[Analysis of environmental and genetic influences on the urea and acetone content in milk from the breeds German spotted cattle and German brown cattle].

In total, records of 915 cows of the breed German Simmental and German Brown were available to investigate the influences of herd, month, lactation number, stage of lactation, milk production, diseases at calving, breed-Brown-Swiss blood proportion and additive-genetic effect of the cow on milk urea and acetone content. Significant differences between herds, months and lactation numbers could be shown for milk urea and acetone content. Acetone content decreased significantly in the first 100 days post partum by 0.06 mmol/l. Milk fat content was significantly correlated with milk urea and acetone. The heritabilities for milk urea were estimated in German Simmental cows as h2 = 0.06 +/- 0.04 and in German Brown cows as h2 = 0.25 +/- 0.11. Using milk samples up to 50 days post partum, heritability estimates were between h2 = 0.10 +/- 0.09 and h2 = 0.17 +/- 0.12 in German Simmental cows.