I can approve this as it is proposed to be submitted for journal peer-review, but I suggest that the authors may want to consider revising the paper prior to submission to include information that would, in this reviewers opinion, significantly improve the paper. To mention a few:
- Clarification which version of the GAINS model was used; References that confirm 500 dairy cows as a 'representative' herd size; indication how mitigation options were selected; indication which of the selected technologies would be applicable to which % of current dairy systems and dairy animals; Description and quantification of what is being used as 'current practice' in the models; further explain the validity of the underlying assumptions of the model used to calculate benefits from reduced health impact and mortality (particularly since this is indicated as the potential 'profitability switch); clarify if volatilization during manure application is taken into account in the 'fertilizer saving' benefit calculations; line 30-32 of the abstract need rephrasing; line 243: not clear which survey you refer to, or how/when it was carried out etc.