Table 2.

Effect of zinc¹ supplementation and implant² strategy on the performance of finishing heifers

	NRC		IND		SEM	P-value
	REV-XH	REV-200	REV-XH	REV-200		Zn	IMP	Zn × IMP
Pens (n)	9	9	9	9
Live performance3
BW, kg
Day 0 (Initial)	294	295	294	295	7.0	0.96	0.90	0.98
Day 28	337	342	338	343	1.7	0.34	0.004	0.98
Day 56	381	385	382	387	2.3	0.50	0.04	0.86
Day 91 (Re-implant)	439	442	445	447	2.8	0.06	0.35	0.83
Day 120	485	492	493	498	3.3	0.05	0.09	0.86
Day 168	561	571	570	570	4.6	0.37	0.21	0.27
DMI, kg
Days 0–90	9.5	9.6	9.6	9.6	0.11	0.68	0.51	0.89
Days 91–168	11.4	11.3	11.6	11.7	0.20	0.09	0.97	0.58
Days 0–168	10.4	10.4	10.6	10.6	0.13	0.15	0.80	0.72
G:F
Days 0–90	0.170	0.172	0.176	0.177	0.0025	0.04	0.44	0.94
Days 91–1683	0.137b	0.147a	0.138b	0.135b	0.0030	0.06	0.25	0.03
CA performance4,5
Final BW, kg	561	572	570	571	5.0	0.45	0.25	0.34
Overall ADG, kg	1.58	1.65	1.64	1.64	0.030	0.47	0.28	0.29
Overall G:F	0.154	0.160	0.156	0.156	0.0021	0.71	0.18	0.11

¹The NRC treatment received 30 mg supplemental Zn/kg DM from ZnSO₄ and IND treatment received 100 mg supplemental Zn/kg DM from ZnSO₄.

²Implant strategies included either a single Revalor-XH implant (REV-XH; 20 mg estradiol + 200 mg TBA; Merck Animal Health, Madison, NJ) on day 0 or a Revalor-200 implant on day 0 and again on day 91 (REV-200; 20 mg estradiol + 200 mg TBA; Merck Animal Heath, Madison, NJ).

³Unlike superscripts indicate differences in treatment means (P≤ 0.05).

⁴Day 0 BW was used as a covariate in performance analysis, excluding day 0 BW.

⁵Carcass-adjusted (CA) overall performance was determined with the average dressing percent of treatment groups (63.46%, 63.95%, 64.14,% and 63.90% for NRC/REV-XH, NRC/REV-200, IND/REV-XH, and IND/REV-200, respectively).