Effects of fulvic acid addition on laying performance, biochemical indices, and gut microbiota of aged hens

Abstract

The purpose of this study was to appraise the effect of fulvic acid on production, biochemical indices, and gut microbiota of laying hens. A total of 252 Dawu Golden Phoenix laying hens (55-week-old) were allotted to two treatments randomly, each with six replicates and 21 hens per replicate, including the control group (CG) and fulvic acid (500 mg/kg) group (FA). The trial period was 8 weeks. Adding FA raised egg weight (P = 0.03), shell-breaking strength (P = 0.03), and reduced egg breaking rate (P < 0.01), compared with CG. There was no difference in eggshell thickness and egg shape index between the two treatments; however, the FA group increased egg production by 1.45% and reduced the feed-to-egg ratio by 0.09. Moreover, dietary FA decreased the aspartate aminotransferase levels in serum (P = 0.04), and glutathione peroxidase and total antioxidant capacity were increased (P = 0.02 and 0.04, respectively). Despite this, the two groups had no differences in the alpha diversity indices (PD_whole trees, Shannon, Ace, Simpson, Chao1, and goods_coverage). Obviously, at the phylum level, the abundances of Firmicutes were improved (P < 0.01), Actinobacteriota (P < 0.01), and Proteobacteria (P < 0.01) were reduced by dietary FA. Supplementation with FA could improve the abundances of Megamonas (P < 0.01) and reduce Enterobacter (P < 0.01) at the genus level. To sum up, this study showed the addition of 500 mg/kg FA may boost production and egg quality and modulate the cecal microflora abundance and serum biochemical indices of laying hens.