Variability of milk urea, milk urea nitrogen, and ammonia emission from dairy Simmental and Holstein cows based on the milk recording month

The subject of this paper was to define the variability of milk urea, milk urea nitrogen, and ammonia emission from dairy Simmental and Holstein cows relating to months of milk recording through the precision farming methodology. Test-day records of dairy cows used in the statistical analysis were collected over five years. Regarding the parity, the animals were divided into four classes; regarding the recording date, test-day records were divided into twelve recording months, from January to December. The analysis was performed separately for each breed. The significance of the differences between the recording months was tested by the Scheffe's method of multiple comparisons (using the PROC GLM procedure in SAS). In terms of results, lower ammonia emission per cow was determined in the winter, while the ammonia emission was higher in the summer. Also, higher values of milk urea, milk urea nitrogen, as well as higher ammonia emission per animal, were determined in the Holstein than in Simmental cows.