The effect of myotonia on muscle mass in the myotonic goat Sarah Winningham Dobbins Tennessee Technological University Department of Biology Cookeville, Tennessee

Introduction Myotonic goats have a genetic mutation that causes a decrease in muscle chloride conductance (Beck et al,1996). This creates a condition in which, once stimulated, a muscle is unable to relax in the normal amount of time (Vite et al,1999). The effect of this inability to relax sometimes causes the goat to “faint,” hence the name “fainting goat.”

Introduction continued Lee explored the connection between anthropometric measures, such as skinfold measurement, and specific measures, such as bioelectrical impedence. He found that there is a direct correlation and that the precision of anthropometric measures is roughly equal to that of using the bioelectrical impedance (Lee et al, 2000).Through measurements of height, weight, length, circumference, and body fat, muscle mass was estimated according to the methods of Swantek and used to compare and contrast the myotonic and normal goats (Swantek et al, 1999).

Introduction continued As Ellis stated, a positive correlation can be found between the circumference of muscles in limbs and overall muscle mass. Likewise, a negative correlation can be found between body fat (measured with the skinfold calipers) and overall muscle mass (Ellis 2001).

Objective and Hypothesis The objective of this study is to find whether the genetic condition of myotonia increases muscle mass. The findings may have a direct impact on the use of myotonic goats as meat goats, and an indirect impact on the study of myotonia congenita in humans. I project that the myotonic goats will have increased muscle mass in comparison with the normal goats because of the increased overall stimulation.

Methods and Materials Using a standard tape measure, measurements were taken from the hoof to the shoulder and the rump to the chest. The tape measure was also used to measure the circumference of legs and neck of each goat. Skinfold measurements were taken from the torso. The goats were then weighed on a standard scale. All data was recorded as measured (Ellis 2001).

Data

Methods and Materials continued The data was then grouped, averages were found, and the data was graphed similarly to the methods used by Swantek (1999).

Comparisons of Normal and Myotonic Goats: A Visual Representation

Results According to Ellis, the elevated limb and neck circumference in addition to the added weight and lower skinfold measurements has a direct correlation to elevated skeletal muscle mass (Ellis 2001). Therefore, the myotonic goats were found to, in fact, have a higher skeletal muscle mass than the normal goats.

Discussion The FFM (Fat-Free Mass) of the myotonic goats, in general, was higher than that of the normal goats, even though most of the goats were of the same age. This finding is in agreement with the findings of Wildeus, who also purported that the genetic condition of myotonia in animals would in turn increase their skeletal muscle mass (Wildeus et al, 1998).

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