## 1 Introduction  
Chicken meat has many desirable nutritional properties, including a high nutrient content and relatively low caloric value [1]. It is primarily the breast and thigh muscles that represent the most valuable parts of the chicken. Chicken meat has a low fat content and cholesterol level and a relatively high concentration of PUFA, which consumers consider a positive and healthy reason to consume chicken meat [2]. In terms of nutritional value, broiler chicken meat is also very attractive because of its high protein, mineral, and vitamin content [3]. High dietetic value, very good meat flavor, and easy digestibility are other characteristics that consumers appreciate and prefer in broiler chicken meat [4].  
The fat quality of broiler chickens is significantly influenced by the composition of the feed and especially by the content of individual fatty acids in the feed [5]. On the other hand, intravital factors, such as the breed (the hybrid), sex, age, rearing method, diseases, use of drugs, fatigue, starvation, transport conditions, and stress, have little influence on the composition and quality of the fat content of broiler chickens [6].  
Enrichment of broiler meat with a significant amount of PUFA is a suitable way of increasing the PUFA intake by the population in Europe as poultry meat consumption is high in the EU as well as worldwide [7, 8, 9]. The nature of lipid digestion in animals has a significant impact on the transfer of fatty acids from feed to animal products. During periods when animals are not starving and have sufficient fatty acids in the feed, fatty acidsare not synthetized in the body but are incorporated directly from the feed into the fatty tissue of the animals. Feeding fat, therefore, has a direct and generally predictable effect on the fatty acid composition of fat in broiler chicken meat [10], and the proportion of specific unsaturated fatty acids in tissues can be influenced simply by increasing their proportion in the feed.  
One of the main aims of using biotechnology in animal nutrition is to produce health-promoting active substances using appropriate microorganisms. Important in the production of these substances are the filamentous fungi of the genera _Umhelopsis_ sp., _Mortierella_ sp., _Thammidium_ sp., and _Cuninghamella_ sp., which can produce significant quantities of biologically active substances on various substrates [11], including by-products of the food industry such as bran, meal, and pomace [12]. Solid state fermentation (SSF) enriches the produced waste with significant amounts of PUFA, hydrolytic enzymes, microbial sterols, beta-glucans, and pigments and can thus be utilized as a suitable feed ingredient in animal diets [13; 14]. The fatty acid profile of poultry meat can be significantly influenced by feeding. Feeding a fermented product enriched with important active substances (PUFA, microbial sterols, coenzyme Q, and pigments) will increase their proportion in broiler chicken meat [15].  
To the best of our knowledge, only a few experiments have studied the preparation of fermented feed via SSF using lower filamentous fungi and its application in broiler nutrition with the aim of increasing the proportion of PUFA in broiler meat. This review was designed to present a summary of our recent studies of the use of biotechnology for the production of high-PUFA fermented cereal products and their subsequent use in broiler chicken nutrition. The solid state fermentation method and microorganisms suitable for PUFA production of fermented products (FP) are described. The effect of FP on the growth parameters of chickens is also presented. Subsequently, the effect of FP on the quality of the obtained meat regarding the fatty acid composition is also described.