industry has grown by more than 300% over the past decade and by al most 100% in the 1ast 5 years. This high growth rate is primarily due to the steady development of the slaughter bird industry in which leather, meat and feathers account for more than 80% of the entire industry's turnover. Ostrich products, however, are primarily exclusive fashion products, of which more than 90% is exported. Because the world market is relatively small, expansion prospects for the industry are limited and sensitive to supply and demand.
To ensure the industry's continued economic well-being, ostrich research pays particular attention to production techniques that will help to improve efficiency and result in better product quality and profitability.
For the purpose of increased ostrich chick production, ostrich eggs are presently being incubated in large quantities (ca 200 000 eggs per annum). However, hatching success of ostrich eggs in incubators is considerably below that of natural nests, and Burger & Bertram (1981) suggested that it may be due to high humidities (63% relative humidity) commonly used in ostrich incubators.
Investigations were undertaken to measure incubation temperatures and humidities during the complete course of 41 days of natural incubation in 6 ostrich nests. In addition, the water vapor conductance of the eggs was measured, as well as the incubation water loss which in other species averages 15% of the initial egg mass and has been proposed as an optimal condition for hatching success (Ar & Rahn, 1978; Rahn 1984).
The natural incubation parameters measured during these experiments were adapted and applied to conditions of artificial incubation. This improved the realized hatchability from 50 to 75%.
Furthermore the intensive production and finishing of slaughter birds on complete dry meal diets under feedlot conditions is a new development which contains exceptional possibilities for the industry (Swart & Kemm, 1985). Economically and biologically, efficient diet formulation has accordingly become essential for profitable slaughter bird production. The nutritional value of feed constituents for ostriches is, however, still unknown and without it effective least cost diet formulation and programming is not possible. Present growth and finishing diets for ostriches are based on energy values of the dietary components which have been derived from poultry (Blair, Daghir, Morimoto, Peter & Taylor, 1983; Du Preez, Duckitt & Paulse, 1986) and pig values (Kemm & Ras, 1981; NRC, 1973; IAFMM, 1985). This approach may, however, result in unreal estimation of the actual nutritional value of feed constituents for ostriches, so that quantification of their nutritional value has consequently become necessary.
During 1985 a multi-disciplinary research programme on ostriches was initiated, the objective being to investigate the energy metabolism and the efficiency of energy utilization in growing farm ostriches. For the purpose of these experiments all ostrich chicks were incubated in an ostrich egg incubator, maintained at a dry bulb temperature of 36°C and a wet bulb temperature of 24,0 ± 1,0°C. These temperature settings were extrapolated from the natural incubation parameters measured in the six naturally incubated nests (Swart, Rahn & De Kock, 1987; Swart & Rahn, 1987).
An important aspect of the studies on energy metabolism was to determine the extent to which plant fibre is digested in various segments of the gastrointestinal tract of growing ostriches and whether these birds utilize the end products of fibre digestion, namely volatile fatty acids such as acetic acid, efficiently.
The possible use of metabolizable energy to evaluate feedstuffs for ostriches was an initial aim of this study. Subsequently the effect of crude fibre or energy concentration on the digestibility of gross energy, energy loss as methane, heat expenditure, and the effect on the efficiency of ME utilization were investigated. Finally accretion patterns and the partition of metabolizable energy during growth were studied in the young ostrich chick.
The findings of the studies on incubation aspects (Section 1) are presented in Chapter 2 and 3 and that of the metabolism studies (Section 2) are presented in Chapters 4, 5, 6, 7 and 8 of this dissertation.
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Genetic parameter estimation and breeding plans for the South African dairy goat herdMuller, C. J. C. 03 1900 (has links)
Thesis (PhD (Animal Sciences))--University of Stellenbosch, 2005. / Milk production records of all grade and registered Saanen dairy goats from the Milk
Recording and Performance Testing Scheme of the Animal Improvement Institute of
the Agricultural Research Council of South Africa and pedigree information of these
animals from SA Studbook were analyzed to obtain specific genetic parameters.
Records of goats with lactations exceeding 60 days in milk were used. A sufficient
number of records only became available from 1985 onwards. Reproduction records
were determined from milk recording data. The number of milk production records
for the British Alpine and Toggenburg breeds was too small to warrant a genetic
evaluation. In total, 3190 lactation records of 1413 Saanen does were available for the
initial analysis. First and second parity records, 1190 and 775 records, respectively,
were subjected to a separate genetic analysis. Milk production records (2319) of one
commercial herd providing more than 70% of all the records in the national herd,
were also subjected to a separate genetic analysis.
The fixed effects identified as having a significant (P<0.05) effect on all traits studied
were production year, age of dam, lactation length, parity number, herds (owners) and
year of birth. Although some significant interactions were found, they were ignored as
their effects were very small. Additive genetic variances and heritability estimates were obtained by ASREML
procedures fitting three models. Estimates were generally in accordance with values
found in the literature although estimates for fat and protein percentage were lower
than expected when compared to dairy cow data. This could be explained by pedigree
information lacking in the data set. The h2 estimate for milk yield using all records,
first parity records, second parity records and records from a commercial herd were
0.21±0.05, 0.32±0.08, 0.20±0.10 and 0.31±0.06, respectively. Heritability estimates
for fat percentage showed a large variation and were 0.19±0.05, 0.67±0.08, 0.34±0.12
and 0.12±0.05, respectively for similar data sets as previously mentioned. In contrast
to this protein percentage varied little between data sets and were 0.30±0.06,
0.32±0.00, 0.24±0.11 and 0.28±0.07, respectively.
Genetic and phenotypic correlations among production traits were positive and high
for all data sets. As for dairy cows, milk fat and protein percentages were negatively
related to milk yield. Genetic correlations between milk fat and protein percentages
were positive and moderate to high. Increasing milk volume would have a negative
effect on fat and protein percentages although it would increase fat and protein yields.
Reproduction parameters, i.e. age at first kidding (AFK), age at last kidding (ALK),
productive life (PL) and number of lactations (NL) were derived from milk recording
data. Mean values for these parameters were 457±171 days, 1046±718 days,
19.3±13.9 months and 2.24±1.37 kiddings, respectively. Kidding interval had no
genetic basis and is controlled by management. Heritability estimates were in
accordance with literature values and were 0.25±0.04, 0.28±0.04, 0.08±0.04 and
0.05±0.03 for AFK, ALK, PL and NL, respectively. The genetic correlation between
AFK and ALK was as expected positive and high, i.e. 0.61±0.10, although the
correlation between AFK and PL was negative indicating similar to dairy cows that
PL is shortened by a later AFK.
The genetic trend for milk, fat and protein yield were positive, although it did not
differ from zero. Large variations were observed between years (R2 <0.13). Genetic
trends for fat and protein percentages were positive and negative (P<0.05),
respectively. These trends are in contrast to trends observed in other countries such as France, The Netherlands and the USA where positive trends were generally observed.
This may indicate a higher selection emphasis on milk yield parameters or more
complete data sets in terms of pedigree information.
The dairy goat industry in South Africa should address some of the problems that
were encountered in the analysis of the data. These include factors such as a large
number of small herds, many short lactations, a large number of animals lacking
production data linked to pedigree information, incomplete pedigrees, few does that
have completed three or more lactations, little genetic ties between herds and a small
number of progeny for bucks. Some organizational and logistic issues concerning
pedigree and milk recording need to be addressed by the South African Milch Goat
Society to enable the accurate estimation of the genetic merit of animals in the
national herd.
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Essential amino acid requirements for growth in woolled sheepNolte, Joubert van Eeden 03 1900 (has links)
Thesis (PhD(Agric) (Animal Sciences))--University of Stellenbosch, 2006. / This project consisted of five studies. The objectives were to determine the essential
amino acid (AA) requirements of growing woolled lambs (Merino and Dohne Merino)
and the essential AA profile of duodenal digesta pre-dominantly derived from microbial
protein. The limiting essential AA`s in high rumen degradable protein (RDP) diets to
growing lambs, where microbial protein is the primary source of AA`s, were also
identified.
The first study determined the essential AA profile of duodenal protein on a high rumen
degradable diet and evaluated the impact of dietary RDP concentration and source [true
RDP vs. non-protein nitrogen (NPN)] on the AA composition of supplied in the
duodenum. The first trial in this study evaluated the effects of increasing true RDP levels
on the essential AA composition of duodenal protein primarily derived from rumen
microbes. The lambs had free access to wheat straw and fresh water. The daily RDP
supplements were administered in two equal doses into the rumens through rumen
cannulas at 07:00 and 19:00. Duodenal digesta was extracted with 6h intervals through
T-type cannulas, inserted proximally to the common bile duct. Sampling time was
advanced 2h every day to obtain duodenal samples on every even hour of a 24h period
after three days. As expected, deficient RDP limited the supply of essential AA`s in the iv
duodenum. When the true RDP supplements increased, the duodenal flow of essential
AA`s also increased concomitantly, but appeared to level off at the higher RDP levels.
Despite the positive quantitative effects of true RDP supplementation on AA supply to the
duodenum, the AA profile in the duodenum was unaltered. Consequently, the essential
AA profile of duodenal protein of sheep receiving high RDP diets, where microbial
protein is the primary source of AA`s in the duodenum, is relatively constant and
insensitive to dietary RDP concentration.
In the second trial the effects of RDP source (true RDP vs. NPN) on the essential AA
profile of duodenal protein on high RDP diets were evaluated by substituting increasing
amounts of urea for true RDP in isonitrogenous teatments. Higher NPN increments
reduced the daily supply of essential AA`s in the duodenum. In corroboration of the first
trial, the AA profile of the duodenal protein was very constant, irrespective of the RDP
source. Since microbial protein is the major source of duodenal AA`s on high RDP diets,
this study supports the view that microbial protein has a relatively constant AA profile,
but microbial protein yield varies according to several rate limiting factors in the rumen.
A constant microbial AA profile allows accurate estimates of microbial essential AA
supply in the small intestine if microbial protein production and fluid and particulate
outflow rates from the rumen can be accurately predicted. This allows the development
of more accurate undegradable protein (UDP) supplementation strategies, based on the
essential AA requirements of animals.
In the second study growing male Merino and Dohne Merino lambs were slaughtered at
different weights and body condition scores. The digesta was removed from the stomachs
and intestines and every organ or body part were weighed to determine the whole empty
body (WEB) composition. The WEB was partitioned into the carcass, internall offal
(stomachs, intestines, organs and blood) and external offal (head, feet, skin and wool).
No differences were apparent in the proportional weight distribution of similar body
components of the same breed at different ages. In a comparison between breeds, the
proportional weight contributions of the carcasses from both breeds to the WEB weight
were remarkably similar at both slaughtering stages. The Dohne Merino lambs had
proportionally larger internal offals and smaller external offals than the Merino lambs at
both slaughters. Unless the essential amino acid compositions of the internal and external
offals were identical to the carcass, the dissimilarities in weight and protein allocation to these two components within the WEB`s of Merino and Dohne Merino lambs imply a
distinct WEB essential AA composition for each breed.
The apparent digestibilities of dry matter (DM), crude protein (CP), energy, acid
detergent fibre (ADF), neutral detergent fibre (NDF), fat and ash did not differ between
Merino and Dohne Merino lambs. Energy retention was also similar for the two breeds,
but the Merino lambs retained considerably more N than the Dohne Merino lambs. This
may also impact on the respective amino acid requirements of the lambs. Since the
Merino lambs utilise N more efficiently, they may have potentially lower essential amino
acid requirements to achieve a similar growth rate.
The WEB essential AA compositions of growing Merino and Dohne Merino lambs were
determined in the third study. Based on the ideal protein concept, the WEB essential AA
profile was accepted as representative of the AA requirements for growth. The use of a
single body part as a representation of the WEB AA profile was also evaluated.
Differences in the proportional weight and protein contribution of the three body
components (carcass, internal offal and external offal) of the two breeds strongly
suggested that the WEB AA composition of the breeds would differ, because of likely
differences in the AA profiles of these components. The essential AA profiles of the
carcasses from the two breeds were surprisingly similar. However, the essential AA
compositions of the internal offal and external offal differed substantially from each
other, as well as from the carcass. In addition, the internal offal and external offals of
each breed had characteristic essential AA profiles. Inevitably, the WEB essential AA
profiles of Merino and Dohne Merino lambs differed considerably. Only the leucine and
phenylalanine concentrations in the WEB`s of Merino and Dohne Merino lambs did not
differ. Significant differences in the concentrations of eight essential AA`s implied that
the two breeds have different AA requirements for growth. The different AA
compositions of the internal and external offal within each breed also illustrated that the
use of a single body component, like the carcass, as a predictor of WEB essential AA
composition contains considerable inaccuracies.
The essential AA index indicated that the duodenal protein, primarily derived from rumen
microbes, provided approximately 81 % of the qualitative AA requirements of growing
lambs. During periods of sufficient availability of very low-quality forage, as the diet in this study simulated, microbial protein is not able to support maximum growth. The first
two limiting AA`s (histidine and methionine) could not even support daily growth rates of
100 g/d. This is very low and stresses the need for effective undegradable AA
supplementation under these conditions.
Chemical scores identified histidine as the first limiting AA in high RDP diets
(predominantly microbial protein), followed by methionine, leucine, arginine and
phenylalanine. However, the requirements for histidine and arginine are frequently over
estimated and these AA`s should actually be considered semi-essential, which could
render methionine, leucine and phenylalanine the first three limiting AA`s to growing
lambs receiving high RDP diets. Because of the limitations of static measurement
systems for the determination of AA requirements, a more comprehensive evaluation
method was introduced for determination of the limiting AA`s in duodenal protein of
lambs on high RDP diets, in the fourth study.
The fourth study focused on the identification of limiting AA`s to growing lambs being
limit-fed a high RDP diet. The diet consisted primarily of soybean hulls, for its’ low
rumen UDP content. Microbial protein production was calculated as 13 % of total
digestible nutrient intake and complementary AA supplements prepared to simulate the
WEB AA profile, determined in the previous study, in the small intestine. To eliminate
the influence of the rumen on the AA supplements, the latter were infused into the
abomasums via flexible tubing. Each essential AA was in turn removed from the control
treatment (simulating the WEB composition) and the effect on N retention measured.
When methionine or the branched-chain amino acids (BCAA`s) were removed from the
infusate, N retention of the lambs was reduced. Consequently, methionine and at least
one of the BCAA`s limited growth performance of young lambs when microbial protein
was the predominant source of AA`s.
The concomitant increased plasma concentrations of total AA`s when methionine or the
BCAA`s were removed from the infusate corroborates the effects on N retention, since it
indicates that AA utilisation was reduced when these AA imbalances were introduced.
Amino acid imbalances had no effect on apparent DM, organic matter (OM) or NDF
digestion, but N digestibility was reduced. The final study verified whether the BCAA’s were co-limiting the growth of lambs, or if
any single BCAA was responsible for the limitation. Again the WEB AA profile of
growing lambs was simulated in the small intestine via abomasal infusions to lambs
receiving a soybean hull-based diet. Leucine, isoleucine and valine were individually or
simultaneously removed from the infusate and the impact on N retention measured. On
an individual basis valine had the largest negative impact on the efficiency of N
utilisation. However, the simultaneous removal of the BCAA`s resulted in the lowest N
retention, suggesting that valine might be limiting, but the three BCAA`s are more likely
to be co-limiting in diets to growing lambs where microbial protein is the primary source
of AA`s. Once again, neither DM, OM or NDF digestibility were affected by the AA
imbalances. Nitrogen digestibility was, however, negatively affected by AA imbalances.
This project succeeded in establishing the essential AA profile of duodenal protein in
sheep receiving high RDP diets. The WEB essential AA compositions of growing lambs
from two prominent sheep breeds in South Afica were then determined and the duodenal
essential AA profile evaluated against the calculated AA requirements. Finally, the AA`s
that limit growth in diets where microbial protein is the predominant source thereof were
identified. These results contribute to the current knowledge of AA requirements in
growing lambs, and highlight areas for future research, as discussed in the General
Conclusion.
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Studies on embryonic development and hatchability of ostrich eggsBrand, Zanell 03 1900 (has links)
Thesis (PhD(Agric))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The ostrich industry experiences high rates of embryonic mortalities during artificial incubation of eggs. Studies have been carried out to investigate factors influencing hatchability, as well as determining genotypic effects for commercial production. Eggs from the combination of South African Black (SAB) male ostriches crossed with Zimbabwean Blue (ZB) female ostriches had embryonic losses of 45.7%. The embryonic mortality of eggs produced by pure bred SAB or ZB breeding birds subjected to pure breeding was similar at around 33 - 34%, but embryonic mortality was improved in eggs produced by ZB males and SAB female crosses (27%). Female age had a significant effect on the proportion of chicks pipped, as well as on early and late the embryonic mortalities. Chicks from eggs stored for intermediate periods, i.e. 3, 4 and 6 days prior to being set, were more likely to pip than chicks from those eggs set directly after collection without storage. Embryonic mortality was increased in eggs that were set directly (32.0%) or subjected to longer than 6 days of storage (43.5%). Chicks that pipped in the correct position had a higher probability of successfully hatching than those pipping in the incorrect position. Transfer of eggs between setters (i.e. disturbance of eggs) during incubation reduced the number of ostrich chicks pipping in the correct position. Incubated ostrich eggs with intermediate levels of water loss, i.e. between 9.0 and 19% of fresh egg weight, were more likely to pip in the correct position than those with higher or lower levels of water loss. Such eggs were also less likely to sustain early, late or overall embryonic mortalities.
To optimise hatching success it is important to understand embryonic development. After 2 days of incubation the blastoderm area in eggs from the SAB x ZB crosses (104.5 mm) was lower (P < 0.05) compared to the pure SAB (141.0 mm), pure ZB (161.7 mm) and ZB x SAB crosses (166.1 mm). For embryos incubated for 7 to 42 days, both embryonic and leg growth during the 42 days of incubation was similar and approximately linear, more or less doubling in size up to 35 days of incubation. The embryo eye size increased more rapidly than beak length and reached full size of approximately 16.2 mm by 28 days of incubation, whereas the beak length continued to increase until the chick hatched at 42 days. Incubation position, vertical or horizontal, did not affect any of the measurements of the developing embryo throughout the 42-day incubation period. Air cell volume at 29 day of incubation for infertile eggs (19.3%) was significantly (P < 0.05) higher when compared to dead-in-shell eggs (14.3%) and eggs that hatched successfully (13.8%). Air cell volume was largely independent of strain (SAB or ZB) and whether chicks were assisted to hatch or not. After 41 days of incubation there was a significantly greater (P < 0.05) air cell volume in eggs that hatched normally compared to dead-in-shell eggs (28.3% vs. 21.7%, respectively, suggesting that insufficient water loss contributed to reduced survival. This study provides an insight into the complexity of embryo development and all the factors playing a role in successful hatching of ostrich eggs.
Data from a pair-mated ostrich flock were used to estimate genetic parameters for egg weight (EWT), weight of day-old chicks (CWT), water loss to 21 (WL21) and 35 (WL35) days of incubation, and pipping time (PT). Single-trait estimates of heritability (h2) were high and significant (P < 0.05) at 0.46 for EWT, 0.34 for CWT, 0.34 for WL21, 0.27 for WL35 and 0.16 for pipping time. Genetic correlations with EWT amounted to -0.21 for WL21 and to -0.12 for WL35. Corresponding correlations of CWT with WL were highly significant (P < 0.05) at -0.43 and -0.54.
Physical characteristics of the eggshell were found to affect water loss and hatchability. Estimates of genetic parameters of 14 146 ostrich eggs for eggshell traits showed that heritability was 0.42 for pore count (PC), 0.33 for shell thickness (ST) and 0.22 for permeability (PERM). PC was negatively correlated with average pore diameter (-0.58) and ST (-0.23), while PC was positively correlated with total pore area (0.58), WL21 (0.24) and WL35 (0.34). The correlations of PC with total pore area and PERM were high and significant. ST was negatively correlated to WL21 and WL35. Additive genetic parameters strongly indicate that it should be possible to alter evaporative water loss and eggshell quality of ostrich eggs through genetic selection.
When assessed as a trait of the individual egg or chick, embryonic mortalities exhibited moderate levels of genetic variation both on the normal scale (h2 = 0.16 - 0.22) and the underlying liability scale (h2 = 0.21 - 0.31). Early embryonic survival and late embryonic survival was governed mostly by the same genes (rg = 0.78). Late embryonic survival was genetically correlated to WL35, at -0.22. It was concluded that embryonic survival could be improved by using husbandry measures, a knowledge of the stage when incubation mortalities occur, and by genetic selection, using an integrated approach.
Findings from this study will help to understand the mechanisms involved in hatching from artificial incubation better to improve hatchability and also implement selective breeding programs. / AFRIKAANSE OPSOMMING: Die volstruisbedryf ondervind tans ‘n baie hoë voorkoms van embrionale mortaliteite tydens die kunsmatige uitbroei van eiers. Studies is uitgevoer om die faktore wat uitbroeibaarheid beinvloed te ondersoek en om genotipiese effekte te bepaal vir kommersiële produsente. Eiers van die kombinasie van Suid-Afrikaanse swart (SAB) mannetjie volstruise, met Zimbabwean blou (ZB) wyfies, het embrionale mortaliteite van 45.7% gehad. Embrionale mortaliteite van eiers gelê deur suiwer SAB of ZB volstruise was dieselfde op omtrent 33 - 34%, maar embrionale mortaliteite was laer vir eiers geproduseer deur SAB wyfies wat gekruis was met ZB mannetjies (27%). Wyfie ouderdom het ‘n betekenisvolle effek gehad op die proporsie van kuikens wat gepik het, asook die aantal vroeë- en laat embrionale mortaliteite. Kuikens vanuit eiers wat vir die periode 3, 4 dae en 6 dae voor pak in die broeikaste gestoor is, was meer geneig om te pik as kuikens vanaf eiers wat direk na kolleksie gepak is. Embrionale mortalitiete het verhoog vir eiers wat direk na kolleksie gepak was (32.0%) of vir eiers wat langer as 6 dae gestoor was (43.5%). Kuikens wat in die korrekte posisie pik het ‘n hoër kans op uitbroei gehad as kuikens wat in die verkeerde posisie gepik het. Die skuif van eiers tussen verskillende broeikaste (of enige steurnisse) gedurende die broeiproses het ‘n verlaging in die aantal kuikens wat in die korrekte posisie pik, gehad. Volstruiseiers met ‘n gemiddelde vogverlies van tussen 9.0 en 19% van die vars eier massa, was meer geneig om in die korrekte posisie te pik as eiers met laer of hoër vlakke van vogverlies. Sulke eiers was ook minder geneig tot vroeë, laat en totale embrionale mortaliteite. Vir optimale uitbroeisukses is dit belangrik om die ontwikkeling van die embrio te verstaan. Na 2 dae van broei was die blastoderm area in eiers van SAB x ZB kruisings (104.5 mm) kleiner (P < 0.05) as die blastoderm area van suiwer SAB (141.0 mm), suiwer ZB (161.7 mm) en ZB x SAB kruise (166.1 mm). Beide embrionale- en beengroei tydens die 42 dae broeiproses was dieselfde en nagenoeg lineêr, met ‘n verdubbeling in grootte tot en met 35 dae broei. Die embrio se oog vergroot vinniger as wat die snawel verleng en bereik reeds volle grootte van ongeveer 16.2 mm op 28 dae van broei, terwyl die snawel aanhou groei tot uitbroei van die kuiken op 42 dae. Nie die vertikale of horisontale broeiposisie het enige invloed op die metings van die ontwikkelende embrio tot op 42 dae gehad nie. Lugsakvolume vir geil eiers (19.3%) op 29 dae van broei was groter (P < 0.05) as beide die lugsakke van eiers wat dood-in-dop (14.3%) en eiers wat suksesvol uitgebroei het (13.8%). Die lugsakvolume was onafhanklik van beide genotype en of die kuiken met of sonder hulp uitgebroei het. Na 41 dae broei was lugsakvolume groter (P < 0.05) vir eiers wat uitgebroei het teenoor eiers wat dood-in-dop was (28.3% vs. 21.7%, onderskeidelik), wat impliseer dat onvoldoende vogverlies moontlik kan bydrae tot ‘n verlaging in embrionale oorlewing. Hierdie studie gee ‘n insig in die kompleksiteit van embrionale ontwikkeling en al die faktore wat ‘n rol speel in die suksesvolle uitbroei van volstruiseiers.
Tydens die bepaling van genetiese parameters vir spesifieke uitbroei-eienskappe in volstruise, is data gebruik afkomend van ‘n teelkudde in ‘n enkelparing stelsel om genetiese waardes vir eiermassa (EWT), dagoud kuikenmassa (CWT), vogverlies tot 21 dae broei (WL21), vogverlies tot 35 dae broei (WL35) en piktyd (PT) gebruik. Enkeleienskap-beraming vir oorerflikheid (h2) was hoog en betekenisvol teen 0.46 vir EWT, 0.34 vir CWT, 0.34 vir WL21, 0.27 vir WL35 en 0.16 vir piktyd. Genetiese korrelasies met EWT was -0.21 vir WL21 en -0.12 vir WL35. Ooreenkomstig was korrelasies van CWT met WL21 en WL35 hoog (P < 0.05) met -0.43 en -0.54 onderskeidelik.
Fisiese eienskappe van die eiers het beide vogverlies en uitbroeibaarheid beinvloed. Beramings van genetiese parameters vir 14 146 volstruiseiers se dopeienskappe het gewys dat oorerflikehid 0.42 was vir die aantal porieë (PC), 0.33 vir dopdikte (ST) en 0.22 vir deurlaatbaarheid (PERM). PC was negatief gekorreleerd met gemiddelde porieë deursnee (-0.58) en ST (-0.23), terwyl PC positief gekorreleerd was met totale porieë area (0.58), WL21 (0.24) en WL35 (0.34). Die korrelasie van PC met totale porieë area en deurlaatbaarheid was hoog en betekenisvol. ST was negatief gekorreleerd met WL21 en WL35. Additiewe genetiese parameters het sterk daarop gedui dat dit moontlik sou wees om vogverlies en eierkwaliteit (bv. dopkwaliteit en poreusiteit) van volstruiseiers te verander deur genetiese seleksie.
Indien embrionale mortaliteit geevalueer word as ‘n kenmerk van die eier of kuiken, toon dit matige vlakke van genetiese variasie op beide die normale (h2 = 0.16 - 0.22) en die onderliggende skale (h2 = 0.21 - 0.31). Beide vroeë- en laat embrionale oorlewing word deur dieselfde stel gene beheer (rg = 0.78). Laat embrionale oorlewing was geneties gekorreleerd met WL35 teen -0.22. Die gevolgtrekking was dat embrionale oorlewing verbeter kan word deur verbeterde broeikamerpraktyke, kennis van op watter stadium van ontwikkelings embrionale mortaliteite plaasvind en deur genetiese seleksie.
Bevindinge vanuit hierdie studies sal help om die meganismes betrokke by die kunsmatige uitbroei van volstruiskuikens beter te verstaan om sodoende uitbroeibaarheid te verbeter en ook suksesvolle seleksie programme te implementeer.
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The effect of different incubation temperatures on chick qualityDu Preez, J. H. 03 1900 (has links)
Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Over the last few decades various authors have reported the influence of day old chick quality
on integrated broiler industries. Although various methods of determining chick quality have
been reported, defining a good or a first grade day old chick can be problematic as it involves
many subjective measurements. Incubation temperature (embryo temperature) is probably
the biggest, most influential factor during incubation on chick quality. High temperatures
cause the most damage. It leads to poor growth, stress, black buttons, threads, weak chicks,
chicks with poorly erupted down that are bleached in appearance, low hatchability, late
embryonic death and early broiler mortality. This trial was designed to test whether 37.2,
37.4 or 37.5ºC was the optimum incubation temperature for hatching Hybro G+ chicks with
superior quality. The parameters that were measured were the chick length, bodyweight, and
the yolk residue of the day old chicks of the flocks set at different setter temperatures. After
hatching, 1 440 chicks (480 chicks per temperature treatment) were placed at a broiler facility
where the daily mortalities, weekly bodyweight gain and feed conversion were recorded and
calculated. The age of the breeder flock had a significant effect on all three parameters
measured in the incubation trial with p values of <0.001, <0.001 and 0.005 respectively.
There were no significant differences in chick quality parameters due to different incubation
temperatures. The age x temperature interaction could be attributed to the large influence of
the age of the breeder on egg size and consequently chick parameters. The results could be
related to the fact that bigger eggs from older breeder flocks have higher initial egg mass,
which will result in heavier embryos and thus converted to a larger day old chick. The
performance trial performed after the incubation trial showed no significant effect of the
incubation temperature on 7-day and daily mortalities, weekly bodyweight gain and feed
conversion efficiency to 42 days of life. The lack of effects observed in these trials could be
attributed to the small range of temperatures used in addition to the difficulties brought about
the use of multi-stage incubators.
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Alternatives to replace antibiotics in broiler diets : effects on protein utilization and production performanceKritzinger, Magdel 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Different substances were evaluated and compared to an antibiotic, in terms of their effect on nitrogen
- and amino acid digestibilities. Two digestibility trials and one performance trial were conducted.
Trials one and two apparent nitrogen (AND)- and amino acid (AAD) digestibilities were determined
from digesta collected at the terminal ileum (ileal digestibility method). In Trial 3 the substances were
evaluated in terms of their potential to improve production performance. Broilers were fed a maizesoya
based diet throughout the three trails.
In the first trial, garlic and a commercial prebiotic (Bio-Mos®), were tested and compared in terms of
AND and AAD, to an antibiotic (doxycyclin, Doxyvete-SOS). A starter and finisher diet were fed as
either mash or pellets. The garlic was included at 8g/kg, 13g/kg and 18g/kg to the starter and finisher
diets. Bio-Mos® was added at 1g/kg, 2g/kg and 3g/kg to the starter diet, and 0.5g/kg, 1g/kg and
1.5g/kg to the finisher diet. The doxycyclin was added at 0.3 g/kg. None of the treatments had any
beneficial effects in terms of AND. Feeding a pellet seem to have some negative effects in terms of
AND. In general most of the treatments did not show any improvement in AAD at any determination
period (day 21, 28 or 35). At day 21 and day 35, the mash diet supplemented with 18g/kg garlic had a
negative effect on AAD, when compared to the negative and positive control. It doesn’t seem that
feeding either a mash or a pellet had an influence on the effects exerted by the different treatments.
In the second trial the influence of Bio-Mos®, a blend of organic acids, probiotics and electrolytes
(Acid-Pak 4-way®) and a medium-chain triglyceride (MCT) were evaluated and compared in terms of
AAD and AND, to the effect of an antibiotic, doxycyclin. The starter and finisher diets were fed as a
mash. Bio-Mos® was included at 1g/kg, 2g/kg, and 3g/kg in the starter diet, and at 0.5g/kg, 1g/kg,
1.5g/kg in the finisher diet, respectively. Acid-Pak 4-way® was included at 0.4g/kg, 1g/kg and 1.6g/kg
for both the starter and finisher diets. Medium-chain triglycerides (MCT) were allocated at 3g/kg,
3.6g/kg, 4.2g/kg for the starter diet, and 2.1g/kg, 2.7g/kg and 3.4g/kg for the finisher diet. An antibiotic,
doxycyclin, was included at 0.3 g/kg. With AND, no treatment had any significant effect for the entire
experimental period. At day 21, the treatment supplemented with MCT (3.4g/kg) had the most
significant beneficial effect on AAD, when compared to the negative- and positive controls, as it
increased AAD for the majority of the amino acids. The treatment with Acid-Pak 4-way® (1g/kg) had
the most significant negative effect on AAD when compared to the positive control. At day 28, the
treatments with Bio-Mos® (0.5g/kg and 1.5g/kg) and Acid-Pak 4-way® (0.4g/kg) had the most
significant beneficial effect on AAD when compared to the positive control. It increased AAD for more
than half of the 17 amino acids evaluated. The treatment supplemented with MCT (2.7g/kg) has
shown the most significant negative effect on AAD, when compared to the positive control.
In the third trial the effect of Bio-Mos®, Acid-Pak 4-way® and MCT on production performance was
evaluated, and compared to the effects of the presence or absence of doxycyclin. Body weight (BW),
body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured. The starter and finisher diets were fed as a mash. Bio-Mos®, MCT and Acid-Pak 4-way® were included at
3.0g/kg, 4.2g/kg and 1.6g/kg, respectively in the starter and finisher diets. Birds were weighed (per
pen) on arrival and on days 7, 14, 21, 28, 35. Feed intake (FI) per pen was measured at days 7, 14,
21, 28 and 35, and mortality was recorded daily. In terms of BWG, Acid-Pak 4-way® had a higher
BWG, when compared to the negative control, Bio-Mos® and MCT.
It can be concluded that Bio-Mos®, Acid-Pak 4-way®, as well as MCT can be a possible alternatives
to antibiotic supplementation. These three treatments did not necessary prove to be more effective
than antibiotics, but are definitely competitive alternatives. / AFRIKAANSE OPSOMMING: Verskillende behandelings is geëvalueer en vergelyk met ‘n antimikrobiese produk, in terme van hul
uitwerking op stikstof - en aminosuur verteerbaarhede. Twee verteringstudies en produksieprestasie
studie is uitgevoer.
In die eerste twee studies is die skynbare stikstof (AND)- en aminosuur (AAD) verteringskoöeffisiënte
bepaal deur gebruik te maak van digesta wat by die terminale ileum ingesamel is (ileale
verteringsmetode). In die derde studie is die produksie prestasie van braaikuikens op ‘n
gebalanseerde metaboliseerbare energie (AME) rantsoen, soos beïnvloed deur die verskillende
behandelings, geëvalueer.
In die eerste studie is knoffel en ‘n kommersiële prebiotikum (Bio-Mos®) geëvalueer en met ‘n
antibiotikum (doksisiklien, Doxyveto-SOS) in terme van AND en AAD vergelyk. Beginner- en
afrondingsrantsoene is as ‘n meel of pille gevoer. Die knoffel is teen 8g/kg, 13g/kg en 18g/kg in die
rantsoen ingesluit. Bio-Mos® is teen 1g/kg, 2g/kg en 3g/kg in die beginner rantsoen en teen 0.5g/kg,
1g/kg en 1.5g/kg in die afrondingsrantsoen, ingesluit. Die antibiotikum is teen 0.3g/kg in beide
rantsoene ingesluit. Geen van die behandelings het enige positiewe invloed op AND gehad nie. Deur
‘n verpilde rantsoen te voer het sekere negatiewe invloed op AND gehad. Oor die algemeen het geen
behandelings enige positiewe invloed op AAD gehad nie. Op dag 21 en 35 het die insluiting van
knoffel teen 18g/kg in ’n meel rantsoen ’n negatiewe invloed op AAD gehad, wanneer dit met die
negatiewe- en positiewe kontroles vergelyk is. Dit blyk nie dat om ‘n pil of meel te voer enige invloed
op die invloede van die verskillende behandelings gehad het nie.
In die tweede studie is Bio-Mos®, ‘n organiese suur (Acid-Pak 4-way®) en ‘n medium-ketting
trigliseried (MCT) geëvalueer en met ‘n antbiotikum, doksisiklien (Doxyveto-SOS) in terme van AND
en AAD, vergelyk. Beginner- en afrondingsrantsoene is gevoer as ‘n meel. Bio-Mos® is teen 1g/kg,
2g/kg, and 3g/kg in die beginner rantsoen en teen 0.5g/kg, 1g/kg, 1.5g/kg in die afrondingsrantsoen,
ingesluit. Acid-Pak 4-way® is teen 0.4g/kg, 1g/kg en 1.6g/kg vir die beginner –en afrondingsrantsoene
ingesluit. Die MCT is teen 3g/kg, 3.6g/kg, 4.2g/kg in die beginner rantsoen en teen 2.1g/kg, 2.7g/kg en
3.4g/kg in die afrondingsrantsoen ingesluit. Die antibiotikum is ingesluit teen 0.3g/kg. Geen
behandelings het enige betekenisvolle invloed in terme van AND gehad nie. Op dag 21 het MCT
(3.4g/kg), in vergelyking met die negatiewe- en positiewe kontrole, die grootste positiewe invloed op
AAD gehad. Acid-Pak 4-way® (1g/kg) het, in vergelyking met die positiewe kontrole, ‘n positiewe
invloed gehad op AAD. Op dag 28, het Bio-Mos® (0.5g/kg en 1.5g/kg) en Acid-Pak 4-way® (0.4g/kg)
die grootste positiewe invloed op AAD gehad. Die behandeling met MCT (2.7g/kg) het die mees
negatiewe invloed op AAD gehad.
In die derde studie is die insluiting van Bio-Mos®, Acid-Pak 4-way® en MCT getoets om die invloed op
braaikuiken produksie prestasie te evalueer, en te vergelyk met die invloed van die insluiting of
afwesigheid van ‘n antibiotikum. Liggaamsmassa (BW), liggaamsmassa toename (BWG), voerinname (FI) en voeromsetverhouding (FCR) is gemeet. Beginner- en afrondings rantsoene is gevoer as ‘n
meel. Bio-Mos®, MCT en Acid-Pak 4-way® is onderskeidelik teen 3.0g/kg, 4,2g/kg en 1.6g/kg in die
rantsoen ingesluit. Die kuikens is met aankoms (per hok) geweeg, asook op dae 7, 14, 21, 28, 35.
Voerinname per hok is gemeet op dae 7, 14, 21, 28 en 35. Mortaliteite is daagliks aangeteken. Die
insluiting van Acid-Pak 4-way® het in vergelyking met die negatiewe kontrole, Bio-Mos® en MCT
insluiting ‘n hoër BWG tot gevolg gehad.
Die gevolgtrekking wat gemaak kan word is dat Bio-Mos®, Acid-Pak 4-way® en MCT gebruik kan
word as ‘n moontlike alternatief vir antibiotika insluiting. Hierdie drie behandelings was nie
noodwending meer effektief as die antibiotika nie, maar het wel bewys dat dit kompeterende
alternatiewe is.
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