Table 3. In vitro fermentation parameters of experimental diets incubated in buffered rumen fluid

Items	Treatments				SEM	p-value1)
	No-citric acid		Citric acid
	No-heat (SBM)	Heat (HSBM)	No-heat (CSBM)	Heat (HCSBM)		Heat	CA	H×C
IVDMD (%DM)	74.6a	63.9b	76.4a	60.6b	3.02	< 0.001	0.780	0.339
IVCPD (%CP)	71.8a	51.3b	71.5a	45.8b	3.47	< 0.001	0.151	0.180
NH3-N (mg/dL)	64.5a	52.8c	59.5b	46.1d	1.48	< 0.001	< 0.001	0.459
MCP (mg/mL)	0.28a	0.24b	0.26b	0.18c	0.009	< 0.001	0.016	< 0.001
pH	6.90a	6.82b	6.83b	6.79b	1.48	< 0.001	< 0.001	0.459
TVFA (mM)	65.4ab	62.7b	67.5a	57.2c	1.01	< 0.001	< 0.001	0.020
VFA proportion (mmol/mol)
Acetate	535d	548c	566b	581a	1.96	< 0.001	< 0.001	< 0.001
Propionate	191a	190a	175b	166c	0.54	< 0.001	< 0.001	< 0.001
Iso-butyrate	45.4a	42.5b	42.4b	43.3b	0.45	0.007	< 0.001	< 0.001
Butyrate	110a	111a	108b	103c	0.74	< 0.001	< 0.001	< 0.001
Iso-valerate	64.5a	56.3c	59.3b	56.1c	0.63	0.006	< 0.001	0.002
Valerate	53.9a	51.7b	50.1c	49.9c	0.53	< 0.001	< 0.001	< 0.001
A:P ratio	2.81c	2.89c	3.23b	3.50a	0.028	< 0.001	< 0.001	< 0.001

CA, effect of citric acid addition; H×C, interaction.
Values within a row with different superscripts differ significantly at p < 0.05.
SBM, untreated soybean meal; HSBM, heat-treated soybean meal; CSBM, citric acid-treated soybean meal; HCSBM, heat and citric acid-treated soybean meal; IVDMD, dry matter degradability; IVCPD, crude protein degradability; NH₃-N, ammonia nitrogen; MCP, microbial crude protein; TVFA, total volatile fatty acids; VFA, volatile fatty acids; A:P ratio, acetate to propionate ratio.