If the current population, assumed to be 80,000 horses, is reduced to AML (27,000), the goal of the rancher-friendly plan, and the excess forage is shifted to the ranchers, the revenue increment at current rates would be
(80,000 – 27,000) × 12 × 1.35 = $858,600 per year
The cost to remove 53,000 animals at $1,000 per head would be $53 million.
Few will be adopted, as the system is already flooded with captured animals.
The cost to stockpile them in long-term holding, around $2 per day per head, would be
53,000 × 2 × 365 = $38,690,000 per year
If they are placed in short-term holding the cost would be around $5 per day per head.
The government will spend $53 million initially to get them off the range, plus $39 million annually to care for them, so it can collect approximately $0.9 million per year from the ranchers.
Nobody in the private sector would do that. There is no net present value, no positive rate of return. A waste of taxpayer money.
UPDATE: Refer to Attachment 2 in the 2018 BLM Report to Congress for unit costs.