Abstract: The degree of rigor in a bird or animal carcass is measured. The carcass is carried on a carrier which runs along a rail and over a slight step or drop, which subjects the carcass to a mechanical shock. A sensor monitors the variation with time of the force exerted by the carcass on the support means which arrests its fall. Circuitry analyzes the response to determine the degree of rigor. The carcass is then subjected to appropriate treatment, e.g., by its further processing being delayed to allow rigor to develop further. This can be done by providing a switch in the rail to route the carcass along a short path or a long path. The particular feature of the response which is monitored by the circuitry may, for example, be the time of fall, the amplitude of oscillation after the carcass has been arrested by the support means, the frequency of that oscillation, the rate at which that oscillation is damped, or some combination of those features.