Use of protected zinc oxide in lower doses in weaned pigs in substitution for the conventional high dose zinc oxide

Abstract

This study tested the hypothesis that protected zinc oxide (ZnO) in lower doses can substitute the high dose conventional ZnO in weaned pigs for improved growth performance and alleviation of digestive disorders. A total of 150 crossbred weaning pigs (28 days old) with an average body weight (BW) of 6.48 ± 1.58 kg were blocked and stratified based on sex and randomly allotted to 1 of 6 dietary treatments [5 pigs per pen (2 barrows and 3 gilts); 5 pens per treatment] for a 6-wk trial in two phases. Treatments consisted of basal diet (NC); Basal diet without Zn in mineral premix with either 2500 ppm unprotected ZnO (PC) or 250, 500, 750 and 1000 ppm protected ZnO (PZ1, PZ2, PZ3 and PZ4 respectively). As a result of this experiment, the growth performance in pigs fed protected ZnO diets was comparable with PC diet during phase 1 and 2, except for G/F ratio in phase 1. There were cubic effects (P < 0.05) of protected ZnO dose on average daily gain (ADG) and average daily feed intake (ADFI) during phase 2. The coefficient of apparent total tract (CAATD) nutrient digestibility in pigs fed protected ZnO diets was comparable with PC diet. The concentration of Zn in the serum of pigs fed PC diet was higher (P < 0.05) than protected ZnO diets during wk 1, 3 and 6. The faecal Zn concentrations were higher (P < 0.05) in pigs fed PC diets compared to NC and PZ diets during wk 1, 3 and 6. A linear response of protected ZnO dose was observed on faecal Zn concentration. The E.coli and Clostridium spp counts were lower (P < 0.05) in the digesta from colon of pigs fed PC diet than protected ZnO diets during wk 3. Quadratic and cubic effects (P < 0.05) of protected ZnO dose were observed on E.coli counts in the digesta of ileum and colon of pigs. Linear effects (P < 0.05) of protected ZnO dose were observed on Lactobacillus and Clostridium counts on the digesta of ileum and colon respectively. The faecal E.coli counts were greater in protected ZnO than in conventional ZnO during wk 1 and 3. The faecal Lactobacillus counts were greater (P < 0.05) and Salmonella counts were lower (P < 0.05) in PZ1 and PZ2 diets than PC diets during wk 6. Linear and quadratic effects (P < 0.05) of protected ZnO dose on E.coli counts during wk 3 and linear effects on Lactobacillus and Salmonella counts during wk 6 were observed.In conclusion, a lower dose of protected ZnO could replace the higher dose of conventional ZnO because it has comparable or better effects than conventional ZnO in a higher dose.