From the Fonterra website ...
"Every milk collection is tested by an independent provider – MilkTestNZ"
https://www.fonterra.com/nz/en/what-we-stand-for/trusted-goodness/food-safety-quality-proof.html
... and HRL have recently announced a strategic alliance with MilkTestNZ.
Fonterra now partnering with A2M could increase milk testing revenue for HRL significantly.