Disclosed is a system for initiating an action regarding animals allowed to enter and exit a paddock (12) for grazing when it is determined that grass in the paddock (12) is or will soon be exhausted. The system includes a process and control device (17) provided for determining the content of grass in the grazing paddock (12) in terms of a total amount of grazing time left. The system also includes animal counting or identification means (18) operatively connected to the process and control device (17) and provided for automatically registering each entry to the grazing paddock (12) by an animal and each exit from the grazing paddock (12) by an animal, thereby continuously monitoring the number of animals in the grazing paddock (12). The process and control device (17) is further provided for repeatedly or continuously updating the total amount of grazing time left in the grazing paddock (12) based on the determined content of grass in the grazing paddock (12) and the continuously monitored number of animals in the grazing paddock (12). The process and control device (17) can predict a point of time when the grazing paddock (12) will run out of grass based on the repeatedly or continuously updated total amount of grazing time left in said grazing paddock (12) and initiates an action with respect to the animals at a point of time which is related to the predicted point of time when the grazing paddock (12) will run out of grass.
