Factual error: During the ship scene, the computer graphic of splicing bat DNA into human DNA is wrong. DNA strands are complementary to each other. If you remove a segment from one side, what you can put back is predetermined by the other side, regardless of the source (bat, elephant, fish, etc). The graphic should have shown both sides of human DNA replaced (or just added) by both sides of bat DNA. As it is in the movie, the injection should not have any anatomic/physiologic effect.
Factual error: When Martine enters the passcode to reveal the bats, you see her hit "3" first followed by what seems to be "5" (the rest is blocked by her body). She then tells Michael his passcode is the first 6 digits of pi backwards. The first 6 digits backwards would be "951413."
Answer: He still had a compassionate side, the donated blood was for people who had blood diseases. The reason he did all this in the first place. As for animal blood, that's only for undead vampires, he was a living vampire, who needed specific fresh blood to combat his disease. Plus, vampires drinking animal blood was made up in movies and TV shows.