Organic Dairy--How to Judge

A set of bullet points from a study of organic dairy:

• The average cow on organic dairy farms provides milk through twice as many, markedly shorter lactations and lives 1.5 to 2 years longer than cows on high-production conventional dairies;
• Because cows live and produce milk longer on organic farms, milking cow replacement rates are 30% to 46% lower, reducing the feed required and wastes generated by heifers raised as replacement animals;
• Cows on organic farms require 1.8 to 2.3 breeding attempts per calf carried to term, compared to 3.5 attempts on conventional farms;
• The enhanced nutritional quality of milk from cows on forage based diets, and in particular Jersey cows, significantly reduces the volume of wastes generated on organic dairy farms; and
• The manure management systems common on most organic farms reduce manure methane emissions by 60% to 80%, and manure plus enteric methane emissions by 25% to 45%. 

I've some quibbles: how does quality of milk reduce volume of wastes? What's unique about organic manure management? (Presumably the organic dairies are small enough to spread manure on the fields, while the non-organic are too big for that?)  3.5 breeding attempts strikes me as high, particularly if we're talking actual inseminations. 

But my bigger criticism is that these don't seem to me to be the right metrics.  What would be right?  Taking a dairy-wide view over years, standardizing the units for both conventional and organic. For example, take a 10-cow dairy (i.e., 10 milkers, plus appropriate replacements) over 10 years.  What's the total feed input and its cost, what's the total output of milk, and meat over the 10 years, what's the total manure output and their related emissions?  Throw in some metrics for quality of milk (is more fat better--it used to be but maybe not now).  Once you do that comparison you can proceed to the advantages of large versus small, as in the manure issue.