Table 6.

Main effects of MS and backgrounding estradiol benzoate and progesterone on interim performance corresponding to management in steer calves fed for 168 d in Exp. 2^a

	Mature sizeb			Implantc			Pooled
Item	SMS	LMS	P value	NI	SS	P value	SEM
Backgrounding-phased
n, steers	80	79	–	80	79	–	–
n, pens	10	10	–	10	10	–	–
Initial body weight, kg	308	371	<0.01	339	340	0.04	0.3
Interim body weight, kg	436	503	<0.01	466	474	0.01	1.7
Average daily gain, kg	1.52	1.57	0.14	1.50	1.59	0.01	0.021
Dry matter intake, kg	8.68	9.84	<0.01	9.14	9.38	0.01	0.055
Dry matter intake/MBSe, g/kg	102.4	103.0	0.49	101.8	103.7	0.03	0.53
Gain:feed	0.175	0.160	<0.01	0.165	0.170	0.08	0.0018
GEDf, Mcal/kg	4.14	4.58	<0.01	4.40	4.32	0.31	0.050
Finishing-phased
n, steers	79	79	–	80	78	–	–
n, pens	10	10	–	10	10	–	–
Interim body weight, kg	436	503	<0.01	466	474	0.01	1.7
Final body weight, kg	587	660	<0.01	618	629	<0.01	1.9
Average daily gain, kg	1.79	1.87	0.01	1.81	1.84	0.24	0.018
Dry matter intake, kg	11.41	12.68	<0.01	11.82	12.27	<0.01	0.044
Dry matter intake/MBSe, g/kg	106.0	107.0	0.04	105.2	107.8	<0.01	0.31
Gain:feed	0.157	0.147	<0.01	0.154	0.150	0.15	0.0015
GEDf, Mcal/kg	5.89	6.29	<0.01	5.99	6.19	0.05	0.064

^aShrink (3%) was applied to all body weights.

^bSMS, smaller mature size; LMS, larger mature size.

^cNI, nonimplanted during backgrounding-phase, implanted with 24 mg estradiol and 120 mg trenbolone acetate on d 85; SS, implanted with 20 mg estradiol benzoate and 200 mg progesterone on d 2 and with 24 mg estradiol and 120 mg trenbolone acetate on d 85.

^dBackgrounding-phase, d 1–84; Finishing-phase, d 85–168.

^eMBS, metabolic body size, calculated as weight^3/4 (Kleiber, 1961).

^fGED, gain energy density, calculated as estimated retained energy divided by ADG.