Cow and Goat milk are both very good for you. It's actually the processed products that are unhealthy. Raw milk is full of fantastic nutrients and is very easy to digest. Also, the time and energy spent caring for a farm is by far healthier for you than sitting at a desk all day.You save a lot of time and energy........and its better for you health, if you don't consume any dairy products. Its not natural for adult mammals..(which we are) to drink milk anyway.
Grow lots of vegetables, fruits, some grains like corn, and eat small animals like chickens, ducks, rabbits, etc, which are very fast at reproducing and don't consume vast amounts of feed or take up a lot of space.
Your garden and small animal point is very valid and why I raise dwarf goats rather than their larger counter-parts

True enough. I personally wouldn't want to have to supplement for 9 months. I would prefer to pasture for the majority. Far less workWell, you will need more land in Canada then say California.
http://www.backwoodshome.com/articles2/lewis122.html
"Cows can indeed be kept on small plots—an acre or two—but they must be fed. We used to own a home with a two-acre pasture on which we kept three bovines (cow/calf and yearling steer). We needed to supplement their feed about nine months out of the year."

Efficiency and finding the simplest ways to do things is absolutely necessary if you don't plan to hire labor or buy feed and crops.