A reaction norm model approach to estimate the genetic effect of temperature on sportive performance of trotter horses

Abstract

The performance results of Spanish Trotter Horses were merged with the information from the nearest official weather stations, to estimate the effects of temperature (T) on speed during the day of the race. The resulting data set included: 104 125 individual results from 7653 races with 3772 participant horses and driven by 1402 jockeys. After a classical repeatability animal model in which the effects of T were assumed null, a total of five different random regression models (RRM) with the same fixed part were applied in a parsimonious nested process in which the (co)variance components for each random effect were estimated considering homo/heterogeneous responses across the trajectory of T during the race. The results demonstrate that performance is better when T increases from 4°C to 12°C, followed by a comfort zone (12-19°C) and a light but more stressful zone (>20°C). A significant change in the T during 20 years (+4°C) was observed whilst the speed of the race improved by +2.1 m/s during the same period. The information criterion (LogL, AIC and BIC) confirmed the existence of heterogeneity of (co)variance components along the trajectory of T scale. The model in which T effect was assumed non-constant across the T scale for animal genetic effects; the individual environmental permanent effects and the jockey effects fit the data better. Heritability had higher values (0.19-0.20) when T was <12°C and slightly decreases within the comfort and stressful zones. Genetic correlations were high and, as was expected, it decreases when difference between T increases. The best 150 animals for speed during the comfort zone were selected according to the Expected Breeding Value (EBV) estimated with the best RRM, and important variations were detected in the evolution of EBV across the trajectory of T. The presence of a genetic base related to T effect during the race in this type of performance is demonstrated.

Benefits and risks of barefoot harness racing in Standardbred trotters

“…smhi.se). This is in accordance with observations of good performance in Spanish Standardbreds (Gómez et al, 2015). In that study, performance was negatively affected at higher temperatures (around + 0.5 s/m lower speeds at temperatures > 20°C).…”

“…Good performance horses racing with elite drivers not only gained in terms of velocity, but also showed lower risks of galloping, penalties, and disqualification. (Gómez, Menéndez-Buxadera, Valera, & Molina, 2015;Solé et al, 2017;Štrbac et al, 2015). In the present study, the national arena showed faster velocity times, with no statistically associated risk factors.…”

“…Weather variations during the different seasons, the track and its condition are important factors for the performance of racing horses. Racing under different weather conditions affects velocity times, while there is great variation between different race tracks in terms of risk factors for durability traits (Gómez, Menéndez‐Buxadera, Valera, & Molina, 2015; Solé et al., 2017; Štrbac et al, 2015). In the present study, the national arena showed faster velocity times, with no statistically associated risk factors.…”

Plasticity effect of rider–horse interaction on genetic evaluations for Show Jumping discipline in sport horses

“…Reaction-norm models (where the phenotype is described as a continuous function of an environmental variable) have been used previously in different animal species, as cattle (Mota et al, 2016), pigs (Verardo et al, 2017) or even wild animals (Sae-Lim, Komen, Kause, & Mulder, 2014). In horses, this methodology has been used for different purposes, such as to study the influence of heat stress on performance (G omez, Men endez-Buxadera, Valera, & Molina, 2015) or sport performance in Show Jumping competitions (Bartolom e et al, 2013). G omez, Menendez-Buxadera, Valera, and Molina (2010) also described different sport performances in Trotter horses due to race distances, finding that the estimates of breeding values showed different evolutions for each animal according to race distance, thus differentiating between sprinters and stayer horses.…”

“…In horses, this methodology has been used for different purposes, such as to study the influence of heat stress on performance (G omez, Men endez-Buxadera, Valera, & Molina, 2015) or sport performance in Show Jumping competitions (Bartolom e et al, 2013). G omez, Menendez-Buxadera, Valera, and Molina (2010) also described different sport performances in Trotter horses due to race distances, finding that the estimates of breeding values showed different evolutions for each animal according to race distance, thus differentiating between sprinters and stayer horses.…”