The effect of inclusion in drinking water, either singly
or alternating, of oregano oil and a probiotic
Enterococcus faecium strain on feed and water
intake 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 not negatively affect feed and water intake of broiler chickens during a 42-day growth period. 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. Water and feed intakes were determined on a pen basis during the 42-day period. Water intake was not affected by additives supplied in drinking water. Feed intake was also not different between the groups during the trial, only a slightly higher feed intake was determined in the oregano oil-probiotic group in the finisher phase (days 14–42). Congruently, the water to feed intake ratio was not influenced by additives in drinking water. The data showed a strong correlation between water and feed intakes. Only the alternating supply of oregano oil and a probiotic in drinking water had a slight positive effect on water and feed intake but consistent responses compared to the control were not observed in any supplemented group. Consequently, the administration with drinking water may be a viable way to supply these types of feed additives to diets of young chicken without compromising their acceptance to consume water.