A number of interesting controversies have revolved around the differences in milk from various species (especially as to the relative appropriateness for use as milk for humans, notably babies). There are some notable differences in composition of milks according to the USDA’s Handbook of the Nutritional Contents of Foods, by Watt and Merrill, United States Department of Agriculture, Dover Publications, Inc, New York (1973). (See Table I, pp 38 & 39.) Data for sheep, water buffalo and reindeer came from Food Values, Pennington and Church, Perennial Library, (1985)
I have picked out nutrients from their table which have the greatest variation and compiled them in the table below. (100 mL is a little less than 1/3rd cup):
For your own research, consult the USDA Food Composition Database where you can determine the nutritional content of almost any food.
Additional Milk Nutrients from Food Values, Pennington and Church, Perennial Library, 1985
One could write a whole paper on these differences. I think the most interesting are:
- Human milk has about 1/3rd as much protein as either cow or goat.
- Human milk has twice the carbohydrate as either cow or goat
- Human milk has 1/4th the phosphorous as either cow or goat
- Human has five times the of vitamin C. This is not surprising, since of these three species, only human are unable to synthesize their own vitamin C, and thus must get it through the diet.
It may be notable that the fat content is about the same for all three species. Also, there are relatively few differences between cow’s and goat’s milk in this table, and yet our experience is that goat’s milk is more easily digested than cow’s. Persons with peptic ulcers have said that it helped considerably to consume goat’s milk.
We do not know, but we know that goat milk has smaller fat globules than cow milk. Besides making the fat content more easily digested, this explains why cream separates much faster from cow than from goat milk.
Also, over many years, we have had parents of young infants come to us for goat’s milk because their infants could not digest either cow’s milk formula, or soy milk formula, and the mother had dried up (or been dried up by the pediatrician!). These parents have been emphatic that their infants thrived on goat’s milk as opposed to cow’s or soy “milk.” The differences in digestibility of goat’s versus cow’s is apparently in some category not listed in this table.
We know that goat’s milk is naturally homogenized, since the cream does not separate nearly as readily as cow’s milk. We have interpreted this as the reason for goat’s milk digestibility. However, we have received email correspondence indicating that human milk does separate overnight, so there is probably more to the story.