Muscle characteristics of dutch warmblood foals with different genetic background at ages 6 and 12 months.

The research investigates the muscle fibre composition, development and enzyme activity in Dutch Warmblood foals, specifically those of an average population compared with those genetically selected for showjumping. By studying their muscle characteristics at 6 and 12 months of age, the research aims to understand how genetics influence muscle properties related to performance ability.

Objective of the Study

• The main objective of the study was to gain insights into the muscle characteristics of Dutch warmblood foals with different genetic backgrounds, primarily focusing on muscle fibre composition, postnatal muscle development and the activity of citrate synthase – an enzyme involved in energy production within muscle fibres.
• An additional goal was to determine if and how these muscle characteristics were influenced by genetics, and if they were linked to performance ability, essentially shaping these foals’ capacity for specific physical activities like showjumping.

Methodology

• The foals were divided into two groups: Group A (16 foals), considered representative of the average population, and Group B (36 foals), which was selectively bred for showjumping.
• Muscle biopsies were taken from a specific muscle (gluteus medius) in the foals for analysis.
• Fibre type identification was conducted when the foals were 6 and 12 months old using immunohistochemistry, a technique that detects proteins in cells of a tissue section.
• At the age of 6 months the activity of citrate synthase – an enzyme involved in the energy production of muscle cells – was also measured.

Results

• At the age of 6 months, significant differences were observed between Groups A and B in terms of the proportion of different types of muscle fibres.
• Group B (showjumping foals) had more Oxidative fibres (Type I and IIad), whereas Group A (average population) had a larger proportion of fast-glycolytic fibres (Type IId).
• By the age of 12 months, the fibre type composition equalised between the two groups, with the exception of Type IIa fibres.
• While differences in the sum of Oxidative fibres (Types I, IIad, and IIad) were observed between the two groups at six months, this was not significantly correlated with the activity of citrate synthase.

Conclusions

• Significantly different muscle fibre compositions between the two groups were evident at 6 months, but these disparities largely disappeared by the time the foals reached 12 months of age.
• Knowledge of these muscle characteristics and their postnatal development can therefore guide early-life training strategies for horses selected for activities like showjumping.