Supplementation of Paraformic Acid as a Substitute for Antibiotics in the Diet Improves Growth Performance and Liver Health in Broiler Chickens

Simple Summary Paraformic acid (PFA) is a hyperpolymer formed by polymerization of formic acid monomers, and PFA has a lower pungent smell and corrosiveness to the gastrointestinal tract compared with formic acid. The liver is a crucial metabolic organ, playing a momentous role in nutrients biosynthesis and metabolism, defense against bacterial invasion, and endotoxin clearance. However, in the condition of intensive poultry husbandry, the broiler's liver is susceptible to inflammatory damage. Our results showed that PFA supplemented to the diet improved growth performance, inhibited inflammatory response, and benefited liver protection, which provided a direction for the use of PFA in broiler production. The current study aimed to explore the effects of supplementing paraformic acid (PFA) into broilers' diet on growth performance, inflammatory responses, and liver protection. A total of 567 healthy one-day-old broilers were used in a 42-d study, and they were randomized into three groups. Broilers were fed a basal diet (CON group) or the basal diet supplemented with either 50 mg/kg aureomycin (AB group) or 1000 mg/kg PFA (PFA group). The results showed that the PFA and AB groups had a higher feed conversion rate than the CON group from day 21 to 42 (p < 0.05). Dietary PFA or aureomycin supplementation decreased serum levels of interleukin (IL)-1 beta, IL-6, IL-10, alanine transaminase, diamine oxidase, and D-lactate, and significantly increased serum concentrations of immunoglobulin (Ig) A, IgM, and complement C4 (p < 0.05). Moreover, dietary PFA or aureomycin supplementation decreased hepatic levels of caspase-1, NOD-like receptor family pyrin domain containing 3 (NLRP3), tumor necrosis factor-alpha, IL-6, and IL-18, as well as NF-kappa B mRNA expression (p < 0.05). Above all, PFA supplementation into the broilers' diet improved growth performance, inhibited inflammatory responses, and benefited liver protection. The protective effects of PFA on the liver might be related to inhibition of caspase-1-induced pyroptosis via inactivating the NF-kappa B/NLRP3 inflammasome axis in broiler chickens.