Hello Jane,
In Breastfeeding and Human Lactation by Riordan & Auerbach, it states in Ch.
5  that the "caloric density of human milk is generally considered to be 65
kcal/100 ml" (p. 106).  And also that "Using breastmilk as the 'gold
standard', the American Academy of Peds recommends a calorie content of 67
kcal/100ml for commercial formulas."  When you thought 50-70 cals/oz it
should have been per 100ml or 100cc.  In the US, we tend to be more familiar
with ounces and that equates to about 20 cals/oz for human milk and
artificial milk (formula).
So if human milk is available it has the appropriate no. of cals (of course!)
and also all the wonderful properties of breastmilk - especially colostrum.
 Emphasize that and the hazards of infant formula - perhaps offer some of the
consents that may make them think of liability issues if they use artificial
feeding.  Remind them of "first, do no harm".
The other thing to remember is sugar water or D5W only has 6 cals/oz if I'm
not mistaken - even 3 oz of that will not equal 1 oz of human milk or
colostrum in terms of calories.
Hope this helps,
Laurie Wheeler, Rnc, Mn, Ibclc