Milk and {HEAD ~ other animal products} are important as {TAIL ~ a food source} contributing more than a third of the calories, and between a third and all of the major nutrients in the U.S. food supply 
important as
Milk and { HEAD ~ other animal products } are important as { TAIL ~ a food source } contributing more than a third of the calories , and between a third and all of the major nutrients in the U.S. food supply
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH