Winter Tick in Moose and Other Ungulates


Last Update: August 2000

Author: F. A. Leighton

Reviewer: W.M. Samuel (August 2000)

To measure the fat content of bone marrow

The fat content of bone marrow commonly is used as a crude index of the nurtirional condition of ungulates. The various fat reserves in ungulates in different parts of the body are used for energy in a sequence and the last reserve used is bone marrow fat. This rule applies only to ungulates; other species may use their fat reserves in a different sequence.

The fat content of bone marrow can be estimated easily and cheaply.

  1. Secure a sample of marrow from the mid-shaft region of a leg bone (the femur or thigh bone is used most commonly). The segment should be about 5 cm long or weigh 30-50 g. (To secure the sample, crack the bone in the middle with some hard instrument, and then twist the ends apart to fracture the bone along the cracks).
  2. Pre-weigh a light, water-proof container that will hold the piece of marrow. Mark the weight on the container.
  3. Place the marrow in the container and weigh the marrow and the container together. Record this weight and subtract the weight of the container to arrive at the weight of the piece of fresh marrow.
  4. Place the container with the marrow in it some place where the marrow will dry out and become desiccated. In moist climates, it may be necessary to place the container and marrow in some sort of drying oven at a low but warm temperature ( less than 35-50C).
  5. Weigh the container and marrow every few days until there is no further weight loss from drying.
  6. Record the final weight of the container and marrow and subtract the weight of the container from this final weight to obtain the final weight of the dried marrow.

The weight lost during drying represents the water content of the marrow and the weight of the dried marrow represents the weight of the solid material of the marrow, most of which will be fat in anything other than a starving animal. Thus, to obtain an estimate of the proportion of the total weight of the marrow that is fat, perform the following calculation:

Weight of dried marrow (from No. 6 above) X 100 = Percent of fat in the Original Bone Marrow
Weight of fresh marrow (from No. 3 above)

Lorsque vous observez des signes de maladie ou de la mortalité chez les animaux sauvages du  Canada, veuillez communiquer avec votre bureau local de la faune ou en le rapportant directement au CCCFS :
Call Toll-Free (in Canada):
1-800-567-2033

Courriel