EN
The aim of this study was to analyse the acetone concentration in the blood of cows in the period immediately preceding the first calving and during the whole first lactation. The study was conducted on 124 clinically healthy primiparous cows of Polish Holstein-Friesian breed born, reared and managed on the same farm (Agricultural Experimental Farm D³oñ) at least up to the second calving. Blood samples were collected from the animals according to the following schedule: 7-8 and 1-2 weeks before the expected calving, as well as 2, 5, 30 (± 3), 60 (± 3), 90 (± 3), 120 (± 3), 200 (± 3), and 280 (± 3) days after calving. The concentration of acetone was determined in the blood serum by the gas chromatography method. The mean acetone concentration in the blood of cows examined was 0.41 mmol/L (SD = 0.18). The highest acetone concentration, exceeding the physiological level (0.4 mmol/L), was noted 7-8 and 1-2 weeks before calving, and at 5, 200 and 280 days of lactation. The threshold corresponding to symptoms of clinical ketosis (above 2 mmol/L) was not exceeded in any of the samples. It was found that the blood acetone level is a feature of low repeatability (ρ up to 0.07). Significant positive correlations (p ≤ 0.01) were observed between acetone concentrations determined 30 to 120 days after calving (r from 0.26 to 0.39). Significant positive correlations (p ≤ 0.05) were also found between the acetone concentration before calving and in the first 60 days of lactation (r from 0.19 to 0.22), whereas no correlation was observed between concentrations determined before calving. The results obtained in this study prove that the blood acetone concentration in dairy cows is of special significance during late pregnancy because of a relatively high level of this ketone body and because of its impact on the blood acetone concentration in the initial phase of lactation.