Sorry to hear this. So often the birds you have plans for seem to be to one a hawk takes a particular interest in, or don't make to the breeding pen for whatever reason.
As to the respiratory issue, going through a similiar issue with my young birds. Just about finished with a course of Gallimycin, and Pennchlor, per suggestion of Victor of Twin City Poultry Supplies. Mine started when high wind took the turbine vent off the coop a few weeks back, combined with more birds than I usually carry this late in the year, resulting in too humid conditions. Started with a few birds getting a slight rattle, and a few looking a little ruffled. Have a new vent on coop now, and conditions much improved. Victor said seems with the weather this year, it was a common problem. Anyway, why I started this ramble, I did loose a couple birds, two pure white Cornish cockerels, out of Dad's good birds. This leaves me with one cockerel and a couple pullets. Out of all the birds in that coop, many who showed no sign of any kind, I thought it interesting that the pure Cornish took the worst, and the project cornish seems to be somewhat more affected than the Brahmas.
