Effects of phytobiotic feed additives on growth traits, blood biochemistry, and meat characteristics of broiler chickens exposed to Salmonella typhimurium

Because of concerns over the use of antibiotics in poultry feed, this study was designed to determine the effectiveness of phytobiotic supplementation as an alternative to antibiotic use based on growth performance and meat characteristics of broilers exposed to Salmonella typhimurium. The effects of an antibiotic and 3 phytobiotic feed additives (PFA), Mix-Oil Mint (MO_{mint}), Mix-Oil Liquid (MO_{liq}), and Sangrovit Extra (Sang_{ext}), were compared. At day of age, 280 Ross chicks were randomly allocated into 6 treatments. At 15 d, all chicks except negative control were exposed to S. typhimurium. The offered 6 diets were as follows: T1, negative control; T2, infected with S. typhimurium; T3, infected + avilamycin (0.1 g/kg); T4, infected + MO_{mint} (0.2 g/kg); T5, infected + plant extract in liquid form MO_{liq} (0.25 mL/L); and T6, infected + Sang_{ext} (0.15 g/kg). During the cumulative starter period, PFA improved performance over that of the control, and the food conversion ratio (FCR) was lower for T3 and T5 compared with T1 (P < 0.05). During the cumulative finisher period (15-35 d), a lower body weight gain (P < 0.01) was observed in T2. T1 had the best FCR and production efficiency factor, but they were not significantly different from those of T3, T4, and T6 (P < 0.001). At 35 d, T1 and T4 had a higher breast percentage as compared with those of T2 (P < 0.05). Blood glucose decreased significantly (P > 0.05) in T2 and T5 compared with that in T1 and T4. Alanine transaminase concentration decreased significantly (P < 0.01) in T4 and T5 compared with that in T1, T2, and T3. Treatments had significant effects on breast temperature and pH (P < 0.001). A significant decrease in the myofibril fragmentation index occurred in T1 and T6. Hardness and chewiness were influenced by treatments (P < 0.05). In conclusion, dietary supplementation with PFA could effectively compare with that of antibiotic avilamycin in the maintenance of growth performance and improvement in meat characteristics of broilers challenged with S. typhimurium.