Table 4.

Effects of dietary treatment and group size, and their interaction, on nursery pig growth performance, day 0–41

	Treatment1
	Large group				Small group					P value
Item, kg	NC	PC	ZA	DR	NC	PC	ZA	DR	SEM	Diet	Group size	Diet × group size
Start BW	6.12	6.11	6.11	6.12	6.09	6.09	6.09	6.08	0.089	0.997	0.013	0.958
End BW	17.32	20.13	18.25	17.16	18.46	20.01	17.94	17.69	0.361	<0.001	0.154	0.080
ADG	0.26	0.33	0.28	0.25	0.29	0.33	0.27	0.28	0.009	<0.001	0.006	0.012
ADFI	0.40	0.47	0.43	0.40	0.43	0.47	0.42	0.42	0.011	<0.001	0.144	0.015
G:F	0.64	0.69	0.65	0.62	0.67	0.69	0.66	0.66	0.010	<0.001	0.004	0.203

¹NC = negative control; PC = positive control: NC + dietary antibiotics; ZA = NC + ZnO + dietary acidifier; DR = NC + Bacillus-based direct-fed microbial + 5% resistant starch. Group size treatments: pigs were housed in groups of either 31 (large group) or 11 (small group) pigs per pen.