Meeting Abstract
The poultry industry has bred domestic turkeys to have much larger muscles than wild turkeys, but it is unclear if this intense artificial selection for greater muscle mass affects other muscle properties. Our recent work on the differences in force production during locomotion in the two strains has revealed low maximum speeds and low ground reaction forces in the domestic broad-breasted white strain. One possible explanation for these findings is that the hypertrophied muscles are somehow structurally or mechanically compromised. This study’s goal was to assess the capacity for muscle force production in a domestic strain. To test for possible effects of muscle-force capacity, an in situ preparation of the lateral gastrocnemius (LG) muscle in the domestic turkeys (n=6) allowed comparison with past studies on wild turkeys. The domestic LG muscle produced 21% less force than wild strain (P=0.048), (mean muscle force of 31.8 N/cm2 versus wild mean force of 40.3 N/cm2). However, the maximum velocity was high in domestic turkeys at 21.5 L/s, compared to 13.0 L/s in the wilds. The average peak instantaneous power was similar to the wild turkeys, at 362.1 W/kg. The architectural gear ratio (AGR) did not change with increased muscle force in the domestic turkeys (P=0.80), indicating there may be differences in intramuscular connective tissue. AGR remains high, which may explain the higher velocity of whole muscle and lower force we observe. These results suggest that artificial selection for increased muscle mass results in small differences in the contractile performance of domestic turkeys, but this alone does not explain the differences in ground reaction force. Nevertheless, however minor, these changes could exacerbate locomotor issues in commercial turkeys that already have many leg health issues.
