Q. I have seen it argued that the Igros Moshe’s heter for cholov stam is no longer relevant, because more than one in sixty milk cows has undergone an operation that renders them treif (LDA*). What is Rav Miller shlita”s view on this issue?

A. Horav Shlomo Miller’s Shlit”a opinion is that even if the LDA statistics quoted are accurate, we follow the rules of “Holchin Achar Harov,” and majority rules that any given animal comes from most animals that are kosher.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a

* LDA . Cows have a specialized digestive system that helps them process their high fiber diet. They have four distinct compartments to their stomach—the rumen, reticulum, omasum & abomasum. 
The abomasum is suspended by a loose attachment to the body wall, which means it can potentially move out of its normal position where it can fill up with gas and prevent normal flow of feed through the digestive track (called an abomasal displacement).
Abomasal displacements typically occur in high production dairy cows. There are 2 types of commonly seen abomasal displacements: Left Displaced Abomasum (LDA), is themost common
The abomasum can also twist on itself, called a abomasal “volvulus”. This can cut off the blood supply to the abomasum. If this isn’t corrected quickly the abomasum will start to die.
From; the American College of Veterinary Surgeons Web Site