My Uncle, who operated the farm the majority of the time it has been in operation, also had 12 chicken houses. I would be that he did use chicken manure at some point, although I don't know it for cerain.
The lbs per acre value is 1705 in one sample and 975 on the other. Both indicate that 0.0 lb/ac of limestone is required. Maybe it all came from liming the pastures over time.