In the control, non-pressure-heat treated samples, the only breed difference detected was in peak minus initial yield force value, which was significantly lower for the beef Semimembranosus muscles. However, for the pressure-heat treated samples of both muscles, peak force and peak minus initial yield force values were significantly lower for beef than for buffalo. The pressure-heat treatment could thus be used to detect differences in the contribution of connective tissue to toughness which would otherwise be obscured by the differences in the myofibrillar toughness.