r itionally ▁ade qu ate ▁when ▁cal or ic ▁requirements ▁are ▁met . ▁Diet ▁for ▁a ▁Small ▁Planet ▁contains ▁an ▁extensive ▁list ▁of ▁suggested ▁combination ▁( Append ix ▁D ). ▁ ▁Prote in ▁quality ▁ ▁Vari ous ▁attempts ▁have ▁been ▁made ▁to ▁express ▁the ▁" quality " ▁or ▁" value " ▁of ▁various ▁kinds ▁of ▁protein . ▁Me asures ▁include ▁the ▁bi ological ▁value , ▁net ▁protein ▁util ization , ▁protein ▁efficiency ▁ratio , ▁protein ▁dig est ibility - correct ed ▁am ino ▁acid ▁score ▁and ▁complete ▁prote ins ▁concept . ▁These ▁concepts ▁are ▁important ▁in ▁the ▁liv est ock ▁industry , ▁because ▁the ▁relative ▁lack ▁of ▁one ▁or ▁more ▁of ▁the ▁essential ▁am ino ▁ac ids ▁in ▁animal ▁fe eds ▁would ▁have ▁a ▁limit ing ▁effect ▁on ▁growth ▁and ▁thus ▁on ▁feed ▁conversion ▁ratio . ▁Thus , ▁various ▁feed st uff s ▁may ▁be ▁fed ▁in ▁combination ▁to ▁increase ▁net ▁protein ▁util ization , ▁or ▁a ▁supp lement ▁of ▁an ▁individual ▁am ino ▁acid ▁( m eth ion ine , ▁l ys ine , ▁thre on ine , ▁or ▁try pt oph an ) ▁can ▁be ▁added ▁to ▁the ▁feed . ▁ ▁Prote in ▁per ▁cal orie ▁Prote in ▁content ▁in ▁food s ▁is ▁often ▁measured ▁in ▁protein ▁per ▁serving ▁rather ▁than ▁protein ▁per ▁cal orie . ▁For ▁instance , ▁the ▁US DA ▁lists ▁ 6 ▁gr ams ▁of ▁protein ▁per ▁large ▁whole ▁egg ▁( a ▁ 5 0 - gram ▁serving ) ▁rather ▁than ▁ 8 4   m g ▁of