Dietary Thymol–Carvacrol Cocrystal Supplementation Improves Growth Performance, Antioxidant Status, and Intestinal Health in Broiler Chickens

This study investigated the impacts of dietary thymol–carvacrol cocrystal (CEO) supplementation on broiler production performance, antioxidant status, intestinal health, and cecal microbiota. Eight hundred one-day-old chicks were randomly divided into four groups, receiving basal diets supplemented with 0, 40, 60, or 80 mg/kg CEO. The results showed that CEO addition increased average daily gain, superoxide dismutase activity in the serum, liver, and jejunum, jejunal villus height/crypt depth ratio, cecal butyric acid concentration, and Lactobacillus abundance, while reducing serum alanine transaminase activity and malondialdehyde content in the serum, liver, and jejunum. Furthermore, 60 mg/kg CEO enhanced the final body weight, dressing percentage, serum total protein and glucose levels, and jejunal trypsin and amylase activities, while lowering the feed-to-gain ratio and serum cholesterol, urea nitrogen, and aspartate transaminase concentrations; it also increased the activities of superoxide dismutase, catalase, and glutathione and mRNA expressions of related genes in the liver and jejunum. It also increased cecal concentrations of acetic acid and isovalerate acid, while decreasing serum diamine oxidase and D-lactate concentrations, as well as malondialdehyde concentrations in the serum, liver, and jejunum. Therefore, dietary CEO supplementation improved the production performance, antioxidant status, and liver and gut health and function in broilers, with 60 mg/kg CEO demonstrating the most pronounced effects.