You can hear the blood rushing out of the buffalo's throat, even over an idling pickup truck and the stiff May wind that blows across the grassy hills of western South Dakota. Lying on its side, the 800-pound bull labors through its final breaths, kicking its legs and trying to stand up. A dozen men, women and children, representing three generations, have gathered here on the Pine Ridge Reservation to watch Ed Iron Cloud's nephew, Bob Iron Cloud, kill the animal. This coming-of-age ritual -- a sacred ceremony for the Iron Cloud family -- is also a preparation for the upcoming Sun Dance, when the bison's heart will be buried under the pole at the center of the summer renewal ceremony. The buffalo itself came from a small herd managed by the Iron Cloud family in the rolling pastures above their homes near the community of Porcupine. As the