“What do you get from a pampered cow?”/“Spoiled milk.”

A popular joke is that a certain type of milk comes from a certain quality of cow, such as “chocolate milk comes from brown cows.” A similar type of joke is:
 
“What dp you get from a pampered cow?”
“Spoiled milk.”
 
The “pampered cow gives spoiled milk” joke dates to at least 1998.
 
   
Google Groups: alt.humor.puns
COW PUNS WANTED
Stan Kegel
7/30/98
(...)
Forgetful cows give . . . milk of amnesia. Pampered cows give . . . spoiled milk. Nervous cows give . . .  milk shakes.
   
Dumb Groaner Puns and Jokes
Date Received: Thu, 27 Aug 1998
(...)
What do you get from a pampered cow?
Spoiled milk.
 
Google Groups: alt.support.thyroid
Friday humor
Marcia Albert
9/11/98
(...)
What do you get from a pampered cow?
Spoiled milk.
 
Google Books
February 1999, The Rotarian, “No pun intended,” pg. 64, col. 3:
What do you get from a pampered cow?
Spoiled milk.
 
Google Books
Offensively Gross Jokes
By Julius Alvin
New York, NY: Kensington Pub.
2000
Pg. 134:
What do you get from a pampered cow?
Spoiled milk.
 
Google Books
Blonde Walks into a Bar:
The 4,000 Most Hilarious, Gut-Busting Gags, One-liners and Jokes
By Jonathan Swan
Berkeley, CA: Ulysses Press
2008
Pg. ?:
What do you get from a pampered cow?
Spoiled milk.
 
Twitter
Firecracker!
‏@Firecracker16
What do you get from a pampered cow???  [Spoiled Milk] No Milk Today – Herman’s Hermits (1967)  ♫ http://blip.fm/~7d6h9
3:11 AM - 31 May 2009
 
Twitter
Doyle Brunson
‏@TexDolly
Question..What do you get from a pampered cow? Blonde answer…spoiled milk
10:12 PM - 14 Jul 2010
   
Google Books
Riddle Jokes - Funny Questions For Adults
Riddles and Conundrums That Make You Laugh
By Mature Jokemaker Jr.
Kuppenheim, Germany: Emo Media GmbH
2014
Pg. ?:
What do you get from a pampered cow?
Spoiled milk.