Search Results (3)

(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. Full article

The purpose of this study was to examine the effects of high temperature on internal egg yolk quality parameters and their possible mechanisms in Huaixiang chickens. This study consisted of two treatments, and each treatment had six replicates with six birds per cage. A total of seventy-two 26-week-old female Huaixiang chickens were randomly divided into a normal-temperature group (NT) and a high-temperature group (HT) for 6 weeks. And these hens were exposed to 25 ± 2 °C and 32 ± 2 °C, respectively. Their relative humidity was maintained at 55–65%. The results showed that the HT group significantly reduced yolk weight, yolk color, and egg weight compared to the NT group (p < 0.05). Heat stress caused vacuolar degeneration of the liver and reduced the absolute liver weight (p < 0.05). Both yolk triglyceride (TG) and liver TG in the HT group were significantly higher than in the NT group (p < 0.05). However, the liver total cholesterol (TC) level in the HT group was remarkably lower than that in the NT group (p < 0.05). Additionally, heat stress remarkably enhanced SREBP-1c, ACACA, and FASN lipid metabolism-related gene mRNA expression levels in Huaixiang chicken liver after 6 weeks of heat exposure (p < 0.05). Furthermore, the HT group had remarkably reduced total amino acid, Cys, and Tyr levels in the yolk when compared with the NT group in our experiment (p < 0.05). In conclusion, heat stress causes egg yolk quality reduction and abnormal lipid metabolism in Huaixiang chickens. These findings provided novel insights into the role of high temperature on egg yolk parameters and the underlying mechanisms in Chinese indigenous laying hens. Full article

Canthaxanthin(CX) is a ketocarotenoid, which is widely used in poultry production as a lipophilic antioxidant. Huaixiang chickens are a local breed in China famous for their excellent meat quality; improving their laying rate via nutritional regulation has attracted extensive attention. The aim of this study was to evaluate the effects of dietary CX on the laying rate and follicular development in Huaixiang hens. A total of 180 Huaixiang hens were randomly divided into five groups with six replicates, and six chickens per replication. The control group (CON) were fed a basal diet, and the treatment group (NT) were fed a basal diet supplemented with 4, 6, 8 and 10 mg/kg CX. All chickens were 26 weeks old, living at an average environmental temperature of 25 ± 2 °C with a relative humidity of 65–75%. The results showed that supplementing the CX improved the laying rate and large white follicles (LWF) number (p < 0.05) and increased the concentration of reproductive hormones (LH, FSH, E₂ and Prog) (p < 0.05), and the basal diet supplemented with 6 mg/kg CX worked best. Moreover, CX could increase the activities of antioxidant enzymes SOD and GSH-Px (p < 0.05) and reduce the content of the lipid peroxidation product MDA in Huaixiang chickens (p < 0.05); again, 6 mg/kg CX was best. In conclusion, dietary CX had positive effects on the laying rate, ovarian structure, reproductive hormone secretion, follicle development, and the antioxidant capacity of Huaixiang hens, and 6 mg/kg CX was recommended to be added to the diet of Huaixiang chickens. Full article