When my cousin was selling raw milk, the most animals that he was milking at any one time as I recall was about 24. He was very finicky about cleanliness, both in the milk room and the milking parlor.
He milked into surge buckets and then poured the milk through a paper filter into the bottling machine. Then he would bottle (plastic) the milk while it was still warm, place the filled and capped bottles in a plastic rack, then place the rack of filled bottles into the milk tank that was full of water that he kept at 38 degrees. This system worked very well for him as he always had very low bacteria counts. In fact, the milk inspector told him one time that with one sample he had taken, the state lab technician was unable to detect ANY bacteria and accused my cousin of putting disinfectant in the milk, although they apparently could not detect any such contamination. To make the lab technician happy, he just did not clean as much, his count went up to detectable levels and the lab tech was happy!
His special attention to hygiene, not using a milk pipeline to transport the milk and bottling the milk while it was still warm and then cooling the bottled milk, were the likely reasons he was able to achieve such a low bacteria count.