Dietary pyrroloquinoline quinone improvement of the antioxidant capacity of laying hens and eggs are linked to the alteration of Nrf2/HO-1 pathway and gut microbiota

Pyrroloquinoline quinone disodium (PQQ center dot Na2) has been considered a human food supplement for human health promotion with its antioxidant properties. To determine whether PQQ center dot Na2 had similar functions to improve the antioxidant ability of layers and eggs, 180 laying hens were fed with 0 or 0.4 mg/kg PQQ center dot Na2 diets. Supplementation with PQQ center dot Na2 increased the albumen height, Haugh unit of the eggs. PQQ center dot Na2 also led to a higher glutathione peroxidase (GSH-Px) concentration in plasma and a lower malondialdehyde (MDA) content in the liver and egg yolk. Similarly, liver gene and protein expression of nuclear factor erythroid 2-related 2 (Nrf2) and heme oxygenase 1 (HO-1) were up-regulated by PQQ center dot Na2. Moreover, PQQ center dot Na2 increased the abundance of Firmicutes, Microbacterium, Erysipelatoclostridium, Mailhella, Lachnospiraceae_UCG-010, and Herbaspirillum in gut. Overall, these results suggested PQQ center dot Na2 increased the antioxidant ability of layers and eggs which might be in connection with the activation of the Nrf2/HO-1 pathway and optimized gut microflora.