I could applaud you for suggesting all animals are sentient...
... but as of yet there is very little proof that the animals most humans use for meat come close to sentience. In fact, the most sentient species on Earth seem to all be meat eaters, whether they be the fox and the wolf, bobcat, mountain lion or tiger while the grass eaters seem to lack even the most basic levels of common 'horse' sense. Oh, I don't deny there are exceptions on both sides of the bar, but those exceptions are really quite rare.
As humans mature, maybe they don't need as much meat as when they are younger, but meat they still need, or some means of offering the same minerals and vitamins, proteins and amino acids that meats provide.
Oh, and if you're taking dietary supplements? You might take a closer look at that bottle's list of ingredients. Quite often the binder used to hold all those different ingredients together is animal-based.
