Richie has been spoiled with eight litres of milk a day and a rich diet of feed and muesli which Mr Underwood has made the calf become more solid by the day.
"He's really been getting the special treatment ... he's been getting much more than what the other cows normally get," he said.
"He's getting very solid. But I guess that's what you're after when you're connected with the All Blacks."
Richie has been separated from the rest of the herd and lives up at Mr Underwood's house.
"I've been become as fond of him as I've ever been of one of the calves," his owner said.
Born a month ago, the Northland bull was deemed by his owner as a lucky omen for the All Blacks.
Richie is entirely black except for a white forehead marking which looks remarkably like a silver fern.
The young bull won a legion of fans through the whirlwind of media attention he received.
While McCaw faces pressure to succeed, his calf-brother has received a stay of execution no matter how the All Blacks perform.
Richie will not go to the slaughterhouse and will instead become a steer.
"Maybe there will be other Richies in the future," Mr Underwood said.
Mr Underwood's dream is to have Richie McCaw meet the calf - which would mean he would also be able to meet the All Blacks captain.
This weekend, the calf's fans will be able to meet him at the Animal & Pet Expo on the North Shore for a gold-coin donation. The money will go to the SPCA.
STEERING IN THE RIGHT DIRECTION
Getting a result
McCow will be presented with two milk bottles - one bottle marked with a New Zealand flag, the other with an Australian flag. McCow will then make his choice - will it be the choice of champions or a chump?
Getting in shape
McCow is spoiled with 8 litres of milk a day and a diet of feed and muesli.
Getting the chop?
No. McCow won't go to the works, even if his predictions of the All Blacks' results aren't accurate. He'll become a steer.
