It shall be unlawful for any person engaged in the business of handling or selling milk or cream or any by-product of the same or in the preparation, manufacture, or sale of any food products for man from milk or cream or any by-product of the same to maintain his premises or utensils in an unsanitary condition or to knowingly sell milk or cream drawn from sick or diseased cows or cows kept in an unsanitary place or cows fed on unwholesome feeds or slops.