Fat distribution and indices of carcass composition in Coats Island caribou (Rangifer tarandus groenlandicus)

Abstract

Twenty-seven barren-ground caribou (Rangifer tarandus groenlandicus) carcass sides were dissected on Coats Island, Northwest Territories, Canada, to calibrate indices of dissectible fat, muscle, and bone. Carcass muscle weight was accurately predicted from weight of the gastrocnemius muscle (In (carcass muscle, kg) = −2.791 + 1.071 In (gastrocnemius, g); r2 = 0.98), and carcass bone weight was accurately predicted from weight of the femur (In (carcass bone, kg) = −4.878 + 1.137 In (femur, g); r2 = 0.98). These allometric relationships held for calves and adults and for animals gaining and losing fat. The subcutaneous, intermuscular, pelvic, and internal omental and perirenal fat depots were weighed for each of 23 animals. The intermuscular and subcutaneous depots were largest and subcutaneous fat increasingly predominated at advanced fatness. Total dissectible fat in the five depots was most accurately predicted from depth of back fat and weight of kidney fat (dissectible fat (kg) = −0.178 + 1.058 depth of back fat (cm) + 24.147 kidney fat (kg); r2 = 0.98) and the regression was unaffected by age or condition. Comparison with similar studies suggests that such within-tissue relationships may be valid for all subspecies of Rangifer.