High-temperature environments significantly compromise the productivity of laying hens by damaging intestinal mucosal structure and impairing nutrient absorption. The effects of dietary canthaxanthin (CX) supplementation on egg production rate and intestinal health in Huaixiang chickens raised at high temperatures were assessed in this study. Six groups were randomly selected from among 216 hens: NC (basal diet, 25 ± 1°C), HC (basal diet, 32 ± 1°C for 8 h/day), and four HCX groups (basal diet supplemented with 4, 6, 8, or 10 mg/kg CX, 32 ± 1°C for 8 h/day), with six replicates of six birds each over 28 days. High temperature significantly decreased feed intake, egg production rate, and feed conversion ratio (FCR; p < 0.05), reduced serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities (p < 0.05), while increasing malondialdehyde (MDA) and reactive oxygen species (ROS; p < 0.05). High temperature also decreased T-AOC activity in the duodenum, jejunum and ileum (p < 0.05), and increased MDA and ROS levels in these intestinal segments (p < 0.05). Relative to the HC group, dietary CX increased egg production rate and FCR, enhanced serum T-AOC, SOD and GSH-Px activities, while reducing MDA and ROS levels (p < 0.05). CX increased T-AOC activity in the small intestine and decreased MDA and ROS levels (p < 0.05). In addition, heat stress impaired intestinal morphology, lowering villus height (VH), villus surface area (VSA), and villus height to crypt depth ratio (V/C; p < 0.05) while increasing apoptosis rate (p < 0.05). This was accompanied by decreased jejunal fatty acid binding protein 1 (FABP1) expression and lowered serum concentrations of total protein (TP), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C; p < 0.05). Relative to the HC group, dietary CX alleviated intestinal villus atrophy and rupture, effectively maintained normal small intestinal VH, VSA, and V/C ratios, and significantly reduced intestinal epithelial cell apoptosis rate. CX significantly increased serum TP, TG, TC, LDL-C, and HDL-C while maintaining normal expression levels of FABP1 mRNA in the jejunum. These results demonstrate that dietary supplementation with 8 mg/kg CX effectively mitigates high temperature-induced declines in egg production by improving intestinal nutrient absorption.

Oxidative stress during egg production disrupts hepatic lipid metabolism and impairs laying performance in hens. This study investigated the effects of dietary canthaxanthin (CX) supplementation (0, 4, 6, 8, 10 mg/kg) on hepatic histomorphology, lipid metabolism, antioxidant capacity, and egg production in indigenous chickens reared under controlled conditions (25 ± 2°C, 65–75% humidity). A total of 180 one-day-old female chickens were randomly assigned to a control group (NC) and four treatment groups (NT1, NT2, NT3, NT4). The trial lasted 9 weeks, with sampling performed at weeks 3, 6, and 9. During the experimental period, compared with the control group, dietary CX supplementation improved the liver weight, egg production rate, serum HDL-C, TG, TC in liver and serum (p < 0.05). At week 6, dietary 6 mg/kg CX supplementation significantly reduced yolk TG and serum LDL-C levels (p < 0.05), while 10 mg/kg CX significantly increased serum T-AOC and SOD activities (p < 0.05). At week 3, 10 mg/kg CX significantly enhanced serum CAT and GSH-Px activities (p < 0.05). At week 9, 8 mg/kg CX significantly decreased serum MDA levels (p < 0.05). Histological analysis revealed that CX improved liver cell structure, reducing vacuolar degeneration and lipid droplet deposition. Additionally, CX significantly upregulated the expression of SREBP-1c, FASN, ACC, ME, and LXRα in the liver (p < 0.05). In conclusion, dietary supplementation with CX demonstrates beneficial effects on lipid metabolism, antioxidant capacity, and egg production in laying hens, with an optimal recommended dosage of 8 mg/kg. This study provides theoretical evidence supporting CX as a functional feed additive to ameliorate lipid metabolic disorders and enhance laying performance in poultry production.

(1) Background: Thermal stress in Guangdong’s tropical/subtropical regions significantly compromises yolk quality in Huaixiang chickens. Canthaxanthin (CX), an effective feed additive, has been demonstrated to not only enhance the nutritional composition of egg yolks but also mitigate heat stress. This study systematically evaluates the effects of dietary CX supplementation on egg production rate and yolk nutritional components (e.g., amino acids, lipids, vitamin B2) in Huaixiang hens under both normal and high-temperature environments. (2) Methods: A factorial design was implemented, exposing hens to either thermoneutral (25 ± 2 °C, 65–75% RH) or high-temperature (32 ± 2 °C, 65–75% RH) conditions. Diets were supplemented with graded CX levels (0, 4, 6, 8, or 10 mg/kg) for 9 weeks. Laying performance and yolk nutritional profiles (amino acids, lipids, minerals, vitamin B₂) were evaluated at 3-week intervals (3rd, 6th, and 9th weeks. (3) Results: Under normal temperature conditions, the addition of CX significantly enhanced the laying rate, relative yolk weight, yolk color score, lecithin (LEC) content, and it optimized the amino acid profile of the yolk. Under high-temperature conditions, the laying rate, yolk weight, yolk weight ratio, total amino acid content, yolk triglyceride (TG), LEC, and vitamin B₂ (VB₂) levels in Huaixiang chickens all decreased. However, supplementation with CX under high-temperature conditions effectively mitigated these adverse effects: the laying rate was restored to levels observed under normal temperature conditions, while the relative yolk weight, color score, TG, total cholesterol (TC), LEC, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), calcium (Ca), and VB₂ levels were significantly higher than those in the heat-stressed control group. Additionally, the amino acid composition of the yolk was improved. (4) Conclusion: CX enhances the nutrient content of egg yolks under both normal and high-temperature conditions, providing a valuable reference for the production of healthy and high-quality eggs.