Efeitos da ingestão de concentrado à base de grãos na ingesta do cólon dorsal direito em eqüinos

• Autor(a) principal: Lima, Leonardo Rodrigues de
• Data de Publicação: 2005
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5043
• topic: Equino; Fisiologia gastrintestinal; Cólica; Compactação; Horses; Gastrointestinal physiology; Colic; Impaction; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::CLINICA E CIRURGIA ANIMAL

Large colon (LC) impaction is the most commonly diagnosed disease causing colic in horses, however the complete ethyopathogenesis of this condition is still unknown.Changes produced by diet in the properties of ingesta not yet investigated may also be important contributing factors to impaction formation and to other gastrointestinal diseases. The aim of this study was: 1- to create a tube viscometer able to measure the viscosity of horse ingesta, 2- to assess the effects of grain intake on hydration, gas content, particulate matter content, density, viscosity, and pH of ingesta, 3- to assess the potential for impaction formation with large colon contents in an ex vivo model, 4- to testify a modification on surgical technique for right dorsal colon fistulation. Using a cross-over design, 4 horses with experimental fistulas in the right dorsal colon were alternately fed two diets: 1- exclusively free choice grass hay or 2- pelleted feed rich in hydrolazable carbohydrates plus free choice grass hay. The ingesta were dried at 80°C to determine the water content. The gas content was estimated by the difference in volume after centrifuging the ingesta sample. The amount of particulate mater was determined by flushing a 1 Kg fresh sample of ingesta in a sequence of sieves with 100 L of water and weighing the dry matter of the material retained at the sieves. Ingesta density was calculated by the formula: density = sample weight / sample volume. After measuring the force to move 1 kg of fresh ingesta within a tube viscometer and the force to penetrate a probe into the ingesta in a texture analyzer, the sample was tested for impaction formation with a funnel attached to the viscometer end, in order to increase the resistance to flow. The water content of ingesta as well as density were significantly decreased; gas content and viscosity were increased and pH and particulate matter was not altered, when grain was fed. Despite diet, impaction did not form with any of the fresh ingesta samples. After adjusting ingesta viscosity, impaction was formed in eight repetitions when only hay was fed. Only one impaction could be produced when hay and grain were fed in eight repetitions, even after adjusting ingesta viscosity. Ingesta dehydration produced by grain intake may be explained as the result of reduced water consumption or an increase in the absorption of water following the absorption of larger amounts of volatile fatty acids. Formation of foamy ingesta and the increase in gas content of ingesta is explained by an increase in microbial production of gas and substances that stabilizes the froth. The decreased density may be explained by the increased amount of gas trapped within the ingesta. The increase in viscosity may be explained by the reduced water content of ingesta. It is possible that these changes may affect the likelihood of impaction formation. Although it has been demonstrated that grain ingestion has the potential to increase the risk of colic by several mechanisms, the findings of the present study suggest that grain ingestion may actually have a protective effect for large colon impaction.