No person shall sell, transport, offer for sale or transportation or receive for transportation in intrastate commerce any carcasses of horses, mules or other equines, domestic rabbits or parts of such carcasses or the meat or meat food products thereof, unless they are plainly and conspicuously marked or labeled or otherwise identified as required by rules and regulations adopted by the secretary of agriculture to show the kinds of animals from which they were derived. When required by the secretary with respect to establishments at which inspection is maintained under this act, such animals and their carcasses, parts thereof, meat and meat food products shall be prepared in establishments separate from those in which cattle, buffaloes, sheep, swine or goats are slaughtered or their carcasses, parts thereof, meat or meat food products are prepared.