Necrotic enteritis in poultry is caused by Clostridium perfringens type A, and is estimated to cost the worldwide poultry industry approximately $2 billion dollars a year, due to increased mortality and decreased feed conversion and weight gain. Very little is known about the pathogenesis of this disease due to the lack of a consistently reproducible experimental model. This dissertation outlines the development of an effective and consistent experimental model for necrotic enteritis in broiler chickens. It was also found that in vivo passage through the chicken's intestinal tract let to increased virulence; we increased the proportion of birds developing disease from 34.6% to 81.4%. Researchers have proposed that alpha toxin (CPA) is believed to be the critical virulence factor of the disease. All type A isolates have the potential to produce CPA, thus we challenged birds with numerous type A isolates that are virulent in other animal hosts. However, we found that they did not produce necrotic enteritis in broiler chickens. In addition, challenge with culture supernatant alone failed to produce gross lesions in the birds, although challenging with washed whole cell cultures did do so. Vaccinating birds with HIS-tagged recombinant CPA provided partial protection against disease; there was a 42.0% decrease in lesion development. The conclusion of this doctoral research is that CPA does have a role in the pathogenesis of necrotic enteritis in broiler chickens, but there are apparently other critical virulence factors involved in the development of disease.

Infectious bursal disease virus (IBDV) has a tropism for the lymphoid tissue of poultry and infects actively dividing and differentiating B-lymphocytes in the bursa of Fabricius. This results in a high mortality rate and severe immunosuppression. These immunodepressed chickens are highly susceptible to secondary infections and have a reduced capacity to respond to vaccination. The principal method to control IBDV is through extensive vaccination using either attenuated live or inactivated IBDV vaccines. However, in recent years due to the emergence of new virulent strains, risk of reversion to pathogenicity, cost considerations and intervention by maternal antibodies, the effectiveness of these vaccines in the veterinary field is being reduced. An alternative approach to prevent infection is by interfering with the binding of IBDV to its receptor protein on the surface of bursal cells. Hence this study was undertaken on the characterisation of a possible IBDV receptor on bursal membranes. Infectious bursal disease virus was isolated from infected bursal tissue using CsCl density gradient centrifugation and visualised with Tris-Tricine sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and transmission electron microscopy. Following purification of double stranded RNA from infected bursal tissue and commercially available live IBDV vaccines, a polymerase chain reaction (PCR)-based diagnostic assay based on sequences from the highly conserved viral protein (VP2) region was performed. The presence of the virus was demonstrated by the amplification of a 150 bp band in 2% agarose and 15% nondenaturing PAGE gels. The correctness of this product was confirmed byrestriction digestion with a specific restriction endonuclease (BamHI) that resulted in the predicted digestion fragments of 93 and 57 bp. Following preparation of bursal membrane proteins from uninfected bursal tissue, using sucrose density gradient centrifugation, isolation of IBDV receptor protein was carried out by immobilising IBDV on a Sepharose 4B chromatography matrix. After affinity purification, two prominent protein bands around 40 kDa were visualised using a silver stained Tris-Tricine SDS-PAGE gel. Previous work in this laboratory identified two possible IBDV receptor proteins on bursal membranes of 32 and 40 kDa. Antibodies against peptide sequences derived from the 32 kDa receptor protein were raised in rabbits in the present study. These anti-IBDV receptor peptide antibodies recognised the affinity purified native 40 kDa IBDV receptor proteins in an enzyme-linked immunosorbent assay (ELISA). However, due to the possible epitope denaturation by the reducing treatment buffer prior to Tris-Tricine SDS-PAGE such as SDS and 2-mercapthethanol or detergent (Na-deoxycholate) used during the affinity purification of the IBDV receptor protein, the anti-IBDV receptor peptide antibody did not recognise the receptor protein on a western blot. An inhibition assay was performed in an ELISA format by coating the 40 kDa IBDV receptor protein to see if the anti-IBDV receptor peptide antibody could inhibit IBDV binding to the receptor. The result showed that the anti-IBDV receptor peptide antibody effectively inhibited the binding of IBDV to the receptor. This result could pave the way for reducing IBDV infection by interfering at the viral attachment stage prior to crossing the bursal cell membrane barrier. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The use of antibiotic growth promoters has been limited all around the world because of the concerns about antibiotic resistant bacteria and the presence of antibiotic residues in poultry products. Yeast-derived products are rich sources of ß1,3-1,6-glucan, mannan polysaccharides, and nucleotides and are considered as possible antibiotic alternatives due to their potential intestinal health benefits, growth promotion, and immune system stimulation. The objectives of the current research were: (1) to the evaluate effect of yeast products derived from yeast Saccharomyces cerevisiae on growth performance, gut histomorphology, and innate immune response of broiler chickens; (2) to investigate the effect of yeast products, including distillers dried grains with solubles (DDGS), on innate and antibody-mediated immune response following immunization with different antigens; and (3) to examine the effect of yeast-derived products and DDGS on growth performance, incidence of necrotic enteritis (NE), and local innate immunity in broiler chickens challenged with Clostridium perfringens. Overall, supplementation of diets with yeast products did not affect growth performance of broilers. However, the diets containing yeast cell walls (YCW) and nucleotides increased the villus height in the jejunum and enhanced the number of goblet cells in the ileum. Inclusion of diets with yeast products did not activate the innate immune response of birds under non-pathogen challenge conditions. However, the diet containing YCW activated Th2 cell-mediated immune response in birds immunized with sheep red blood cells and bovine serum albumin. Furthermore, supplementation of diets with YCW and DDGS in birds challenged with Escherichia coli lipopolysaccharide, activated the systemic innate immune response. Regarding antibody-mediated immune response, when compared to the control, serum antibody titer and specific antibody response against different antigens were not affected by dietary treatments. In the C. perfringens challenge study, growth performance, NE lesions and C. perfringens counts in the intestine were not affected by yeast-derived products. However, diets containing YCW and nucleotides stimulated the local innate immune response of birds by upregulation of cytokines and receptors involved in innate immunity. Such findings suggest that the immune-adjuvant like properties of YCW and nucleotides activate the innate immunity of broiler chickens following immunization or challenge with different antigens. / October 2015

This problem consists primarily in determining the numerical value of the leukocytes after different amounts of roentgen rays had been applied to the subjects. The Atomic Energy Commission set up a problem concerning the effects of roentgen rays on the fertility in chickens, and grants were given to two institutions to study this. The blood work in this paper was an off-shoot from one of these five fertility grants.

Call number: LD2668 .T4 1986 M37 / Master of Science / Human Nutrition

Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Animal Sciences and Industry.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

O sucesso da produção animal consiste em menores custos dos fatores de produção. A busca por fontes alternativas na alimentação de frangos de corte, que reduzam custos e mantenham a produtividade, é uma estratégia importante em períodos de crise do setor. Dessa forma, o presente estudo teve como objetivo avaliar os efeitos de diferentes níveis de grãos de sorgo secos por destilação com solúveis em dietas para frangos de corte sobre as características zootécnicas de desempenho (ganho de peso, consumo de ração, conversão alimentar, rendimento de carcaça e cortes), digestibilidade aparente, coloração da carne e viabilidade econômica da utilização do ingrediente. Foram realizados dois ensaios experimentais. No primeiro ensaio, 864 frangos de corte machos da linhagem Cobb, foram distribuídos em seis tratamentos, com 12 repetições de 12 aves cada, criados de 1 a 41 dias de idade para avaliação do desempenho. Aos 42 dias de idade, as aves foram abatidas e submetidas a avaliações da carcaça. No segundo ensaio experimental, 336 pintainhos foram distribuídos em seis tratamentos, com oito repetições de sete aves cada. Foi realizada a coleta de total de excretas de 16 a 19 dias de idade das aves e verificados os parâmetros de digestibilidade aparente. Os tratamentos experimentais atenderam as exigências de Rostagno et al. (2011), sendo isoprotéicas e isoenergéticas. O delineamento experimental foi inteiramente casualizado em ambos ensaios experimentais, sendo 0, 5, 10, 15, 20 e 25% de inclusão de DDGS de sorgo nas dietas. As aves apresentaram menores ganhos de peso médio (p<0,0001) com inclusões de 20 e 25% de DDGS, respectivamente, em relação aos demais tratamentos, nas dietas pré-inicial, inicial, crescimento e durante o período total de criação (1 a 41 dias). O consumo médio de ração também foi menor (p<0,0001) pelas aves com o fornecimento do nível máximo (25% de DDGS de sorgo) nas fases inicial, crescimento e durante todo o período de criação. A conversão alimentar também foi pior (p<0,0001) nas fases pré-inicial, inicial e de 1 a 41 dias nas aves que consumiram dietas com 25% de DDGS de sorgo. Inclusões de 20 ou 25% de DDGS de sorgo nas dietas resultaram em menor (p<0,0001) rendimento de carcaça e rendimento de peito. As digestibilidades aparentes da matéria seca, do extrato etéreo e da energia não diferiram entre o fornecimento de dieta convencional ou com 5% de inclusão de DDGS de sorgo na dieta (p<0,0001). A digestibilidade aparente da proteína bruta e do fósforo não diferiram (p<0,0001) com o fornecimento de dieta convencional ou com até 10% de inclusão do DDGS de sorgo. A luminosidade foi menor (p<0,0001) com inclusão de 20 ou 25% de DDGS nas dietas em relação aos demais tratamentos. Já a intensidade da cor vermelha foi maior (p=0,0009) com o maior nível de inclusão de DDGS de sorgo. A margem bruta foi menor (p<0,0001) no período total de criação com inclusão de 20 e 25% de DDGS de sorgo nas dietas, respectivamente, em relação aos demais tratamentos. É viável a inclusão de até 15% de DDGS de sorgo em dietas para frangos de corte machos. / The success of animal production is based in its lower costs of production factors. The search for alternative sources in broilers diet wich reduce costs and maintain productivity, is an important strategy in times of industry recession. Thus, the present study aimed to evaluate the effects of different levels of sorghum dried distillers grains with solubles in broilers diets on the zootechnical performance features (weight gain, feed intake, feed conversion, yield carcass and cuts), apparent digestibility, meat color and economic viability of the ingredient usage. Two experimental trials were performed. In the first trial, 864 Cobb male broilers, were distributed into six treatments, with 12 replicates of 12 birds each, raised from 1 to 41 days of age for performance evaluation. At 42 days of age, birds were slaughtered and submitted to carcass evaluations. In the second experimental trial, 336 chicks were distributed into six treatments with eight repetitions of seven chicks each. Total excreta was collected for 16-19 day old birds and checked the parameters of apparent digestibility. Experimental treatments met the requirements of Rostagno et al. (2011) and there were isoprotein and isoenergetic feed intakes. A completely randomized design was used in both experimental essays, with 0, 5, 10, 15, 20 and 25% inclusion of sorghum DDGS in diets. The birds gained less average weight (p<0.0001) with inclusions of 20 and 25% sorghum DDGS in diets, respectively, compared to other treatments, in pre-starter, starter, grower and also during the total period of growing (1-41 days). Average feed intake was also lower (p<0.0001) for the supply of birds maximum level (25% sorghum DDGS) at initial, growth and throughout the rearing period. The feed conversion ratio was also worse (p<0.0001) in the pre-starter, starter phases and 1-41 days on the birds fed with 25% sorghum DDGS in diets. Inclusions of 20 or 25% sorghum DDGS in diets resulted in lower (p<0.0001) carcass yield and breast meat yield. Apparent digestibility of dry matter, ether extract and energy did not differ between the supply of conventional diet or 5% inclusion of sorghum DDGS in the diet (p<0.0001). Apparent digestibility of crude protein and phosphorus did not differ (p<0.0001) with providing conventional diet or with up to 10% inclusion of sorghum DDGS. The brightness was lower (p<0.0001) with the inclusion of 20 or 25% DDGS in the diets compared to other treatments. Already the red color intensity was higher (p=0.0009) with the highest level of inclusion of sorghum DDGS. Gross margin was lower (p<0.0001) in the total period including 20 and 25% sorghum DDGS in diets, respectively, compared to other treatments. It is recommended to include up to 15% sorghum DDGS in broilers diets.

The objective of this thesis was to investigate the effect of age and feeding length on phytase efficacy in broiler chickens during the starter phase. Two studies were carried out to evaluate this objective.<br>Study 1 was a randomized complete block design with 4 × 5 factorial arrangements of treatments. There were four diets; a positive control (PC), negative control (NC) and two phytase supplemented diets with inclusion levels of 1,000 and 2,000 phytase units/kg. There were five age and duration of feeding groups; Three 2-d feeding lengths terminated at d 8, 14, and 22 (d 6 to 8, d 12 to 14, and d 20 to 22), a 5-d feeding length terminated at d 14 (d 9 to 14) and a 16-d feeding length terminated on d 22 (d 6 to 22). Growth performance and sample collections were collected at the end of each phase i.e. d 8, 14 and 22. There was a difference (P < 0.01) in weight gain, feed intake, and feed efficiency between birds fed the PC diets and birds fed the NC diets across all groups as birds on the NC diets had lower performance (P < 0.05) than birds on the PC diet. However, birds fed the phytase supplemented diets had higher (P < 0.05) growth performance compared with birds fed the NC diet across all groups. Similarly, phosphorus (P) and calcium (Ca) digestibility and retention of birds fed the NC were lower (P < 0.05) as compared with birds fed the PC diet while birds fed the phytase supplemented diets had higher mineral digestibility and retention (P < 0.05) compared with birds on the NC diet. Age effect was evaluated by comparing the performance of birds fed the experimental diets for 2 d until d 8, 14, and 22. Birds fed until d 14 had the highest impact of the NC diet on mineral utilization, and the largest improvement of phytase on mineral utilization as compared with birds fed until d 8 and 22. Similarly, when feeding length effect was considered, birds fed for a shorter period had greater response to phytase (P < 0.05) on nutrient utilization than birds fed for a longer period at d 14 and 22. Tibia ash was higher (P < 0.05) in birds fed phytase supplemented diets for a longer period (i.e. 16 d) compared with birds fed or 2 or 5 d. The results from this study observed that age and duration of feeding influenced phytase efficacy especially in younger birds fed for a short period. However, it could not be determined if feeding birds for a short period at different ages in the starter phase would have a similar effect.<br>In study 2, the effects of age and feeding low P diets to birds for a short period of time on phytase efficacy and super dosing were evaluated at two critical points in the starter phase. This study had 3 × 2 × 2 factorial arrangements of treatments comprising 3 diets; a PC, NC, and a NC with phytase supplemented at 2,000 phytase units/kg; and 2 ages (i.e d 14 and 22) and 2 feeding lengths (i.e 2-d and 5-d). Thus, birds were fed the experimental diets from d 12 to 14, 9 to 14, 20 to 22, and 17 to 22 respectively. Results observed were similar to the first study. Birds fed the NC diet had lower (P < 0.01) performance as compared with birds fed the PC diets across all age and feeding length groups. Similarly, birds fed diets with the super dose level of phytase had greater growth performance (P < 0.01) compared with birds fed the NC diets. When age effect was considered, birds fed for 2 or 5 d until d 14 had the greatest improvements of phytase on nutrient utilization and bone mineralization compared with birds fed for both periods until d 22. When effect of feeding was considered, birds fed for 2-d at both ages had greater responses to phytase in performance and nutrient utilization compared with birds fed for 5-d at both ages. Plasma myo-inositol was higher (P < 0.01) in birds fed the super dose level of phytase compared with birds fed the NC diet.<br>In summary, we could conclude that the efficacy of phytase both at 1,000 and 2,000 FTU/kg was higher in birds fed for 2 d until d 14 as compared with the other groups. This could potentially help in designing studies to evaluate new phytase products or for comparing the efficacy of phytase from various sources. Feeding broiler chickens during the suggested time phase would potentially reveal the maximum efficacy of the phytase product.<br>

Orientador: Raphael Lucio Andreati Filho / Resumo: Este estudo foi conduzido com o objetivo de avaliar a capacidade protetora de Lactobacillus spp. em frangos de corte desafiados com Salmonella Enteritidis, utilizando-o como tratamento no primeiro dia de idade, e posterior desafio com Salmonella Enteritidis fagotipo 04, observando-se possíveis alterações histopatológicas e imunológicas na mucosa intestinal, como o comprimento das vilosidades, a produção de imunoglobulina A e o peso corporal. Foi observada maior eficácia do tratamento com Lactobacillus spp. somente quando as aves foram desafiadas com Salmonella Enteritidis aos 21 dias de idade. O comprimento das vilosidades intestinais apresentou-se reduzido após os desafios, mostrando posterior regeneração. Com o desafio de Salmonella Enteritidis ocorrendo no terceiro dia de idade, verificou-se que aves jovens possuem maior sensibilidade à infecção. / Abstract: This study was driven with the objective of evaluate the protective capacity of Lactobacillus spp. in chickens challenged with Salmonella Enteritidis, utilizing as handling on one-day old chicks and posterior challenge with Salmonella Enteritidis phagotype 04, observing possible histopathological and immunological alterations in the intestinal mucosa, like the length of the villus, the production of immunoglobulin A and body weight. Greater efficacy in the treatment with Lactobacillus ssp. was observed only when the chicks were challenged with Salmonella Enteritidis at 21 days old. The length of the intestinal villus always diminished after challenge, regenerating later. After the first challenge of with Salmonella Enteritidis (at three-days old), we verified that young chicks possess a greater sensibility to infection. / Mestre