Abstract
This study was conducted to determine the effect of selected antibiotic alternatives on growth performance and inflammatory gene expression in broiler chickens challenged with Eimeria oocysts from Coccivac® vaccine. A randomized complete block design with 6 treatments and 8 replicate pens per treatment was used. The treatments were; negative control (NC) with neither antibiotic nor antibiotic alternatives, Salinomycin positive control (PC), essential oil (Orego-Stim®), commercial yeast (AlphamuneTM), direct fed microbial (Avicorr®) and crude yeast extract. The study lasted 42 d and measurements were taken on d 0, 21 and 42. There was no significant difference in body weight (BW), daily gain (BWG) between treatments on d 21. From d 21 to d 42, BWG of birds treated with Salinomycin (2058 g) was higher (P<0.05) than Avicorr (1919 g) and Orego-Stim (1933 g) treated groups. Feed efficiency (g/kg) was improved (P<0.05) by Salinomycin (605) compared with NC (578) and Orego-Stim (578) treatments. Immune-related genes, interleukin-6 (IL-6) and 10 (IL-10), lipopolysaccharide-induced TNF-α factor (LITAF), toll-like receptor 4 (TLR-4) and interferon γ (IFNγ) were measured by PCR. On d 21, expression of IL-6 was reduced (P<0.05) in the Salinomycin, Avicorr, Alphamune and Orego-stim treatments relative to the NC and the crude yeast treatments. On d 42, LITAF was lower (P<0.05) in the Orego-Stim treatment group than NC. Birds in the crude yeast treatment had higher (P<0.05) expression of IL-10, IFN-γ and TLR-4 compared to the Orego-Stim treatment, but similar to NC. For digestibility trial, Salinomycin and crude yeast treatments had higher apparent ileal dry matter (DM), energy, N and P digestibility on d 21. These differences were not apparent on d 42. Overall, these results confirm the expected improved animal performance with antibiotic (Salinomycin) and further show reduced inflammation in the cecal tonsils with organic acid (Orego-Stim) treatment in broiler chickens.
