Sachko S. Metabolic disorders in cows with ketosis and their correction with ionophores, vitamin E and hepatoprotectors - Qualification scientific paper with manuscript rights

The dissertation investigates the effects of monensin and bioactive compounds of hop cones on rumen fermentation, metabolism, and productivity in cows, as well as the efficacy of a combined feed additive containing hop cones, vitamin E, and protected forms of choline, methionine, and carnitine for the prevention and treatment of ketosis. The transition period in cows is accompanied by profound metabolic changes, including glucose deficiency, intensified lipolysis, hepatic overload with fatty acids, and the formation of ketone bodies. Additionally, an excess of protein in the diet leads to ammonia accumulation, which complicates metabolism and reduces protein feeding efficiency. One way to regulate microbial protein synthesis is the use of ionophore antibiotics such as monensin. Monensin inhibits the growth of ammonia-producing bacteria and reduces the production of methane and ketone bodies, though its use is prohibited in the EU. This necessitates the search for natural alternatives, particularly bioactive compounds from hop cones, which possess antimicrobial and antioxidant properties. Three experiments were conducted in this study. The first examined the effects of monensin (400 mg/day) and hop cones (20 g/day) on cows’ metabolism. The second evaluated the combined use of hop cones and vitamin E. The third assessed the therapeutic efficacy of a complex additive in cows with clinical and subclinical ketosis. Both monensin and hop cones reduced ammonia and volatile fatty acid concentrations in the rumen, inhibited proteolysis, increased blood glucose levels, and decreased concentrations of β-hydroxybutyrate, urea, and non-esterified fatty acids (p<0.05–0.01). Monensin also increased daily milk yield by 2.2 kg. The combination of hop cones with vitamin E enhanced cellulolytic activity and reduced oxidative stress indicators. In cows of the experimental groups, post-calving blood tests showed increased concentrations of glucose, triacylglycerols, and cholesterol esters, along with decreased levels of β-hydroxybutyrate and lipid peroxidation products. In cows with clinical ketosis, β-hydroxybutyrate levels decreased from 4.58 to 2.78 mmol/L (p<0.01), and glucose increased from 1.95 to 2.93 mmol/L (p<0.01). In animals with subclinical ketosis, β-hydroxybutyrate dropped from 1.65 to 1.06 mmol/L (p<0.001), while glucose rose from 2.05 to 2.69 mmol/L (p<0.001). A reduction in the activities of aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase indicated a decrease in liver load. The feed additive facilitated the transition from clinical to subclinical ketosis, normalized blood parameters, improved energy metabolism, and reduced oxidative stress. These findings confirm its feasibility for use in feeding cows during the postpartum period. Scientific novelty lies in the first-time comparison of monensin and hop cone bioactive compounds on fermentation, ketogenesis, and the metabolic state of cows. The study demonstrates the benefit of combining hop cones with vitamin E to enhance anti-ketogenic effects, as well as the efficacy of a complex additive for different forms of ketosis. Practical significance of the results includes the potential use of the developed additive as an alternative to ionophore antibiotics in feeding high-yielding cows, as well as a component of comprehensive therapy and prevention of ketosis during periods of high metabolic risk.