According to Etter, a deer’s sex, age and physical condition closer to winter are the three biggest factors affecting fat coloration. Yearling deer — both bucks and does — that are in good condition typically display the almost pure-white fat that’s commonly seen by hunters who butcher their deer in October and November. Fawns, especially later in the season, will often display yellowish fat layers.

Older bucks are more likely to exhibit fat that’s a deeper shade of yellow — and even reddish in some cases. Fat starts turning color when it is being metabolized.

T.P. Kistner of the Oregon Department of Fish and Wildlife was one of the first researchers to document the physiology of deer-fat deposits in deer when he authored the manual “Technique for Evaluating Physical Condition in Deer” in 1980. His studies concluded that deer fat turns white when it forms and is stored on a deer’s muscle tissue and around the heart, liver and other internal organs.

Here’s What Causes that Nasty Yellow Fat in a Deer’s Body

The fat on that deer looks normal to me....the yellow looks to be something else. Not sure what it is but don't look anything like any fat that I've ever seen.

How far did the deer run after the shot? Was it chasing or being chased? I've seen rutted up and stressed deer look like that once in a while.