Preliminary study to investigate the effects of zinc oxide on growth performance, total tract digestibility, and fecal scores in growing pigs fed a diet based on corn and wheat

This study investigates the effects of the dietary inclusion of zinc oxide (ZnO) on the growth performance, apparent total digestibility, and the fecal scores of growing pigs fed a corn-wheat-based diet. In total, 84 crossbred (Landrace × Yorkshire × Duroc) growing pigs with an initial body weight of (20.86 ± 0.64 kg) (4 pigs·pen^-1; 2 gilts and 2 barrows; 7 replications·treatment^-1) were randomly assigned to three treatment groups based on body weight (BW) and sex in a three-week trial. The dietary treatments were as follows: TRT1 (CON [basal diet]), TRT2 (CON + 0.07% ZnO), and TRT3 (CON + 1% ZnO). Dietary ZnO supplementation significantly (p < 0.05) improved body weight gain (BWG) of growing pigs at weeks 2 and 3 compared to the control diet. In addition, dietary ZnO supplementation significantly (p < 0.05) increased the average daily gain (ADG) and average daily feed intake (ADFI) at weeks 2, 3, and overall. However, the feed conversion ratio (FCR) remained unaffected throughout the trial. Regarding the total tract nutrient digestibility of nitrogen, dry matter was significantly improved with an increased level of ZnO supplementation. In addition, dietary supplementation of ZnO significantly reduced fecal scores in grower pigs at the initial period compared to the control diet. In summary, dietary inclusion of zinc oxide via supplementation improved growth performance, and total tract digestibility and reduced the fecal scores of growing pigs.