Effects of oregano essential oil supplementation to diets for broiler chicks with delayed feeding after hatching. 1. Performances and digestibility of nutrients [Einfluss eines Zusatzes von essentiellen Ölen aus Oregano zu Broilerrationen bei verzögerter Anfütterung nach dem Schlupf. 1. Leistung und Nährstoffverdaulichkeit]

The study was conducted to investigate the effects of dietary supplementation of oregano essential oil at different levels (0, 250 or 500 mg kg-1) on growth performance, digestive organs, nutrient composition of carcass, nutrient digestibility and bacterial populations of the small intestine of broiler chicks with immediate, 24, 48 or 72 h delayed feeding from d 0 to 21. The following diets were used from 0 to 21 d. Diet 1 (control, CONT): a commercial diet containing no essential oil, diet 2 (OO250): supplemented with oregano essential oil at 250 mg kg-1 and diet 3 (OO500): supplemented with oregano essential oil at 500 mg kg-1. Especially, with extended delay of access to diet and water body weight gain during the period of 0 and 21 d was significantly decreased and feed conversion ratio from 4 to 21 d-old broilers was significantly aggravated. Experimental treatments did not affect the relative weights of yolk sac and digestive organs except gizzard and the nutrient composition of carcass in broilers at 21 d. CONT group or the group with delayed access to diet and water for 72 h showed a significantly reduced ileal digestibility of organic matter and crude protein. The extension of the delayed access to diet and water significantly increased total aerobic bacteria and coliform bacteria contents of chickens' small intestine at 21 d. The supplemented levels of oregano essential oil to the diet have not been sufficient to compensating the negative effects on growth performance. The reason was probably the aggravated bacterial content of small intestine and the nutrient ileal digestibility by the delayed access to diet and water. There is need for further research to determine the effects of the optimal level or of the combined use of the active compounds in oregano essential oil in diet to remove the negative effects on growth performance, digestive organs, nutrient digestibility and bacterial populations of small intestine of broilers with delayed access to diet and water. © Verlag Eugen Ulmer, Stuttgart