The potential of supplementing compound organic trace elements at lower levels in Chinese yellow- feathered broiler diets, part II: Impacts on growth performance, gut health, intestinal microbiota, and fecal mineral excretion

This study aimed to investigate the effects of reducing inorganic trace minerals (ITM) by supplementing compound organic trace minerals (OTM) chelates on growth performance, fecal mineral excretion, intestinal health, and cecal microbiota of yellow-feathered broilers. A total of 960 one day old male broilers were randomly assigned to 6 treatments, among which birds were fed with the basal diets (negative control, NC), or supplemented with 1,000 mg/kg (positive control, PC), 300, and 500 mg/kg ITM or OTM, respectively. Dietary supplementation of OTM significantly increased the average daily gain (ADG) during 22-53 d and 1-53 d, and reduced the fecal emissions of Fe, Cu, Zn, and Mn of Chinese yellow-feathered broilers (P < 0.05). Furthermore, the OTM300 group significantly reduced the crypt depth in the duodenum, and increased the ratio of villus height to crypt depth (V/C) in the duodenum and jejunum (P < 0.05). The mRNA expression of TGF-β, Bcl-2, CAT, and GPX4 as well as tight junction proteins (occludin, ZO-1, claudin-1, and claudin-5) in jejunum mucosa were significantly increased by compound OTM when comparing with ITM300 group (P < 0.05). Moreover, dietary compound OTM significantly changed the Chao1 index and β diversity index of cecal microbiota of Chinese yellow-feathered broilers. The abundances of Firmicutes (phylum), Eubacterium_coprostanoligenes_group (family) and Oscillibacter (genus) were increased, while the abundances of Bacteroidetes (phylum) and Rikenellaceae RC9 group (genus) were decreased by OTM treatment. Spearman correlation analysis showed that the mRNA of occludin and jejunal V/C ratio were positively correlated with the abundance of Firmicutes (phylum), but negatively correlated with the abundance of Bacteroidota (phylum). In addition, the abundance of Eubacterium_coprostanoligenes_group (family) was positively correlated with the mRNA of claudin-1, Bcl-2, and TGF-β. PICRUST prediction of microbial function revealed that OTM treatment enriched the pathways related to amino acid metabolism and DNA replication. In conclusion, dietary supplementation at lower levels of compound OTM to replace ITM could improve growth performance and intestinal health, and reduce the fecal excretion of trace elements by modulation of cecal microbiota community and diversity in Chinese yellow-feathered broilers.