Animal Welfare
Animals are enslaved by humans ~ if this is not true then what are they, free?  Are pigs, cows, sheep, goats, chickens, turkeys free to roam and live and nest and laze in the sun and do what they want to do, in the wild, with their families? 
No; they are enslaved by humans, subjected to psychological and physical abuse, torture, dismemberment and murder.  They are kept alive just long enough to be considered fat enough to be killed and dissected.

There is no such thing as 'humane slaughter'.  You cannot humanely kill another, who doesn't want to die.  The continuous and unabated murder of our fellow earthlings at a rate of 80 billion a year (more each year than the number of humans who have ever lived) is a holocaust.
'Holocaust' ~ a massacre of innocent beings

There are four reasons humans eat animals: habit, tradition, convenience, taste.

But animals do not belong to us.  They are not stupid or simply objects or ingredients that cannot think or feel.  We know differently yet continue to do what we grew up doing without question. 

Speciesism
The belief that the human species has the right to exploit, enslave and murder another species.  That we are the only ones that count, that matter.  That other lives are not important.
This belief, that somehow we have been born more worthy than another, simply because of the colour of our skin or where we were born, or that we have skin and hair not fur and feathers, or because we understand our language but not another, is the basis of all discrimination.

We know that animals have brains, thoughts, communication and the capacity for emotions and pain.  Place yourself therefore in the position of an animal heading to a slaughterhouse and view what happens there from the victims' point of view.  It is easy to rationalise cruelty when you are not the victim.

At any one moment in the USA (and likewise around the world) there are 5000 concentration camp trucks on the road.  Inside are living, terrified, innocent beings.  When the trucks arrive the animals are so terrified they can be heard screaming.  They can be seen crying.  They won't even get off the truck, they are so frightened.  So someone will go on the truck with an electric prod and force them to walk down the ramp to their own death.
Inside, still alive, they are hung upside down.  They go in, petrified and come out chopped into pieces.   Again and again, day after day.

This behaviour is inexcusable and unbecoming of a species that claims to know right from wrong.
You may have paid 'lip service' and spoken the speak about how sad animal cruelty makes you feel.  Veganism is the chance to walk the compassionate walk that everyone is talking about. 
Veganism is the chance for your personal revolution.

In Western countries each person on average consumes 3000 land animals and thousands of other marine animals in their life.  In fact 98% of the animals that are abused and killed on this planet are killed by the meat, dairy and egg industries because every single meat eating and milk drinking human is paying for them to do it.

But didn't humans evolve to eat meat?
News from the animal kingdom, and yes we are a part of it!
While most mammals may display "omnivorous" behavior patterns depending on conditions of supply, culture, season and so on, they will generally prefer a particular class of food, to which their digestive processes are adapted.

Physiologically the human body is 100% herbivorous

> Human intestines are 7-13 times the length of their torso.  EVERY herbivore is within this ratio.  Hyenas, coyotes, tigers, lions, bears ~ theirs are 3-6 times the torso length.  Their shorter intestinal tract enables them to push through their diet quickly, of decaying and rotting flesh.  It is impossible for a genuine meat eater to clog their arteries!

> Humans and all other herbivores sweat through their pores to cool down.  Carnivores pant.

> Humans have carbohydrate digestive enzymes in their saliva.  Only herbivores have that as it enables efficient digestion of plants and fruits.

> Our teeth are broad, short, blunt and flat, not sharp and pointed.  Our 'canine' teeth, just like other herbivores, assist us with eating hard fruits like apples.

> Our lower jaw moves from side to side and we grind and chew.  Carnivores and omnivores have jaws that move up and down.

> Behaviourially we are just not cut out to be meat eaters ~ we have zero omni/carnivorous instincts... we don't hunt with out bare hands and teeth. 
We don't eat raw flesh and are not equipped for it.  We don't eat all body parts. We're squeamish.  Kids  naturally want to cuddle animals not eat them!

ALL the nutrients we need come from the soil, but illogically we are filtering them through someone else's body.  Once again, natural meat eaters do not get clogged arteries.  In fact any carnivore can be saturated with fat and cholesterol but plaques do not develop.

Dairy is Big Business
Meat, dairy and medicine ~ globally the three biggest money earners. 
Advertising material is swamped with ads for meat and cheese, along with ads for supplements, vitamins, diet pills, energy drinks, acid stomach pills, heart pills...

If our food is so great why are we so sick and why do we need so much medicine and nutrition in pill format?
According to the dairy industry they exist to provide a service to the nation; so you and your kids can get calcium and build strong bones.  Then why do Western countries have the highest rates of osteoporosis and why would we need calcium supplements?

Neither humans nor ANY OTHER MAMMAL needs millk after weaning.  Our own mother's milk, as a baby, is all we need.  NO ONE needs milk or its products after that, not for bones, or teeth or any other reason they tell you!
Drinking calves milk, crammed with the hormones to grow a baby into a heifer, is not natural or necessary.  Along with the pus cells that milk contains, there is a milk protein called casomorphine.  It's designed to ensure calves get hooked and keep guzzling.  It's an opioid!  No wonder most people think they could never give up cheese ~ they're addicted!

There is more cruelty in a glass of milk than a steak ~ the industry involves, as standard, here in New Zealand:
~ forced impregnation every year
~ forced removal of baby from mother
~ murder of male calves
~ forced and often excessive milking, leading to mastitis and exhaustion.
~ collapse and inability to produce after 4-6 years.
~ THEN the cow is murdered and hacked up for meat.
90% of hamburger meat comes from the dairy industry.

Before reading this you may have had the excuse of not knowing.  If you have read this far and you are not a vegan, what's your excuse now?  You CAN choose to never intentionally harm another animal for breakfast, lunch or dinner again.
These animals have never harmed you or violated you in any way, shape or form.  The least you can do is return the favour.

Click below for Gary Yourofsky's full speech at Georgia Tech.