TABLE 2.

[¹³C]acetate accumulation in ruminal contents incubated with alfalfa and 100% N₂^a

Addition to ruminal contents		Mean concn (mmol) ± SEM (n = 3)
BES	A. ruminis 190A4 (CFU/ml)	[1- or 2-13C]acetate-carbon	[U-13C]acetate-carbon
+	4.1 × 108	0.35 ± 0.008b	0.08 ± 0.000b
	None	0.17 ± 0.008c	0.04 ± 0.002c
−	4.1 × 108	0.13 ± 0.002	0.04 ± 0.002
	None	0.14 ± 0.004	0.03 ± 0.002

^aReaction mixtures were as described in the legend to Fig. 4. 

^b,c Means for BES treatment and ¹³C-labeling pattern with different superscripts are different (P < 0.001).