Effects of phytogenic feed additive on growth performance, digestibility, blood metabolites, intestinal microbiota, meat color and relative organ weight after oral challenge with Clostridium perfringens in broilers

A total of 405 mixed sex broilers with a BW of 42±1g (1d of age) were used in a 35-d trial to investigate the effects of phytogenic feed additive (PFA) containing essential oils of thyme and star anise as main active components on growth performance, energy and nutrient apparent total tract digestibility (ATTD), blood metabolites, intestinal microflora, meat color, and relative organ weight after oral challenge with Clostridium perfringens. Broilers were randomly assigned to 1 of 3 treatments (9 replicate pens per treatment with 15 broilers per pen). Dietary treatments were: control (CON); antibiotics (ANT), CON+10mg/kg of avilamycin); and PFA, CON+250mg/kg of PFA. Broilers were oral challenged with 5mL C. perfringens (107cfu/mL) culture suspensions on d 19, 20, and 21. Broilers fed PFA diets had greater (P<0.01) feed conversion ratio than those fed CON and ANT diets during the finisher phase (d 21–35). Broilers fed PFA diet got lower (P<0.01) FCR than those fed CON diet during d 0–35. The chicks fed PFA had greater (P<0.01) ATTD of dry matter, and gross energy than that fed CON and ANT diets at d 21. The ATTD of crude protein and crude ash were increased (P<0.05) by dietary supplementation of avilamycin or PFA at d 21. Dietary supplementation of avilamycin or PFA improved (P<0.05) the ATTD of gross energy at d 35. At d 35, supplementation of PFA reduced (P<0.01) the serum total cholesterol (TC) content and increased (P<0.01) high density lipoprotein-cholesterol (HDL-C) than CON and ANT treatments. The HDL-C concentration was increased (P<0.01) by avilamycin inclusion in the diet compared with that of broilers in CON. The PFA inclusion reduced (P<0.01) C. perfringens and Escherichia coli counts in small and large intestine. The lesion score of small intestine was also reduced (P<0.05) by supplementation of the diet with PFA compared with ANT and CON diets. In conclusion, our results indicated that supplementation of PFA improved growth performance, reduced blood TC, and also inhibited C. perfringens and E. coli proliferation in small and large intestines in broiler chicks under oral C. perfringens challenge.