ADG	Average Daily Gain
A:P ratio	Acetate-to-Propionate Ratio
BW	Body Weight
CDDGSs	Corn Dried Distillers’ Grains with Solubles
CH4	Methane
CO2	Carbon Dioxide
CP	Crude Protein
CRD	Completely Randomized Design
CSM	Cottonseed Meal
DDGSs	Dried Distillers’ Grains with Solubles
DE	Digestible Energy
DM	Dry Matter
DMI	Dry Matter Intake
ECM	Energy-Corrected Milk
GE	Gross Energy
GEI	Gross Energy Intake
GHG	Greenhouse Gas
GSM	Grape Seed Meal
H2	Hydrogen
ME	Metabolizable Energy
N	Nitrogen
NDF	Neutral Detergent Fiber
NE	Net Energy
NH3	Ammonia
OM	Organic Matter
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
RF diet	Reduced-Forage Diet
RS diet	Reduced-Starch Diet
Rusitec	Rumen Simulation Technique
SF6	Sulfur Hexafluoride
SUN	Serum Urea Nitrogen
TMR	Total Mixed Ration
VFA	Volatile Fatty Acids
WDDGS	Wheat Dried Distillers’ Grains with Solubles
Ym	Methane Conversion Factor