What is the fatty acid composition of beef bone marrow fat? I have been roasting organic marrow bones for lunch salad for some time, and saving the fat drippings on my cast iron skillet, i jar it and save for later use.I have noticed that its more opaque than muscle fat and seems much softer (less saturated?) than my home made tallow. Tallow and butter are much more "yellow" fats to my eye. I think i will be using marrow fat even more in cooking due to have more variety of fats.
Thus far, I've not been successful in finding bone marrow nutrient analysis down to the specific phospholipids. Apparently it does contain considerable amounts of phosphatidylcholine and phosphatidylserine but references weren't available. By taste perception, that does seem accurate though.
Those phospholipids are polyunsaturated.
It may also be that bone marrow is high in glycine as Chris Masterjohn mentioned bone broth as a suggetion for increasing glycine in the diet in his March 15, 2011 article.
While this interesting 1964 paper regarding lipid content human bone (healthy and diseased) doesn't answer the question about the bones we eat, it still may be worth reading: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1215201/pdf/biochemj00768-0259.pdf "1. A modified method for the analysis of phospholipid mixtures by selective hydrolysis is described. 2. The phospholipid compositions of normal human bone marrow and of the bone marrows of patients who died with anaemia or various forms of leukaemia were investigated. 3. Phospholipids from normal bone marrow comprised about 44% of lecithin, 4% of choline plasmalogen, 7% of glyceryl ether phospholipid (choline base), 10% of sphingomyelin, 22% of phosphatidylethanolamine plus phosphatidylserine, 8% of ethanolamine plasmalogen and 5 % of glyceryl ether phospholipid (ethanolamine base). 4. The proportion of kephalin (i.e. phosphatidylethanolamine plus phosphatidylserine) in the pathological bone marrows tended to be lower than normal. No other consistent differences were observed between the normal and pathological samples. 4. A ceramide dihexoside was isolated from normal bone marrow."
A google answers response to someone's query regarding the nutritional value of bone marrow: http://answers.google.com/answers/threadview/id/112897.html
General information about the fat content (total) of a few ruminants..the comments yield more info with at least one of them written by Stephen - likely Stephen Guyenet from WholeHealthSource: http://www.darwinstable.com/2009/01/07/getting-accurate-fat-composition-in-your-diet/
I'm very interested to hear what others have to say on the topic.