Necrotic enteritis affects bone growth and bone microstructure in non-selected conventional and modern meat-type chicken strains

Modern meat-type chickens have achieved maximum growth efficiency through successful genetic improvements over the past few decades, but bone health has not been enhanced along with it. Necrotic enteritis (NE), an intestinal disease primarily caused by Clostridium perfringens, can disrupt mineral uptake and can be lethal to immunocompromised chickens, and it remains an important issue in poultry production. To understand the relationship between NE challenge and bone health, a study was conducted using a 2 × 3 factorial arrangement, consisting of two chicken strains: (1) the non-selected conventional-type Athens Canadian Random Bred (ACRB) and (2) Cobb 500, and three NE challenge groups: a non-challenged control and two NE challenge models. Two different doses of Eimeria maxima oocysts (NE1, 2,500 oocysts; NE2, 12,500 oocysts) were inoculated on d 14 and followed by 1 × 10⁹C. perfringens on d 18. On d 14, a total of 216 male ACRB and 216 Cobb 500 chickens were allocated to each cage. The Cobb 500 group had significantly increased body weight (BW) and d 14 to 25 BW gain (BWG) compared to all ACRB chickens, and the NE2 group had decreased BWG compared to the other groups in Cobb 500 (P < 0.05). The ACRB chickens had decreased most of body composition measurements, femoral mineral apposition rate, femoral tissue volume (TV), bone volume (BV), and bone mineral content (BMC) compared to the Cobb 500 (P < 0.01). However, Cobb 500 chickens had decreased femoral bone mineral density and cortical bone volume ratio (BVR), and increased cortical porosity compared to the ACRB (P < 0.05). Necrotic enteritis challenge decreased total tissue weight, BMC, BMC ratio, bone area, and femoral TV and BV compared to the non-challenged group (P < 0.05) regardless of chicken strains. In conclusion, the negative effects of NE infection on bone development occur regardless of chicken strains, and modern meat-type chickens may experience further deterioration of bone health due to increased femoral cortical porosity and decreased BVR.