New genes involved in the Bacterial Chondronecrosis with Osteomyelitis in commercial broilers

Locomotor problems have a great economic impact on world poultry production, because difficulty of locomotion leads to a decrease in animal performance and an increase in partial or total carcass condemnation. In addition, locomotor problems greatly affect the chicken welfare. Bacterial Chondronecrosis with Osteomyelitis (BCO) or Femoral Head Necrosis (FHN) is responsible for altering the bone tissue degenerating the cartilage and femoral epiphysis. Despite its not well known etiology, it is believed that this disorder causes a decrease in tissue vascularization, interfering with blood flow and affecting the angiogenesis processes, predisposing broilers to bone problems. Genetic factors associated to rapid growth rate of the modern broilers are pointed out as predisposing chickens to BCO. Therefore, the aim of this study was to evaluate the expression of 13 functional candidate genes in femur samples of normal and BCO-affected commercial broilers at 35 days of age to clarify the genetic mechanisms involved in the BCO in chickens. From the 13 genes studied, 10 were differentially expressed (DE) between groups: ADIPOQ, PRRX1, ANGPTL5, GFRA2, SFRP5, COL14A1, ABI3BP, ANGPTL7, COL8A1 and SLC30A10, which were downregulated in broilers affected by BCO, except for the SLC30A10, which was upregulated in the affected chickens. Although their functions are not well established in chickens, these genes participate in important biological processes in mammals, such as osteogenesis, formation of connective tissue and collagen production, and general bone development. The genes expression pattern, their functions and interactions, altogether, pointed out those DE genes as strong candidates to be involved with BCO in broiler chickens. The DE genes evaluated in this study might contribute to tissue necrosis, which could lead to the development of Bacterial Chondronecrosis with Osteomyelitis in chickens. Those should be further investigated aiming to reduce this bone anomaly in broilers.