Table 3.

Equations utilized to evaluate gaNE_m and gaNE_g using gas flux data from an automated head chamber system and performance data from feedlot steers consuming one of three finishing rations

Variable1,2	Equation	Source
HP, Mcal/d	$(3.866\times {\mathrm{O}}_2+1.200\times \mathrm{C}{\mathrm{O}}_2-0.518\times \mathrm{C}{\mathrm{H}}_4-1.431\times \mathrm{U}\mathrm{N})/1,000$	Brouwer (1965)
HP, Mcal/d	$4.96+(16.07/\mathrm{R}\mathrm{Q})\times \mathrm{C}{\mathrm{O}}_2$	Kaufmann et al. (2011)
RE, Mcal/d	$0.0635\times \mathrm{E}\mathrm{B}{\mathrm{W}}^{0.75}\times \mathrm{E}\mathrm{B}{\mathrm{G}}^{1.097}$	NRC (1984)
ME, Mcal/kg DMI	$(\mathrm{H}\mathrm{P}+\mathrm{R}\mathrm{E})/\mathrm{D}\mathrm{M}\mathrm{I}$	NRC (1984)
NEm, Mcal/kg DM	$1.104\times \mathrm{M}\mathrm{E}-0.0946\times \mathrm{M}{\mathrm{E}}^2+0.0065\times \mathrm{M}{\mathrm{E}}^3-0.7783$	Galyean et al. (2016)
NEg, Mcal/kg DM	$1.1376\times \mathrm{M}\mathrm{E}-0.1198\times \mathrm{M}{\mathrm{E}}^2+0.0076\times \mathrm{M}{\mathrm{E}}^3-1.2979$	Galyean et al. (2016)

¹HP = heat production; RE = recovered energy; NE_m = net energy for maintenance; NE_g = net energy for gain; O₂ = oxygen (L/d); CO₂ = carbon dioxide (L/d) CH₄ = methane (L/d); UN = urinary nitrogen (g/d); EBW = empty body weight; EBG = empty body gain; DMI = dry matter intake; ME = metabolizable energy (Mcal/kg DM); DM = dry matter.

²EBW calculated as 89.1% of shrunk body weight (96.0% live weight) and EBG calculated as 95.6% of shrunk ADG over an 80-d feeding period.