It is common in commercial practice to feed high levels of zinc oxide (ZnO) to weaned piglets to alleviate post-weaning diarrhea and improve gut health and growth performance. However, the use of pharmacological levels of ZnO must be reduced due to the potential environmental pollution related to the high amount of zinc excreted in the pigs’ feces. The aim of the present study was to evaluate the effects of coated ZnO on growth performance, nutrient digestibility, fecal scores, fecal zinc and intestinal morphology in weaned pigs. For this purpose, a total of 192 crossbred [(Yorkshire × Landrace) × Duroc] weaned pigs (7.4 ± 0.97 kg) were randomly assigned into one of six dietary treatments: (1) negative control (NC) with a basal diet; (2) positive control (PC): NC + 2500 mg/kg conventional ZnO; (3) CZO300: NC + 300 mg/kg coated ZnO; (4) CZO500: NC + 500 mg/kg coated ZnO; (5) CZO1000: NC + 1000 mg/kg coated ZnO; (6) CZO2000: NC + 2000 mg/kg coated ZnO. The feeding trial was carried out for 42 days.
As a result, pigs fed PC, CZO500, CZO1000, and CZO2000 diets had higher average daily gain (ADG) than those fed NC diet during days 0–21. During days 0–42, CZO500, CZO1000, and CZO2000 showed an increased ADG compared with NC treatment. All pigs fed with ZnO supplemented diets had lower fecal scores than those fed the NC diet during weeks 1, 2, and 3. Likewise, ZnO supplementation increased serum and fecal zinc concentrations in contrast to the NC group. Additionally, low doses of coated ZnO reduced the amount of zinc excreted into the feces compared with 2500 mg/kg conventional ZnO. Pigs fed the PC, CZO1000 and CZO2000 diets had greater coefficient of total tract apparent digestibility of dry matter than pigs fed NC diet. The duodenal villus height and the ratio of villus height to crypt depth of pigs fed PC, CZO1000, and CZO2000 diets were higher than those of pigs fed NC diet, whereas no significant differences were observed between them.
To sum up, 500–1000 mg/kg coated ZnO has proven to be as effective as 2500 mg/kg conventional ZnO in relation to enhance growth and alleviate post-weaning diarrhea while diminishing the excretion of zinc to the environment via feces.
Lei, X. J., & Kim, I. H. (2018). Low dose of coated zinc oxide is as effective as pharmacological zinc oxide in promoting growth performance, reducing fecal scores, and improving nutrient digestibility and intestinal morphology in weaned pigs. Animal Feed Science and Technology, 245, 117-125. https://doi.org/10.1016/j.anifeedsci.2018.06.011