Anotace:
The aim of the present study was to investigate inline lactate dehydrogenase (LDH) changes in clinically healthy dairy cows according to the number and stage of lactations, milk yield, and the reproduction status The LDH activity (μmol/min per litre) was measured using the dry-stick technology. A total of 378 cows were selected and classified according to their reproductive status into the following groups: fresh (1–44 days after calving); open (45–65 days after calving); inseminated (1–35 days after insemination); pregnant (35–60 days after insemination). According to their milk productivity, the cows were classified into the following groups: <15 kg/d, 15–25 kg/d, >25–35 kg/d, and >35 kg/d. They were milked with a DeLaval milking robot in combination with a Herd Navigator analyser. The results showed that the inline LDH concentration had a tendency to increase along with the increase in the number of lactation periods (P < 0.05). The highest level of LDH was observed in fresh cows 5–10 days in milk (DIM), and the highest LDH concentration was found in the milk of fresh cows. A positive statistically reliable relationship was found between the milk yield and LDH concentration (P < 0.05); LDH and milk somatic cell counts (SCC) were positively related in all groups of cows, although LDH concentration and SCC were the highest correlated variables in inseminated cows (P < 0.05). The present study shows that measuring LDH activity in milk is both easy and cost effective with high sensitivity and specificity, having a great potential as a diagnostic tool for detection of subclinical mastitis.