2.4. Statistical analysis
All dietary treatments were assigned by a completely randomized design. Data were analyzed by one-way analysis of variance (ANOVA) in SPSS version 11.0 (SPSS Inc., Chicago, IL, USA). When ANOVA identified differences among groups, the difference in means was made with Tukey's HSD multiple range test. Statistical significance was determined at P b 0.05. A broken-line regression model was used for determination of optimum dietary arginine level based on weight gain (WG). Data are presented as mean ± SD. Percentage data were arcsine transformed before statistical analysis.