Day-old chicks were weighed at the beginning of the trial and housed in special pens under controlled ambient conditions (temperature, relative humidity and light). Chicks had ad libitum access to feed and water. Chicks received identical iso-protein and iso-energy diets without (control group) and with (trial group) probiotic supplementation. Probiotic «Probios» produced by the company Hansen Bio System from Denmark was included in the trial diets at 1 kg/1000 kg of feed.