Author:

Abstract:

In their natural environment, horses move between spots to meet their needs. This might be due to a thermoregulatory reason to go to specific areas, possibly related to weather conditions. Because horses are mainly domesticated, it is the responsibility of the owner to provide all necessities to a horse so that it can be in a good state of thermal well-being. Therefore owners can use research on the thermoregulation of horses to take the right actions. Previous research has shown that in a controlled-climate chamber the thermo-neutral zone (TNZ) of an adult horse is situated between +5°C and +25°C. Seeking shelter is one of the first reactions of a horse to maintain its deep body temperature, however, seeking shelter is not always due to a thermoregulatory motivation. Horses also spend more time in shelter during hot weather conditions, probably not only because of the heath, but also because of all the insects that might be annoying. Therefore, this study is aimed to determine if the use of shelter by horses in a pasture in a temperate region, i.e. Flanders, is related to thermoregulation reasons caused by weather conditions and/or the presence of insects in sunny and hot circumstances, as well as other (management) factors. The use of sheltered areas was registered (artificial or natural shelter), horse behavior during using a shelter and outside the shelter, weather influences and the presence of insects that might annoying. Horses were visually observed in a field study, and cameras were continuously recording shelter structures on two pastures of horse owners' properties. Weather factors such as temperature, wind speed, humidity and black globe temperature were measured. The presence of insects was investigated by catching them with an insect trap. The number of insects on and around the horses and the comfort behaviors of the horses were also counted. These counts took place on three sites (namely under artificial shelter, in open air and under natural shelter) in the pastures. In addition characteristics of shelter, pasture, management, horses and herd, were noted. The results indicated that horses spent more time in shelters at temperatures below and above the TNZ. During all the daytime observations, horses spend 41.5% of the time in a shelter. Below the TNZ the use of shelter, mainly artificial shelter, could rise to 70.6%, and above the TNZ to 72.5%. During cold conditions (TNZ) and sunny conditions the horses spent more time in shelter than during lower temperatures or during cloud cover. Shadow areas were clearly more often used on an afternoon in the summer than during other seasons. This might be caused by a combination of thermal discomfort and harassment of insects. Also those two parameters were significantly related. Horseflies were most active during a dry, hot and sunny afternoon. Furthermore, there was also a positive relationship between the presence of insects and use of shelter in summer. In addition the number of insects was higher in open air and natural shelter than in artificial shelter. Presumably, insects have more difficulty detecting their host in a shelter than in open air. Some sources suggest that natural shelter attracts insects and provides insufficient shelter in winter. Natural shelter was less used than artificial shelter, especially in periods of low dense vegetation. The results suggested that natural shelter was insufficient at protecting the horses against weather influences. It was interesting to determine that a feeling of discomfort does not always seems to be the reason to spend time in shelter. A shelter with a comfortable floor was used almost every night used by the horses. This suggests that the shelter was also used as a resting place. On the other hand, a shelter with a wet floor was on the contrary less used. Access to feed and pasture were also factors related to the use of shelter. The ability to eat, seemed to be preferred over using shelters, which were often without food. Future research should find out more precisely what the exact reason is to use shelter. This can make it easier to take appropriate measures for the owners. Examples could provide the right type of shelter on the summer pasture, which is not necessarily the same during winter. Also, the use of insect blankets on days that horses will encounter a lot of harassment by insects can be a suitable measure. However these might cause thermal discomfort. To find out the correct form of protection, it may help to investigate effects of other environmental factors, such as micro-environment. The micro-environment is strongly influenced by specific weather conditions, the environment and horse characteristics. This can be observed in very cold or hot conditions on pastures with the same shelter conditions (ratio natural/artificial shelter and its characteristics). It should be possible to make a clearer distinction whether or not time spent in shelter is a result of thermoregulation and/or insect barrier. Therefore, it can be determined if comfort behaviors such as tail swings as a result of insect harassment, increase the heat production of the horse. This can have a cumulative effect on sweat production, with possibly attracting more insects and increasing shelter behavior. It would also be interesting to do some data collection in an insect free environment where the horses can choose from different shelter structures (artificial and natural). This can help to find the most ideal construction in various weather circumstances. To conclude, it is recommended to provide shelter against the weather for a horse in the pasture, so that the horse is able to control its own environment by choosing whether or not to shelter. If sufficient feed and water are provided, it is unnecessary to keep horses in boxes for thermal reasons, if they are healthy and thermally adapted. A well designed shelter also ensures that all horses can stand protected in all-weather circumstances. Important in the design are the orientation, adequate access, ventilation and insulation. In addition, the harassment of insects can be reduced by blanketing the horses and placing insect traps to reduce the population of insects. Possible breeding and dwellings places are best removed, especially water, rotten plant material and manure. The most ideal measurments may vary by location.