Uso de modelo experimental para estudos relacionados ao estresse animal

Abstract

Stress is a topic relevant importance to both human and animal area. Animal meat producers are subjected to different pre-slaughter factors from the production unit to the slaughterhouse. These stressors factors to animals may cause physiological changes leading to an adverse effect on the final quality of the meat. In Brazil, in last years, sheep meat is a growing market, especially in developing countries, where economic growth more abundant, and increasingly demanding, consumers. In this contest, we conducted a literature review in the last 40 years, that addresses to slaughter handling of these animals, aspects of ovine behavior, and its consequences on final meat quality. In the second chapter, there was a study with the objectives of (1) to describe and standardize the pH curve transformation into meat muscle Triceps brachii, Longissimus dorsi and Biceps femoralis of rats subjected to normal breeding conditions from euthanasia to 24 hours post-mortem; (2) to determine whether the analysis in each muscle modify significantly the pH curve; (3) to determine whether the stress by rats restraining in the ante-mortem period cause qualitative changes in meat and affects the time and pH values for the transformation of muscle in meat. For the determination of muscle pH curves were used 12 male Wistar rats, and animals were euthanized and the carcasses were placed under refrigeration for measurements of pH. Another group of 12 animals was subjected to stress by restraining and after euthanasia was performed the pH evaluations. The results indicate that: (1) the post-mortem muscle pH values in rats show a downward trend similar commercial species; (2) the average values of muscle pH in the three muscle groups do not differ significantly in all the analyzed periods; (3) The medium muscle pH are significant differences between time 0 to 6 hours after slaughter, when the minimum value is determined. Thus, we conclude that although known different pre-slaughter factors that may cause physiological changes that culminate with detrimental effects on the final quality of the meat, there are few reliable methods, easy to perform and non-invasive to detect this stress in animals were standardized until now. Rats are a promising experimental model to detect post-mortem changes, because the decrease in the muscle pH follows the values and time similar to what happens to the commercial species.