INFLUENCE OF PROPYLENE GLYCOL TO ENDOCRINE AND METABOLIC CHARACTERISTIC IN COWS DURING PERIPARTURIENT PERIOD

During periparturient period must be provided extra energy. Propylene glycol can rapidly supply transition dairy cows with energy and can be converted to propionic acid in the rumen and transport to liver, where it is converted in glucose. The aim of this study is to estimate influence of propylene glycol to metabolic and endocrine profile in periparturient period. We hypothesized that influence of propylene glycol in protection of energy metabolism in early lactation should be proven trough analysis of the relationship between metabolic and endocrine parameters with NEFA (level of lipolysis) and BHB (level of ketogenesis). Experiment involved 50 healthy
holstein-frisian cows (25 – group supplemented with propylene glycol 100g per meal, twice daily, three weeks before calving and three week after calving and 25 – control group). Blood samples were collected one week before expected calving, at calving day and one week after calving by venipuncture of v.coccigea. Concentration of NEFA, BHB, insulin, IGF-I, glucose and bilirubin was measured. The results show that cows that received propylene glycol are less burdened with metabolic stress. Thus, cows treated with propylene glycol have higher concentrations of glucose, insulin, IGF-I and lower concentrations of NEFA, BHB and bilirubine. Post-hock analysis it can be concluded that cows in early lactation show these differences, but the differences in metabolite concentrations before calving were not significant. Cows in which was applied propylene glycol are less burdened by metabolic stress, which is reflected in lower proportion of cows with signs of metabolic stress. Efficacy of propylene glycol may be seen in the fact that propylene glycol is changing relationships and strength of links between metabolites. In the first week after calving, when
there is most pronounced metabolic load was found a significant negative correlation between plasma NEFA or BHB with insulin, IGF-I and glucose concentration and positive correlation with bilirubin concentration. Correlation between metabolite was significantly lower or was absent in the group of cows that received propylene glycol. We performed the analysis of the regression model and tested the difference between the b parameters in cows that received propylene and control groups. For each unit of NEFA or BHB was found significantly lower decrease in the concentration of insulin, IGF-I and glucose and significantly lower increase in the concentration of bilirubin in relation to the test value of the control group. Energy added by propylene glycol changes metabolic characteristics of cows characterized by reduced lipid mobilization and ketogenesis with their reduced relationship with other metabolic parameters.