The levels of TFR-F index and TBIC in FE and VF groups before intervention ( ( @ @ ) , ( @ @ ) and ( @ @ ) , ( @ @ ) mg/kg , respectively ) were all lower than those of after intervention ( TFR-F index : ( @ @ ) , ( @ @ ) and TBIC : ( @ @ ) , ( @ @ ) mg/kg ) ( t values were @ , @ , @ and @ , respectively , all P values were < @ ) .