Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
The Yearling is an Oscar-winning coming-of-age tearjerker about a young boy and his family who farm and hunt in a forest in the middle of Florida. It won an Oscar for its cinematography with includes some great wildlife scenes, especially the scene with dogs chasing a bear through the woods then fighting it. And there's a rattlesnake scene.
The boy Jody and his father Penny, played by Gregory Peck, are searching for some stolen pigs when Penny reaches down to move some plants and he gets too close to a rattlesnake and the snake bites his arm. Then Penny shoots the rattlesnake with his rifle. He then sucks the wound and shoots a doe that just happens to show up. He puts the doe's heart and liver on the wound to extract the venom. I don't know if this is an actual folk treatment for snakebite or one they made up for the book or the movie. The real reason for the snakebite scene is to give Penny an excuse to kill a mother doe so Jody, who is lonely because his three siblings are all dead, can take the fawn to raise as a pet. The fawn grows up to be the yearling of the film's title.
The first snake we see striking at a stuntman's arm is a Western Diamond-backed Rattlesnake, which does not occur in Florida. It looks like they might have used a pane of glass between the arm and the snake. It's not likely that they removed the snake's venom glands or sewed the snake's mouth shut because there's a disclaimer at the end that all of the animals were monitored by the American Humane Society, which should include rattlesnakes. The snake that is shot is a different rattlesnake, possibly an Eastern Diamond-backed Rattlesnake which is found in Florida. It's a real snake, not a prop, but it is not shown long enough to tell if it's alive or dead. The snake does appear to have been shot, or they could have used a small explosive charge, to send it flying up. Since no blood or gore is seen they either used a dead snake or it's possible they used some other kind of Hollywood magic.