"Bull mates" joke

A man takes his wife to the Cheshire Farm Show.
They start heading down the alley that houses all the bulls.
The sign on the first bull's stall states:
"This bull mated 50 times last year."
The wife turns to her husband and says,
"He mated 50 times in a year, isn't that nice!."
They proceed to the next bull and his sign stated:
"This bull mated 65 times last year."
The wife turns to her husband and says,
"This one mated 65 times last year.
That is over 5 times a month.
You could learn from this one!"
They proceeded to the last bull and his
sign said: "This bull mated 365 times last year."
The wife's mouth drops open and says,
"WOW! He mated 365 times last year.
That is ONCE A DAY!!! You could really learn from this one."
The fed up man turns to his wife and says, "Go up and inquire if it was 365 times with the same cow."