Investigation of MSTN Genotype Association with VO 2peak in Untrained Yearlings

Abstract

Introduction In Thoroughbreds, genetic variation in myostatin (MSTN g.66493737C/T) is highly predictive of optimum race distance and influences mRNA expression, precocity, skeletal muscle development, two-year-old earnings, speed variables and skeletal muscle fibre type. The aim of this study was to investigate MSTN variation associations with VO2peak in untrained yearling Thoroughbreds. Methods Peak oxygen consumption (VO2peak) was measured in 41 untrained Thoroughbred yearlings (16 colts, 25 fillies, 19.8?±?1.4 months) from one flat racing yard (November-December). Data was collected as horses freely travelled up an all-weather gallop (2% incline) with no rider. VO2 was measured using an ergospirometry and oximetry mask and associated customized software validated for field testing. Horses were instrumented with a GPS-HR monitor, light-weight mask and data-capture equipment. HRpeak, maximal velocity (Vmax) and exercise distance were recorded. MSTN genotypes were determined using a customised Taqman SNP genotyping assay. Tests of association between genotype and phenotype were performed using PLINK software. Results Average exercise distance was 1700.5?±?33.4?m, Vmax 15.0?±?1.4?m/s, and HRpeak 221.2?±?9.6?bpm. MSTN genotypes and VO2peak based on 6 breaths were n?=?16 CC, VO2peak?=?119.49?±?21.8; n?=?22 CT, VO2peak?=?116.40?±?-27.2; n?=?3 TT, 115.08?±?20.2.There was no association (P>0.05) between genotype and VO2peak. Conclusions In yearling Thoroughbreds no association between MSTN genotype and untrained peak oxygen consumption was observed. This may be a function of the small number of TT genotype individuals evaluated or a reflection of a requirement for MSTN-associated skeletal muscle entrainment in VO2peak changes resulting from a period of exercise training. Such changes may be associated with MSTN genotype and this requires further investigation. Ethical Animal Research Institutional Animal Research Ethics Committee approval was obtained. Explicit owner informed consent for participation in this study is not stated. Sources of funding:?Science Foundation Ireland under Grant Number 11/PI/1166. Competing interests:?Dr Hill is a co-founder and Chairman of Equinome Ltd.