The land and quota constraints are binding, the farmer uses all of his land and starts a dairy farm that allows him to produce the totality of the milk quota which he has been allocated, that is to say 300 000 litres of milk per year. He does not use all of his permanent grassland for he cannot make his herd any bigger (quota limitation).
For that purpose, he breeds 43 dairy cows*. The farm also counts 13 heifers for renewal purposes (0,3% of 43) and 26 calves (0,6% of 43). The distribution of the arable land among among the different crops is carried out so as to choose between wheat production for selling purposes and other crops destined for animal feed.
Here the model dedicates 23 ha to fodder production (which is shared between prairies and maize in order to be able to respect the food rations of the animals). The rest of the land, i.e. 26 ha, is dedicated to wheat for selling purposes.
It can be noted that he produces more hay and wrapped bales than he needs. The necessary quantity of grazing determines the number of hectares dedicated to grassland. He could theoretically sell or store his hay and wrapped bales, or simply not mow all of his grassland.
*Note that : the number of animals is not expressed using integers in GAMS. Expressing the variables of animal numbers as integers could be imposed on the model (Integer Variable). But the resolution of a model that contains a high number of integer variables being significantly more difficult for solvers and leading to errors in the solution, it is preferable to continue to express the variables as rational numbers and to round them off in the analysis of the results.
