The effect of inclusion in drinking water, either
singly or alternating, of oregano oil and a probiotic
Enterococcus faecium strain on performance of growing broiler chickens

The hypothesis of this study was that the inclusion of oregano oil and a probiotic Enterococcus faecium strain in drinking water, either singly or alternating, would improve growth performance of broiler chickens during a 42-day growth period. One-day-old Ross 308 chicks (mixed sex; mean body weight 45.1 g (standard deviation 1.04 g) were randomly assigned to four experimental groups at the start of the experiment: control (without supplement), probiotic (continuous supply of an E. faecium commodity [minimum activity per kg: 3.3 × 10¹² colony forming units] with drinking water at 200 mg/L), oregano oil (75,000 mg/kg of product; first three days of each week at 0.2 mL/L drinking water), and oregano oil-probiotic (addition of oregano oil (0.2 mL/L) for three days and E. faecium commodity (200 mg/L) for four days to drinking water), each group with 10 replicates and each replicate with 10 chicks. Intakes of water and feed and body weights were determined. Body weight gain and feed conversion ratio were calculated to determine overall performance. Moreover, weights of liver and abdominal fat pad were assessed. Different additives supplied with drinking water did not affect (P > 0.05) performance of broiler chickens or liver and abdominal fat pad weights. Future studies should be conducted applying varying concentrations of the additives supplied with drinking water.