Humans are responsible to minimize the suffering, oppression, death and slavery we are causing to other sentient beings.
We are responsible to do our utmost to minimize the death and suffering caused by humans.
When it comes to other species - if I had the possibility I would definitely defend a being that is attacked by a predator. Right now I think the best thing I can do is to spend my time to inspire humans to stop treating animals as slaves, confining them, mutilating them, oppressing them and killing them.
One cannot claim one is acting in the interest of the animals if one is taking what is most precious to them - their family and their own life.
Neither is an animal-based diet good for the environment, the starving people and people's physical and emotional health:
The plant-based foods that the more than 56 billion land animals (who have the sadly misfortune to grow up to become someones food) brutally slaughtered each year eats could feed more than 9 billion people.
15 million children are dieing of starvation in the world each year. Hundreds of millions don't get enough food. If we care of them we must let our eating habits reflect this. If everyone ate plant-based food, the food would suffice for everyone's need.
This is not the only effect. By eating animal products 3 times a day we teach our children that it is okay to take the life of innocent sentient beings, and that some individuals are of less value than others; instead of increasing our children's love and compassion by loving all sentient beings for their different qualities (just as many parents teach their children to extend their love and compassion for some dogs). I became a vegan this autumn and notice how this also increases my love and compassion for other humans, and not only all other animals.
This articles shows how eating animal products effects the environment and effects poverty and starvation: http://www.guardian.co.uk/commentisfree/2013/jan/22/quinoa-bolivian-farmers-meat-eaters-hunger
This book shows how our violence against other animals also leads to violence against us- the human animal: http://www.worldpeacediet.org/
Research -see e.g. the research referred to here: http://www.adelicatebalance.com.au/ - has proven that animal products are unhealthy.
We are herbivores.
"And if you took a baby and put a bunny in front of him, and if you had a cat and a bunny, the cat at any age would want to attack and kill the bunny and the child would say, “Oh, look at the bunny!” So the idea that we have some innate aggression towards animals…we don’t."
We have characteristics as herbivores: http://therumpus.net/2012/09/the-rumpus-interview-with-dr-neal-barnard/
and animal protein is dangerous for us: http://www.adelicatebalance.com.au/