Abstract. The objective of this study was to determine relationships between breast muscle thickness measured by ultrasonography and meatiness and fatness characteristics in broiler chickens. The experiment was conducted on 80 Ross 308 chickens aged 42 days. Breast muscle thickness was determined before and after slaughter, using an ultrasonic diagnostic apparatus (Dramiński Animal Scanner with an abdominal, sector mechanical probe). The chickens were weighed and carcasses were subjected to detailed dissection.

In males breast muscle thickness measured before slaughter was found to be statistically correlated with the weight of a carcass, meat and breast muscles as well as with the percentage content of breast muscles in the carcass. The same measurement taken after slaughter showed a high correlation with all analyzed traits except for the percentage content of fat with skin in the carcass. The coefficients of correlation between the analyzed traits, characterizing meatiness in females, were in most cases slightly higher than in males.