Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Acute Interstitial Pneumonia (AIP) is a costly issue that affects feedlot cattle, especially during hot and dry summers. Research has yet to elucidate the exact etiology of AIP; therefore this study was conducted to determine possible factors that contribute to AIP in feedlot cattle. During the summer of 2011 in a 55,000 head feedyard in southwest Kansas, animals exhibiting clinical signs of AIP were selected for ante-mortem examination and data collection. The animal population within the feedlot consisted of 75% heifers and 25% steers. Approximately 50% of the animal population was black hided animals. Ante-mortem data consisted of rumen gas cap measurement for NH3 and H2S, rumen pH, serum chemistry, rectal temperature, and body weight. Post-mortem cases with and without ante-mortem evaluations were also selected for an additional examination. Postmortem examination included similar data as ante-mortem examination with addition of visual and histological examination of lung tissue. There were 31 ante-mortem cases of clinical AIP with the following observations (mean ± SD): rectal temperature 105.3 ± 0.7 °F, weight 1098 ± 123 lbs., H2S 136 ± 133.3 ppm, and rumen pH 6.4 ± 0.5. Twenty-five healthy cohorts were selected from identical pens to serve as controls. Observations from control animals were: rectal temperature 103.7 ± 1.1 °F, weight 1113 ± 133.3lbs, H2S 269.8 ± 311.6 ppm and rumen pH 6.2 ± 0.6. A total of 61 post-mortem cases with a preliminary diagnosis of AIP were analyzed and displayed the following values: H2S 1279.7 ± 1569 ppm, and rumen pH 6.3 ± 0.36. Fifty-three of these postmortem cases had diffuse, focal and /or patchy AIP confirmed by histology.

Regardless of the type of diet used, the search for increased digestion of nutrients has been the target of most research worldwide. The objective of this thesis was to evaluate the effects of the inclusion of essential oils, enzymes, ionophores and combinations of additives in animal performance, ruminal health and apparent digestibility in Nellore cattle fed with high concentrate diets. The study was composed of two performance experiments and two of metabolism In Chapter 1 of this thesis 2 experiments were conducted to evaluate the performance responses of finishing feedlot cattle receiving diets containing essential oils and exogenous enzymes. The treatments in each experiment consisted of (dry matter basis): MON - sodium monensin (26 mg/kg); BEO - a blend of essential oils (90 mg/kg); BEO+MON - a blend of essential oils plus monensin (90 mg/kg + 26 mg/kg, respectively); BEO+AM - a blend of essential oils plus exogenous α-amylase (90 mg/kg + 560 mg/kg, respectively); and BEO+AM+PRO - a blend of essential oils plus exogenous α-amylase and exogenous protease (90 mg/kg + 560 mg/kg + 840, mg/kg respectively). Exp. 1 consisted of a 93-d finishing period using 300 Nellore bulls in a randomized complete block design. Compared with MON, the combination of BEO+AM resulted in greater dry matter intake, greater average daily gain, 12 kg heavier hot carcass weight, although feed efficiency was not significantly different between BEO+AM and MON. BEO+MON and BEO did not improve performance when compared to MON. In Exp. 2, five ruminally cannulated Nellore steers were used to evaluate intake, apparent total tract digestibility of nutrients, and ruminal parameters in a 5 × 5 Latin Square design. Intakes of all nutrients measured, except for EE were greater in animals fed BEO+AM when compared with MON, with no differences on total tract nutrient digestibilities between these two treatments. Feeding BEO increased the total tract digestibility of CP compared to MON. In summary, diets containing the BEO used herein enhanced dry matter intake of growing-finishing feedlot cattle compared with a basal diet containing MON without impair feed efficiency. A synergism between BEO and AM was detected, resulting in increased carcass production. This study evaluated the growth performance and digestion responses of finishing feedlot beef cattle fed high-concentrate diets containing 82.5% flint corn (DM basis) ground to medium (1.66 mm; MG) or coarse particle sizes (2.12 mm; CG), added with monensin (26 mg/kg; DM basis; MON) or a blend of essential oils + exogenous α-amylase (90 mg/kg + 560 mg/kg commercial product, respectively, DM basis; BEO+AM). In Exp. 1, 256 Nellore bulls were blocked by initial body weight (360 ± 12 kg), assigned to 48 pens and pens within blocks were randomly assigned, in a 2 × 2 factorial arrangement, to treatments during 99 d. Feed additive effect was detected for DMI, which was greater for bulls fed BEO+AM vs. MON. The HCW was 11 kg heavier for bulls fed BEO+AM vs. MON in diets containing CG, but not MG particle size. In Exp. 2, four ruminally cannulated Nellore steers were offered the same treatments of Exp. 1, in a 4 × 4 Latin Square design, to evaluate intake, apparent total tract digestibility of diets and ruminal fermentation parameters. Effect of corn particle size was detected for intake of DM, CP, NDF, NFC, starch and TDN which were greater for steers fed CG than steers fed MG corn. Feed additive affected (P = 0.02) ruminal NH3-N concentration, which was less for steers fed BEO+AM compared to MON. In summary, reducing flint corn particle size from 2.12 to 1.66 mm in finishing diets failed to improve cattle growth performance, digestibility of most nutrients and ruminal fermentation characteristics. A blend of essential oils associated with exogenous α-amylase resulted in the heavier carcass weights compared to monensin supplementation when included in diets containing coarse ground corn. / Independente do tipo de dieta utilizada, a busca por aumento da digestão dos nutrientes tem sido alvo da maior parte das pesquisas realizadas no mundo. O objetivo dessa tese foi avaliar os efeitos da inclusão de óleos essenciais, enzimas, ionóforos e combinações de aditivos na performance animal, saúde ruminal e digestibilidade aparente em bovinos de corte da raça Nelore confinados alimentados com dietas de terminação com alto concentrado. O estudo foi composto por dois experimentos de desempenho e dois de metabolismo. No Capítulo 1 dessa tese 2 experimentos foram conduzidos para avaliar o desempenho de bovinos terminados em confinamento recebendo dietas que continham óleos essências e enzimas exógenas. Os tratamentos em cada experimento consistiram em: MON (monensina sódica, 26 mg/Kg); BEO (blend de óleos essenciais - 90 mg/kg); BEO+MON; BEO+AM (blend de óleos essenciais mais α-amilase - 90 mg/kg + 560 mg/kg, respectivamente) e BEO+AM+PRO (óleos essenciais mais α-amilase mais protease (90 mg/kg + 560 mg/kg + 840 mg/kg, respectivamente). No Exp. 1 foram utilizados 300 animais Nelore distribuídos aleatoriamente em 60 baias. Comparado com MON, a combinação BEO+AM resultou em maior CMS, maior GPD e proporcionou 12 kg a mais de carcaça, sem alterar a eficiência alimentar. BEO+MON e BEO não proporcionaram melhora no desempenho, quando comparada com MON. No Exp. 2, 5 animais canulados no rúmen foram usados para avaliar, CMS, digestibilidade aparente dos nutrientes e parâmetros ruminais em um quadrado latino 5 x 5. BEO aumentou a digestibilidade no trato total da PB comparada com MON. Os consumos de todos nutrientes, com exceção de EE foram maiores para animais alimentados com BEO+AM, quando comparados com MON, sem diferenças na digestibilidade no trato total. Em resumo, BEO aumenta o CMS de animais confinados em relação a MON, sem alterar a eficiência alimentar. Um sinergismo entre BEO e AM foi observado, resultando em aumento da produção de carcaça. No Capítulo 2, avaliou-se o desempenho e respostas metabólicas de animais confinados recebendo dietas com alto teor de milho (82.5% da MS), processado em moído (1,66 mm; MG) e moído grosso (2,12 mm; CG), combinado com monensina (monensina sódica, 26 mg/Kg; MON) ou com blend de óleos essenciais mais α-amilase (90 mg/kg + 560 mg/kg, respectivamente; BEO+MON). No Exp. 1, 256 animais Nelore foram blocados em 48 baias, as quais foram distribuídas aleatoriamente a um arranjo fatorial 2 x 2 nos tratamentos por 99 dias. Animais alimentados com BEO+MON apresentaram maior CMS do que animais alimentados com MON. Foi observada interação entre processamento e aditivo para PCQ, na qual animal alimentados com BEO+MON e CG obtiveram 11 kg a mais. No Exp. 2, quatro animais canulados no rúmen foram assimilados as mesmos tratamentos do Exp. 1, em um quadrado latino 4 x 4. Efeito de processamento foi detectado no consumo de MS, PB, FDN, CNF, amido e NDT, os quais foram maiores para animais alimentados com milho CG do que MG. Efeito de aditivo foi observado na concentração de NH3-N ruminal, a qual foi menor para animais alimentados com BEO+AM comparado a animais que receberam MON. Em suma, reduzir o tamanho de partícula de 2,12 mm para 1,66 mm não melhorou o desempenho e os parâmetros de fermentação ruminal. A suplementação com BEO+AM resulta em maior produção de carcaça comparada com monensina, quando incluída em dietas com milho moído grosseiramente.

O surgimento de mercados consumidores cada vez mais exigentes quanto a segurança alimentar é uma realidade crescente. A proibição do uso de antibióticos promotores de crescimento, como a monensina, pela União Europeia é um indicativo disto. Em busca de alternativas aos antibióticos, intensificou-se na última década os trabalhos de pesquisa que visam explorar e desenvolver alternativas economicamente interessantes para a produção animal. Neste sentido, objetivou-se neste trabalho, avaliar o uso de princípios ativos extraídos dos óleos de caju e mamona como moduladores da fermentação ruminal alternativos à monensina sódica. Foram realizados seis experimentos. Um experimento de desempenho, com animais confinados a fim de mensurar o GPD, CMS, eficiência alimentar, características de carcaça. Outro experimento para avaliação de características metabólicas, com a avaliação de CMS, digestibilidade da MS, características da fermentação ruminal, consumo de oxigênio, produção de calor e de metano. Também foi realizado um experimento in vitro para a avaliação da produção de gás e tempo de colonização. Este conjunto de três experimentos foi realizado em uma a base de coprodutos e outra a base de milho moído. A dieta a base de coprodutos foi composta por 5% de bagaço de cana, 50 % de farelo úmido de glutem de milho, 43,5% de casca de soja, 1,5% de núcleo mineral, sendo avaliados os seguintes tratamentos: T1 - Controle, que consistiu em dieta base, sem aditivos; T2 - dieta base com adição de monensina sódica na dose de 25 mg/kg MS; T3 - dieta base com adição de Essential® na dose de 300 mg/kg MS e T4 - dieta base com adição de monensina sódica (25 mg/kg MS) e Essential® (300 mg/kg MS). A dieta a base de milho moído foi constituída de 12% de feno de tyfton, 80 % de milho moído, 4% de farelo de soja, 2,5% de núcleo mineral e 1,5% de uréia e foram avaliados os seguintes tratamentos: T1 - Controle, que consistiu em uma dieta base, sem aditivos; T2 - dieta base com adição de monensina sódica na dose de 30 mg/kg MS; T3 - dieta base com adição de Essential® na dose de 300 mg/kg MS; e T4 - dieta base com adição de Essential® na dose de 500 mg/kg MS. Para o experimento de metabolismo com a dieta a base de milho, foi utilizado bagaço de cana como volumoso e os tratamentos foram os os mesmos aplicados na dieta a base de coprodutos: Os tratamentos foram: T1 - Controle, que consistiu em dieta base, sem aditivos; T2 - dieta base com adição de monensina sódica na dose de 25 mg/kg MS; T3 - dieta base com adição de Essential® na dose de 300 mg/kg MS; e T4 - dieta base com adição de monensina sódica (25 mg/kg MS) e Essential® (300 mg/kg MS). A suplementação com OF melhora o desempenho de bovinos na fase inicial do confinamento em relação ao não uso de aditivos ou ao uso de monensina sódica, porém essa vantagem não se mantêm ao longo do período total de confinamento. Ao contrário do esperado, no presente estudo os aditivos testados não contribuíram para o aumento da eficiência de produção de bovinos em confinamento e para a redução do seu impacto ambiental. / The emergence of increasingly demanding consumer markets as food safety is a growing reality. The ban on antibiotic growth promoters such as monensin, by the European Union is indicative of this. Thus, research looking for alternatives to antibiotics, has been intensified in the last decade, with research works aimed at exploring and developing economically attractive alternative to animal production. In this sense. The aim of this study was to evaluate the use of active ingredients extracted from cashew oils and castor as modulators of ruminal fermentation alternative to monensin. Six experiments were carried out. A performance experiment with animals confined in order to measure the GPD, CMS, feed efficiency, carcass characteristics. Another experiment to evaluate metabolic characteristics with the assessment of CMS, digestibility, ruminal fermentation characteristics, oxygen consumption, heat and methane production. Also an in vitro experiment for evaluation of gas production and colonization time was conducted. This set of three experiments was carried out on two base diets, one with ground corn and other with byproducts. Ground corn basal diet consisted of 12% of tyfton hay, 80% of ground corn, 4% soybean meal, 2.5% mineral mixture and 1.5% urea. The treatments were: T1 - control, which consisted of basal diet, no additives; T2 - basal diet with addition of sodium monensina (30 mg / kg DM); T3 - basal diet added Essential® (300 mg / kg DM); and T4 - basal diet added Essential® (500 mg / kg DM). The bast dosis of functional oils were used in a second trial that used combination of functional oils and monensis. In the second trial was used a byproducts base diet comprised 5% of sugar cane bagasse, 50% of wet corn gluten feed, 43.5% of soybean hulls, 1.5% mineral mixture, being evaluated the following treatments: T1 - control, which consisted of basal diet without additives; T2 - basal diet with addition of sodium monensina (25 mg / kg DM); T3 - basal diet added Essential® (300 mg / kg DM); and T4 - basal diet with addition of sodium monensin (25 mg / kg DM) plus Essential® (300 mg / kg DM). For metabolism experiment with diet from corn was used bagasse as roughage and treatments were: T1 - control, which consisted of basal diet without additives; T2 - basal diet with addition of sodium monensina (25 mg / kg DM); T3 - basal diet added Essential® (300 mg / kg DM); and T4 - basal diet with addition of sodium monensin (25 mg / kg DM) plus Essential® (300 mg / kg DM). Functional oils supplementation improves performance of feedlot cattle during the initial phase with the non-use of additives or the use of monensina only. However , this advantage is not maintained over the total period of feedlot. In study, evaluated additives did not contribute to the increase feedlot cattle performance and to reduce their environmental impact.

O objetivo desse experimento foi avaliar a inclusão (7 e 15% com base em MS), de 2 co-produtos, derivados da indústria de ácido cítrico: Micélio (77% de FDN e 0,5% de lignina com base em MS) e Raffinate (25,5% de açúcares solúveis e 32% de fibra solúvel com base em MS) em dietas com alto teores de milho do tipo Flint para 200 tourinhos Nelore em terminação (peso inicial = 396,4 ± 37,7kg). Os animais foram blocados com base no peso inicial e foram distribuídos aleatoriamente em 25 baias. A dieta controle conteve 11,73% de bagaço de cana de açúcar, 67,2% de milho moído, 18% de farelo proteinoso de milho, 2,07% de suplemento mineral e 1% de ureia. Os outros 4 tratamentos foram: Micélio 7, Micélio 15, Raffinate 7 e Raffinate 15. Os co-produtos substituíram parcialmente o milho nas dietas. Os parâmetros avaliados foram ingestão de matéria seca (IMS), ganho médio diário (GMD), eficiência alimentar (GMD/IMS) e características de carcaça. Os dados foram analisados pelo PROC MIXED do SAS e as médias foram comparadas por contrastes, considerando blocos como efeito aleatório e tratamento como efeito fixo. A inclusão de 7 e 15% de Micélio na dieta (base seca) em substituição parcial ao milho \"flint\" moído aumentou (P=0,1) de forma quadrática o CMS. Já os animais alimentados com dietas contendo Raffinate apresentaram aumento linear no CMS (P<0,1) em relação ao tratamento controle e também maior CMS quando comparados com os animais que receberam o tratamento Micélio (P<0,1). Não houve diferença na eficiência alimentar (GPD/CMS) entre os tratamentos (P > 0,1). A inclusão de ambos co-produtos (Micélio ou Rafinatte) resultou em aumento no GDP dos animais (P< 0,1). O efeito positivo foi quadrático (P<0,1) para a inclusão de Micélio e linear (P<0,1) para a inclusão de Raffinate. A densidade energética das dietas não foi alterada pela inclusão de co-produtos. Não houve efeito de tratamento (P> 0.01) para as características de carcaça. Os valores médios para rendimento de carcaça (%), espessura de gordura subcutânea (mm) e áreas de olho de lombo (cm2) foram 53,79, 2,84 e 64,08 respectivamente. A inclusão de 7% de Micélio ou de 15% de Raffinate melhora o GPD dos animais em virtude do maior CMS. Micélio, Rafinate e milho \"flint\" moído têm o mesmo valor energético para bovinos em Terminação. / The objective of this experiment was to evaluate the inclusion (7 and 15%, DM basis) of two corn by-products derived from the citric acid industry: Micelio (77% NDF, 0.5% lignin, DM basis) and Raffinate (25.5% soluble sugars, 32% soluble fiber, DM basis) in diets with high levels of flint corn fed to 200 finishing Nellore bulls (initial BW = 396.4 ± 37.7 kg). Animals were blocked according to initial BW and randomly allocated to 25 pens. The control diet contained 11.73% sugarcane bagasse, 67.2% corn, 18% corn gluten feed, 2.07% mineral supplement and 1% urea. The other four treatments were Micelio 7, Micelio 15, Raffinate 7 and Raffinate15. The by-products partially replaced corn in the diets. The parameters evaluated were dry matter intake (DMI), average daily gain (ADG), feed efficiency (ADG/DMI) and carcass traits. The data were analyzed using PROC MIXED of SAS and means were compared by contrasts, considering the block as random effect and treatment as fixed effect. The inclusion of 7 and 15% of Micelio in the diet (dry basis) in partial replacement of ground corn increased (P = 0.1) DMI quadratically. The animals fed diets containing Raffinate showed linear increase in DMI (P <0.1) compared to the control treatment and DMI was, also higher when compared with animals that received the Micelio treatment (P <0.1). There were no differences in feed efficiency (ADG / DMI) among treatments (P> 0.1). The inclusion of both by-products (Micelio or Rafinatte) resulted in an increase in ADG animals (P <0.1). The positive effect is quadratic (P <0.1) for adding Micelio and linear (P <0.1) for adding Raffinate. The energy density of the diet was not altered by the inclusion of by-products. There was no treatment effect (P> 0.01) for carcass traits Average values for dressing (%), back fat thickness (mm) and rib eye area (cm2) were 53.79, 2.84, and 64.08, respectively. The inclusion of 7 or 15% of Micelio or Raffinate in partial replacement of ground flint corn in finishing diets does not affect cattle performance. The inclusion of 7% of Micelio or a 15% Raffinate improved ADG of animals because of the increased DMI. Micelio, Raffinate and ground corn have the same energy value for cattle finishing.

Two trials were conducted, one using crossbred steers (Trial 1; N=275; 376±24 kg) and a second using Hereford heifers (Trial 2; N=5; 420±6 kg) to evaluate the performance, carcass quality, rumen fermentation and nutrient digestibility of cattle fed wheat or corn dried distillers grains with solubles (DDGS). The control ration averaged 87.7% rolled barley grain, 5.6% supplement and 6.8% barley silage (DM basis) over both trials. Dietary treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. For Trial 1, steers were slaughtered at a constant finish weight of 645 kg. Data was analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS quadratically increased dry matter intake (DMI) (P<0.01), whereas increasing levels of corn DDGS quadratically decreased DMI (P=0.01). Average daily gain was not influenced (P=0.13) by feeding wheat or corn DDGS but cattle fed corn DDGS exhibited a quadratic increase (P=0.01) in gain:feed. As a result, a quadratic increase (P<0.01) in calculated NEg of the diet was observed as corn DDGS levels increased. A linear decrease (P=0.04) in days on feed (169, 166 and 154 days) was noted when increasing levels of wheat DDGS (0, 20 and 40%) were fed. Dressing percentage increased in a linear fashion with wheat DDGS (P<0.01) inclusion level and in a quadratic fashion (P=0.01) as corn DDGS inclusion level increased although other carcass traits were not affected (P>0.10) by treatment.<p> Trial 2 evaluated the effects of corn and wheat DDGS on rumen fermentation and nutrient digestibility parameters. Rumen pH, duration and area under rumen pH thresholds of 5.8, 5.5 and 5.2 were not affected (P>0.05) by treatment. Wheat DDGS inclusion increased (P=0.01) rumen ammonia-N levels in a linear fashion, while the inclusion of both wheat and corn DDGS resulted in quadratic (P=0.01) and linear (P=0.01) increases in butyrate concentration, respectively. Feeding corn DDGS also decreased total rumination time linearly (P=0.01) and DMI in a quadratic (P=0.04) fashion. Feeding wheat DDGS decreased (P=0.01) DM digestibility in a linear fashion. Wheat and corn DDGS inclusion quadratically increased (P=0.01) the digestibility of crude fat while feeding corn DDGS also linearly increased (P=0.01) the digestibility of crude protein. Neutral detergent fiber digestibility increased in a linear fashion (P=0.01) as both wheat and corn DDGS inclusion increased while ADF digestibility increased in a linear fashion (P=0.03) for wheat and in a quadratic (P=0.02) fashion for corn DDGS. The digestibility of both NDIN and ADIN increased (P=0.01) in a quadratic fashion for both corn and wheat DDGS inclusion level. Increased inclusions of wheat DDGS resulted in a linear decrease in gross energy digestibility (P=0.01), but neither wheat nor corn DDGS inclusion affected diet digestible energy content (P>0.05). Feeding both wheat and corn DDGS increased (P=0.01) the excretion of nitrogen and phosphorus.<p> Replacement of barley grain with up to 40% corn or wheat DDGS improved gain:feed and reduced days on feed, respectively with no detrimental effect on carcass quality grade or sub-primal boneless boxed beef yield. The results of this project also indicate that the inclusion of corn and wheat DDGS (up to 40%) in feedlot rations does not mitigate ruminal acidosis, however the inclusion of both byproducts strongly impacts nutrient (crude fat, ADF, NDF, ADIN and NDIN) digestibility.

This research used classical and molecular epidemiology tools to assess the potential importance of feedlot cattle as Campylobacter reservoirs. The project was conducted from November 2004 to September 2005 in southern Alberta.<p> Fresh pen-floor fecal samples were collected from commercial feedlot cattle near slaughter weight in seven feedlots. Overall, 87% of 2,776 fecal samples were culture positive for Campylobacter species (86% of 1,400 in winter, 88% of 1,376 in summer), and 69% of 1,486 Campylobacter positive isolates were identified as <i>Campylobacter jejuni</i>. After accounting for clustering within pen and feedlot, the number of days-on-feed and feedlot size were associated (p ¡Ü 0.05) with Campylobacter species isolation rates.<p> Retail ground beef was collected from 60 grocery stores (four chains, three cities). None of the 1,200 packages were culture positive for Campylobacter species. Polymerase chain reaction (PCR) results from a subset of samples (n=142) indicated that 48% of packages were positive for Campylobacter DNA. By species, 14.8% (21/142), 26.8% (38/142) and 1.4% (2/142) of packages were PCR positive for <i>C. jejuni</i>, <i>C. coli</i> and <i>C. hyointestinalis</i> DNA, respectively. The collection period (1, 2, 3 or 4) was associated (p ¡Ü 0.05) with the odds of detecting Campylobacter species DNA using PCR.<p> Oligonucleotide DNA microarrays were used as a platform for comparative genomic hybridization (CGH) analysis of 87 C. jejuni isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Of the 13 CGH clusters identified based on overall comparative genomic profile similarity, nine contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. In addition, human clinical and feedlot cattle C. jejuni isolates were compared on a gene-by-gene basis and only a small number of the 1,399 genes tested were unequally distributed between the two groups (p ¡Ü 0.05).<p> The high isolation rates of Campylobacter species and <i>C. jejuni</i> reported here may have implications for food safety, public health and environmental contamination. Our findings suggest that feedlot cattle and human <i>C. jejuni</i>strains are very similar and may be endemic within southern Alberta.

<i>Mycoplasma bovis</i> is generally considered the causative pathogen associated with Chronic Pneumonia and Polyarthritis Syndrome (CPPS) in feedlot cattle. However, <i>M. bovis</i> virulence may vary between strains as it is also isolated from asympytomatic cattle. The following study aims to determine the prevalence of <i>M. bovis</i> in the respiratory tract of western Canadian cattle using two sampling methods and at two time points following feedlot entry. Three study groups were sampled. In the first group nasal swabs (NS) and bronchoalveolar lavages (BAL) were taken from 36 clincally healthy cattle at the University of Saskatchewan feedlot at both 14 and 90 days on feed (DOF). In a second experiment, NS were taken from 56 animals upon arrival at a commercial feedlot and one week to three months later upon treatment for respiratory disease. Lung and joint tissue swabs were collected at necropsy from a third group of 19 animals with CPPS clinical pathology originating in 10 different western Canadian feedlots. All samples were selectively cultured for <i>Mycoplasma</i> spp. DNA was extracted from isolated putative <i>Mycoplasma</i> colonies and amplified with universal 16S rRNA gene primers for identification. Amplified Fragment Length Polymorphism (AFLP) was used to genetically differentiate <i>M. bovis</i> positive isolates. More <i>M. bovis</i> was isolated from NS than BAL and <i>M. bovis</i> prevalence increased with DOF in the feedlot in both the University of Saskatchewan and commercial feedlot trials. Three genetically distinct clusters (A, B, and C) were isolated from the necropsy group. Two of these clusters were primarily associated with isolates collected from feedlot cattle and one strain was exclusively found in CPPS-associated mortalities. No significance difference in the prevalence of <i>M. bovis</i> strains was observed between different days on feed or sampling methods. It was concluded that either the difference in disease state is a host dependent outcome, due to a multi-factorial disease complex, or the AFLP assay was not sensitive enough to differentiate strains based on virulence.

This research used classical and molecular epidemiology tools to assess the potential importance of feedlot cattle as Campylobacter reservoirs. The project was conducted from November 2004 to September 2005 in southern Alberta.<p> Fresh pen-floor fecal samples were collected from commercial feedlot cattle near slaughter weight in seven feedlots. Overall, 87% of 2,776 fecal samples were culture positive for Campylobacter species (86% of 1,400 in winter, 88% of 1,376 in summer), and 69% of 1,486 Campylobacter positive isolates were identified as <i>Campylobacter jejuni</i>. After accounting for clustering within pen and feedlot, the number of days-on-feed and feedlot size were associated (p ¡Ü 0.05) with Campylobacter species isolation rates.<p> Retail ground beef was collected from 60 grocery stores (four chains, three cities). None of the 1,200 packages were culture positive for Campylobacter species. Polymerase chain reaction (PCR) results from a subset of samples (n=142) indicated that 48% of packages were positive for Campylobacter DNA. By species, 14.8% (21/142), 26.8% (38/142) and 1.4% (2/142) of packages were PCR positive for <i>C. jejuni</i>, <i>C. coli</i> and <i>C. hyointestinalis</i> DNA, respectively. The collection period (1, 2, 3 or 4) was associated (p ¡Ü 0.05) with the odds of detecting Campylobacter species DNA using PCR.<p> Oligonucleotide DNA microarrays were used as a platform for comparative genomic hybridization (CGH) analysis of 87 C. jejuni isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Of the 13 CGH clusters identified based on overall comparative genomic profile similarity, nine contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. In addition, human clinical and feedlot cattle C. jejuni isolates were compared on a gene-by-gene basis and only a small number of the 1,399 genes tested were unequally distributed between the two groups (p ¡Ü 0.05).<p> The high isolation rates of Campylobacter species and <i>C. jejuni</i> reported here may have implications for food safety, public health and environmental contamination. Our findings suggest that feedlot cattle and human <i>C. jejuni</i>strains are very similar and may be endemic within southern Alberta.

Two trials were conducted, one using crossbred steers (Trial 1; N=275; 376±24 kg) and a second using Hereford heifers (Trial 2; N=5; 420±6 kg) to evaluate the performance, carcass quality, rumen fermentation and nutrient digestibility of cattle fed wheat or corn dried distillers grains with solubles (DDGS). The control ration averaged 87.7% rolled barley grain, 5.6% supplement and 6.8% barley silage (DM basis) over both trials. Dietary treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. For Trial 1, steers were slaughtered at a constant finish weight of 645 kg. Data was analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS quadratically increased dry matter intake (DMI) (P<0.01), whereas increasing levels of corn DDGS quadratically decreased DMI (P=0.01). Average daily gain was not influenced (P=0.13) by feeding wheat or corn DDGS but cattle fed corn DDGS exhibited a quadratic increase (P=0.01) in gain:feed. As a result, a quadratic increase (P<0.01) in calculated NEg of the diet was observed as corn DDGS levels increased. A linear decrease (P=0.04) in days on feed (169, 166 and 154 days) was noted when increasing levels of wheat DDGS (0, 20 and 40%) were fed. Dressing percentage increased in a linear fashion with wheat DDGS (P<0.01) inclusion level and in a quadratic fashion (P=0.01) as corn DDGS inclusion level increased although other carcass traits were not affected (P>0.10) by treatment.<p> Trial 2 evaluated the effects of corn and wheat DDGS on rumen fermentation and nutrient digestibility parameters. Rumen pH, duration and area under rumen pH thresholds of 5.8, 5.5 and 5.2 were not affected (P>0.05) by treatment. Wheat DDGS inclusion increased (P=0.01) rumen ammonia-N levels in a linear fashion, while the inclusion of both wheat and corn DDGS resulted in quadratic (P=0.01) and linear (P=0.01) increases in butyrate concentration, respectively. Feeding corn DDGS also decreased total rumination time linearly (P=0.01) and DMI in a quadratic (P=0.04) fashion. Feeding wheat DDGS decreased (P=0.01) DM digestibility in a linear fashion. Wheat and corn DDGS inclusion quadratically increased (P=0.01) the digestibility of crude fat while feeding corn DDGS also linearly increased (P=0.01) the digestibility of crude protein. Neutral detergent fiber digestibility increased in a linear fashion (P=0.01) as both wheat and corn DDGS inclusion increased while ADF digestibility increased in a linear fashion (P=0.03) for wheat and in a quadratic (P=0.02) fashion for corn DDGS. The digestibility of both NDIN and ADIN increased (P=0.01) in a quadratic fashion for both corn and wheat DDGS inclusion level. Increased inclusions of wheat DDGS resulted in a linear decrease in gross energy digestibility (P=0.01), but neither wheat nor corn DDGS inclusion affected diet digestible energy content (P>0.05). Feeding both wheat and corn DDGS increased (P=0.01) the excretion of nitrogen and phosphorus.<p> Replacement of barley grain with up to 40% corn or wheat DDGS improved gain:feed and reduced days on feed, respectively with no detrimental effect on carcass quality grade or sub-primal boneless boxed beef yield. The results of this project also indicate that the inclusion of corn and wheat DDGS (up to 40%) in feedlot rations does not mitigate ruminal acidosis, however the inclusion of both byproducts strongly impacts nutrient (crude fat, ADF, NDF, ADIN and NDIN) digestibility.

<i>Mycoplasma bovis</i> is generally considered the causative pathogen associated with Chronic Pneumonia and Polyarthritis Syndrome (CPPS) in feedlot cattle. However, <i>M. bovis</i> virulence may vary between strains as it is also isolated from asympytomatic cattle. The following study aims to determine the prevalence of <i>M. bovis</i> in the respiratory tract of western Canadian cattle using two sampling methods and at two time points following feedlot entry. Three study groups were sampled. In the first group nasal swabs (NS) and bronchoalveolar lavages (BAL) were taken from 36 clincally healthy cattle at the University of Saskatchewan feedlot at both 14 and 90 days on feed (DOF). In a second experiment, NS were taken from 56 animals upon arrival at a commercial feedlot and one week to three months later upon treatment for respiratory disease. Lung and joint tissue swabs were collected at necropsy from a third group of 19 animals with CPPS clinical pathology originating in 10 different western Canadian feedlots. All samples were selectively cultured for <i>Mycoplasma</i> spp. DNA was extracted from isolated putative <i>Mycoplasma</i> colonies and amplified with universal 16S rRNA gene primers for identification. Amplified Fragment Length Polymorphism (AFLP) was used to genetically differentiate <i>M. bovis</i> positive isolates. More <i>M. bovis</i> was isolated from NS than BAL and <i>M. bovis</i> prevalence increased with DOF in the feedlot in both the University of Saskatchewan and commercial feedlot trials. Three genetically distinct clusters (A, B, and C) were isolated from the necropsy group. Two of these clusters were primarily associated with isolates collected from feedlot cattle and one strain was exclusively found in CPPS-associated mortalities. No significance difference in the prevalence of <i>M. bovis</i> strains was observed between different days on feed or sampling methods. It was concluded that either the difference in disease state is a host dependent outcome, due to a multi-factorial disease complex, or the AFLP assay was not sensitive enough to differentiate strains based on virulence.