Enzymatically prepared alginate oligosaccharides improve broiler chicken growth performance by modulating the gut microbiota and growth hormone signals

The coding sequences of five alginate lyases from bacteria were cloned into <em>Pichia pastoris</em> GS115 and the hydrolysis characteristics of the expressed enzymes were evaluated. Animal trials were carried out using 320 1-day-old male Arbor Acres broilers (four groups) receiving either a basal diet or the same diet supplemented with 100, 200 and 400 mg/kg AOS for 42 d. The effects of AOS were evaluated by broiler growth performance, intestinal morphology and associated enzyme activities, barrier function, immunity, and integrated microbiome analysis. Assays of AOS <em>in vitro</em> fermentation, pathogen inhibition, and growth promotion of selected gut bacterium were performed. <br>