Mankind has a close relationship with animals, specially herds (cows, horses, sheep, pigs, etc.). One of the ways to keep these animals ingress or egress controlled is to use fences.

Conventional fences do this job, but they are not flexible and require maintenance care, being based on physical labour. According to Anderson [5], virtual fences (VF) promises to change animal management and control through cognitive rather than manual labour.

Physical fences are static tools, although they effectively control the entrances and exits of animals they fail to offer managers the flexibility they need to optimise the physiological requirements of the vegetation with the nutritional needs of foraging animals ( [1]).

Physical fences need to be built regardless the limits size and when finished it requires a lot of maintenance either because cattle or wild animals break poles or wires, either because humans break down the fences to steal cattle or stored food. Since the fencing costs are one of the most expensive aspects of livestock grazing, Jouven [6], VF could be the solution to the problem. According to Meyer, when building a fence, the type of fence determines impact on cost such as cost per foot, total and annual ownership cost. Besides the initial construction costs, labour and material, owners have to determine the

maintenance costs and taking in consideration the damage of the materials, Meyer [4]. So like any other thing, fences had to undergoing changes. The fences have evolved and in this digital age, virtual fences are being studied, built and improved. According to Anderson [5], the development of the virtual fences was possible because of advancements in global navigation satellite systems. The concept of virtual fence was firstly patented in 1971 targeting dogs and cats, and used for the first time to control livestock in 1987, according to Umstatter [7]. VF are non ground-base fence method to controlling animals , Anderson [1], instead sensors are utilised to manage animals behaviour without compromising the safety and health of the animal.

VF has the advantage to be flexible so it can be changed according pasture that can better feed the cattle. It also allows a better problem management related to theft, runs or lost animals once they have a monitoring 24h/24h. They also imply less maintenance costs and time. An adequate plane of nutrition become a fundamental task since the cattle domestication occurred. Simultaneously, a sustainable production implied a plane to manage vegetation, Anderson [5]. According to Provenza [8] and Anderson [5], animals physiology and morphology, and external factors to the animal affect the behaviour of searching for wild food resources, also known as foraging behaviour. Pasture growth is also important to create certain habitats needed for rare species. One example that Umstatter [9] gives is the plant Early Gentian and Adonis Blue butterfly. VF easily manage the distribution of livestock, allowing areas to be unclogged and therefore food is available in a way that allows for better pasture growth without jeopardizing the feeding of the entire herd or the surrounding animals or plants, Wark [10].