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.

Keywords: Hypophosphatemic; Laying hens; Metabonomics.