Have heifers (1 year old now) that had pink eye in a distant pasture (group A) brought them home end of August and put with 3 other heifers that had been part of a group of 26 weaned calves (group B).  Group B had no pink eye problems before this.  All 3 from group B get pink eye along with some from group A after being combined.  It has a month since there was any pink eye in any of my animals.  

It has not froze here yet and temps next week are supposed to be around 70 for highs, might get some frost this weekend. I would like to put these heifers with my spring born weaned calves together (these 2 groups have been 3/8 mile apart for last 2 weeks) and graze corn/tricticale, corn is 2 to 3 feet tall. 

The heifers are currently across the fence from my fall cows that have just started calving. 

What are the likelihood that after combining these groups that the spring calves get pink eye? or the new born calves across the fence?