Two experiments with a total of 120 weanling pigs (21 to 56 d of age) were conducted to evaluate the effects of antimicrobials and herbal extracts on intestinal microbiota (experiment 1) and on fecal score (experiments 1, 2 and 3). Pigs were allotted in pairs (pens with a barrow and a female) to a randomized complete block design 12 replications of five treatments. Treatments consisted of: control - basal diet; antimicrobial - basal diet plus Zn bacitracin, olaquindox, and colistin (50 ppm of each); herbal extract A, B and C - basal diet plus 700 ppm, 1,400 ppm and 2,100 ppm of herbal extract, respectively. The herbal extract consisted of a mixture of essential oils of thyme, clove, oregano, eugenol and carvacrol. At the end of experiment 1, one animal of each experimental unit was slaughtered to collect samples of small intestine for microbiological analysis, that showed no significant difference. During 1-35 days of experiment, diarrhea incidence of pigs fed antimicrobials was lower than those fed control or herbal extract diet. Therefore, even though no statistical difference was observed in intestinal microbiota, antimicrobials were effective in diarrhea control.
additives; herbal extract; microbiology; swine
