Effects of different plant extracts at various dietary levels on growth performance, carcass traits, blood serum parameters, immune response and ileal microflora of Ross broiler chickens

A study was conducted to evaluate the effects of different plant extracts (common nettle, coriander, dill and thyme) at various dietary levels (0, 150, 300 and 450 mg/L) on growth performance, carcass traits, blood serum parameters, immune response and ileal microflora of 650 male Ross chickens (13 treatment groups; five replicates/treatment group; 10 birds/replicate) in a 42-day trial. Plant extracts were added to drinking water. Supplementation, except for coriander, increased feed intake (p <.05). Thyme extracts at 300 mg/L improved both weight gain and feed efficiency (p <.05). Thyme or dill (300 mg/L) improved carcass and drumsticks yields (p <.05). Pre-slaughtered body weight was increased by supplementation with plant extracts at 300 mg/L (p <.05). Plant extracts positively affected blood serum parameters decreasing concentrations (p <.05) of total protein, albumin, urea and total cholesterol. Dill extract increased IgG against sheep red blood cells at d 28 (p <.05) and d 42 (IgG; tendency p=.0698), whereas coriander extract (450 mg/L) raised immune response against avian influence within 42 d from vaccination (p <.05). Plant extracts reduced coliforms (except dill at 300 mg/L level; p <.05) and aerobic bacteria (except dill; p <.05). Negative gram bacteria were increased by thyme and dill treatments at 150 mg/L (p <.05) whereas lactobacilli bacteria were raised by thyme at 150 mg/L level (p <.05). In conclusion, supplementation with thyme at 300 mg/L level had the greatest benefits on the evaluated parameters.HIGHLIGHTS Thyme supplementation at 300 mg/L level could improve broiler chicken growth performance, carcass traits and blood serum parameters. Thyme supplementation at 150 mg/L could positively affect ileal microbiota increasing lactobacilli bacteria and reducing coliforms. However, no relevant effects of the thyme treatment were observed on broiler chicken immune responses.