Morfofunkcionalne karakteristike dubokog grudnog mišića brojlera uslovljene intenzivnom aktivnošću mišića krila

One of the problems in modern intensive production of broiler chickens isthat the intensive activity of the chicken wings which can be caused by various factorssuch as entry of people into the building, improper capture of chickens, inadequatedensity of chickens in the buildings, etc., can lead to creating pressure on the bloodvessels that supply blood to deep pecoral muscles. As a result, changes in themorphological characteristics of the muscle and connective tissue cells of this musclemay occur. The consequences of such changes can be reflected in the organolepticcharacteristics and quality of the meat. The aim of this doctoral dissertation is todetermine the effect of intense wing muscle activity on the morphofunctionalcharacteristics of broiler breast muscle, and to determine the possible treatment thatwould reduce the intensity of the morphological changes that the said activity cancause in this muscle. Within this doctoral dissertation, the first phase of the researchwas a review of broiler carcasses on the 42nd day of postnatal development on theslaughter line (broilers were collected from 5 farms, 200 individuals each), with theaim of categorization of broiler carcasses based on morphological characteristics ofdeep pectoral muscle. The second phase of the study involved the use of the "WingFlapping" method to initiate intense muscle activity of broiler wings. Fourexperimental groups were formed, with 4 repetitions each. In each group of 30chickens, treatment was applied during different days of postnatal development. Afterthe 42nd day, the deep pectoral muscles of the chickens were examined on theslaughter line and categorized on the basis of morphological characteristics in order todetermine the most suitable age of the chickens for the application of the said treatment. The third phase of the study involved the addition of coenzyme Q10 (CoQ10)supplementation during the diet of broiler chickens with the view to increase theintensity of morphological changes in the deep pectoral muscle which are caused byintense wing muscle activity. The experiment was conducted on 576 chickens, ofwhich 288 chickens belonged to the heavy Ross 308 hybrid, and 288 chickensbelonged to the heavy Cobb 500 hybrid. In both types of hybrids, 4 experimentalgroups with 4 replicates were formed: a control group (chickens fed standard diet); agroup in which 20 mg of CoQ10 per kg of food was added to the food; a group in whichchickens were fed a standard diet and exposed to Wing Flapping; a group in whichchickens were fed 20 mg of CoQ10 per kg of food and were exposed to Wing Flapping.For the purposes of categorization of changes in the deep pectoral muscle anddetermination of production parameters, as well as for the purpose of microscopicanalysis, after the end of the fattening period (end of 42nd day of postnataldevelopment), 5 male individuals from each experimental groups of both types ofheavy chickens (Ross 308 and Cobb 500) were sacrificed. The fourth phase of thestudy involved the sampling of deep pectoral muscles for the purpose of microscopicanalysis, as well as the analysis itself. Samples were taken after examination of thismuscle and after categorization performed (end of day 42 postnatal development).Samples were taken for histological, histochemical and immunohistochemical analysesby light microscopy as well as electron microscopy analyses. The fifth phase of theresearch included statistical data processing and determining the significance ofdifferences between the obtained results. The results of the study indicate that in bothtypes of heavy chick hybrids, from groups exposed to Wing Flapping treatment had agreater volume density of non-necrotic muscle cells (16.9%) and a lower volumedensity of necrotic muscle cells (12.51%) in the CoQ10 diet group. In both types ofheavy chick hybrids, the group exposed to Wing Flapping treatment had a higherpercentage of carcasses with M3stadium of deep chest muscle morphologicalcharacteristics (40.62%), and a smaller percentage of carcasses with M0 stadium ofmorphological deep pectoral muscle change (53.12%), a higher volume density ofnecrotic cells (by 20.29%), and a lower volume density of non-necrotic muscle cells(by 35.44%), and also a greater volume of real connective tissue cell density (10.50%)and higher fat cell volume density (3.09%) compared to the group that was notexposed to Wing Flapping. The analysis of the obtained results show that the intensiveactivity of the wing muscles causes the interruption of normal deep chestvascularization, the appearance of hypoxia and oxidative stress, and as a consequenceof these phenomena, these morphofunctional changes in the deep chest muscle occur.The addition of CoQ10 in the diet of chickens reduced the intensity of morphologicalchanges in the deep pectoral muscle, which was primarily reflected in the reducedvolume density of necrotic cells. The aforementioned treatment, which is based on theaddition of CoQ10 in the diet of heavy chicken hybrids, may represent a step towardsreducing the formation of morphological changes in the deep pectoral muscle ofchickens during farm breeding.