Mirna Gavran, Robert Spajić, Ivana Jožef, Franjo Poljak, Danko Šinka, Gantner
Test-day records of dairy cattle were used for the analysis of variability of daily milk yield, milk urea nitrogen, and ammonia emission due to breeding regions (Eastern, Central, and the Mediterranean). Based on the analysis it was determined that Holstein cows bred in Mediterranean Croatia had highest daily milk production, milk urea nitrogen and ammonia emission. The lowest values of daily milk yield (20.23 kg), milk urea nitrogen (9.87 mg dL-1) and ammonia emission (74.68 g/cow daily) were recorded in Holsteins in Central Croatia. On the other hand, the highest recorded daily milk yield was in Simmental cows bred in Eastern Croatia (16.55 kg); while the milk produced in Mediterranean Croatia had the highest content of milk urea nitrogen and therefore those cows had the highest ammonia emission. The lowest values of milk urea nitrogen and ammonia emission were recorded in Central Croatia. The results indicate significant effect of breeding region on the variability of ammonia emission. Besides, test day records can be used not just for evaluating animal productivity but also for estimation of ammonia pollution from dairy cattle farms.