This informative article is straight from Animals Australia "the voice for animals":
11 November 2011
One of the most common questions posed by people who are distressed by the cruelty of dairy production, is 'without dairy — where do I get my calcium?'
A good source of calcium in our diet is essential to maintaining strong and healthy bones. Through clever marketing, the dairy industry has convinced many of us that onlyby consuming lots of dairy products can we maintain healthy bones. Nutritionally speaking, this is completely untrue.
Not only is dairy not the only source of calcium — there's a body of evidence to suggest that dairy and other animal products could well be a significant cause of calcium loss and weakened bones. Surprised?
Here's a quick lesson in biochemistry. It is well known in nutritional circles that animal protein tends to leach calcium from the bones. That's right — animal protein tends to leach calcium from the bones.  This is because animal protein can cause the blood to become acidic. In order to neutralise the acidity of the blood, our body draws on its most readily available reserves of calcium phosphate — or, what bones are made of.  In this process known as 'protein-induced hypercalciuria', phosphate is used to neutralise the blood while calcium is excreted out of the body through the urine. 
In short, in order for the body to process protein in animal products, calcium is pulled from the bones and ends up in the toilet.
While you're chewing on that, consider this — the countries that are known to consume the highest levels of dairy also tend to have the highest incidence of osteoporosis .
Fortunately, protein found in plant-based foods does not have the same impact on calcium loss as that from animal origin. And calcium is found in a wide variety of plant-based foods. Some of the best sources include fortified soya drinks, sesame seeds, white/brown bread, fortified fruit juice, dried figs, broccoli, green leafy vegetables (except spinach), molasses, beans and pulses, tofu, and soya mince.
It's important to note that animal protein is not the only 'calcium thief' to be wary of — excessive salt, sugar, caffeine and alcohol can cause calcium loss too.  In addition, regular exercise is also essential to maintaining healthy bones. 
So when you next hear a dairy advertisement tell you that you need calcium for healthy bones, and that dairy contains calcium — think about what they aren't telling you. The evidence suggests that along with a healthy lifestyle, obtaining calcium from plant-based sources may be the most effective way to maintain strong and healthy bones while helping to stave off osteoporosis.
Food for thought.
Source of this article: ANIMALS AUSTRALIA: The Voice For Animals
"Ask not what an animal can do for you; ask what you can do for an animal." Jasper
"The animals of the world exist for their own reasons. They were not made for humans any more than black people were made for white, or women created for men." ~Alice Walker
The source of the quote is Walker's preface to Marjorie Spiegel's 1988 book, "The Dreaded Comparison" . Her next sentence was, "This is the gist of Ms. Spiegel's cogent, humane and astute argument, and it is sound."