Bentley Czech (Czechia)

Good health is important for animal reproduction and support of foodstuff chain quality and safety. Milk is suitable for noninvasive monitoring. Analyses of milk composition and result interpretation along environmental conditions and physiological principles plays important role in health control. Ketosis is a disorder of energy metabolism in dairy cows. It deteriorates milk yield (MY) and quality and animal reproduction and can have a fatal impact. Aim was to analyse relationships between milk energy metabolism indicators as acetone (AC) and component quotients which can serve in health control and estimate their thresholds. AC and fat/lactose (F/L) and fat/crude protein (F/CP) ratio could represent good ketosis indicators. There were 960 individual milk samples from the Holstein (H) and Czech Fleckvieh (CF) dairy cows (1:1). Their whole lactations, first third of lactations (FTL) and summer and winter seasons were analysed. Lactation MY of included herds (7) varied from 5,500 to 10,000 kg. Milk AC levels did not differ (P > 0.05) between H and CF breed in whole lactation but differed in FTL (H 3.88 and CF 2.72 mg.l–1; P < 0.05). This difference 1.16 mg.l–1is equal to 29.9 % and this is not too much essential. The F/L ratio was not affected (P > 0.05) by parity and season in whole lactation but was influenced (P < 0.01 and < 0.05) in this way during FTL. As maximum there can be explained only 17.8 % of variability (correlation index 0.42; P < 0.001) in log AC values by F/L quotient variability for CF in FTL in summer season. As maximum there can be explained up to 84.4 % of variations (correlation index 0.92; P < 0.001) in F/CP values by F/L quotient variations for H in FTL in summer season. Equations were used for model calculation of AC and F/L cut‑off limits to subclinical ketosis indication in FTL period. These were from 2.05 to 3.29 mg.l–1about AC and from 0.84 to 0.87 about F/L according to breeds (CF and H) and lactation parity (1stand others). The results can be used in methods of cow health problem identification, prevention, treatment and troubleshooting during lactation.