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Vztah negativní energetické bilance a poruch reprodukce u dojnic
Drlíčková, Zuzana
This bachelor thesis focuses on excessive negative energy balance (NEB) in dairy cows, resulting from high milk yield, and its effects on reproductive performance. The aim was to present the principles of dairy cow nutrition, the occurrence, consequences, and monitoring of NEB and to describe the interrelationships with metabolic and reproductive disorders. In the practical part, the analysis of the dairy cows (n = 177) of Holstein cattle was carried out from 1 January to 30 June 2022. The reproductive technician evaluated reproductive disorders based on the veterinary examination and sonographic examination with a linear rectal probe. Of all monitored dairy cows, retained placenta was detected in 10,73 %, uterine inflammation in 31,07 %, follicular cysts in 16,38 %, and luteal cysts in 5,65 %. The prevalence of NEB was determined using individual milk samples collected as part of performance monitoring. Samples taken on days 5 – 30 after calving and days 31 – 60 after calving were used for the analysis. A statistically significant (p < 0,05) positive correlation was found for the observed milk components (acetone, beta-hydroxybutyrate, fat/protein ratio), and a statistically significant (p < 0,01) higher concentration in the first sample after calving compared to the second sample. For selected components, threshold values indicating risk of excessive NEB and ketosis were determined: acetone concentration ≥ 0,12 mmol/l, beta-hydroxybutyrate ≥ 0,10 mmol/l, and fat/protein ratio ≥ 1,3. When evaluating the first samples after calving, the values were exceeded on average in 48,77 % of the dairy cows and 31,64 % of the dairy cows in the case of the second samples. The fat/protein ratio was used to evaluate the relationship between NEB and reproductive disorders. The threshold value (≥ 1,3) indicating the risk of NEB was exceeded in 90 dairy cows, which, compared to healthy individuals, showed a higher incidence of the retained placenta by 5,28 %, uterine inflammation by 6,85 % and follicular cysts by 5,10 %. The analysis results showed a higher incidence of ovarian cysts connected to higher productivity (p < 0,01). In first-lactation dairy cows there was statistically significantly (p < 0,01) more intense NEB than in second-lactation dairy cows and the highest incidence of uterine inflammation. The results of the work demonstrate the connection between high productivity, NEB and reproductive disorders.
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