Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 199-219). Also available via the Internet.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains iii, 50 p. : ill. Includes abstract. Includes bibliographical references (p. 43-50).

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 151-172).

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Li Liao, Dept. of Computer & Information Sciences. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 34 p. Includes abstract. Includes bibliographical references.

The operators of a sample of 104 British Columbia broiler farms were questioned to obtain information concerning all aspects of their broiler rearing operation. The results contained information on all aspects of brooding, feeding and watering, vaccination and medication and sanitation practices. The data thus obtained were compiled and the sample characterized. The data were analysed to determine the relationship of the number of broilers reared to management practices. An evaluation of certain management practices was also carried out. / Land and Food Systems, Faculty of / Graduate

The effect of intramuscular corticosterone injection on post mortem muscle metabolism and shear resistance of Pectoralis Major muscle was studied. Short term studies, conducted over an 8 hour post-injection period, showed no significant effect of injection until 6 hours post injection at which time shear values increased from those of the controls. Blood glucose levels rose significantly from 2 to 8 hours post injection. A comparison of shear values of P. Major muscle from 6 week-old broilers and 8 week-old broilers after both had received corticosterone injections showed that the only difference was due to the difference of age not to any alteration in the physiological handling of the injected corticosterone. The greatest difference in treatment effect was found between birds of different stress level. Stress level was subjectively evaluated with respect to the birds reaction to a person entering the range house and to the birds response to handling. Long term studies conducted over 5 and 15 days illustrated homeostatic adjustments to daily corticosterone injections and recovery after cessation of injections. Shear testing was performed on P. Major muscle which was chilled on the carcass and on muscle excised at death. Excised muscle displayed a greater reaction to injection and cessation of injection than did intact muscle due to a lack of skeletal restriction. Shear values decreased on initial injection and increased upon cessation of injection. Homeostatic adjustments returned values to near-normal between these times. Chemical tests were found to display a much more definite reaction to corticosterone injection than did shear testing. Blood glucose and tissue glycogen increased steadily on injection of corticosterone and decreased rapidly at cessation. As expected ultimate muscle pH decreased with muscle glycogen increase. Blood cholesterol increased during injection period as endogenous corticosterone production, for which it is a precursor, was not required. / Land and Food Systems, Faculty of / Graduate

The radiosity method of radiant interchange analysis of enclosures was used to predict the intensity and the uniformity of thermal radiation within a controlled environment chamber. The chamber was designed for testing the effects of infrared radiation on young broilers. The walls of the chamber were assumed to be grey and separated by a radiatively non-participating medium. Also the black globe thermometer method was used to calculate the incident radiation at different locations in the chamber. Then, the results obtained by the two mentioned methods, were compared. Two separate experiments were designed for different purposes. The first experiment was to study the influence of infrared radiation on poultry. In this experiment, two levels of radiation were tested and the results were compared to those obtained by use of a conventional heat lamp brooding system. The second experiment was to compare a controlled temperature, warm air brooding system, to a conventional heat lamp brooding system. The relative effects in both sets of experiments were measured by use of the weekly growth rate index. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Antibiotic growth promoters (AGP’s) have been used in feed of production animals to improve their growth performance and disease resistance. However, there has been an increase in the presence of antibiotic residue in animal products, as well as an increase in untreatable illnesses due to antibiotic resistant bacteria. This led to the European Union banning the use of antibiotic growth promoters, in production animals, in 2006. An alternative to AGP’s is therefore needed in animal feed in order to maintain performance. Plant extracts and essential oils have gained much attention, due to their natural antimicrobial, antibacterial, anticoccidial and antioxidant properties. This study tested the efficiency of Ateli plus®, an oregano plant extract based product, as a replacement to AGP’s on production parameters, carcass characteristics and organ and gut health of broilers. This study consisted of five treatments fed to broilers from hatch till 33 days of age, fed in three phases; starter, grower and finisher. The treatment diets consisted of a negative control (no AGP), positive control (AGP), Ateli plus® at 1kg/ton (Ateli plus® min), Ateli plus® at 2kg/ton for week one followed by 1kg/ton for the remainder of the period (Ateli plus® max), and AGP plus Ateli plus® max (AGP plus Ateli plus® max). Results from this study show that there was no difference in performance parameters between treatments. The performance parameters tested included liveability, average daily gain (ADG), average weekly feed intake, average cumulative feed intake, average weekly live weight, average cumulative weight gains, feed conversion ratio (FCR), cumulative FCR and the European production efficiency factor (EPEF). Broiler breast and thigh muscle pH and colour (L*, a* and b*) reading values were measured, showing a trend for improved L* colour reading value and ultimate pH, in broilers supplemented with Ateli plus®. This leads to an increase in water binding capacity and tenderness, therefore resulting in an improvement in meat quality. No differences were shown for dressing percentage and portion percentages relative to carcass weight. No significant differences were seen for tibia bone Ca and P content, or tibia bone fat, moisture or ash percentages. However a significant decrease in tibia bone strength was found in all broilers supplemented with Ateli plus® diets and the negative control diet, compared to AGP supplemented broilers. Gut morphology showed no consistent effect of treatment on villi height or crypt depth of the duodenum, jejunum and ileum. No significant differences between treatments were found for organ pH or organ weights, except the gizzard, which was heavier for Ateli plus® max supplemented broilers. Ateli plus® shows promise on improving meat quality characteristics of broilers, however the significant decrease in tibia bone strength in Ateli plus® supplemented broilers is a major concern and needs to be researched further. Ateli plus® acts as a good AGP replacement, as broiler performance for the Ateli plus® supplemented broilers was maintained, and not decreased, when compared to the AGP supplemented broilers. However, the broilers fed the negative control diet had performance parameters statistically equal to both the Ateli plus® and AGP supplemented broilers, as well as no significant differences between organ weights were found. It can therefore be said that the broilers were raised under good management, and their optimal environmental conditions. Therefore conclusive effectiveness of Ateli plus® as a replacement for AGP on broiler performance cannot be reported from this study. / AFRIKAANSE OPSOMMING: Antibiotiese groeistimulante (AGP’s) word gereeld as voerbymiddels vir diere gebruik om groei en siekte weerstandbiedenheid te verbeter. Die verbod op die gebruik van antibiotika as 'n groeipromotor in die Europese Unie (sedert 2006) kan toegeskryf word aan die toename in onbehandelbare siektes as gevolg van weerstandbiedende bakterieë, asook die teenwoordigheid van residue in die dierlike produkte. Alternatiewe vir AGP’s in dierevoeding word dus benodig om produksie te handhaaf. Plant ekstrakte en essensiële olies het baie aandag gekry as gevolg van hul natuurlike antimikrobiese, antibakteriële, antikoksidiese en antioksidatiewe eienskappe. 'n Studie is gedoen om die doeltreffendheid van Ateli plus® ('n origanum plant ekstrak gebaseerde produk) op groei produksie parameters, karkaseienskappe, orgaan- en dermgesondheid te bepaal wanneer Ateli plus® as 'n AGP plaasvervanger in die dieëte van braaikuikens gebruik word. Gedurende die proef was vyf verskillende diëte/behandelings vir 33 dae vir braaikuikens gevoer. Die behandelings het bestaan uit 'n negatiewe kontrole (geen AGP), positiewe kontrole (AGP), Ateli plus® teen 1kg/ton (Ateli plus min), Ateli plus® teen 2kg/ton vir die eerste week gevolg deur 1kg/ton vir die res van die tydperk (Ateli plus® max), en AGP plus Ateli plus® max (AGP plus Ateli plus® max). Resultate van hierdie studie toon dat behandelings nie 'n effek op produksie parameters gehad het nie. Die groei produksie parameters wat getoets is sluit in oorlewing, gemiddelde daaglikse toename (GDT), die gemiddelde weeklikse voer-inname, gemiddelde kumulatiewe voerinname, gemiddelde weeklikse lewendige massa, gemiddelde kumulatiewe gewig toename, voeromsetverhouding (VOV) en die Europese produksie doeltreffendheid faktor (EPEF). Die pH en kleur (L*,a* en b* waardes) van die dy- en borsspier is gemeet. Ateli plus® aanvulling in braaikuiken diëte het 'n tendens getoon vir verbeterde L * en finale pH waardes in die spiere, wat lei tot 'n toename in waterhouvermoë en sagtheid en dus verbeterde vleiskwaliteit. Geen verskille tussen behandelings is gevind vir uitslagpersentasie en die massa van porsies (uitgedruk as persentasie relatief tot karkasgewig) nie. Behandelings het nie 'n effek op die vet, vog, as persentasies of Ca- en P-inhoud van die tibia gehad nie. In vergelyking met AGP aangevulde braaikuikens, is 'n beduidende afname in die tibia breeksterkte van kuikens in die negatiwe kontrole groep en kuikens wat met Ateli plus® aangevul is, gevind. Spysverteringskanaal morfologie het getoon dat behandeling geen konsekwente effek op villi hoogte of krip diepte van die duodenum, jejunum en ileum gehad het nie. Slegs die krop massas van kuikens wat met Ateli plus® max aangevul is, was swaarder in vergelyking met hoenders in die ander behandelings; verder is geen beduidende verskille tussen behandelings gevind vir orgaan pH of orgaan gewigte nie.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The use of phytase enzymes to liberate phosphorus and other phytate bound nutrients in monogastric animal diets are becoming common practice and several commercial phytase enzymes are available on the market. Phytase manufacturers supply nutritionists with matrix values for the specific phytase, enabling nutritionists to effectively decrease the dietary concentrations of phosphorus and nutrients during diet formulation. A 32 day experiment was conducted with 5120 broiler chicks fed diets supplemented with different commercial phytase enzymes (1000 FYT or 1500 FYT HiPhos/kg diet, 1500 FYT Ronozyme/kg diet, 500 FTU Natuphos/kg diet or 500 FTU Phyzyme/kg diet) at levels recommended by the manufacturers and with similar phosphorus equivalence. The nutrient content of the diets supplemented with 500 FTU Natuphos, 500 FTU Phyzyme 1500 Ronozyme and 1000 FYT HiPhos were reduced according to the matrix values of 1000 FYT/kg HiPhos, whilst the diet supplemented with 1500 FYT HiPhos /kg diet was reduced according to the matrix values 1500 FYT HiPhos. The objectives of this study were threefold: (i) to confirm the matrix value for a newly developed phytase (HiPhos, DSM Nutritional Products, Basel, Switzerland), at two different inclusion levels, using weight gain and bone parameters of broilers as response criteria; (ii) to compare production and bone parameters of broilers reared on three different commercial phytases to broilers reared on HiPhos (iii) to investigate the effect that supplementation of these four phytases has on water intake, carcass characteristics, organ weights and gastrointestinal tract morphology of broilers. The matrix values for 1500 FYT HiPhos were confirmed by using live weight gain as response criteria, but results for bone parameters were insufficient in confirming the matrix values. The matrix values for 1000 FYT HiPhos were confirmed by the results for tibia weight and tibia strength, but results for weight gain were insufficient to confirm the values. The matrix values for 1000 FYT HiPhos and 1500 FYT HiPhos could not be confirmed nor disproved, nevertheless results from the current trial proved diets supplemented with HiPhos to be more economically viable when compared to the standard commercial broiler diet. Total feed and water intake were not influenced by phytase supplementation. Production parameters (live weight, feed intake, feed conversion ratio, European production efficiency factor and average daily gain) and bone parameters (tibia strength, fat free tibia weight, fat free tibia ash and mineral content) did not differ between phytase treatments and therefore all the commercial phytases were equally effective to the HiPhos phytase. Furthermore, results indicate that the investigated phytases had no effect on internal organ weight or gastrointestinal tract morphology in broilers. Overall the results obtained from the study indicate that the use of phytase as feed additive has no negative effects on growth performance, carcass characteristics or bone parameters. No major differences for the production and bone parameters were observed between broilers supplemented with different phytases. Therefore the costs of these phytases can be the determining factor when nutritionists decide which commercial phytase to use. / AFRIKAANSE OPSOMMING: Die gebruik van fitase ensieme in die diëte van enkelmaagdiere om fitaat-gebonde fosfor en voedingstowwe vry te stel, word al hoe meer algemeen in die bedryf en verskeie kommersiële fitase ensieme is in die mark beskikbaar. Die ensiemvervaardigers verskaf die fitases se matryswaardes aan voedingskundiges wat hul in staat stel om die fosfor- en nutrientvlakke in die dieet effektief te verminder. ´n Studie met 5120 braaikuikens was vir 32 dae uitgevoer. Die braaikuiken diëte was met verskillende kommersiële fitase ensieme (1000 FYT & 1500 FYT HiPhos/kg dieet, 1500 FYT Ronozyme/kg dieet, 500 FTU Natuphos/kg dieet of 500 FTU Phyzyme/kg dieet) aangevul. Die nutrientvlakke van die diëte wat met fitase aangevul was, was verminder volgens die matryswaardes van 1000 FYT of 1500 FYT HiPhos fitase. Die doelstellings van hierdie studie was drievoudig: (i) om die matryswaardes van ´n nuwe fitase (HiPhos, DSM Nutritional Products, Basel, Switzerland) by twee verskillende insluitingsvlakke te bevestig deur massa toename en been parameters as reaksie maatstawwe te gebruik (ii) om produksie- en been parameters van braaikuikens, wat een van drie kommersiële fitase ensieme as voerbymiddel ontvang het, met dié van braaikuikens wat die nuwe ensiem gevoer was te vergelyk (iii) om die effek wat fitase op water inname, karkaseienskappe, orgaan massas en spysverteringskanaal morfologie het te bestudeer. Die matryswaardes vir 1500 FYT HiPhos was bevestig deur lewendige massa toename as respons kriteria te gebruik, maar resultate vir die been parameters was onvoldoende om die matryswaardes te bevestig. Die matryswaardes vir 1000 FYT HiPhos was slegs bevestig deur die resultate vir die breeksterktes van die tibias, maar resultate vir massa toename was onvoldoende om die matryswaardes te bevestig. Dus kon die matryswaardes vir die HiPhos fitase nie bevestig of verkeerd bewys word nie. Desondanks het die resultate in die huidige proef bewys dat diëte wat met HiPhos aangevul was meer ekonomies as die kommersiële braaikuiken dieet is. Totale voer- en water-inname was nie deur die aanvulling van fitase beïnvloed nie. Produksie parameters (lewendige massa, voeromset, die Europese produksie doeltreffendheids faktor, gemiddelde daaglikse toename) en been parameters (tibia breeksterkte, vet vrye tibia massa, vet vrye tibia as en mineraal-inhoud) het nie verskil tussen die fitase behandelings nie en dus was al die kommersiële fitases ewe effektief. Vanuit die studie is getoon dat die gebruik van fitase as ´n voerbymiddels geen negatiewe effek op groei, karkas eienskappe of been parameters het nie en dat fitase ook nie die orgaan gewigte of die spysverteringskanaal morfologie van braaikuikens beïnvloed nie. Geen groot verskille in produksieen been parameters was waargeneem tussen hoenders wat verskillende fitases as voerbymiddel ontvang het nie, daarom kan die koste van die ensiem die bepalende faktor wees as voedingkundiges die keuse maak tussen hierdie kommersiele fitases.