Stress des animaux et qualités de leurs viandes. Rôles du patrimoine génétique et de l'expérience antérieure

Abstract

Stress reactions during the slaughtering procedure affect muscular metabolism before and after slaughter and consequently, meat quality. The phenomenon is principally related to a reduction in muscle glycogen stores and an increase in ATPase activity. The way animals react behaviourally, physiologically and metabolically to stress, depends on the animal's genetic background and prior history. For example, certain breeds are more reactive to human presence or to an unfamiliar environment. The effect of physiological changes on metabolism depends amongst others on the number of functional receptors on or in muscle cells, which appear to vary according to genetic background. Concerning history, the experience of a defeat in an agonistic encounter, of being housed in isolation or attached, may increase behavioural and physiological reactivity to an unfamiliar object or to the distribution of the daily meal. It is likely that such an increase reinforces the effects of slaughter stress on meat quality. The ease of handling, loading and unloading depends on the degree of the animal's familiarity with the situation. For veal calves, the caretaker's attitude towards his animals has some influence on the calves' reactions towards slaughter procedures and on meat quality. In summary, we have some knowledge of the effects of genetic background, rearing method and stress reactivity towards slaughter procedures on meat quality. It is necessary to extend this knowledge and to elucidate underlying mechanisms.