african black-rhinoceros collagen creases critically-endangered Diceros bicornis eating endangered folds food gray grazer grey heavy herbivore herbivorous herbivorous-browser hide hook-lipped-rhinoceros horns keratin large lattice-structured mammal megafauna odd-toed-ungulate offspring perissodactyl placid powerful rhino rhinoceros skin snout southern-white-rhinoceros square-lipped rhinoceros strong surface texture textures thick threatened tough wrinkled wrinkles zoo adaptable agricultural agriculture animal-husbandry appearance bos bos-taurus bovine breed breeders butterfat-producer calvers cattle commercial cow dairy dairy-breed dairy-cattle dairy-cow docile domesticated-ungulates farming fawn fertile field fodder grass grazer grazing green herd high-milk-yields livestock longevity milk-production milkers milking-cows paddock pasture productive quality reproductivity ruminant ruminating rural small-breed solid ungulates versatile alpaca animal Australia brown camelid chewing-the-cud cleft-upper-lip coat cria dark domesticated Ears exotic eye-lashes eyes face facial-expressions farm farmed fiber fibre fleece fur gentle hair hardy head herd-animal lama-pacos lamoid lips long-necked social soft South-American split-lip terrestrial-animal two-toed vicugna-pacos wool woolly-mammal