The microstructure of the liver in broiler chickens under the administration of a probiotic complex of <i>Bifidobacteria </i>and <i>Lactobacilli</i>

The global consumption of broiler chicken meat is increasing annually, which involves the use of intensive technologies in poultry farming and the application of a significant number of additives aimed at preventing infectious diseases in livestock. One such means is the probiotic preparation TIMM-P, which includes Bifidobacterium gallinarum, Lactobacillus rhamnosus, Lactobacillus plantarum, and Lactobacillus paracasei subsp. paracasei. To determine the effectiveness of its use, two groups of one-day-old Cobb 500 broiler chickens, each comprising 50 birds, were formed. The probiotic TIMM-P was administered via drinking over 2 hours in the morning, before feeding, on days 1–5, 21–25, and 30–35 of the rearing period. The liver microstructure of one-day-old broiler chickens did not differ between the groups, more pronounced changes were recorded at an older age. On the 14th day of growth in broiler chickens that received the basic diet, the cytoplasm of hepatocytes was characterised by a reduced optical density and contained small lipid droplets. During the administration of the probiotic TIMM-P to the chickens in this period, the cytoplasm of hepatocytes had a uniform and intense colouration while maintaining the radiality of the tubular structure of the liver lobules. On the 28th day of growth in broiler chickens of the control group, the development of fatty liver dystrophy was observed. The administration of probiotics to broiler chickens was associated with the development of small-droplet fatty liver dystrophy. On the 42nd day of growth, the phenomena of apoptosis, necrosis of hepatocytes, and fatty liver dystrophy with sections of the portal tracts in a state of interstitial inflammation, with stasis in various sections of the venous bed were detected in the liver of broiler chickens of the control group. The use of probiotics in broiler chickens partially reduced the intensity of pathological changes in the liver; however, in some animals, destruction of the tubular structure within its lobules was detected, accompanied by perivascular infiltration by polymorphic cells. The use of probiotics in broiler chickens did not significantly affect the volume of hepatocytes and their nuclei. Still, it contributed to a tendency to reduce their nuclear-cytoplasmic ratio, which indicated a higher intensity of liver function regeneration. The results obtained from the study indicate a positive effect of the complex probiotic TIMM-P on the liver microstructure, which, considering the indicators of meat quality and safety, may justify its introduction into industrial-scale broiler chicken meat production.