The county boards of supervisors of counties engaged in eradicating tuberculosis in livestock under the area plan in co-operation with the board of animal health and the United States Bureau of Animal Industry may pay out of the general funds of the county money for necessary expenditure including the employment of accredited or approved veterinarians and for the payment of indemnity to cattle owners who have animals slaughtered because of having reacted to a tuberculin test authorized by the board and the United States Bureau of Animal Industry. Provided that said animals so classed are appraised and slaughtered as provided in the rules and regulations of the board of animal health. The indemnity received shall not exceed Fifty Dollars ($50.00) for each grade animal or One Hundred Dollars ($100.00) for each registered animal so condemned.