Table 2.

Effects of antibiotics and low-crude protein diets on pig growth performance¹

Item	ATB–2		ATB+3		SEM	P-value
	18.5% CP4	13.0% CP5	18.5% CP4	13.0% CP5		ATB	CP	CP × ATB
BW, kg
Initial	18.5	18.5	18.5	18.5	0.02	0.610	0.610	1.000
66 d of age	21.1	20.7	21.7	21.2	0.15	<0.001	0.004	0.705
73 d of age	25.9	25.3	26.9	26.7	0.21	<0.001	0.044	0.425
87 d of age	39.9	37.5	40.2	38.8	0.43	0.085	<0.001	0.287
ADG, g
59 to 66 d of age	367	308	458	385	19.8	<0.001	0.002	0.716
59 to 73 d of age	529	487	604	582	14.3	<0.001	0.033	0.479
73 to 87 d of age	998	872	944	864	19.7	0.123	<0.001	0.251
Overall	763	679	774	723	15.0	0.077	<0.001	0.278
ADFI, g
59 to 66 d of age	1004	1026	1058	1074	17.6	0.007	0.303	0.873
59 to 73 d of age	1169	1194	1226	1274	17.7	<0.001	0.047	0.541
73 to 87 d of age	1886	1810	1821	1819	27.9	0.321	0.168	0.194
Overall	1527	1502	1524	1546	21.0	0.345	0.949	0.263
G:F
59 to 66 d of age	366	299	434	354	15.4	<0.001	<0.001	0.686
59 to 73 d of age	452	407	493	455	7.6	<0.001	<0.001	0.672
73 to 87 d of age	531	482	519	475	6.2	0.136	<0.001	0.775
Overall	500	452	509	467	5.0	0.030	<0.001	0.586

¹Experimental medicated diets (ATB+) were fed from 59 to 73 days old. In the postmedicated period, all pigs were fed their respective crude protein (CP) control diets from 73 to 87 days of age.

²ATB−, diet without antibiotics.

³ATB+, diet with 100 mg/kg tiamulin and 506 mg/kg oxytetracycline.

⁴18.5% CP, diet with 18.5% of CP.

⁵13.0% CP, diet with 13.0% of CP.