Table 4.

Effects of soybean small peptide (SSP) infusion into rumen at the rates of 0 (Control), 100 (SSP100), 200 (SSP200) and 300 (SSP300) g/d on characteristics of rumen fermentation and microbial abundance as determined by marker gene copy number in total bacterial 16 S rRNA (percentage of total bacterial 16 S rRNA ) (n = 4)

Item	Treatment				SEM1	Contrast2
	Control	SSP100	SSP200	SSP300		L	Q
pH	6.54	6.48	6.54	6.56	0.618	0.686	0.820
Ammonia N (mg/L)	66.91c	84.39b	96.79b	116.31a	9.363	<0.001	<0.001
Microbial protein (mg/L)	62.49c	74.99b	82.27b	92.45a	8.594	<0.001	<0.001
Total VFA (mmol/L)	86.03b	89.92ab	91.74a	92.01a	1.313	0.029	0.092
Acetate (mol/100 mol)	75.97a	71.93c	73.74bc	74.35ab	1.035	0.423	0.038
Propionate (mol/100 mol)	13.98c	14.53c	16.48b	19.14a	0.8	<0.001	<0.001
Butyrate (mol/100mol)	10.05b	13.55a	9.78b	6.51c	1.004	0.022	<0.001
Acetate:propionate	5.45a	4.95b	4.49c	3.92d	0.672	<0.001	<0.001
Ruminal microbial
P. ruminicola (×10−2)	1.94	2.18	2.03	2.21	0.732	0.231	0.437
R. flavefaciens (×10−2)	5.51	5.91	5.78	5.75	0.832	0.699	0.93
B. fibrisolvens (×10−4)	1.50b	1.68ab	1.82a	1.70ab	0.622	0.162	0.194
S. bovis (×10−6)	5.91a	4.87b	4.85b	4.94b	0.801	0.049	0.020
Ciliate protozoa (×10−2)	3.82	3.83	3.98	3.87	0.771	0.686	0.866

¹SEM = Standard error of mean.

²p values for the linear (L) or quadratic (Q) effects of SSP infused at the rates 0, 100, 200, 300 g·cattle⁻¹·d⁻¹.

^a–dMeans within a row with different superscript letter differ (p<0.05).