▁account ed ▁for ▁ 4 % ▁of ▁value . ▁In cre ased ▁demand ▁for ▁free ▁range ▁eggs ▁due ▁to ▁customer ▁concerns ▁over ▁animal ▁w elf are ▁has ▁led ▁to ▁a ▁number ▁of ▁different ▁standards ▁developing ▁in ▁relation ▁to ▁three ▁core ▁w elf are ▁measures ▁- ▁ind oor ▁stock ing ▁density , ▁out door ▁stock ing ▁density , ▁and ▁be ak ▁trim ming . ▁The ▁Model ▁Code ▁of ▁Pract ice ▁recomm ends ▁practices ▁for ▁free ▁range ▁far ming ▁with ▁the ▁following ▁standards : ▁ ▁Max imum ▁stock ing ▁dens ities ▁ind o ors ▁of ▁ 3 0   kg / m 2 , ▁equivalent ▁to ▁about ▁ 1 4 - 1 5 ▁birds / m 2 . ▁ ▁Max imum ▁out door ▁stock ing ▁density ▁of ▁ 1 5 0 0 ▁birds / ha , ▁although ▁this ▁can ▁be ▁increased ▁with ▁rotation ▁onto ▁fresh ▁past ure ▁ ▁Access ▁to ▁the ▁out door ▁range ▁for ▁a ▁minimum ▁of ▁ 8 ▁hours ▁per ▁day , ▁except ▁in ▁ad verse ▁weather ▁conditions ▁▁ 2 ▁metres ▁worth ▁of ▁pop hol es ▁per ▁ 1 , 0 0 0 ▁birds ▁for ▁access ▁to ▁the ▁range ▁ ▁Be ak ▁trim ming ▁is ▁permitted , ▁and ▁to ▁be ▁undert aken ▁by ▁an ▁acc red ited ▁operator ▁ ▁The ▁above ▁standards ▁are ▁not ▁always ▁met , ▁and ▁on ▁some ▁occasions ▁produ cers ▁may ▁want ▁more ▁eth ical ▁standards . ▁As ▁such , ▁cert ified ▁trade ▁marks ▁play ▁a ▁significant ▁role ▁in ▁the ▁determ ining ▁of ▁what ▁constit utes ▁free ▁range . ▁The