Farm milk transport operators hauling milk from the producer to the dairy plant, processing plant, creamery, or other destination, shall be liable for any and all damage or destruction to said milk en route and shall be required to carry cargo and casualty insurance covering such milk en route in an amount approved by the commissioner of agriculture and commerce with an insurance company authorized to do business in the state. In the event such farm milk transport operator does not obtain and have such insurance at all times, his license to grade, sample and weigh milk shall be subject to cancellation.