High proportion of type I fibres in the gluteus medius muscle of young Norwegian–Swedish coldblooded trotters

Sammanfattning

In a previous study of young Norwegian–Swedish coldblooded trotters (NSCT), aged 17–24 months, a high proportion (>30%) of type I fibres in the gluteus medius was found in 33 of 141 horses. These findings were surprising and the purpose of the present study was to find an explanation for the high type I fibre proportion in these horses. Possible explanations might be an inaccuracy in the procedure of analysing the biopsy sample, inaccuracy in the method of sampling or a muscular disorder in these individuals. Further, the high type I fibre proportion might be age related. The accuracy of the procedure for determination of the fibre composition from a biopsy sample was tested by analysing the same biopsy sample at two different occasions in nine horses. Four of the nine horses had high type I fibre proportions on both occasions and the five others had proportions within the expected range on both occasions. The repeatability of the procedure was tested by an agreement analysis, where the agreement index (AI) is calculated. This analysis revealed an AI of 0.70, where an AI >0.5 shows a good repeatability. Eight of the nine horses were re-sampled at the age of 3 years. At this age, all horses had type I fibre proportions < 30%. The biopsy technique with an absolute depth of 4 cm might give a relatively more superficial sample of the muscle in larger horses, which may explain the age-related differences. However, in young horses, high proportions of type I fibre seemed to be found in the larger individuals. The light sedation given to the horses before sampling may also have influenced the relative sampling depth. Muscular disorders were ruled out as performances in the 3-year season did not differ between 33 horses with high type I fibre percentage and 106 horses with normal type I fibre percentage. In conclusion, the high proportion of type I fibres in some young NSCT was not caused by the analysing procedure or by muscular disorders, but is probably related to the sampling point within the muscle. © 2010, Cambridge University Press. All rights reserved.

Nyckelord

cold-blooded trotters; fibre types; muscle biopsy; repeatability

Publicerad i

Comparative Exercise Physiology
2010, volym: 7, nummer: 2, sidor: 97-101

SLU författare

• Essen-Gustavsson, Birgitta

  • Institutionen för kliniska vetenskaper, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Medicinsk biovetenskap

Publikationens identifierare

• DOI: https://doi.org/10.1017/S1755254010000279

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/132454