The ability to fatten lambs of Tunisian breeds according to the diets available is an important or even compulsory demand for our breeders today in order to find a synergy between the cost of production of one kg of meat and the price of sale. For this, we carried out a performance test of lambs of different breeds led to sheepfolds and receiving a classic food ration based on oat hay and concentrated food in the educational farm of the Higher School of Agriculture of Mateur. The results obtained were within the standards taking into account the ration and the age of the lambs. The average dry matter intake of oat hay was 551 g / d / lamb, the average consumption index was 6.34 Kg DM / Kg of weight gain, the live weight of lambs changes '' One control to another to reach a final weight of 18.17 kg.