Although pemmican has traditionally been used for a very long time as an expedition ration especially in very cold climates and although it does have a very high energy to weight ratio (mainly because of the high animal fat content) it shouldn't really be relied on completely as it has some disadvantages. The disadvantages are the lack of available carbohydrates within the mixture. The addition of berries such as black currants within the mixture will also help overcome the lack of vitamin C, which is normally lacking within a traditional pemmican mixture. The high levels of animal fat within pemmican makes it difficult for the body to absorb the energy stored with the pemmican itself. Breaking down animal fat into muscle glycogen is a very energy and time consuming process for the body to achieve. Carbohydrates are much more easily consummed by the body as a readily available energy source especially if the body is having a very high energy output requirements such as man hauling, trekking, cycling for example. A more balanced ratio of proteins, carbohydrates, fats and nutrients is required. Rather than having 60-70% fat as in the pemmican, I would reduce this to less than 40% with the same percentage of carbohydrates i.e. a more balanced diet for the wilderness.

Ben Saunders has some interesting observations regarding expedition nutrition.

http://www.bensaunders.com/resources/expedition_nutrition.html

Pemmican is an excellent food resources at supplementing a wilderness diet of hunting and foraging and the craving for sweet sugary/starchy foods is just as powerful as is the hunger for animal fats and protiens.