Impacto do estresse no bem-estar dos animais e na qualidade da carcaça e da carne
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Data
2016-01-22
Autores
Borges, Tâmara Duarte [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
No primeiro capítulo da tese é apresentada uma revisão bibliográfica sobre o assunto, trazendo à tona conceitos importantes sobre estresse e bem-estar animal juntamente com resultados práticos de pesquisas que servem como exemplos dos efeitos do manejo pré-abate de bovinos e do estresse térmico em suínos. O capítulo dois tem como objetivo principal apresentar os fatores de risco associados ao manejo pré-abate de bovinos que estariam relacionados à presença de hematomas e alto pH da carne. As avaliações foram realizadas em dois frigoríficos da região sudeste do Brasil, considerando 15 variáveis medidas durante o manejo pré-abate, utilizando-se 27 661 bovinos. Para transporte, o tipo de veículo, duração da viagem e condições das rodovias foram mensuradas. No desembarque, o tempo de espera para desembarcar os animais, o número de animais que chegaram deitados no caminhão, as batidas lateral e dorsal dos animais contra estruturas do caminhão, a frequência de quedas e o uso de bastão elétrico foram avaliados. Durante o manejo de condução dentro do frigorífico avaliou-se as frequências de quedas dos animais, batidas contra os portões de manejo, uso do bastão elétrico, animais feridos e pisoteados e tamanho do lote conduzido. A frequência e localização dos hematomas nas carcaças e os valores de pH também foram mensurados, juntamente com as categorias animais. Os resultados indicaram alta porcentagem de hematoma nas carcaças (64,14% no frigorífico 1 [F1] e 72,16% no frigorífico 2 [F2]). Também foi encontrada alta porcentagem de pH24 acima de 5,8 (17,67% (F1); 20,30% (F2)). A categoria animal vaca obteve maiores médias de hematomas. Animais transportados por caminhões dois andares, por longas distâncias (mais de 5 horas de viagem) e em condições ruins de estrada obtiveram maiores médias de hematomas também. Durante o desembarque e manejo dos animais dentro do frigorífico, quedas demostraram um efeito claro em hematomas e a utilização de bastão elétrico, juntamente com o tamanho do grupo de manejo causaram efeito negativo no pH da carne. O capítulo três teve por objetivo estudar o efeito do estresse por calor em suínos na fase de crescimento e terminação, avaliando o desempenho, sujidade e qualidade da carcaça e carne, testando dois tipos de competição por alimento (um ou dois comedouros para quatro animais) e dois tipos diferentes de piso (30% slat ou 100% slat). Os principais resultados encontrados foram que animais em situações de estresse por calor ou alojados em pisos 100% slat tiveram menor ganho de peso na fase final de terminação. Animais em baias com comedouro simples tiveram maiores ganhos de peso nas fases de crescimento e terminação. Quanto à sujidade, animais alojados em pisos 30% slat e em situações de estresse por calor foram os mais sujos. A porcentagem de magro foi maior em animais sobre condições térmicas de controle em comparação aos sob estresse térmico. Escatol e indol foram mais altos em carnes de animais previamente alojados em situações de estresse e o indol também foi mais alto em animais alojados em pisos 30% slat.
The first chapter presents a literature review, bringing up important concepts about stress and animal welfare using practical results of pre-slaughter handling in cattle and thermal stress management in pigs. Chapter two presents the risk factors associated with transport and pre-slaughter handling in cattle with impact on presence of bruising and high pH meat. The evaluations were performed on two slaughterhouses located in southeastern of Brazil, considering 15 variables measured using 27,661 cattle. For transport, the type of vehicle, journey duration and road condition were assessed. For unloading, the time spent in the queue to unload the animals, number of animals lying in the truck, back and lateral hits at the truck´s door, frequency of animals that fell down and were electric prodded were evaluated. During handling procedures the frequencies of animals that fell down, that were hit by the gate, that were electric prodded and the occurrence (yes or no) of injured and trampled animals in the lot, and the number of animals per handling group were measured. Frequency and location of bruises in the carcasses and meat pH were assessed, as well the animal´s categories.The results indicated a high percentage of carcass with at least one bruise (64.14% [S1] and 72.16% [S2]) and a high percentage of meat pH greater than 5.8 (17.67% [S1] and 20.30% [S2]). Cows were the category with higher number of bruises. Double decker was the type of vehicle with high risk of bruises. Animals transported for long journeys (up to 5 hours) and in poor road conditions had higher number of bruises too. During unloading and driving procedures, falls had a clear effect in bruises, and electric prod use had an effect in meat pH. Number of animals per handling group also affected meat pH. In chapter three a pig heat stress study was performed during growing and finishing period, evaluating performance, dirt and meat quality, testing two types of feeders (single or double feeder for 8 animals) and two different types of floor (30% slat or slat 100%). The main findings were that animals under heat stress and housed in floors 100% slat had less weight gain in the finishing phase. Animals in pens with one feeder had greater weight gain during growing and finishing period. Animals housed under heat stress and 30% slat floors were dirtiest than the other treatments. Lean meat percentage was high for animals on thermal control conditions than heat stress. Skatole and indole were higher in meat from animals previously housed in stressful situations and indole was also higher in animals housed in 30% slat floors.
The first chapter presents a literature review, bringing up important concepts about stress and animal welfare using practical results of pre-slaughter handling in cattle and thermal stress management in pigs. Chapter two presents the risk factors associated with transport and pre-slaughter handling in cattle with impact on presence of bruising and high pH meat. The evaluations were performed on two slaughterhouses located in southeastern of Brazil, considering 15 variables measured using 27,661 cattle. For transport, the type of vehicle, journey duration and road condition were assessed. For unloading, the time spent in the queue to unload the animals, number of animals lying in the truck, back and lateral hits at the truck´s door, frequency of animals that fell down and were electric prodded were evaluated. During handling procedures the frequencies of animals that fell down, that were hit by the gate, that were electric prodded and the occurrence (yes or no) of injured and trampled animals in the lot, and the number of animals per handling group were measured. Frequency and location of bruises in the carcasses and meat pH were assessed, as well the animal´s categories.The results indicated a high percentage of carcass with at least one bruise (64.14% [S1] and 72.16% [S2]) and a high percentage of meat pH greater than 5.8 (17.67% [S1] and 20.30% [S2]). Cows were the category with higher number of bruises. Double decker was the type of vehicle with high risk of bruises. Animals transported for long journeys (up to 5 hours) and in poor road conditions had higher number of bruises too. During unloading and driving procedures, falls had a clear effect in bruises, and electric prod use had an effect in meat pH. Number of animals per handling group also affected meat pH. In chapter three a pig heat stress study was performed during growing and finishing period, evaluating performance, dirt and meat quality, testing two types of feeders (single or double feeder for 8 animals) and two different types of floor (30% slat or slat 100%). The main findings were that animals under heat stress and housed in floors 100% slat had less weight gain in the finishing phase. Animals in pens with one feeder had greater weight gain during growing and finishing period. Animals housed under heat stress and 30% slat floors were dirtiest than the other treatments. Lean meat percentage was high for animals on thermal control conditions than heat stress. Skatole and indole were higher in meat from animals previously housed in stressful situations and indole was also higher in animals housed in 30% slat floors.
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Palavras-chave
Bem-estar animal, Bovinos, Manejo pré-abate, Suínos, Estresse térmico, Animal welfare, Cattle, Pre-slaughter handling, Pigs, Heat stress