My meat birds have been doing really well. Yesterday DH comes in and says there's problem with one of my birds. He's not going for the food like the others. He'd move a little but acted very lethargic. I went out and brought him in. He acted half dead. DH kept asking me what was wrong with him. I said I didn't know, acting half dead is a common symtom of most any chicken disease. Then this morning I lost another one. I didn't notice any others acting strange yesterday. It's been very cold here but I've kept 2 heat lamps in the tractor with them so they could go warm up if they needed too. I've not noticed and bloody poops. Any ideas? Anything I should do to prevent more losses.