The thesis is devoted to the study of liver diseases of laying hens in the settings of industrial production. Based on a set of clinical, haematological, biochemical, pathomorphological, and zootechnical studies, the age-specific dynamics of the development of liver pathology in laying hens was established and the efficiency of “Hep-A-Stress” and “Hepasan-VS” hepatoprotectors for therapeutic and prophylactic purposes was substantiated. The changes of the level of high-density lipoproteins (HDL), low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), and bile acids in the serum of healthy hens and those with hepatosis during the productive period were studied.
Medical examination of laying hens of the cross “Lohmann Brown” in the first (166 days), second (300 days), and third (530 days) phases of the productive period was carried out for timely detection of liver diseases. According to the results of serum biochemistry of the experimental groups, hyperalbuminosis, hypocalcemia, hypophosphatemia, hyperuricemia, increased alkaline phosphatase (ALP), alanine aminotransferase (ALT), and decreased aspartate aminotransferase (AST) concentrations were found.
Pathomorphological examination of the liver was performed and the discomplexation of the lobular structure of the organ and the presence of small and large fat vacuoles in hepatocytes (300 and 530 days) were established.
In laying hens with hepatosis aged 166, 300, and 530 days, an increase in total protein (P<0.001, P<0.01), ALT activity (P<0.01, P<0.001), AST (P<0.001)) and ALP (P<0.001), uric acid levels, total cholesterol (P<0.001) and urea reduction were detected. Lipid profile parameters (total cholesterol, triacylglycerols, HDL, LDL, VLDL) and bile acid concentration in laying hens with hepatosis were higher (P<0.001) compared to clinically healthy birds aged 224 and 300 days.
The feasibility of administration of “Hep-A-Stress” and “Hepasan-VS” hepatoprotectors for 10 days at a dose of 1 ml/L of drinking water for the treatment (300-day-old bird) and prevention (224-day-old bird) of hepatosis in laying hens was scientifically substantiated and experimentally confirmed.
The study results of the therapeutic efficacy of “Hep-A-Stress” and “Hepasan-VS” hepatoprotectors at the age of 300 days indicate a positive effect of experimental drugs on the morphofunctional state of the liver (decreased total protein (P<0.001) and increased albumin fraction (P<0.001), decrease in ALT and AST activity (P<0.001), uric acid content, total cholesterol (P<0.001) and increase of urea to normal values) and indicators of viability and productivity of poultry after 30 days of the experiment.
The use of hepatoprotectors restores the structure of the liver, limits the development of dystrophic processes in the hepatocytes of laying hens with hepatosis, and has a positive effect, as indicated by the lack of pronounced inflammatory and destructive changes in hepatocytes.
The prophylactic efficacy of “Hep-A-Stress” and “Hepasan-VS” hepatoprotectors for the hepatosis of laying hens at the age of 224 days is indicated by positive changes in liver pathology-specific indicators of biochemical analysis of blood serum and improvement of poultry viability and productivity.
The prophylactic effect was established on the 30th day after the administration of hepatoprotectors, which is indicated by an increase in the level of albumin (P<0.001; P<0.05), urea (P<0.01; P<0.05) and a decrease in total protein (P< 0.001; P<0.01), such hepatospecific enzymes as ALT (P<0.01; P<0.001) and AST (P<0.001; P<0.01), uric acid (P<0.01), total cholesterol (P<0.001), concentrations of triacylglycerols (P<0.05; P<0.001), HDL (P<0.001), LDL (P<0.001), LDL (P<0.001), and bile acids (P<0.001) in blood serum of experimental groups.
Thus, studies indicate that a disturbed protein-synthesizing liver function, increased enzyme activity and impaired lipid metabolism are observed in hepatosis of laying hens. The normalization of metabolic processes in the body of laying hens and the positive effect of drugs on morphofunctional processes in the liver have been revealed when “Hep-A-Stress” and “Hepasan-VS” hepatoprotectors are used for therapeutic and prophylactic purposes. The lipotropic effect of hepatoprotectors is worth noting, as indicated by changes in the lipid profile of laying hens aged 224 days and the absence of pronounced dystrophic changes and the presence of fat vacuoles in the pathomorphological examination after treatment of laying hens aged 300 days.
Keywords: laying hens, liver, hepatosis, treatment, prevention, metabolism, hepatoprotector.
