Data was statistically analysed using the GenStat for Windows (2003) statistical computer programme. Fat class and age were used as the main factor for each cut and tested at a significance level of 95% (p 6 0.05). The significance of the variables measured (protein (N 6.25), total amino acids, and individual amino acids) for each cut and fat code, and cut and age, was analysed using analysis of variance (ANOVA). Interactions were tested at the 5% level