Consequences on corporal composition variables of pig carcasses for introducing new weighing and grading methods in France in 1997

The new EU definition of lean meat proportion (called TVM : Teneur en Viande Maigre) has been introduced in France in 1997. Grading methods and carcass dressing have changed, leading to a modification of the variables measured on the slaughterline. Analysis of the changes in the distributions has been performed from the data of 5 regional organizations covering 9 / 10 th of french slaughtering. Normality, means, standard deviations and correlations have been studied for the CGM (Capteur Gras Maigre = Fat lean meter) grading method on pigs slaughtered on April 1998 for the new method and on samples from 1995 for the old method.Main regional difference concerns standard deviations which are lower in North-West area.Choosing one equation for each sex has increased of 0,5 point grading differences between sexes. Standard deviation has decreased of 0,6 to 0,7 point for females. TVM variance for castrates is now equal to twice and half those for females. Even if no bimodality appears for TVM it is an evidence that distribution differences justify separate analysis for females and castrates. Furthermore, as TVM and fat depths do not follow normal distribution it is necessary that users of these corporal composition variables use specific statistical tools, as robust or non parametric methods.