Today’s Mother Goose and Grimm, with a proverb altered spooneristically (and a pun folded in):
(A pun on gnu and new and a transposition of dog and new in You can’t teach an old dog new tricks — though a transposition of a N and an Adj is unlikely, though not unknown, in the world of inadvertent errors.)
On the wildebeest, from Wikipedia:
The wildebeest …, also called the gnu … is an antelope of the genus Connochaetes. It is a hooved (ungulate) mammal. Wildebeest is Dutch for “wild beast” or “wild cattle” in Afrikaans (beest = cattle), while Connochaetes derives from the Greek words κόννος, kónnos, “beard”, and χαίτη, khaítē, “flowing hair”, “mane”. The name “gnu” originates from the Khoikhoi name for these animals, gnou.