Heritability of percentage of fast myosin heavy chains in skeletal muscles and relationship with performance

Abstract

Summary The purpose of this study was to determine the percentage of fast myosin heavy chains (fast MHCs = MHC 2A+2B) in 2 propelling muscles to estimate the heritability and to identify any relationship with performance. The gluteus medius and the biceps femoris muscles were biopsied in 100 related French Anglo‐Arabian horses. The percentages of slow and fast myosin heavy chains were measured using an ELISA technique. The heritability (s.e.) of the fast MHCs percentage was estimated at 13% (0.1) using a restricted maximum likelihood resolution of a mixed animal model. There were significant (P<.05) correlations between the performance level and the fast MHCs percentage of the gluteus medius and biceps femoris muscles: 0.47 and 0.34 respectively. An analysis of variance revealed a significant (P<.05) effect of performance level in gallop racing and show jumping on the fast MHCs percentage of the gluteus medius muscle. The good performers in gallop racing (75.5>69.6% fast MHCs) and show jumping (74.1>67.8% fast MHCs) had a higher percentage of fast MHCs in the gluteus medius than poor performers (P<.05). This muscular analysis could be one of the interesting physiological traits to measure for early selection of gallop racing and show jumping horses.

Association of sequence variants inCKM(creatine kinase, muscle) andCOX4I2(cytochrome c oxidase, subunit 4, isoform 2) genes with racing performance in Thoroughbred horses

“…To date, a range of approaches has been taken to investigate measurable associations with athletic performance phenotypes in Thoroughbred racehorses including assessment of heart size (Young et al 2005), muscle fibre type (Rivero et al 1993(Rivero et al , 1995Barrey et al 1999;Young et al 2005), musculoskeletal conformation (Fang et al 2000), post exercise lactate concentration (Evans et al 1993), speed at maximal heart rate (Gramkow and Evans 2006), haematological (Revington 1983) and other physiological variables (Harkins et al 1993). The availability of the horse genome sequence (Wade et al 2009) and the parallel development of molecular genomics tools for the horse have rapidly enabled the identification of sequence variants associated with athletic performance phenotypes in Thoroughbreds.…”

A genome-wide SNP-association study confirms a sequence variant (g.66493737C>T) in the equine myostatin (MSTN) gene as the most powerful predictor of optimum racing distance for Thoroughbred racehorses

“…Sprinters are generally shorter, stockier animals with greater muscle mass than animals suited to endurance performance, and generally mature earlier. Performance aptitude for speed and stamina has also been associated with muscle fibre type phenotypes [3,4] and metabolic adaptations to training [5]. Variation in cardiovascular function contributing to aerobic capacity may also play a role in distinguishing individuals suited to shorter or longer distance races.…”

Muscle characteristics in young Norwegian‐Swedish Coldblooded Trotters and associations with breeding index, body size and early training

“…1993a). The highest percentages of the fast contracting type II fibres have been found in the fastest sprinters (Snow and Guy 1980; Barrey et al . 1999), while endurance capacity is correlated with high percentages of the slower contracting, more fatigue resistant fibre types I and IIA (Rivero et al .…”