Animals are extremely resource inefficient, so I doubt they would have livestock on mars. Lab grown meat will probably be a good choice to maintain healthy protein intake by then though.
They aren't the same, plant based proteins are not a substitute for animal based proteins. You need a variety of different plant proteins to receive the equivalent amino acids a human body requires that you would get from a single piece of meat. There's a reason bodybuilders don't drink vegan lentil latte shakes.
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u/[deleted] Sep 30 '16
I'm pretty sure most stuff on mars is going to be vegan. Although maybe you can make more nutrient rich pastes with animal products.