A computer-aided method for muscle fibre type determination and qualitative analysis of glycogen at a cellular level is described. The operational system consists of a microscope, a CCD videocamera, an image analysis card, a colour monitor and a standard workstation computer (32 Mb central memory, 22 mips) running under the UNIX operating system. The programme was developed with 512 × 512 pixel images. Four main steps can be distinguished: digitization, network extraction, network matching and measurement of staining intensities. The data generated for each analysed fibre included, diameter, cross-sectional area, ATPase staining intensity and type. Ten minutes of batch processing and 36-41 min of interactive work were needed to analyse 200-300 fibres. Results have shown that this image analysis system can distinguish four types of myofibres denoted I, IIA, IIB and IIC, on the basis of myosin ATPase sensitivity at three preincubation pH values (4·10, 4·35 and 10·4). Preliminary results have also shown that the image analysis system can be used to measure post-mortem glycogen depletion according to fibre type.

Records on 1852 female pigs tested in 1985 in four central progeny test stations were analysed for assessing the influence of genetic type (four pure breeds : Large White = LW, French Landrace = FL, Belgian Landrace = BL and Pietrain = P, as well as various crosses and some environmental factors (station-slaughterhouse, day of slaughter and body weight at slaughter), on killing out percentage and overnight drip loss of pig carcasses.