## Abstract  
The use of natural feed additives could be a beneficial approach to maintaining the health of chickens and a way to improve food digestion. Flaxseed is a rich source of omega-3 fatty acid, alpha Inlonicnic acid, oleic acid, and fiber. The purpose of this study was to evaluate the effects of dietary inclusion of 4% flaxseed on the intestinal morphology, specific enzymatic activity, and cecal supplementation of Passed Meal on the novel  
humans and animals contributes to the increasing resistance of microorganisms to these therapeutic agents [3; 4]. The Cobb 500 hybrid is the most widely used in industry and is also the broiler with the earliest growing time and the best feed conversion rate. It is appreciated due to its superior productive performance in conditions with low nutrient density [5]. Macronutrients in the diet of birds are represented by monosaccharides, monopylcrerides, amino acids, free fatty acids, and dipeptides, all of which can be absorbed [6]. High growth rate and feed efficiency are crucial aims to be achieved in poultry production [7]. Several aspects should be considered for the optimum performance of birds, including weight gain, genetic potential, diet quality, feed intake, feed conversion ratio, disease status, and environmental conditions [8; 9]. Apart from these mentioned factors, a well-functioning and healthy gut is essential in poultry production, improving nutrient digestion, absorption, metabolism, and overall health and growth performance [10]. When gut homeostasis is disturbed, digestion and nutrient absorption are impaired, impairing the health and performance of birds [9; 11]. Recent studies indicate that the nutritional quality of feed used in poultry farming is correlated with the activity of digestive enzymes [12]. In birds, the proventirulus/gizzard participates in grinding and mixing ingested feed to facilitate the activity of endogenous enzymes; therefore, the gastrointestinal tract of poultry produces enzymes to aid in the digestion of nutrients [13; 14]. Nutrients from the diet are absorbed along the gastrointestinal tract through the intestinal mucosa, folded into villi and polarized epithelial cells that are present on the apical domain of the microvilli forming the brush border. This enhances the small intestinal surface by around 600-fold, leading to higher capacity for nutrient absorption [12; 15]. Among the determinants that may be involved in the gut health and performance of chickens, the commensal microbiome is of paramount importance due to its multiple roles in host physiology, including the maturation of the immune system and protection against pathogenic microorganisms [10; 16]. Previously, it was suggested that the gut microbial profile can be shaped by changes in the host diet [17]. In addition to these, some feed or feed ingredients, referred to as nutraceutical, have been shown to generate protective effects on the intestinal tract of chickens by modulating the microbiome and the immune system [9; 18]. In broiler nutrition, probiotic species such as _Bifidobacterium_, _Lactobacillus_, _Streptococcus_, _Enterococcus_, _Bacillus_, _Candida_, _Saccharomyces_, and _Aspergillus_ are used to improve broilers' growth performance and counteract infections [19; 20; 21]. Phytogenic feed additives (PFA) are plant-derived natural bioactive compounds that are incorporated into animal feed to enhance productivity [22; 23]. In recent years, PFAs have been employed as natural growth promoters in the poultry and pig industries [24]. Flaxseeds contain about 34% oil and 50% \(\alpha\)-linolenic acid, and they are a common feed ingredient in poultry diets. Due to their rich content in omega-3 fatty acids, they represent an increasingly popular additive to the diets of many consumers [25; 26]. Also, they contain some anti-nutritional factors, such as cyanogenic glucosides and mucilage, which can reduce the enzymatic activity of the pancreas, leading to decreased digestion and lower bird performance [27].