I have recently delved into the unknown and mysterious world of raising cornish crosses. I bought myself almost 300 birds from a local hatchery. 10 have died so far. I want to grow them until they reach 9 pounds but I am afraid that they will die of heart attacks before that. Has anyone grown there birds this big before and are there any remedies or preventative measures I can use or put in place to prevent them from dying before they reach 9 pounds.