The present disclosure provides methods and systems for optimizing a cost efficiency or a nitrogen-use efficiency (NUE) for a feeding regimen of a herd of interest of milk-producing animals, for monitoring a urinary urea-N excretion (UUNE) for a herd of interest of milk-producing animals, and for monitoring a NUE for a herd of interest of milk-producing animals. The methods include use of a milk urea-N yield (MUNY) value or a ratio of MUNY to a protein yield (PY) in milk produced by the herd of interest.
