Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern poultry production practices are associated with regular use of AGPs, potentially increasing selection pressure on bacteria to become resistant. AGP-alternatives are being sought to improve poultry performance. While the industry is focused on developing alternate solutions; their mode of action still remains unclear. Present study is undertaken to establish probable mechanism of action of phytogenic growth promoter Herbiotic FS (M/S Indian herbs Specialities, India) in 120 Vencobb broiler by assessing global gene expression of chicken gut. There were 4 experimental groups (30 birds per group of 6 replicates); Healthy control, infected control (Salmonella gallinarum (1×108 CFU/ml) infection was induced on day 4th), infected & treated with Herbiotic@500g/ton and infected & treated with Linomycin@250g/ton of feed. High-throughput microarray technology provides comprehensive view of global gene expression changes in host. We report here chicken-specific microarray to profile host gene transcription of caeca between Salmonella infected & treated chicken to characterize their host response. Microarray was designed using mRNA sequences reported in NCBI database. 40944 target mRNA sequences were used to design probes. Cluster of differentially upregulated & downregulated genes, heatmap analysis and fold change(fc?) were performed to analyze gene expression data. The normalization was done using GeneSpring GX Software. The functions & pathway analysis was done for the differentially regulated genes using DAVID database. Differential cut off Fold Value (> = 0.6) in the treated samples indicated Up Regulation & vice versa and was used to determine significant differential expression. Gene ontology performed for 45 upregulated genes with Herbiotic FS treatment compared to other treatments yielded 15 mapped gene ids, 28 unmapped gene ids and 2 multiple mapping ids. Supplementation of Herbiotic induced upregulation of genes of immune system process(XM_421205, fc?5.84), transporter activity (XM_425129, fc?2.39), metabolic process (CR353567, fc?3.08), cellular processes & biological regulation(X56772; fc?10.09), growth(CR87077, fc?2.50) etc. Upregulation of genes suggest that Herbiotic FS possess multi-dimensional mechanism of action involving antimicrobial, anti-inflammatory, gut histomorphology & innate immunity promoting, growth promoting properties as compared to AGPs(Lincomycin). Gut microarray reveals that Herbiotic FS can successfully replace AGPs in poultry ration with additional advantages of no AMR & residues in meat.
Key Words: Antimicrobial resistence, Phytogenic, gut microarray, mode of action, AGP Alternates