Reatividade animal e indicadores fisiológicos de estresse: avaliação das suas relações com a qualidade final da carne bovina em distintos períodos de jejum pré-abate

Abstract

Evaluation was made of the effect of different pre-slaughter fasting periods on animal reactivity, physiological stress indicators and final meat quality, considering glucose as a potential stress indicator. Thirty three (33) castrated Aberdeen Angus breed young bulls were used, approximately 24 months old, average weight of 450 kg, with similar origin, time and transportation conditions, being slaughtered in a commercial packing plant in Pelotas, RS, Brazil. Animals were classified in four different fastening periods. Reactivity was classified accordingly to a scale ranging from zero (0) to five (5), the lesser reactive being attributed 0 and the most reactive being attributed 5. Blood samples were collected to determine glucose and cortisol levels. Samples of chilled Longissimus dorsi muscle were obtained 24 h after slaughter, to determine final meat quality through the characteristics of colour, water retention capacity (CRA) softness and pH. Data were analyzed by statistical multivariate analysis with grouping test and ordination by the method of component analysis (PCA). Levels of cortisol and glucose showed simultaneous increase. The most reactive animals presented higher blood levels of glucose and cortisol, as well as meat final pH. Less reactive animals showed best meat characteristics for softness, coloration, pH and CRA. Pre-slaughter fastening did not affect the biochemical parameters and meat quality characteristics. Glucose may be used as physiological stress indicator.