A COMPARISON OF LACTATION PHYSIOLOGY EFFECTS AT HIGH AND LOWER YIELD ON COMPONENTS, PROPERTIES AND HEALTH STATE INDICATORS OF MILK IN CZECH FLECKVIEH

The milk yield (MY) is one of the main efficiencies of Czech Fleckvieh (CF) cattle. It is evaluated through milk recording. MY is a significant economic and health factor. Differences within milk indicators (MIs) between two CF dairy cow groups with high (CF1; n = 213 individual milk samples (animals)) and lower (CF2; n = 265) MY were tested. The files were balanced in factors of lactation. Group 1 had higher genetical value and even better nutrition according to the MY. Average daily milk yield of CF1 was higher by 56% as compared to CF2 (P ≤ 0.001). Significant differences (P ≤ 0.001) were determined for: fat (FAT); lactose (LAC); solids non fat (SNF); log somatic cell count (log SCC); crude protein (CP); casein (CAS); true protein (TP); fat/crude protein ratio (F/CP). FAT, LAC and SNF differed markedly (P ≤ 0,001) in this way the CF1 cows had lower milk FAT, LAC and SNF as compared to CF2 (3.71–4.33%, 5.00–4.92% and 8.83–8.97%). The log SCC was significantly lower in CF1 dairy cows (xg 50–74 103.ml–1). It was found higher level of milk lactation in the cow herds without diseases. However, the difference was relatively small. CF1 group had higher genetic potential and higher feedstuff consumption within herd. Further, there were significant differences between CF1 and CF2 in milk nitrogen fraction for CP, CAS and TP (3.30–3.53%, 2.62–2.81% and 3.11–3.33%). The next significant (P ≤ 0.05) differences were at electrical conductivity (CF1 CF2), time for enzymatic coagulation (renneting ability; CF1 CF2), rennet curds firmness (CF1 CF2), whey volume after renneting (CF1 CF2), whey protein (CF1 CF2) and ratio of urea nitrogen in the non protein nitrogen (CF1 CF2). Insignificant differences existed for the next 9 MIs (as acetone, pH, titration acidity, alcohol stability, casein number). Surprisingly, higher milk urea (U) was not linked with higher MY in CF breed. The differences in MIs between CF1 and CF2 do not represent health troubles. High MY which was reached by genetic improvement and more effective nutrition did not lead to aggravated milk quality, but lead to its lower technological recovery.