The effects ofphytogenic feed additives on piglet performance and fecal score (FDD), as wellas on lipid oxidation of pork meat were evaluated. One hundred and twenty crossbredweaned piglets were randomly assigned to six treatments according to a 2 ×3 factorial design with five replicates per treatment. Factors were: challengewith Salmonella Typhimurium at 35 days of age or no challenge, and threedifferent additives (control (CTR), basal diet; phytogenic feed additives (PHY),basal diet plus 2000 ppm of phytogenic feed additives - Rosmarinus officinalis,Mentha piperita, Lippia sidoides and Porophyllum ruderale; and antimicrobialagent (ATB), basal diet plus 100 ppm of tylosin, 2000 ppm of zinc and colistinsulfate, 30 ppm in the pre-starter basal diet, 10 ppm in the starter basal dietI and II, and 5 ppm in growth and finishing basal diet). Body weight (BW) ofthe piglets of ATB was greater throughout the experimental period, without anydifferences detected between CTR and PHY. Nevertheless, from 96 to 106 daysof age, the BW of the CTR group was greater than PHY. From 21 to 34 days ofage, feed conversion of ATB was lower than CTR; however, PHY showed an intermediateresult, which did not differ from either ATB or CTR. Challenged animals reducedfeed intake from day 35 to 48 compared with unchallenged animals. Piglet performanceand fecal score from 21 to 48 days of age were lower in piglets that receivedATB compared with the other treatments. However, from 35 to 48 days of age,the FDD of PHY was lower than CTR. Lipid oxidation was not reduced in treatedanimals. Antimicrobial agent improved the growth performance of piglets until63 days of age, and no difference was observed between the treatments from 64to 131 days of age. Antimicrobial agent reduced FDD; the FDD of PHY was similarto that of ATB after 48 days. None of the treatments affected lipid oxidationof pork meat.
