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1. The present experiment was conducted to describe the effects of thymol, cinnamaldehyde and a commercial preparation of essential oil components (CRINA Poultry), in female broilers. Feed and water were provided for ad libitum consumption. 2. Feed intake, weight gain and feed:gain ratio were not different among the treatments. Water intake was significantly lowered by cinnamaldehyde. Relative liver weight (g/100 g of body weight) was highest in birds given thymol, but this was seen only at the age of 21 d and not at 40 d. Patterns of digestive enzymes in pancreatic tissue were similar for the 4 treatments. 3. Amylase activity in intestinal digesta was highest in chickens given CRINA Poultry for 21 d, but the effect had disappeared after 40 d. Ileal digestibility coefficients for starch and protein were high and identical for all treatments. 4. Fatty acid composition of diet was reflected in that of adipose tissue. Plasma lipid concentrations were not changed by any dietary treatment. 5. Thus, the present results show no effect of essential oil constituents on growth performance in female broiler chickens, but it cannot be excluded that positive effects would have been observed under less hygienic environmental conditions or when using a less digestible diet.

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The increasing trends of legislative restrictions and voluntary removal of antibiotic growth promoters worldwide has already affected, and will continue to affect, poultry production and animal health. Necrotic enteritis (NE) is being considered among the most important infectious diseases in the current poultry production system globally, with an estimated annual economic loss of more than $2 billion, largely attributable to medical treatments and impaired growth performance. Thus, there is an urgent need to develop rational, alternative, and integrated management strategies not only to control NE, but also to prevent it. In both humans and many warm-blooded animals and birds, NE is caused by Clostridium perfringens, a gram-positive, anaerobic, spore-forming bacterium. To accomplish these goals, better understanding of host- and environmentally related factors on the development of NE and potential vaccination strategies against C. perfringens infection will be necessary. Furthermore, a reliable and reproducible NE disease model is needed for characterization of C. perfringens pathogenesis and host protective immunity. This review summarizes recent developments in NE disease models, pathogenesis, host immunity, risk factors, and vaccine development for C. perfringens-associated NE in poultry.

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