This trial was conducted to evaluate the effects of dietary supplementation of phytogenic product containing an equal mixture of thymol and carvacrol at 4 levels (0, 60, 100, and 200 mg/kg of diet) on performance, antioxidant enzyme activities, fatty acid composition, digestive enzyme activities, and immune response in broiler chickens. Each of the 4 diets was fed to 5 replicates of 12 chicks each from d 0 to 42. The inclusion of thymol + carvacrol linearly decreased (P < 0.05) feed intake, but the highest (P < 0.05) BW gain (ADG) and feed efficiency was observed in broilers offered 200 mg/kg of phytogenic product. The phytogenic product linearly increased (P < 0.05) superoxide dismutase and glutathione peroxidase activities and decreased (P < 0.05) malondialdehyde level in thigh muscle at d 42 and serum and liver at d 24 and 42. Total saturated fatty acids were depressed (P < 0.05) and total polyunsaturated fatty acid and n-6 were linearly increased (P < 0.05) in serum and thigh by the inclusion of phytogenic product compared with the control diet. Supplementation with thymol + carvacrol also increased intestinal and pancreatic trypsin, lipase, and protease activities in 24-d-old (linear, P < 0.05) but not in 42-d-old birds. Thymol + carvacrol modified (linear, P < 0.05) immune response by increasing hypersensitivity response, total and IgG anti-sheep red blood cell titers, and decreasing heterophil to lymphocyte ratio compared with the control group. However, hematological parameters and lymphoid organ weight were not affected by thymol + carvacrol. Thus, feed supplementation with thymol + carvacrol enhanced performance, increased antioxidant enzyme activities, retarded lipid oxidation, enhanced digestive enzyme activities, and improved immune response of broilers.

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This study investigated the effects of an antimicrobial peptide (AMP), cLF36, on growth performance and the histophysiological changes of the intestine in E. coli-challenged broiler chickens. A total number of 360 day old male chicks were randomly assigned to 4 groups of 6 replicates as follows: T1) negative control diet based on corn-soybean meal without E. coli challenge and additives; T2) positive control diet based on corn-soybean meal and challenged with E. coli without any additives; T3) positive control diet challenged with E. coli and supplemented with 20 mg AMP (cLF36)/kg diet; T4) positive control diet challenged with E. coli and supplemented with 45 mg antibiotic (bacitracin methylene disalicylate)/kg diet. Results showed that T3 improved growth performance and the jejunal morphology of E. coli-challenged chickens similar to those of T4. While antibiotic non-selectively decreased the population of ileal bacteria, AMP increased the population of Lactobacillus spp. and decreased harmful bacteria in the ileum of E. coli-challenged chickens. Supplementing E. coli-challenged chickens with AMP improved the gene expression of immune cells and upregulated the expression of tight junction proteins compared to other challenged groups. In conclusion, although cLF36 beneficially affected growth performance and the intestinal morphology of E. coli-challenged chickens similar to those of the antibiotic group, this AMP drastically improved the intestinal microbiome, immune cells, and junctional proteins compared to other E. coli-challenged birds, and can be nominated as an alternative for growth promoter antibiotics.

This study investigated the effect of dietary α-tocopherol (α-Toc), pomegranate peel extract (PPE), and pomegranate peel (PP) on phenolic content and breast meat quality of broilers during 11 days of storage with the addition of α-Toc, PPE, and PP. Broilers were fed eight dietary treatments, including: control diet, α-Toc diet (200 mg/kg), PPE diets (100, 200, and 300 mg/kg), and PP diets (1, 2, and 3 g/ kg) during 0-42 days. The extents of lipid oxidation in samples were assessed by measuring thiobarbituric acid-reactive substances and the 1, 1-Diphenyl-2-picrylhydrazyl radical-scavenging activities were determined. The feed efficiency was improved significantly in chickens fed diet containing 0.2 g/kg PPE, and the growth performance of chickens was impaired in chickens fed with PP diet. Long-chain polyunsaturated fatty acids n-3 were increased in breast muscles of broilers fed α-Toc and high levels of PPE diets (P < .05). Total phenolic contents and antioxidant activity in the breast meat were improved significantly when chickens fed diets containing α-Toc and PPE (P < .05). In conclusion, dietary supplementation with 200 and 300 mg/kg PPE may improve the antioxidant potential and quality indices of broilers breast meat. The antioxidant potential of PPE was equal to that of α-Toc in refrigerated meat.