Table 3.

Effect of treatment and temperature on energy metabolism of finishing steers using indirect calorimetry

Items1	TRT2		TEMP3		SEM	P-value
	CON	ADY	TN	HS		TRT	TEMP	TRT × TEMP
RQ	1.11	1.10	1.11	1.09	0.009	0.6295	0.0734	0.4324
GEI, Mcal/d	28.1	28.1	29.5a	26.7b	0.819	0.9797	0.0004	0.6604
FE, Mcal/d	7.44a	6.77b	7.75a	6.45b	0.513	0.0320	0.0003	0.5638
DE, Mcal/d	20.7	21.4	21.8a	20.3b	0.946	0.1886	0.0096	0.8239
DE, Mcal/kg DM	3.06b	3.16a	3.06b	3.16a	0.082	0.0097	0.0123	0.6485
DE, % GE	73.6b	76.0a	73.7b	75.9a	1.96	0.0094	0.0136	0.6543
UE, Mcal/d	0.882	0.896	0.912	0.866	0.061	0.8279	0.4941	0.8978
GASE, Mcal/d	0.690	0.644	0.607	0.727	0.078	0.5287	0.1109	0.3458
GASE, % GE	2.47	2.33	2.07b	2.73a	0.300	0.5644	0.0147	0.3550
ME, Mcal/d	18.9	19.8	19.9	18.8	1.00	0.1687	0.0991	0.9802
ME, Mcal/kg DM	2.80b	2.93a	2.80b	2.92a	1.03	0.0281	0.0347	0.6054
ME, % DE	91.4	92.5	91.5	92.5	1.48	0.3360	0.3591	0.6967
HE, Mcal/d	17.5	17.6	17.0	18.1	0.663	0.8852	0.0743	0.2589
HE, % GE	62.6	62.9	57.5b	67.9b	1.68	0.8834	<0.0001	0.3668
RE, Mcal/d4	1.43	2.22	2.95a	0.695b	0.884	0.3166	0.0091	0.3696
RE, Mcal/kg DM	0.199	0.313	0.412a	0.100b	0.131	0.3355	0.0147	0.3297
RE, % ME	6.42	9.95	14.3a	2.04b	4.56	0.3855	0.0062	0.4731
SWG, kg/d	0.123	0.186	0.251a	0.058b	0.073	0.3208	0.0054	0.4040

^a,bLeast squares means within a row with different superscripts differ at P < 0.05.

¹Items are variables representative of the net energy system for beef cattle, indirect calorimetry procedures and combustion analysis. RQ = respiratory quotient (CO₂/O₂); GEI = GE intake (total feed energy); DE = digestible energy [GEI − fecal energy (FE)]; ME = metabolizable energy [DE − urinary energy (UE) and methane energy (GASE)]; RE = retained energy [ME − heat production energy (HE)]. Shrunk weight gain (SBW) = 13.91 × RE^0.9116 × SBW^−0.683.

²Treatment is control fed (CON) or control + 3 g/d of an active dried yeast (ADY).

³Temperature is thermoneutral [TN; 18 ± 0.55 °C; 20% relative humidity (RH)] or heat stressed (HS; 35 ± 0.55 °C; 42% RH).