The presented research on the application of extrusion-cooking in the production of grain-fat concentrates in this monograph was preceded by literature analysis. The past research mainly concentrated on the methods of fat addition to the mixture or pellet greasing by different machinery construction (e.g. greasing through nozzles, greasing in a conditioner). Many studies were performed on the pellet durability after various levels of fat addition or depending on the greasing method. Research was also conducted on the production of bulk concentrate mixtures based on different raw materials. The composition of those blends comprised: wheat bran, maize meal, dried green grass, fodder yeast and fat. The disadvantage of such concentrates is the necessity of having a number of raw materials for their production, and an extended technological process. Some of the produced fatty concentrates are not suitable for poultry compound because of their high fibre content.

The tendency or even the necessity of implementation of new high-quality products forces to search for new methods and ways of raw materials processing which will realize the challenges posed by the market or the competition. According to those requirements, the concept of various stages of extrudate processing was realized in the context of the achievement of high fat concentrates suitable for easy dosing and mixing in feed mixers.

The realization of this purpose required a number of studies related to the selection of parameters of extrusion, grinding, greasing and concentrate applications in pelleted feed as a component.

The paper presents the results of the application of the extrusion cooking process as a treatment for increasing the amount of fat absorbed into the extrudate structure. It allows to achieve a bulk fat concentrate suitable for application in the feed industry. In addition, the mixture greasing process conducted under the conditions of negative pressure allows to achieve greater absorption of fat. The amount of fat absorbed at negative pressure conditions was approximately 2% higher compared to greasing at atmospheric pressure. The low negative pressure level of 500 hPa achieved  in the laboratory mixer was enough to increase the amount of fat absorbed. The feed additive obtained during the study contained more then 20% of fat (depending on particle size), and it was also characterised by high bulk properties (angle of repose is on the level from 42 to 45^o for the product of particle size between 1 and 2.5 mm). The study of granulation process and pellets durability confirmed the positive application of the fat concentrate. Energy consumption of the pelleting process is not increased after the addition of fat concentrate compared with the liquid fat addition to the mixture.

The conducted research demonstrated that materials after extrusion cooking process are characterised by a high degree of expansion and high porosity. The resulting extrudate is an excellent material for further processing, and processed plant materials are an essential component of feed mixtures.