AbstractReasons of performing study:
To obtain broader insight into the muscle of foals with different genetic background, muscle fibre composition, its post natal development and citrate synthase (CS) activity of thegluteus mediuswere investigated.Hypothesis:
Because muscle properties are influenced genetically and related directly to performace ability, muscle characteristics should be affected by selection and correspond with the requirement of ths sports selected for.Methods:
The foals were divided intoGroup A, (n = 16), considered an average of the population, andGroup B(n = 36), selected for showjumping. Biopsies were taken deeply from thegluteus mediusmuscle. Fibre type identification was performed immunohistochemically at ages 6 and 12 months. Citrate synthase activity was measured at age 6 months.Results:
age 6 months statistically significant differences were found betweenGroups AandBin the proportion oftype I,IIadandIIdfibres. Oxidative fibres (IandIIad) were more abundant inGroup B, while fast-glycolytic fibres (IId) were more abundant inGroup A.Except forIIa, the fibre type composition at age 12 months had become equal in the 2 groups. The difference in the sum of oxidative fibres (I+IIad+IIad) betweenGroups AandBat age 6 months was similar to the difference in CS activity at that age, although the latter was not significant.Conclusions:
At age 6 months the 2 groups had different proportions of fibretypes IandIId, but these differences had disappeared at age 12 months.Potential relevance:
The muscular response to training at an early age can be interpreted with knowledge of muscle characteristics and its post natal development in foals selected for showjumping.