A natural phytogenic formulation (NPF) was tested as an alternative to pharmaceutical zinc oxide (ZnO) in weaned piglets with respect to growth performance, apparent total tract digestibility and faecal microbiota composition and metabolic activity. Two dietary NPF levels (NPF: 1000 and 2000 mg/kg diet) were compared to a positive control (ZnO: 3000 mg ZnO/kg diet) and a negative control (CON: no added ZnO or NPF) using 84 weaned piglets from 29 d to 78 d (days of age). Feed conversion ratio was improved (p < 0.05) in ZnO and NPF piglets were compared to CON at 50 d. Dry matter, organic matter and crude protein (p < 0.05) digestibility was improved in NPF piglets compared to CON at 57 d. Compared to CON, NPF inclusion reduced E. coli (p < 0.05) and increased C. leptum subgroup (p < 0.01) at 57 d and 78 d, and reduced C. perfringens subgroup (p < 0.05; at 78 d). The ZnO reduced (p < 0.001) E. coli and C. perfringens subgroup (p < 0.01) compared to CON at 78 d. Moreover, ZnO and NPF reduced molar ratios of branched chain volatile fatty acids (p < 0.05) compared to CON, while NPF also increased butyric acid (p < 0.05) at 78 d. In conclusion, the NPF appeared to be a promising alternative to pharmaceutical doses of ZnO.
Keywords: digestibility; gut ecology; phytogenics; piglets; zinc oxide.