Diets and animalsIn Exp. 1, two diets (Table 1) with similar nutrient composition were formulated to meet or exceed NRC (1998) nutrientrequirements of swine. The diet with supplemental antibiotics (containing pure Colistin sulfate and Enramycin, respectively,at 0.02 g/kg diet) and ZnO (2.5 g/kg diet) was used as the control (CON) group. Another diet without supplemental ZnO wasprepared by inclusion of the SF3 (provided by Kemira Oyj), at 3 g/kg diet, and referred to the SF3 group. The SF3 containedcalcium formate, calcium lactate, citric acid and MCFA (a mixture of lauric acid, myristic acid and capric acid) at 340, 160, 70and 130 g/kg, respectively. Also, the SF3 contained organic calcium at 151 g/kg and thus 0.50 kg of limestone was replacedwhen 1 kg of SF3 was included. A total of 120 (female 44 and male 76) crossbred piglets [Duroc × Large White × Landrace,6.36 ± 0.80 (SD) kg bodyweight] were weaned at 21-day old, fed the same commercial prestart diet for one week, and then