Urea concentration in milk of dairy cows in Slovenia | Vsebnost secnine v mleku krav v Sloveniji
2009
Verbic, J., Agricultural Inst. of Slovenia, Ljubljana (Slovenia) | Jenko, J. | Glad, J. | Babnik, D. | Perpar, T.
Based on the results of 659.606 determinations during the period 2000-2008 the situation in the field of milk urea concentration in Slovenia is given. During the period 2002-2004 the average urea concentration slightly decreased and was stabilised at a level of about 20 mg/100 ml thereafter. The proportion of samples with the concentration below the recommended value (15 mg/100 ml) was higher (26 %) than the proportion of samples (17 %) with the concentration above the recommended value (30 mg/100 ml). The highest milk urea concentration was found during the summer months (July and August; 24 and 24 mg/100 ml) and the lowest during the winter months (November and December; 20 and 19 mg/100 ml). The milk of Brown breed was characterized by higher milk urea concentration than the milk of Simmental and Holstein breed (23.6 vs. 21.9 and 21.7 mg/100 ml). The relation between milk urea concentration and milk production and composition reveals that very high productivity and high milk protein concentrations can also be achieved at moderate milk urea concentrations (22-24 mg/100 ml). In samples of cows given basal diet of hay only, the combination of hay and grass silage, the combination of maize and grass silage or the combination of maize silage, grass silage and hay higher concentrations of urea were observed (23, 23, 22, and 20 mg/100 ml) than in samples of cows given a combination of maize silage and hay (15 mg/100 ml). The highest average milk urea concentration was observed in summer samples of cows that were grazed or given diets containing fresh grass (31 mg/100 ml). The stage of lactation and the amount of concentrates in diets did not markedly affect the milk urea concentrations.
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