Effect of fermented feed additive on the broilers' histology/morphology of the GIT, immune status, and microbiota

This study was aimed to analyse the effect of a fermented feed additive on the broilers' histology/morphology of the GIT, immune status, and microbiota as an alternative to AGP. Four groups of 288-day-old male and female Arbor Acre broilers were randomly divided (6 replicates in each group each with 12 chicken). Negative control (NC; basal diet), positive control (PC; basal diet +antibiotic virginiamycin 15ppm) one of the 2 fermented feed additives (FFA) diets prepared by adding, fermented feed additive low dose (FFL; basal diet + 0.3kg/t Lactobacillus casei fermented feed additive) and fermented feed additive high dose (FFH; 3kg/t Lactobacillus casei fermented feed additive). Composition of fermented feed: total bacteria count: 2×10 9 CFU/g，Lactic acid 20mg/g, acetic acid 5mg/g, succinic acid 7mg/g, pyruvic acid 0.1mg/g. The research demonstrated that including fermented feed additives (FFA) in the diet provided overall benefits, FFL and PC diets showed improved (1-21 day) feed conversion ratio (FCR) compared to NC from 0-42 day ( P < 0.05). FFH and FFL showed improve intestinal morphology within the duodenum, jejunum, and ileum with higher villus height (VH), and villus height to crypt ratio (VH/CR) ( P < 0.05). Duodenum and ilium crypt depth was highest in PC and FFL respectively ( P < 0.05). FFH had a significantly lower thymus weight compared to NC ( P < 0.05). Furthermore, fermented feeds FFL and FFH influenced the intestinal immunity-related mRNA levels and increased expression of IL-10 ( P < 0.05). FFL down-regulated the mRNA expressions of IL-1β and TLR4 ( P < 0.05). Both fermented feeds FFL and FFH positively modulated the composition and variety of cecal microbiota compared to the NC.