I always thought mammal species were very similar to each other. But
apparently is not so.
We, humans, are told every day that to be in good health we must have
a balanced diet that includes all kinds of nutrients: proteins,
vitamins, minerals, carbohydrates, fiber, fat, etc.
But there are some species that feed only on one group of food. For
example, wild felines such as lions and tigers, eat only meat, which
is basically proteins and fat.
So, my question is, wild mammals that eat only one kind of food, where
do they get their other nutrients from? or is it that they, unlike
humans, don't need them?
Since this question is just out of curiosity, I don't need the
researcher to cite many authors and point to many websites. A good
explanation out of his /her knowledge on the subject would be
sufficient.

Keep in mind that carnivorous wild animals typically consume the
stomachs and/or intestines of their prey, which may contain vegetable
and fruit matter that was eaten by the prey while it was alive. In
this way, a carnivore gets a variety of food substances "second-hand."

Hi Samuel,

Great question. Their guts are different to our digestive system for a
start. Pink has a point, but I guess that is dependant on when the
unfortunate prey had last eaten. I don't expect a lion could choose a
known gazelle from a herd, with a fresh side salad to go.

I suspect that another more educated resident anthropoid than I will
be able to enlighten you correctly. I wonder too about the muscle tone
and fitness of these animals. We don't see them lifting weights.
Humans of course lift weights and tread upon mills to balance our
laziness of hunting and gathering at the local shopping centres. I am
led to believe that humans too should eat only herbivores. Not that we
need semi-digested salads, but apparently we should not eat another
carnivore. Have you heard of this?

Must go, have to find a kangaroo to kill before dark. 

Regards, Phil

I think pink gave an excellent answer = eating the gore.
 Another part of the answer is humans adapted to a very different life
style perhaps a million years ago. That some of us survive to age 100
on poor diets and too little excersizes is a miricle of making do with
whatever we give our bodies, no matter how pathetic.
 The big cats do stretching exersizes = isometrics to suppliment their
rather rare leaps for food.
 While typical health advice is apparently unnecessary for some of us
(we are all different) some of us live longer and have fewer ilnesses,
if we follow mainstream health advice. Likely alternative medicine
type prevention even benefits some of us. I'm reasonably healthy at
age 72, and i have dabled in good nutritician, rather than taking it
seriously. Moderation is likely best for most of us.   Neil

Don't forget, as well, that many animals do not possess the enzymes
needed to process certain types of foods, chemicals, etc because, as
you said, they simply don't "need" them. Every species of human and
animal has evolved in accordance with their particular strenghts and
surroundings. For example, Neanderthal stomachs contained an enzyme
that enabled them to digest large quantities of raw red meat, which
could kill a Cro-Magnon such as ourselves. This is directly because
that was 80% of their diet, and their bodies adjusted. Think of this-
one aspirin is fatal to a cat. Chocolate is poisonous to dogs. In
short, every animal has adapted to need most the items that are
available to it- an animal who has always existed in the Sahara
typically will not require as much water to survive as one who exists
in a rainforest, just as a whale does not need to eat oranges or beef-
it simply is was and is not available in their existence. You may also
want to consider the fact that an animal such as a lion requires far
larger quantities of protein than a human in order to support it's
muscle mass. Do you really see a lion surviving and hunting on a
stomach's worth of salad? Lastly, the human body and brain are
enormously more complicated than that of any other species, with more
subtle gauges and delicate balances, requiring a wider range of
vitamins, etc.

Samuel,

I hope you don't mind my jumping in here. This gold mine of shared
thought is fantastic. When are you coming back to the deliberations?

Pink .. I forgot of course that many grazing animals do exactly that
.. graze all day. So the gut contents are likely to be reasonably
fresh and only semi-digested at best. Semi or pre-digested foodstuffs
may make for a faster absorbtion into the digestive tract of the final
consumer I guess.

Neil .. Isometrics. Is that for the muscle tone, or just continual
stretching to remain limber for opportunities requiring quick action?
I understand your thought on moderation. Too much of any one thing is
simply no good. What nutrition have you dabbled in that makes a
difference for you? I hope you are making 100 years one of your
targets in life and not a limit.  :)

Dulcie .. You refer to enzymes. Is that the same as me saying that our
digestive systems are different, or are they two different things?
Your comments about the natural environment make a lot of sense. You
summed it up. I am yet to see a whale eat an orange. On another note,
you mentioned the cat and dog. I know of friends who give chocolate as
a "treat" to their dog. From what you have stated, I suppose they are
only treating themselves to a "trick" in attempting to humanise the
dog. Agree?

Forever learning, Phil

Being the author of this question, I must confess that I'm quite
surprised that no one came up with a solid answer. However, I'm glad
that it started an interesting discussion.

PINK: Apparently carnivores get their veggies second hand, but then,
herbivores, where do they get their proteins from?

NEIL: Yours is very interesting comment. Congratulations for being
such a healthy person. Maybe you should give us some advise on you
personal techniques to be in good shape. Personally, I'm overwieight
and can't unload the extra pounds around my hips.

DULCIE: Yours seems to be the comment closest to a real answer to my
question. The adaptation approach seems to be a good answer, but then
I'd like to ask you if this is something you know for sure or a mere
hypothesis.

PHIL: Of course I don't mind you joining this interesting forum. On
the contrary, you are welcome to discuss and share your ideas. Thanks
for being a part of it.

Well, anyone out there has an answer to this dilemma based on scientific knowledge?