respiratory infections in feedlot cattle

anyone know anything about respiratory infections that are killing cattle that are not deep lung related?

some cattle out here have died and the "rumor" is that it is a certain breed and that it is related to either closed herd or line breeding.  death losses on pens have been above 4% in pens.  death apparently is fairly quickly, whatever that means.  only thing i have to go on is strain is either x-15 or something to do with 15.  feeders are noticing brands.  is there an immunity problem or an inoculation problem?

I've never heard of that with cattle but we were renting at a guys place that had over 3000 sheep and they had some kind of "genetic" lung disease and it killed like 1.7 a day or something like that.  Want to say it was Colombia.

Mill Iron you are referring to Ovine Progressive Pneumonia I bet, nasty stuff. 

Knabe I wish I knew what you were talking about, but there are no specifics at all in the statement.  Respiratory that isn't deep lung can be fusobacterium (calf diptheria) or a handful of other things.  Any idea what the causative agent is (bacteria, virus, prion)?

Don't know. I know they are out of Idaho and being fed in California.

Comments regarding strain is x-15 probably wrong.  Need to talk to a couple more people. Friend has bought cattle from brand with high incidence in feedlot.

Comments about the cattle were that they were from a closed herd and that their immune response is low.