Ask for advice on cow disease (I don't know if it's okay)

We have a new batch of weaned Shandong Luxi yellow cattle in our cattle farm. We used to feed hay and silage in Shandong. After 11 hours of transportation (no straw mats), we went to the cattle farm and put them into the ring after disinfection. The first meal was milk substitute. The problem is that I didn't eat much for the first meal. After the milk powder was poured out, it was put into silage, there was also hay, and some of it was eaten. Same at night. On the second day, several of them began to vomit and diarrhea, one died after vomiting for a while, others vomited, and three died at night. I would like to ask whether the discrepancy between soil and water leads to vomiting (constant vomiting), or poisoning, there is absolutely no problem with silage and milk substitute powder, and the ambient temperature is slightly lower than that in Shandong. No abnormality was found after autopsy of the dead cow. The question is not detailed enough. There is nothing we can do now. It is estimated that he will have a headache for a long time if we invite a good veterinarian. I hope some of my friends can give me some good advice. Thank you!