We have a Report on Plant Diseases about scab and smut, if you need more detailed information. You may also be seeing early Septoria glume blotch, depending on where your fields are located. Glume blotch causes a dark brown discoloration of the glumes, but doesn't cause a significant loss of grain. It's commonly more damaging if we have a delayed harvest. However, empty heads with no grain filled without a blackening of the whole head probably points to scab.
Scabby wheat can have mycotoxins which are damaging to livestock.
Vomitoxin has been found in some scabby wheat this year, so feed with caution. However, if you have concerns, either have a mycotoxin screening done on your wheat or c onsult with a vet before feeding. The toxicology lab on campus at the Vet School performs mycotoxin screening procedures. Call if you need more information.