Bacillus CotA laccase improved the intestinal health, amino acid metabolism and hepatic metabolic capacity of Pekin ducks fed naturally contaminated AFB1 diet

Abstract Background Aflatoxin B1 (AFB1) is a prevalent contaminant in agricultural products, presenting significant risks to animal health. CotA laccase from Bacillus licheniformis has shown significant efficacy in degrading mycotoxins in vitro test. The efficacy of Bacillus CotA laccase in animals, however, remains to be confirmed. A 2 × 2 factorial design was used to investigate the effects of Bacillus CotA laccase level (0 or 1 U/kg), AFB1 challenge (challenged or unchallenged) and their interactions on ducks. The purpose of this study was to evaluate the efficacy of Bacillus CotA laccase in alleviating AFB1 toxicosis of ducks. Results Bacillus CotA laccase alleviated AFB1-induced declines in growth performance of ducks accompanied by improved average daily gain (ADG) and lower feed/gain ratio (F/G). Bacillus CotA laccase ameliorated AFB1-induced gut barrier dysfunctions and inflammation testified by increasing the jejunal villi height/crypt depth ratio (VH/CD) and the mRNA expression of tight junction protein 1 (TJP1) and zonula occluden-1 (ZO-1) as well as decreasing the expression of inflammation-related genes in the jejunum of ducks. Amino acid metabolome showed that Bacillus CotA laccase ameliorated AFB1-induced amino acid metabolism disorders evidenced by increasing the level of glutamic acid in serum and upregulating the expression of amino acid transport related genes in jejunum of ducks. Bacillus CotA laccase ameliorated AFB1-induced liver injury testified by suppressing oxidative stress, inhibiting apoptosis, and downregulating the expression of hepatic metabolic enzyme related genes of ducks. Moreover, Bacillus CotA laccase degraded AFB1 in digestive tract of ducks, resulting in the reduced absorption level of AFB1 across intestinal epithelium testified by the decreased level of AFB1-DNA adduct in the liver, and the reduced content of AFB1 residues in liver and feces of ducks. Conclusions Bacillus CotA laccase effectively improved the growth performance, intestinal health, amino acid metabolism and hepatic aflatoxin metabolism of ducks fed AFB1 diets, highlighting its potential as an efficient and safe feed enzyme for AFB1 degradation in animal production. Graphical Abstract