Table 4.

Effect of experimental treatments on molar proportions of isobutyrate, isovalerate, and valerate (mmol/mol of TVFA), and ammonia concentration (NH₃-N, mg/L) measured in 48 h gas from the in vitro incubation in experiment 1.

Treatments	Isobutyrate	Isovalerate	Valerate	NH3-N	p-Value 1
					CIsobutyrate	CIsovalerate	CValerate	CNH3-N
Control	10.9	0.61	21.4	282	–	–	–	–
2-nitroethanol	5.16	2.77	16.4	436	0.80	<0.01	0.14	0.39
Nitrate 2	6.63	4.01	16.43	270	NA	NA	NA	NA
Propynoic acid	8.34	2.59	0.77	311	0.91	<0.01	<0.01	0.25
Ferulic acid	14.4	5.23	20.0	320	0.88	0.03	0.67	0.98
p-Coumaric acid	165	4.23	22.6	263	<0.01	<0.01	0.73	0.81
Bromoform	0.00	0.00	28.7	302	0.64	<0.01	0.03	0.17
Fireweed	10.8	5.97	18.5	304	0.99	0.20	0.38	0.78
Rowan berries	10.1	5.85	21.5	289	0.97	0.15	0.98	0.81
A. taxiformis	5.95	5.33	35.4	354	0.83	0.04	0.00	0.52
Rapeseed oil	13.3	8.32	19.1	319	0.92	0.08	0.49	0.25
Dried distiller’s grain	11.5	6.87	20.7	301	0.98	0.91	0.83	0.07
Barley: oat	12.5	6.98	18.5	359	0.95	0.98	0.38	0.75
Maize: grass	10.0	6.10	17.8	281	0.97	0.26	0.28	0.20
Red clover: grass	9.04	5.23	14.6	306	0.94	0.06	0.08	0.45
Lactic acid	9.30	5.29	21.3	323	0.94	0.03	0.97	0.86
Lactic acid + acetic acid	8.95	4.61	16.7	282	0.93	<0.01	0.16	0.77
SEM	4.426	0.370	0.87	12.2	–	–	–	–

NA = not analyzed; SEM = standard error mean. ¹ Orthogonal contrasts of control diet vs. treatment of the different in vitro traits. ² Nitrate treatment was compared to the zero nitrate diet made by adding urea and CaCO₃ to the control diet according to Table 1; numerical differences molar proportions of branched-chain volatile fatty acids and NH₃-N are given in the text.