The relationship between kidney fat index and marrow fat percentage as indicators of condition in Red deer stags (Cervus eluphus)

Abstract

The level of fat reserves of an animal gives a good indication of body condition. Riney (1955) who studied various methods of evaluating condition in Red deer in New Zealand considered that fat was deposited in a pre‐determined sequence over the range of body weight studied, which had been described earlier by Hammond (1932) as a general sequence in farm animals. Fat was deposited firstly in the bone marrow, then around the kidney, and finally subcutaneously. He concluded that kidney fat, expressed as a percentage of kidney weight, was the best index of condition as it embraced almost the entire range of physical condition. However, several authors have noted that small areas of fat are found around the kidneys of starved animals with marrow fat percentages < 80% (Ransom, 1965; Brooks, Hanks & Ludbrook, 1977; Anderson, Medin & Bowden, 1972). This means that values for kidney fat index of below < 40% may not be reliable, as another fat store, the marrow fat is depleted in parallel with it and not after it as Riney (1955) suggested. The relationship between kidney fat index and marrow fat at low levels of kidney fat index has been shown for White tailed deer Odocoileus virginianus (Ransom, 1963, Eland Taurotragus oryx, Impala (Aepyceros melampus) and Cape buffalo (Syncerus caffer) Brooks et al., 1977 and Mule deer 0. hemionus (Trainer, Hartmann & Kistner, 1979) but has never been shown for Red deer. The aim of this study was to accomplish this.