The effects of specific diets for commercial hybrids were investigated on 6 Casertana and 11 Mora Romagnola, two endangered Italian pig breeds. Average daily gain (ADG), feed conversion index (FCI), dressing percentage and meat and fat quality of animals bred under similar environmental and nutritional conditions were compared to define their optimal slaughtering weight. Animals were fed the same diets assuming that requirements of Mora Romagnola and Casertana did not differ, and changed every 30kg of weight gain. ADG and FCI were calculated every 15 days. Weight gains, divided into 5 groups based on live weight (LW) of animals (⩽60kg, 60<kg⩽90, 90<kg⩽120, 120<kg⩽160, >160kg), showed higher values for Casertana than Mora Romagnola, particularly from 121 to 160kg LW (687g/d). Average FCI from 50 to 160kg LW was similar in both breeds (4.2). After 403 days of trial, animals were slaughtered at about 195kg LW. Carcass measurements showed that Casertana had higher dressing percentage and lean cuts than Mora Romagnola. Both breeds showed extraordinary high ultimate pH values of M. longissimus thoracis (5.96 and 6.15 for Casertana and Mora Romagnola, respectively) M. semimembranosus (6.37 and 6.30), showing an incomplete post mortem glycolysis. Colour of M. longissimus thoracis did not differ between breeds and was particularly dark. Chemical analysis of Casertana meat showed lower percentage of water and fat; the total amount of fatty acids (SFA, MUFA and PUFA) and the SFA/UFA ratio did not show significant differences between breeds. Results showed that from a growth point of view the optimal slaughtering weight of Casertana and Mora Romagnola should not exceed 160kg LW. Both breeds had an uncommon reactivity to stress probably due to interactions of genetic, nutritional and management factors.