What is the nutritional breakdown (protein, fat, carbohydrates) in the
milk of various mammals?  In any cases, are there substantial portions
of the diet of infant mammals outside of mothers' milk?  (Specific
print- or web-published references strongly desired.)

Dear Sendhil,

Thank you for your inquiry!

Milk contains high percentages of protein, fat, carbohydrates,
minerals, water, and sugars (especially lactose), and some amount of
vitamins and salts. It is a very rich food source, which varies
considerably among species in composition.  Generally, when possible,
the infant mammals receive almost all of their nutrition from the
mothers milk.
Mammary glands, the source of milk, are unique to mammals, as is milk
itself, though pigeons produce something similar in their crops for
their young. Mammary glands are what give our class of animals their
name. We are the mammals or the mammary gland possessing animals.

To see the percentage constituents, or nutritional breakdown, of the
milk of various mammals, including the Horse, Cow, Goat, Pig, Dog,
Reindeer, Harp Seal and Blue Whale, visit:
Mammalian Milk
http://www.earthlife.net/mammals/milk.html
Note that the constituents, in chart order are:
Water, Fats, Proteins, Sugars, Ash, Potassium, Sodium, Calcium,
Magnesium and Phosphorus.

Here are some other helpful links for additional information:

Introduction to Lactation Biology
http://classes.aces.uiuc.edu/AnSci308/intro.html

University of Michigan – Mammalia
http://animaldiversity.ummz.umich.edu/chordata/mammalia.html

Milk Composition
http://www.foodsci.uoguelph.ca/dairyedu/intro.html

Milk Replacers
http://members.iweb.net.au/~hbird/milk_replacers.htm

Search terms used:
Mammals milk
Mammals milk composition
Constituents of mammalian milk

Thank you and have a great day!

Best Regards,
Skis4JC

You can find Cow, Human, Water Buffalo, Goat, Donkey, Elephant,
Monkey, Mouse, Whale, Seal here:
http://www.foodsci.uoguelph.ca/dairyedu/intro.html and a slightly
fuller list here: http://classes.aces.uiuc.edu/AnSci308/milkcomp.html