Uticaj dodatka biljnih proteinskih koncentrata u hranu za životinje na kvalitet peleta /The effect of addition of plant proteinconcentrates in animal feed on pellet quality

Sunflower meal has a lesser presence in pelleted compound feed than soybean meal due to a higher proportion of raw fiber. Raw fiber has depressing effect on the digestibility and production results, and can have a negative impact on the physical quality of the pellets. Lately, considerable attention is paid to the functional changes of macronutrients in pelleting of animal feed. It is believed that these changes have a positive impact on the physical quality of the pellets. With the development of modern analytica techniques, especially the thermal analysis, it is possible to describe the changes of starch in pelleting process, caused by the impact of heat and moisture. On the other hand, changes of the protein components in the pelleting process are not sufficiently explained. The most common interpretation is reduced to the presumption, with no explanation of changes in the size of protein molecules, as well as in their concentration. The innovative approach of this dissertation is focused on describing the effect of the addition of soybean meal and sunflower meals, with different protein content, in mixtures based on corn, on the technological parameters of the pelleting process, functional changes of macronutrients (starch gelatinization, and protein denaturation and degradation), and physical quality of the pellets. Within each of the mixtures, the influence of process parameters, the diameter of the hammer mill sieve openings (2, 3 and 4 mm), duration of long term steam conditioning (without extended conditioning, 5 and 10 minutes) on the physical quality of the pellets was also investigated. Studies have shown that pelleting temperatures, the specific power consumption and the proportion of dust in pellets were dependent of composition of the mixtures, the diameter of the hammer mill sieve openings, and residence time in the conditioner. Pelleting temperature and specific power consumption increased, and the extent of fines in pellets decreased with increasing of concentration of protein in the diets. Additionally, it is proved that pelleting process affects functional changes of macronutrients, starch gelatinization and structural changes in proteins. It is also proved that for the optimal retention time of material in conditioner, decrease of diameter of the hammer mill sieve openings and increase of protein content in the diets had positive effect on the physica quality of pellets, i.e. pellet hardness and degree of abrasion of pellets. The optimum process conditions in pelleting process were determined by the method of desired function. A proposal has been made for setting the range of process parameters for obtaining the minimum degree of abrasion of pellets, with optimal specific energy consumption. The research within this Ph.D. thesis contributed to the knowledge about the effects of addition of sunflower meal with different protein content (37.3, 40.3 and 42.6 %) on the physical quality of the pellets. Quality of pelleted mixtures with sunflower meal added were compared with the quality of pelleted mixtures with soybean meal added and quality of pelleted corn, in order to explain the effects of starch concentration, protein concentration and protein source. Studies were performed not only for the standard time of conditioning, but with the use of modern techniques for heat treatment of animal feed, i.e. with the use of long term conditioning process for a 5 or 10 minutes. Additional contribution to science has been given with showing that the pelleting process causing not only the denaturation and degradation of proteins, but also synthesis of proteins