CFP	Carbon Footprint
CMA	Comprehensive Meta-Analysis
Cu	Copper
CI	Confidence Interval
DEFRA	Department for Environment, Food and Rural Affairs
FCR	Feed Conversion Ratio
Fe	Iron
GHG	Greenhouse Gas
GWP	Global Warming Potential
HDP	Hen-Day Production
IPCC	Intergovernmental Panel on Climate Change
ITM	Inorganic Trace Minerals
LCA	Life Cycle Assessment
MD	Mean difference
Mn	Manganese
OTM	Organic Trace Minerals
PR	Partial Replacement
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
RBV	Relative Bioavailability
RMD	Raw Mean Difference
ROI	Return On Investment
SBM	Soybean Meal
SD	Standard Deviation
SMD	Standardised Mean Difference
TR	Total Replacement
Zn	Zinc