Early expression of hereditary deep pectoral myopathy in turkeys due to forced wing exercise

In a deep pectoral myopathy selected (DPMS) line, forced wing exercise (FWE) at 20 weeks of age resulted in the same level of expressed deep pectoral myopathy (DPM) as seen in unexercised DPMS turkey by 72 weeks of age. The FWE at 15 and 17 weeks of age in DPMS line females increased the incidence of DPM to 30 and 50% compared to 5% in unexercised controls. There is an apparent developmental age X exercise relationship in the expression of DPM. In varieties, lines, and crosses without a history of DPM, FWE does not induce the myopathy. Additional evidence confirms the modifier effect in the polygenic DPM defect. Body weight and breast width measurements in genetically susceptible turkeys were not closely or consistently associated with expression of the myopathy. The results suggest FWE of turkeys at 20 weeks of age or later as a method for detecting genetic carriers at prebreeding ages.