The effect of peppermint essential oil and fructooligosaccharides, as alternatives to virginiamycin, on growth performance, digestibility, gut morphology and immune response of male broilers

With the increasing concerns over food safety during these years, there has been an intense effort for substituting (eliminating) antibiotic growth promoters in poultry feeds. Therefore, in order to investigate the effect of natural alternatives for antibiotics, an experiment was conducted to examine the effect of virginiamycin, a prebiotic (Fructomix), and peppermint (Mentha piperita) essential oil on productive performance, digestibility, intestinal morphology and immune response of broilers. A total of 240 Ross 308 male broilers were randomly (completely randomized design) allotted to five treatments, with four replicates per treatment (12 chickens per pen). Birds were offered either a maize-soybean meal basal diet (control, CON) or the basal diet supplemented with 200 mg/kg virginiamycin (VM); 200 mg/kg peppermint oil (PO1); 400 mg/kg peppermint oil (PO2); or 500 mg/kg Fructomix (FM). After 6 weeks, daily live weight gain and feed intake were higher (P<0.001) for VM-fed birds compared with other groups. Feed conversion ratio was better (P=0.039) in chicks fed the VM (1.74), and PO1 diet (1.75) compared with birds in the CON (1.84) and PO2 (1.86) groups. Primary antibody titers against sheep red blood cell were higher (P<0.001) in broilers fed FM (6.37) compared with other groups. At 21d of age, crude protein digestibility was higher (P=0.001) in PO1 group (0.8645) compared with other groups except VM (0.8505). Finally, higher ether extract digestibility (P=0.040) was detected in birds fed VM (0.8831) compared with PO2 (0.7940), and FM (0.7561) fed birds. In duodenum, villus height: crypt depth was higher (P=0.008) in VM supplemented group (7.07) in comparison with other groups. In conclusion, this study showed that neither PO nor FM could be suggested as effective alternative for VM.