Escherichia coli O157:H7 is an important human pathogen that resides primarily in cattle and feedlot environments. E. coli O157:H7 can be divided into phylogenetic groups termed lineages; lineage I strains are responsible for most human illnesses. An understanding of the etiology of these lineages within cattle and the feedlot environment could allow for more effective surveillance and mitigation strategies. There were no lineage associated differences in growth or survival of E. coli O157:H7 in bovine feces at 4°C, 12°C or 25°C. Lineage I strains more readily colonized cattle jejunum tissue and a bovine colonic cell line than lineage II and intermediate type strains. Enhanced colonization of cattle by lineage I strains may increase the persistence of these strains in feedlots via re-infection and increased shedding. This outcome could increase the transmission of lineage I strains to the food supply and increase the potential for these strains to cause human illness. / xiii, 101 leaves ; 29 cm

Mannheimia haemolytica is an opportunistic pathogen in cattle and the main bacterial agent in bovine respiratory disease. Despite its economic importance, few studies have characterized the genetic diversity of M. haemolytica, particularly from feedlots. Three genotyping techniques (BOX-PCR, (GTG)5-PCR and PFGE) were compared to discriminate M. haemolytica and strains from the family Pasteurellaceae. PFGE was the most discriminating and repeatable, although BOX-PCR was most accurate in clustering isolates together according to species. Mannheimia haemolytica was isolated from nasal swab samples collected from cattle upon entry and exit from two feedlots in southern Alberta. These were characterized by PFGE and antimicrobial susceptibility using a disk-diffusion assay. Select gene determinants were screened for using PCR. PFGE analysis revealed the isolates to be highly diverse. Ten percent of the isolates exhibited resistance. At present, the development and spread of antimicrobial resistance in M. haemolytica observed within the feedlots examined appears to be low. / xi, 116 leaves : ill. ; 29 cm

Made available in DSpace on 2014-06-11T19:32:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-10Bitstream added on 2014-06-13T21:05:21Z : No. of bitstreams: 1 fiorentini_g_dr_jabo.pdf: 560812 bytes, checksum: 01aaca56def2f62af0e1ab346238e009 (MD5) / O objetivo deste trabalho foi avaliar o efeito de fontes lipídicas com diferentes perfis de ácidos graxos sobre o consumo de nutrientes, digestibilidade, parâmetros fermentativos, microbiota ruminal, desempenho, emissão de metano entérico e características qualitativas da carcaça e da carne de novilhos Nelore terminados em confinamento. Na avaliação de consumo, desempenho, emissão de metano e características qualitativas da carcaça e da carne foram utilizados 45 novilhos castrados da raça Nelore com peso médio inicial de 419 ± 11 kg e aproximadamente 15 meses de idade, recebendo 60% de volumoso (silagem de milho) e 40% de concentrado. Foram testados 5 tratamentos: um sem adição de lipídios e mais quatro dietas com diferentes fontes lipídicas: óleo de linhaça, óleo de palma, soja grão e um suplemento comercial com gordura protegida (Lactoplus). O delineamento experimental utilizado foi o inteiramente casualizado com cinco tratamentos e nove repetições, e as médias foram comparadas pelo teste de Tukey a 5%. As fontes lipidícas influenciaram (P<0,05) os valores de ganho médio diário (GMD) e ingestões de matéria seca e nutrientes. Animais alimentados com dieta sem adição de lipídios apresentaram maior ingestão de matéria seca e nutrientes quando comparado aos que receberam óleo de palma. A eficiência alimentar teve valor médio de 0,13 kg GMD/kg MS nas dietas sem adição de lipídios, gordura protegida, soja grão e óleo de linhaça, enquanto a dieta com óleo de palma apresentou um valor de 0,08 kg GMD/kg MS. Animais alimentados com óleo de palma apresentaram maior força de cisalhamento (P<0,05) quando comparados aos que receberam a dieta sem adição de lipídios (5,87 vs 4,14 kg/cm²). A deposição de CLA foi maior no tratamento com óleo de linhaça (0,67 no músculo e 1,69 % no gordura subcutânea)... / The aim of this study was to evaluate the effect of lipid sources with different fatty acid profiles under the ingestion of nutrients, digestibility, fermentation parameters, rumen microbial, performance, enteric methane emission and qualitative characteristics of the carcass and meat from Nellore steers finished in feedlots. In the evaluation of consumption, performance, methane emission and qualitative characteristics of the carcass and meat were used 45 Nellore steers with an initial average weight of 419 + 11 kg and approximately 15 months of age, receiving 60% roughage (corn silage) and 40% concentrate. Were tested 5 treatments: one without additional fat source and more four diets with different fat sources: linseed oil, palm oil, soybeans grain and a commercial supplement with protected fat (Lactoplus). The experimental design was completely randomized with five treatments and nine replicates, and averages were compared by Tukey test (P<0.05). Lipid sources influenced (P<0.05) values of average daily gain (ADG) and intakes of dry matter and nutrients. Animals fed with the without additional fat source diet presented higher intake of dry matter and nutrients compared to those that received palm oil. Feed efficiency had average value of 0.13 kg ADG/kg DM in the diet control, protected fat, soybeans grain and linseed oil, while palm oil diet showed a value of 0.08 kg ADG / kg DM. Animals fed with palm oil had higher shear force (P <0.05) compared with those who received the without additional fat source diet (5.87 vs 4.14 kg/cm²). The deposition of CLA were higher in treatment with linseed oil (0.67 – muscle and 1.69 – subcutaneous fat). Diets based on linseed oil and soybeans grain present the same feeding efficiency of diets with protected fat and without additional fat source, however produce an average reduction of 57% in methane emissions when compared with these diets... (Complete abstract click electronic access below)

Orientador: Ricardo Andrade Reis / Coorientador: Rondineli Pavezzi Barbero / Banca: Flávio Dutra de Resende / Banca: André Luís da Silva Valente / Resumo: O presente trabalho avaliou o efeito da substituição da virginiamicina (VM) por óleos funcionais (OF) a base de mamona e castanha de caju, na recria (Exp. 1) de tourinhos da raça Nelore mantidos em pastagens de Brachiaria brizantha cv Marandu no período de seca de Junho a Setembro de 2015 e terminação (Exp. 2) em confinamento de Outubro a Dezembro do mesmo ano, sendo que nesta fase o tratamento com VM teve inclusão de monensina sódica (MN). Foram utilizados 40 tourinhos Nelore com peso corporal (PC) inicial médio de 403,8 ± 24 kg. Durante o período de seca foram estudados dois níveis de suplementação x dois aditivos, sendo os tratamentos: suplemento proteico/energético com VM (175 ou 70 mg/kg de suplemento) ou OF (2260 ou 810 mg/kg de suplemento), fornecidos na quantidade de 3 ou 6 g por kg-1 do PC, respectivamente. Foram utilizados oito piquetes com capim Marandu (dois por tratamento) manejados em sistema de lotação contínua com duração de 104 dias. Os tratamentos foram arranjados em delineamento inteiramente casualizado em arranjo fatorial 2 × 2 (doses × aditivos) com medidas repetidas no tempo (três períodos). Na fase de recria foram realizadas avaliações de massa, estrutura e qualidade da forragem e desempenho animal. Durante a fase final em confinamento os animais foram alocados em baias individuais recebendo os mesmos aditivos da fase anterior (VM ou OF nas doses de 29,2 e 700 mg/kg de MS de suplemento, respectivamente) sendo mantido o histórico da suplementação utiliza... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present project aimed to evaluate the effect of virginiamycin substitution by functional oils, based on castor bean and cashew nut, in the rearing phase (Exp. 1) of Nelore bulls kept in pastures of Brachiaria brizantha cv Marandu in transition period of rainy/dry season from June to September 2015, terminating phase (Exp. 2) in confinement from October to December of the same year, which in this stage, virginiamycin treatment included sodium monensin. 40 Nelore bulls were used, with body weight average of 403,8 ± 24 kg. During transition period were studied two levels of supplementation versus two additives, which were: protein / energetic supplement with virginiamycin (175 or 70 mg/kg of supplement) or functional oils (2260 or 810 mg/kg of supplement), supplied in 3 or 6 g.kg-1 of body weight amount, respectively. Eight areas with Marandu grass (two per treatment) were used in continuous stocking system during 104 days. The treatments were arranged in a completely randomized design in a 2 × 2 factorial arrangement (doses × additives) with repeated measures of time (three periods). At rearing phase were performed evaluations of mass, structure and quality of the forage and animal performance. During the final confinement phase, the animals were allocated to individual stalls receiving the same additives from the previous phase (virginiamycin or functional oils at the doses of 29.2 and 700 mg/kg of dry matter supplement, respectively), maintaining the history of the supplementation used in rearing phase, except the inclusion of sodium monensin (31.7 mg/kg of dry matter supplement) in the virginiamycin treatment at confinement phase. It was evaluated the influence of the management adopted in the rearing, on the consumption and performance of the animals at confinement phase. The animals remai... (Complete abstract click eletronic access below) / Mestre

Made available in DSpace on 2015-06-17T19:34:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-27. Added 1 bitstream(s) on 2015-06-18T12:48:34Z : No. of bitstreams: 1 000833017.pdf: 1030044 bytes, checksum: 64ce5ae59ac1ab2cf3290652a62b8191 (MD5) / Foram realizados dois experimentos para avaliar o efeito de planos nutricionais sobre o ganho de peso e carcaça, assim como as mudanças na composição corporal de tourinhos Nelore. O experimento 1 foi realizado de julho de 2009 a setembro de 2010, e foi dividido em três fases. As fases I e II foram referentes ao período de recria e a fase III a terminação dos animais. Na fase I os animais receberam 2 suplementos: 1) suplemento proteico (SPI) ou 2) suplemento proteico energético (SPEI). Na fase II os tratamentos foram distribuídos em esquema fatorial 2 x 4, sendo o efeito de dois históricos nutricionais da fase I associados a quatro tratamentos na fase II: 1) sal mineral (SM) 2) suplemento proteico (SPII), 3) suplemento proteico energético (SPEII); 4) suplemento energético (EN). A fase III correspondeu a terminação, sendo os tratamentos distribuídos em esquema fatorial 2 x 4 x 2, com dois históricos alimentares da fase I, quatro da fase II divididos em duas estratégias de terminação: 1) pasto com alto concentrado (PA) ou 2) confinamento (CO). Utilizou-se 129 tourinhos Nelore, com 8 ± 2 meses de idade e peso corporal de 204,6 ± 5,2 kg. O experimento 2 foi realizado de julho de 2011 a setembro de 2012, e foi dividido em três fases da mesma forma que no experimento 1. Na fase I os tratamentos foram: 1) suplemento proteico (SP) ou 2) suplemento proteico energético (SPEI). Na fase II os tratamentos foram distribuídos em esquema fatorial 2 x 2, sendo o efeito de dois históricos nutricionais da fase I associados a dois tratamentos na fase II: 1) sal mineral (SM) 2) suplemento proteico energético (SPEII). Na fase III os tratamentos também foram distribuídos em esquema fatorial 2 x 2 x 2, com dois históricos alimentares da fase I, dois da fase II divididos em dois níveis de fornecimento de ração: 1) 15 g.kg-1 PC ou 2) 20 g.kg-1 PC. Utilizou-se 78 tourinhos Nelore, com 8 ± 2 meses de idade e peso corporal de ... / Two trials were made aiming to evaluate the effect of different nutritional plans on body and carcass gain, as well as changes in body composition of Nelore cattle. The trial 1 started in July, 2009 and finished in September, 2010, and was divided in three phases. The phases I and II corresponded to the growing phase, and the phase III corresponded to the finishing phase. In phase I the animals were randomly assigned to 1 of 2 treatments consisting of: a) protein (PRI) or, b) protein and energy (PEI) supplement. The phase II for each of the phase I treatments, the animals were randomly assigned in factorial (2 x 4) to 1 of 4 treatments including: a) mineral salt (MN), b) protein (PRII), c) protein and energy (PEII) and d) energy (EN) supplement. The phase III for each of the phase I and II treatments, the animals were randomly assigned in factorial (2 x 4 x 2) to 1 of 2 treatments: finishing in 1) pasture (PA) or 2) feedlot (FE), in both treatments the animals were fed high concentrate. 129 young Nelore bulls, were 8 ± 2 months of age and BW of 204.6 ± 5.2 kg were utilized. The trial 2 started in July, 2011 and finished in September, 2012, and was divided in three phases as the trial 1. In phase I the animals were randomly assigned to 1 of 2 treatments consisting of: a) protein (PRI) or, b) protein and energy (PEI) supplement. The phase II for each of the phase I treatments, the animals were randomly assigned in factorial (2 x 2) to 1 of 2 treatments including: a) mineral salt (MN), b) protein and energy supplement (PEII). The phase III for each of the phase I and II treatments, the animals were randomly assigned in factorial (2 x 2 x 2) to 1 of 2 treatments: 1) medium or 2) high feed. 78 young Nelore bulls, were 8 ± 2 months of age and BW of 171.7 ± 6.4 kg were utilized. Measurements of ADG, gain and composition of carcass were made. All the data were analysed as a randomized factorial design using the PROC MIXED of the SAS ...

Made available in DSpace on 2015-08-20T17:10:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-26. Added 1 bitstream(s) on 2015-08-20T17:25:54Z : No. of bitstreams: 1 000833070.pdf: 276509 bytes, checksum: 168d0b0f9090ec30681d2c2cccd8a266 (MD5) / Este experimento analisou os efeitos da administração do meloxicam nas respostas fisiológicas e no desempenho de bovinos na fase inicial do confinamento após serem transportados. Foram utilizados 84 bezerros Angus × Hereford, divididos por peso vivo (PV) no dia -10 do experimento e distribuídos em 21 baias de confinamento. Do d -10 ao d 0, todos os animais receberam uma dieta composta por feno de alfalfa a vontade e 2,4 kg/animal (base MS) de um concentrado a base de milho. No dia 0, todas as baias foram aleatoriamente atribuídas a receberem um dos seguintes tratamentos: 1) transporte por 1.440 km em um caminhão comercial e administração oral de meloxicam (1 mg/kg do PV) no carregamento (d 0), no descarregamento (d 1) e diariamente do d 2 ao d 7 no período inicial de confinamento (MEL; n = 7), 2) transporte e administração do tratamento nos mesmos dias do grupo MEL, porém com lactose monohidratada (1 mg/kg do PV) (TRANS; n = 7), 3) ausência de transporte e administração de lactose monohidratada (1 mg/kg do PV) nos mesmos dias dos tratamentos MEL e TRANS (CON; n = 7). Logo após o descarregamento (d 1), todos os animais dos tratamentos MEL e TRANS retornaram para suas respectivas baias para o período de 21 dias de confinamento, recebendo a mesma dieta oferecida do d -10 ao d 0. Nos dias 0 e 1, os tratamentos foram aplicados através de solução aquosa e administrados via oral, porém dos dias 2 ao 7, os tratamentos foram misturados no concentrado. Para o cálculo de ganho peso diário (GPD) foram utilizados as médias de ... / This experiment evaluated the effects of meloxicam administration on physiological and performance responses of transported cattle during feedlot receiving. Eighty-four Angus × Hereford steers were ranked by BW on d -10, and assigned to 21 dry lot pens. From d -10 to 0, pens were fed Alfalfa-grass hay ad libitum and 2.4 kg/steer daily (DM basis) of a corn-based concentrate. On d 0, pens were randomly assigned to: 1) transport for 1,440 km in a livestock trailer and oral administration of meloxicam (1 mg/kg of BW) at loading (d 0), unloading (d 1), and daily from d 2 to 7 of feedlot receiving (MEL; n = 7), 2) same transportation and treatment schedule of MEL, but oral administration of lactose monohydrate (1 mg/kg of BW) instead of meloxicam (TRANS; n = 7), or 3) no transport and oral administration of lactose monohydrate (1 mg/kg of BW) concurrently with treatment administration to MEL and TRANS (CON; n = 7). Upon arrival (d 1), MEL and TRANS steers returned to their pens for a 21-d feedlot receiving with the same diet offered from d -10 to 0. Treatments were administered to steers via oral drench on d 0 and 1, or mixed daily with the concentrate from d 2 to 7. Full BW was recorded prior to (d -2, -1, and 0) treatment application and at the end of experiment (d 20, 21, and 22) for ADG calculation. Daily DMI was recorded from d 1 to 21. Blood samples were collected on d 0, 1, 3, 5, 7, 10, 14, and 21. During the initial 7 d of feedlot receiving, hay and total DMI were reduced (P ≤ 0.03) in TRANS vs. CON and MEL, similar between CON and MEL (P ≥ 0.26), whereas concentrate DMI did not differ (P = 0.16) among ...

Made available in DSpace on 2015-03-03T11:52:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-15Bitstream added on 2015-03-03T12:07:25Z : No. of bitstreams: 1 000811614.pdf: 267019 bytes, checksum: a38c4eee0afe8f36692b23f7c2dd48f3 (MD5) / O objetivo deste estudo foi avaliar as diferenças entre os parâmetros qualitativos, quantitativos e sensoriais do músculo Longissimus de bovinos e bubalinos. Foram utilizados animais das espécies bovina (Nelore) e bubalina (cruzados Mediterrâneo e Murrah). Os animais foram mantidos em confinamento comercial, por 102 dias, em baias coletivas, de acordo com a espécie, recebendo, no período de acabamento, 8,07% de proteína bruta e 72,10% de nutrientes digestíveis totais. O delineamento experimental foi inteiramente casualizado com 2 tratamentos (espécie animal) e 40 repetições. As médias foram comparadas pelo teste de Tukey, considerando o nível de significância de 5%, quando o teste F foi significativo. Os bovinos apresentaram melhor rendimento de carcaça (57,16 ± 1,42%), maior área de olho de lombo (59,38 ± 5,72 cm2), maior porcentagem de dianteiro (40,68 ± 1,30%), cortes mais pesados do dianteiro, menor oxidação lipídica (0,155 ± 0,033 mgMDA/kg), maior porcentagem de proteína (21,16 ± 0,97%) e cinzas (1,08 ± 0,06%), enquanto que os bubalinos obtiveram maior espessura de gordura subcutânea (13,85 ± 3,00 mm), menor perda no resfriamento (1,26 ± 0,15%), maior porcentagem de ponta de agulha (14,50 ± 0,57), cortes mais pesados do traseiro, menor porcentagem de perda por cocção (29,42 ± 3,04%), maior porcentagem de umidade (75,13 ± 0,89%), menor porcentagem de colágeno (4,81 ± 0,79%) e maior índice de fragmentação miofibrilar (79,91 ± 17,50). No painel sensorial somente a variável odor apresentou diferença (P<0,05) entre as espécies, sendo a carne bubalina com maior nota (7,30 ± 0,98 pontos). Conclui-se que a carne bovina diferencia da carne bubalina em termos de desempenho, características físicas e químicas. Porém a carne bubalina tem potencial para ... / The aim of this study was to evaluate the differences between qualitative, quantitative and sensory parameters of the Longissimus muscle of cattle and buffaloes. Were used cattle of Nellore breed and buffalo of Murrah and Mediterranean crossed. The animals were maintained on a commercial feedlot for 102 days in collective boxes according to species, getting in the finishing period, 8.07% crude protein and 72.10% total digestible nutrients. The experimental design was completely randomized with two treatments (species) and 40 repetitions. Means were compared by Tukey test, considering significance level of 5%, when the F test was significant. The cattle have higher carcass yield (57.16 ± 1.42%), a larger rib eye area (59.38 ± 5.72 cm2), higher percentage of forequarter (40.68 ± 1.30%), heavier cuts forequarter, lower lipid oxidation (0.155 ± 0.033 mgMDA/kg), increased percentage of protein (21.16 ± 0.97%) and ash (1.08 ± 0.06%) , while buffaloes showed greater fat thickness (13.85 ± 3.00 mm), smaller loss in cooling (1.26 ± 0.15%), higher percentage of spare rib (14.50 ± 0.57), heavier cuts of hindquarter, lower percentage cooking loss (29.42 ± 3.04%), higher percentage of moisture (75.13 ± 0.89%), lower percentage of collagen (4.81 ± 0.79%) and higher rate of myofibrillar fragmentation (79.91 ± 17.50). In sensory panel only odor variable showed differences (P < 0.05) between species, with the buffalo meat with highest score (7.30 ± 0.98 points). It is concluded that beef differs from buffalo meat in terms of performance, physical and chemical characteristics. But the buffalo meat has the potential to enter the consumer market

Made available in DSpace on 2014-06-11T19:28:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-08Bitstream added on 2014-06-13T19:36:58Z : No. of bitstreams: 1 dantas_a_me_botfmvz.pdf: 285512 bytes, checksum: 02e43a11479ebbef1e68d1c1aa53dc28 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este estudo teve como objetivo avaliar a idade à puberdade, a dinâmica corporal e o desempenho de cordeiras Bergamácia submetidas a dietas para baixa e alta velocidades de crescimento, até 1 ano de idade. Vinte cordeiras foram mantidas confinadas (duas por baia) durante todo o período experimental recebendo dois tipos de dietas formuladas para obtenção de ganho de peso médio diário: 1) Baixo (180 gramas); 2) Alto (300 gramas). O experimento foi dividido em duas fases, sendo a primeira o período compreendido até as cordeiras atingirem 30 kg; e a segunda fase a partir de 30 kg até 1 ano de idade. Para avaliação da dinâmica do desenvolvimento corporal, a cada 14 dias os animais foram pesados, determinado o escore de condição corporal e registradas medidas biométricas. A partir do 5º mês de idade foi introduzido, em cada grupo experimental, um macho vasectomizado para realizar a detecção do estro e determinar a idade à puberdade e o intervalo entre os dois primeiros estros de cada cordeira. Foram encontradas diferenças (P˂0,05) entre os tratamentos para ganho de peso médio diário, escore de condição corporal e para as medidas biométricas. Não houve diferença (P>0,05) para idade à puberdade. Verificou-se que os tratamentos baixo e alto proporcionaram desempenhos adequados, porém não revelaram diferentes respostas a idade à puberdade. A dieta para alta velocidade de crescimento proporcionou pesos superiores e melhor escore de condição corporal nas duas fases experimentais / This study aimed to evaluate the age at puberty, body dynamics and performance of Bergamasca lambs submitted to diets for low and high growth rates, up to 1 year old. Twenty lambs were kept confined (two per stall) throughout the experimental period getting two types of diets to obtain average daily weight gain: 1) Low (180 grams) 2) High (300 grams). The experiment was divided into two stages, the first was the period until lambs reached 30 kg, and the second phase with the lambs weighting from 30 kg until they reach one 1 year old. To assess the dynamics of body development, every 14 days the animals were weighed, the body condition score was determined and biometrics measurements were registered. From the 5th month of age was introduced in each experimental group, a vasectomized male to perform the detection of estrus and to determine the age at puberty and interval between the first two estrous of each lamb. Differences were found (P˂0.05) among treatments for average daily weight gain, body condition score and biometric measurements. There was no difference (P>0.05) for age at puberty. It has been found that low and high treatments yielded adequate performance, but did not show different responses in age at puberty. A high growth rate diet yielded higher body weights and better body condition score in both phases

Orientador: Ricardo Andrade Reis / Coorientador: Josiane Fonseca Lage / Banca: Gustavo Rezende Siqueira / Banca: Roberto de oliveira Roça / Resumo: O objetivo do trabalho foi verificar se o histórico de recria no período das águas influenciou a qualidade da carne de tourinhos Nelore terminados no período seco em pasto ou confinamento. Durante a fase de recria os animais foram mantidos, em pasto de capim Marandu manejados em diferentes alturas de pastejo (15; 25 e 35 cm) em lotação continua e taxa de lotação variável, combinado com estratégias de suplementação e terminados no período seco, em pastagens com a dieta suplementada ou confinamento. O trabalho foi constituido de dois experimentos, do ano de 2012/2013, capitulo 2 e ano de 2013/2014, capítulo 3. No primeiro experimento, capitulo 2, foram coletadas amostras de carne de animais provenientes de seis tratamentos: ABSA- recria em pasto de 15 cm de altura e suplemento de 0,6% PC; AMSM- recria em pasto 25 cm de altura e suplemento de 0,3% PC; AASM- recria em pasto de 35 cm de altura e suplemento mineral, cada tratamento com terminação em pasto ou confinamento com nove repetições (animais). Foram utilizadas amostras do M. longissimus thoracis et lumborum (LTL), retiradas da meia-carcaça esquerda, entre a 12ª e 13ª costelas, posteriormente embaladas em filme plástico e, após 24 horas de resfriamento as amostras foram congeladas a -20ºC. Procedeu-se as determinações da maciez (força de cisalhamento) e perdas por cocção, coloração da carne e da gordura subcutânea, pH, composição centesimal, teor de colágeno e porcentagem de gordura intramuscular avaliados em Espec¬trofotôme... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Master of Public Health / Department of Diagnostic Medicine/Pathobiology / John A. Pickrell / Beef cattle feed lots produce significant, local point source pollution of the atmosphere. The dusts generated in the CAFOs are complex mixture of fine and ultra fine particles, organic compounds, transition metals, and adsorbed toxic gases. Since each component is toxic in itself, we do not fully understand the relative importance of each component in the dust and their interactions to inducing inflammatory changes in the lung. We did extensive literature searches to understand the mechanism of dust toxicity in respiratory system. This lead to focusing on solubility of dust in lung simulant fluid, and in-vitro study of release of two common biomarkers of inflammatory processes IL-6 and IL-8 from lung epithelial cells. Various concentrations (1 to 50%) of the dust extract induced release of IL-6, and IL-8 from lung epithelial cell as indicators of pro-inflammatory changes (IL-6), and amplification and maintenance of inflammation (IL-8). IL-6 release had dose dependence; peak production was seen with 25% dust extract. IL-8 production went down as the concentration of the dust extract increased from 1% to 25%. However, 50% dust extract was cytotoxic to the cell leading to 10-15% cell viability. At non-cytotoxic concentrations for lung epithelial cells, production of IL-8 was reduced. These findings suggested that higher exposure concentration were required to initiate inflammation as indicated by IL-6 release. Lower exposure concentrations (1 and 5% extracts) were related to optimal release of IL-8 needed to amplify and maintain the inflammatory response. Inhibition of endotoxin didn't significantly change the pattern of IL-6 or IL-8 release from epithelial cells. This finding suggested that at least a portion of the mechanism by which particle induced cytokine release from the lung epithelial cells was not endotoxin dependent. Heating samples at 1200C for 5 minutes modified some of the toxic properties of the dust extracts but didn't completely detoxify it. We observed that longer incubation period was required to peak release for both IL-6 and IL-8. However, the higher concentration of sample (50% extract) found to be cytotoxic in non-heat treated sample was no longer cytotoxic and induced both IL-6 and IL-8 release from the lung epithelial cells. This result suggested that heat treatment could reduce some of the dust extract's cytotoxic properties. However, the extract's potential to induce peak cytokine release increased.