Clinical and pathological investigations into cases of leg diseases in yellow-feathered broilers

Leg disorders pose significant challenges to the poultry industry, causing substantial economic losses and compromising animal welfare. This study characterized the epidemiology and etiology of major leg disorders, including femoral head necrosis (FHN), tibial dyschondroplasia (TD), valgus-varus deformity (VVD), and arthritis including hock and stifle arthritis in male commercial yellow-feathered broilers ( n = 28,030) through clinical diagnosis, anatomical examination, bacterial isolation, serological analysis, and radiography. The overall cumulative incidence of leg disorders was 3.58% from hatching to slaughter (84 days of age). FHN was the predominant cause of lameness, accounting for 70.82% of leg disorder cases. Approximately 55.32% (26/47) of FHN cases were identified as bacterial chondronecrosis with osteomyelitis (BCO), with presumptive Escherichia coli as the primary isolated pathogen. Notably, significant positive associations were observed between FHN and hock arthritis (aOR = 1.87, 95% CI: 1.33‒2.61), as well as between VVD and hock arthritis (aOR = 7.21, 95% CI: 5.26‒9.90). Furthermore, the incidence of FHN, hock arthritis, stifle arthritis, and TD increased with age, whereas VVD incidence decreased. These findings underscore the necessity for comprehensive management strategies encompassing genetic breeding, environmental control, and pathogen-specific interventions, providing a valuable reference for the clinical diagnosis of leg diseases in yellow-feathered broiler chickens.