A self-sharpening knife used inside an agricultural machine to cut and mix balls of hay or other food destined for animals consumption. The knife comprises a generally triangular steel plate whose base is right or rounded. The base is provided with a series of teeth, each of the teeth includes a pastille made of a material harder than steel and self-sharpening. The pastilles end by a cutting edge having a contour which forms the cutting edge of a tooth.The width of a pastille exceeds that of the steel and ends in a point which becomes round over cuts because of wear. The pastilles wearing out less quickly than steel thus causing that over cuts the width of the pastilles will always exceed the width of the steel. The pastilles cut until all their length and width are worn. The material of the pastille can be carbide or diamond.
