A comperative study on bioefficacy of different tymol/carvacrol sources recommended to use as growth enhancer in broiler diets

The present study was conducted to compare bio-efficacy of tymol/carvacrol sources (natural or synthetic) as growth enhancers in broilers. A day old 120 male broiler chicks were divided into 6 dietary groups with similar mean weight, 20 birds each. Diets were prepared as positive control (antibiotic supplemented), negative control (no growth promoter or enhancer), 300/150 ppm synthetic timol/carvacrol (1:1), 300/150 ppm encapsulated synthetic timol/carvacrol (1:1), 300/150 ppm natural oreganum extract and 300/150 ppm tymol oil) for starter and finisher periods respectively. All the birds were fed ad libitum for a 6 weeks period.The results obtained in the experiment showed that no differences were found between the groups with respect to feed intake, body weight gain, some plasma values (P>0.05). Although significant differences (P<0.05) in feed conversion efficiency were observed between the groups during the firs 3 weeks period, no differences (P>0.05) were found at the end of the experiment. Weigh and length of the digestive system were affected by the treatments. Natural oreganum extracts and thymol oil reduced (P<0.05) the lengh, while the oil supplementation significantly increased duodenum weight. Villi length was also improved (P<0.05) by the treatments, especially by natural sources; oreganum extract and tymol oil.It was concluded that different sources of tymol/carcavrol used in this study had similar bio-efficacy in terms of their poteintial as growth enhancers for broilers, while natural source of tymol/carvacrol in oreganum extract and encapsulated synthetic were found to be more beneficiary for performance.Keywords: Broiler, tymol, carvacrol, performance, digestive system