Metabonomic analysis of hypophosphatemic laying fatigue syndrome in laying hens.

Laying fatigue syndrome (LFS) is a common disease in poultry, which is characterized by low egg laying rate, increased broken and soft shell egg rate and osteoporosis, and even death of poultry. Insufficient phosphorus content in feed is one of the major causes of LFS. In this study, a total of 22-week-old Roman white shell hens were randomly divided into two groups, including control (group C) and low dietary phosphorus (group P) groups. The hens of groups C and P were fed with a full mixed diet and a mixed diet containing 0.18% available phosphorus content, respectively. At 25, 29 and 34 weeks, the production performance of hens was detected and the serum samples of hens were collected to detect the changes of serum phosphorus, calcium, osteopelectin (OPG), parathyroid hormone (PTH), estradiol (E2), tartaric acid-resistant phosphatase (TRACP) and alkaline phosphatase (ALP). The keels were removed and x-rayed. In addition, all serum samples were tested by LC-MS metabolomics. Our results showed that low dietary phosphorus decreased the production performance, phosphorus content, and E2 and OPG levels, while increased calcium and PTH levels, and ALP and TRACP activities in laying hens. The hens of group P had bent keels. Besides, small molecular metabolites in serum were enriched in 10 pathways and 17 metabolites were significantly different according to the area under the receiver operating characteristic curve (AUC) analysis. Our results showed that low phosphorus diet could induce LFS. Also, 17 metabolites detected by metabonomics can be used as biomarkers for clinical diagnosis and early warning of hypophosphatemic laying fatigue syndrome (HLFS). This study provides a scientific basis for the early prevention and treatment of HLFS.

Effects of low dietary phosphorus on tibia quality and metabolism in caged laying hens.

Osteoporosis is a common bone metabolic disease in caged laying hens. This disease affects animal welfare and economic costs. In this study, a model of osteoporosis induced by low dietary phosphorus was established. A total of sixty 22-week-old Roman white laying hens were randomly divided into two groups, including a control group (group C) and a low dietary phosphorus group (group P). The effects of low dietary phosphorus on the endocrine and tibial osteoprotegerin (OPG)/nuclear factor kappa B receptor activating factor ligand (RANKL) signaling pathways of osteoporosis in caged laying hens were analyzed by serology, bone biomechanics, molecular biology and histopathology. The results showed that low dietary phosphorus decreased the production performance, and egg quality of laying hens and increased the contents of serum calcium (Ca), osteocalcin (OCN), alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRACP). The contents of serum phosphorus, calcitonin (CT), OPG and tibial biomechanics index decreased. The bone mineral density (BMD), cortical bone thickness and the expression level of OPG protein in tibia decreased. The expression of OCN, nuclear factor kappa B receptor activating factor (RANK) and RANKL protein increased. Low dietary phosphorus caused thinning and fracture of the bone trabeculae and enlargement of the bone marrow cavity of tibia. Our results suggest that phosphorus may affect bone metabolism by regulating the OPG/RANKL signaling pathway.

[Ixeris sonchifolia induced vasoconstriction effect and its mechanism in rat thoracic aorta].

OBJECTIVE: To investigate the vasoconstriction effect of Ixeris sonchifolia in rat thoracic aortic rings and the underlying mechanisms. METHOD: I. sonchifolia 10-160 g x L(-1) was cumulatively added into organ bath to observe the isometric tension of thoracic aortic rings with intact endothelium or denuded endothelium in basal tension, preconstricted by phenylephrine (PE) or potassium chloride (KCl), and thoracic aortic rings with intact endothelium preincubated frist with captopril, phosphoramidon and indomethacin, respectively, then preconstricted by PE and KCl. The response was recorded and expressed by "relative contraction". RESULT: Cumulative administration of I. sonchifolia 10-160 g x L(-1) did not affect the vasomotion of aortic rings with endothelium or without endothelium in basal tension. Exposure of intact endothelium rings preconstricted by PE or KCl to I. sonchifolia at concentration (20-160 g x L(-1) induced a significant constriction, which was inhibited by preincubation with captopril, but was not inhibited by preincubation with phosphoramidon or indomethacin. Exposure of endothelium-denuded rings preconstricted by PE or KCl to I. sonchifolia at concentration (10 to approximately 160 g x L(-1) did not effect the vasoconstriction. CONCLUSION: The results indicate that I. sonchifolia (20 to approximately 160 g x L(-1) can contract the rat thoracic aortic rings with endothelium. The effect of contraction may enhance angiotensin converting enzyme activity and promote endothelium to synthesize angiotensin II. It has no relationship to endothelin or thromboxane A2.