Thermoneutral zone and critical temperatures of horses

Morgan, Karin

doi:10.1016/s0306-4565(97)00047-8

Cited by 79 publications

(53 citation statements)

References 5 publications

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“…A similar pattern was observed in the three age groups included in the analysis. These results agree with those obtained by Morgan (), who described a thermal comfort zone from 5°C to 25°C in horses. Ott () affirmed that at temperatures below the thermoneutral zone, the animal must increase energy production to keep the body core temperature from decreasing, and at temperatures above the thermoneutral zone, the animal must dissipate energy to cool its body.…”

Section: Resultssupporting

confidence: 93%

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

Gómez

Menéndez-Buxadera

Valera

et al. 2014

J Animal Breeding Genetics

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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.

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Section: Resultssupporting

confidence: 93%

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

Gómez

Menéndez-Buxadera

Valera

et al. 2014

J Animal Breeding Genetics

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“…The effects of weather and breed on use of shelter and specific behaviours were tested using a mixed model of analysis of variance with the following class variables: 'weather category' (1)(2)(3)(4)(5)(6)(7)(8); 'breed category' (1)(2)(3)(4)(5) and 'horse' as class variables. BCS and hair coat sample weights were included as covariates in the model and the denominator degrees of freedom were computed using the Satterthwaite's approximation.…”

Section: Discussionmentioning

confidence: 99%

Preference for shelter and additional heat in horses exposed to Nordic winter conditions

Jørgensen

Aanensen

Mejdell

et al. 2015

Equine Veterinary Journal

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“…Athletic Thoroughbred horses had the highest daily amount of activity during the vernal equinox and the lowest during the winter solstice. The highest daily amount of activity during the vernal equinox would depend on the environmental factors such as the increase of photoperiod (Berger et al, 1999;Arnold et al, 2006) and the ambient temperature comprised in the thermoneutral zone (Morgan, 1998). The lowest amount of horse activity during the winter solstice could be related both to the shortest photoperiods and to the lowest temperatures of the year.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations in daily rhythms of activity in athletic horses

Bertolucci

Giannetto

Fazio

et al. 2008

Animal

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Circadian rhythms reflect extensive programming of biological activity that meets and exploits the challenges and opportunities offered by the periodic nature of the environment. In the present investigation, we recorded the total activity of athletic horses kept at four different times of the year (vernal equinox, summer solstice, autumn equinox and winter solstice), to evaluate the presence of seasonal variations of daily activity rhythms. Athletic Thoroughbred horses were kept in individual boxes with paddock. Digitally integrated measure of total activity of each mare was continuously recorded by actigraphy-based data loggers. Horse total activities were not evenly distributed over the day, but they were mainly diurnal during the year. Daily activity rhythms showed clear seasonal variations, with the highest daily amount of activity during the vernal equinox and the lowest during the winter solstice. Interestingly, the amount of activity during either photophase or scotophase changed significantly throughout the year. Circadian analysis of horse activities showed that the acrophase, the estimated time at which the peak of the rhythm occurs, did not change during the year, it always occurred in the middle of the photoperiod. Analysing the time structure of long-term and continuously measured activity and feeding could be a useful method to critically evaluate athletic horse management systems in which spontaneous locomotor activity and feeding are severely limited. Circadian rhythms are present in several elements of sensory motor and psychomotor functions and these would be taken into consideration to plan the training schedules and competitions in athletic horses.

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Thermoneutral zone and critical temperatures of horses

Cited by 79 publications

References 5 publications

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

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

Preference for shelter and additional heat in horses exposed to Nordic winter conditions

Seasonal variations in daily rhythms of activity in athletic horses

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