Hypoxia further exacerbates woody breast myopathy in broilers via alteration of satellite cell fate

ABSTRACT Woody breast (WB) condition has created a variety of challenges for the global poultry industry. To date, there are no effective treatments or preventative measures due to its unknown (undefined) etiology. Several potential mechanisms including oxidative stress, fiber-type switching, cellular damage, and altered intracellular calcium levels have been proposed to play a key role in the progression of the WB myopathy. In a previous study, we have shown that WB is associated with hypoxia-like status and dysregulated oxygen homeostasis. As satellite cells (SC) play a pivotal role in muscle fiber repair and remodeling under stress conditions, we undertook the present study to determine satellite cell fate in WB-affected birds when reared in either normoxic or hypoxic conditions. Modern random bred broilers from 2015 (n=200) were wing banded and reared under standard brooding practices for the first two weeks post-hatch. At 15 d, chicks were divided in two body weight-matched groups and reared to 6 wk in either control local altitude or hypobaric chambers with simulated altitude of 6000 ft. Birds were provided ad libitum access to water and feed, according to the Cobb recommendations. At 6 weeks of age, birds were processed and scored for WB, and breast samples were collected from WB-affected and unaffected birds for molecular analyses (n =10/group). SCs were isolated from normal breast muscle, cultured in vitro, and exposed to normoxia or hypoxia for 2h. The expression of target genes was determined by qPCR using 2−∆∆Ct method. Protein distribution and expression were determined by immunofluorescence staining and immunoblot, respectively. Data were analyzed by the