"Livestock Show" joke

Ralph takes his wife, Mildred, to the livestock show. As they walk past the pens
holding the bulls, Mildred notices a sign by the first bull stating: "This bull
mated 50 times last year."
Mildred turns to her husband and says, "You could learn from him."
They proceed to the next bull and his sign states: "This bull mated 100 times
last year."
Mildred turns to Ralph and says, "This one mated twice a week! You can learn
from this bull, also."
They proceeded to the last bull and his sign said: "This bull mated 365 times
last year."
The Mildred's mouth drops open and exclaims, "Wow! He mated every single day of
the year! You could really learn a lot from this bull."
Ralph turns to Mildred and smiles, "I doubt if he mated 365 times with the same
old cow."