Procena metaboličkog statusa krava u ranoj laktaciji analizom intraindividualnog variranja metaboličkih parametara (delta check vrednosti)

Comparing the values of biochemical parameters in two or more consecutive blood samples from the same individual, in a certain time interval is called "delta check" analysis, which can determine intraindividual differences in biochemical parameters, but can also be evidence of possible errors in working with samples. The aim of this dissertation is to examine intraindividual variability in cows in early lactation and to determine its limits. Metabolic adaptation of cows corresponds to peripartum metabolic stress that occurs as a consequence of negative energy balance and adaptation to lactation. Adaptation to partus and lactation led to the following general metabolic changes. Concentrations of NEFA, BHB, bilirubin, yerta enzymes, and MDA increased in the first weeks after calving, before returning to baseline. On the other hand, the concentration of total proteins, albumin, glucose, urea, cholesterol, triglycerides and macroelements (Ca, P and Mg) decreased in the first weeks after calving, and later during lactation their value increased. The reference range for intraindividual variation of metabolic parameters depends on the week of lactation. Comparing the obtained values with the values of the standard interindividual reference range, we can conclude that intraindividual values are significantly narrower than interindividual reference values, so these values must be treated and interpreted separately. Delta check values expressed as the difference in metabolite values in two consecutive extractions, 2 weeks before calving and one day after calving, significantly affect the metabolic adaptation in cows. Intense variation in glucose, albumin, cholesterol, triglycerides and Ca leads to lower concentrations of this metabolite in the first two weeks after calving, while extreme variation in BHB, bilirubin, AST, ALT, GGT and AP leads to increased values of these parameters in the first two weeks after calving. calving. With the help of delta check values of metabolic parameters, it is possible to determine the origin of a sample of cows, so this method can overcome the problems of incorrect results as a consequence of losing or replacing the sample. In cows in early lactation, it is necessary to carefully approach the interpretation of metabolic parameters and blood count. For red blood cell, hemoglobin, hematocrit, MCV, MCH, the individuality index is low <0.6, which means that the reference values based on the subject of the test should be used. For all other parameters except for AST, the individuality index (IOI) is 0.6-1.4, which means that population-based reference values should be used with caution. For AST, the high IOI index is> 1.4, which means that population-based benchmarks should be used. The high index of individuality for a large number of metabolic parameters opens the possibility of creating a model for longotudinal monitoring of the metabolic status of individual cows through lactation, which requires additional research.