High producing cows are like Athletes, they need the right food ( and drink) or else they fall over before they get to the finish line.
Specialist advise in this area is available in NZ ( mostly by people with overseas backgrounds and a NZ understanding of grass based farming) We work with various people in the industry, call us for a recommendation
Kelp For Cows
Minerals Are Key For Cow Health
many options available, Kelp is just one.