The present disclosure is related to the manufacturing process of protein foods for ruminants by insolubilizing their protein against bacterial degradation in the rumen. In the present invention, formaldehyde is pulverized into the protein raw material at a dose of 0.2 to 1% after grinding the same into fine particles to then pass the same to a reactor conditioner where steam is applied at a temperature of 70 to 90°C, while exiting with a humidity of 12 to 13% and a yield of 5 tons per hour. Since this is a continuous production method, the characteristics of this conditioner and its performance will depend on the characteristics and performance of the mill and the capacity and performance of the mixer. This manufacturing process of protein foods for ruminants can only be applied to soybean meal or to a mixture of raw materials such as soybean meal with canola meal, whey, casein and/or cereals or other by-products such as corn, sorghum, bran or other beneficial compounds for animal f eeding, such as, vegetable fats or oilseeds such as soybeans, sunflower seeds, canola seeds or flax seeds previously ground or not, or previously treated with heat. The present invention for the manufacturing of protein foods for ruminants allows: 1.- An adequate protection of the protein against bacterial deamination in the rumen. 2.- An increase of by-pass protein content that passes the rumen and reaches the small intestine. 3.- An increase in the metabolizable protein of the treated foods. 4.- An improvement in the protein efficiency of processed foods. 5.- A decrease in the variations in the by-pass and metabolizable protein content of processed foods. 6.- Greater milk production.Esta invención se refiere a la fabricación de alimentos proteicos para rumiantes insolubilizando su proteína contra la degradación bacteriana en el rumen. En este invento, a la materia prima proteica se le pulveriza formol a una dosis de 0.2 a 1 % después de molerse en partículas finas para pasar después a
