Establishing a ovarian cycle in high-yielding dairy cows after calving is a major problem for farms that have intensive milk production. Although high production itself brings a lot of problems, they are still growing with poor management such as inadequate quality food and improperly balanced meal for high-production cows, and therefore metabolic and reproductive problems occur during lactation. The paper analyzes the energy supply level and its impact on the establishment of ovarian cycle after calving and reproductive indexes in high-production dairy cows using the urea and protein content in milk. Investigation was caaried out on dairy cows farm "V.v. Farma"in the area of Međimurje County. Based on the ratio of milk fat and protein as well as urea content in milk samples, it can be concluded that 17.5% of milk samples come from cows that are not sufficiently supplied with energy. The period of early lactation (the first 60 days) is the most sensitive period in view of the sufficient supply of energy and proteins in cows. 45% of the milk samples analyzed in this period indicate a deficit of energy intake and 16.5% of the samples determined IMB> 1.5 suggesting extensive fat mobilization from body reserves and the occurrence of metabolic disorders. The establishment of the ovarian cycle, expressed as the period until the first mating, was within 90 days after calving (74%), while in only 9% of cows this period was more than 120 days. Nevertheless, even 32% of cow gravity appeared after the 120th day of lactation, indicating the absence of ovulation and / or the existence of unfavorable conditions for the survival of embryos (early embryonic mortality). The association between milk parameters and reproductive indicators was not detected.