Table 4.

Ruminal pH variables of Angus crossbred cannulated steers (658 ± 79 kg BW) fed free-choice step-up diets that contained increased concentrations of cracked corn¹ plus 0.45 kg of molasses that was individually fed containing or not 3 g of polyclonal antibody preparations against S. bovis, F. necrophorum, and lipopolysaccharides (40%, 35%, and 25% of the preparation, respectively).

Item	Treatment		STEP						P-value
	PAP	CON	SEM	STEP1	STEP2	STEP3	STEP3-7d	SEM	Treatment	STEP	Treat × STEP
Average pH	5.56	5.51	0.05	5.8a	5.5b	5.5b	5.4b	0.06	0.49	0.002	<0.01
Time <pH 5.6, min/d	308.2	406.4	24	278.6a	462.4b	411.1b	421.1b	30.86	0.45	0.001	0.36
Time <pH 5.2, min/d	93.8	139.2	30.6	43.8a	46.5a	125.2a	250.5b	36.23	0.31	0.004	0.71
Area <pH 5.6, min × pH/d	2053	2190	115	1587a	2521b	2216b	2163b	1550.0	0.40	0.003	0.35
Area <pH 5.2, min × pH/d	535	730.9	165.2	223.2a	263.9a	684a	1339b	193.0	0.39	0.005	0.39

Diets consisted of gradual inclusion of cracked corn from 0 (Bermudagrass hay only) to 35%, 60%, and 82% for STEP1 (d 14–21), STEP2 (d 21–28), and STEP3 (d 28–35), respectively.