Medycyna Wet. 64 (4), 465-468, 2008
Guliński P., Młynek K., Salamończyk E.
Milk urea concentration changes depending on selected environmental factors
The objectives of this study were to describe the influence of lactation month, production season, age of cows, production level, milk protein content and udder health status on black-and-white cow milk urea concentrations. Dairy herd improvement of 61928 test-day data were collected over the period of 2000-2003 from 304 south Podlasie dairy herds. The average milk urea concentrations (mg/l), protein content (%) and milk day yield (kg) were as follows: 199 mg/l, 3.42% protein content and 18.4 kg milk day yield while 50% of the total analyzed tested milk had optimal milk urea concentrations from the nutritional point of view (150-300 mg/l). The lactation month, production season, age of cows, production level, protein content groups and udder health status effects were high and statistically significant in every factor at P < 0.05. The highest level of milk urea concentrations were distinguished in the summer season of the experiment (VI-VIII), for cows with the lowest milk protein content (< 3.2%), and lowest somatic cell counts (< 25 thous./ml), and for milk produced at fourth month of lactations. The average urea milk concentrations for those factors were respectively: 225, 213, 217 and 214 mg/1 l.
Keywords: urea, protein, milk