Denvermartin has a point.. you may want to do a disease test... Lepto and perhaps trich and other STD's at the same time... Your problem seems to be more serious than a lack of mineral of feed (unless your cows are starved and I doubt that). Secondly, I'd pull some blood from the 1 or 2 cows that raise the biggest calves and get a mineral panel done on them.. the two tests (disease done on the bull) will come to under $200, and you'll have a much better starting point. We can hum and haw around here all day, but without some real information, we're all just guessing.
Talltimber: When your grandpa started having problems and had to keep getting the vet in.. perhaps that was something genetic.. It sounded like things were OK at first, and then a host of problems came along.. especially with the breedback, perhaps the sire of those cows was a really high milk EPD, and they milked harder than the feed they were on would support, affecting breedback. I'm just throwing it out there.
Herofan, Even when I did have serious mineral deficiencies here, of the 20 cows I had MOST (lets say 18 of them) would breed within 6 weeks.. I only found the real problem because I had a couple of my best milking cows not breeding back.. The one I did the blood test on raised a 700 lb heifer on her first try, and didn't breed back at all that year.. 2 years later she had a 780 lb steer, and took about 3 tries to breed back.. the year after (exposed to the bull shortly after calving) she bred back right away. the following year, since she was early, she got 'run down' from milking before the bull was out, and once again had trouble. That's when I noticed the pattern, and did the blood tests, and then got the right (the important part is the "right") mineral, after which she bred back fine every time.
The one daughter I have of hers is on her 5th calf, milks very well, and has always been in the 1st cycle EVERY time.
It makes me wonder how many good cows I culled in the previous years and the cow wasn't to blame