Feed structure (particle size) and form (mash, pellets) play very important roles in ensuring the optimal utilization of nutrients by determining the level of feed intake. Modern meat type birds have high appetite for food therefore their FI should be well studied to ensure the realization of their full genetic potential. Pellets consist of ground feed that has been compressed and molded in a pellet mill. Pelleting binds the individual ingredients together to make a whole feed and prevents selective feeding therefore ensuring that all the animals are given well balanced diets. Mash is the nutritionally complete poultry diet in a ground form. The quality of the mash is assessed by the size and uniformity of its particles. Feeding broilers on mash diets have positive effect on gizzard development than feeding pelleted diets by increasing the relative weight. There is proper stimulation by the feed ensuring the optimum function of the gizzard when mash diets are fed. Birds fed pelleted diets have lower length and weight of the duodenum, jejunum, ileum and caeca than those fed mash diets but the villus height and crypt depth of birds fed pelleted diets are higher compared with those fed mash diet. The microbiota composition promotes healthy immune system and growth.