. 2019 Jul 5;9(7):421. doi: 10.3390/ani9070421

Table 2.

Effect of the substrate (S) and the stage of maturity ¹ (SM) on gas and methane production (CH₄), potential gas production (A), rate of gas production (c), in vitro organic matter degradability (IVOMD), ammonia (NH₃-N), and volatile fatty acids (VFAs).

	Alfalfa			Sainfoin			Sainfoin+PEG				P-values
Item	VEG	Start-F	End-F	VEG	Start-F	End-F	VEG	Start-F	End-F	r.s.d.²	S	SM	SxSM
pH	6.42 ^a	6.44 ^a	6.41 ^a	6.35 ^bx	6.32 ^by	6.33 ^by	6.37 ^bx	6.31 ^bz	6.34 ^by	0.032	< 0.001	0.002	0.01
Gas production (mL/g dOM ³)	179	184	188	183	163	181	180	199	173	26.5	0.43	0.97	0.12
A (mL)	68 ^x	67 ^bxy	62 ^y	63 ^y	74 ^bx	70 ^x	65 ^y	78 ^ax	67 ^y	5.7	0.01	< 0.001	< 0.001
c (h⁻¹)	0.2 ^a	0.22 ^a	0.19	0.14 ^by	0.16 ^bxy	0.19 ^y	0.15 ^bx	0.15 ^bx	0.19 ^y	0.037	< 0.001	0.02	0.05
CH₄ production (mL/g dOM ³)	37	38	39	37	33	38	37	39	36	5.0	0.29	0.73	0.17
CH₄:gas (%)	14.5	14.2	14.1	14.1 ^xy	13.4 ^y	14.8 ^x	14.5	14.4	14.4	0.88	0.35	0.13	0.11
IVOMD (%)	85.13 ^bx	83.73 ^bx	76.97 ^by	84.97 ^by	92.59 ^ax	85.58 ^ay	86.81 ^ay	93.59 ^ax	86.41 ^ay	1.692	< 0.001	< 0.001	< 0.001
NH₃-N (mg/L)	240 ^a	247 ^a	210	206 ^b	184 ^b	201	242 ^a	234 ^a	215	31.7	< 0.001	0.06	0.20
Total VFAs (mmol/L)	102 ^xy	105 ^x	97 ^y	96 ^y	103 ^x	101 ^xy	99 ^y	105 ^x	102 ^xy	7.1	0.61	0.02	0.35
Acetic acid (C₂) (mol/100 mol)	63.1 ^cy	63.9 ^bx	64.0 ^bx	65.4 ^ay	66.5 ^ax	66.3 ^ax	63.9 ^by	64.6 ^bx	64.5 ^bx	0.76	< 0.001	< 0.001	0.95
Propionic acid (C₃) (mol/100 mol)	15.5 ^a	15.3 ^a	15.3 ^a	15 ^bx	14.5 ^cy	14.5 ^by	15.3 ^ax	14.9 ^by	15.2 ^ax	0.28	< 0.001	< 0.001	0.09
Butyric acid (mol/100 mol)	13.0 ^a	12.6 ^a	12.6 ^a	12.1^c	12.2 ^b	12 ^b	12.5 ^b	12.8 ^a	12.4 ^a	0.45	< 0.001	0.20	0.16
Iso-butyric acid (mol/100 mol)	1.97 ^ax	1.91 ^axy	1.87 ^ay	1.82 ^bx	1.68 ^by	1.72 ^by	1.97 ^ax	1.83 ^ay	1.84 ^ay	0.100	< 0.001	< 0.001	0.63
Valeric acid (mol/100 mol)	2.14 ^axy	2.09 ^ay	2.22 ^ax	1.87 ^bx	1.7 ^cy	1.83 ^cx	2.12 ^ay	1.95 ^bx	2.04 ^by	0.107	< 0.001	< 0.001	0.11
Iso-valeric acid (mol/100 mol)	4.27 ^ax	4.09 ^axy	4.04 ^ay	3.87 ^bx	3.5 ^by	3.65 ^by	4.19 ^ax	3.91 ^ay	3.93 ^ay	0.223	< 0.001	< 0.001	0.69
C₂:C₃ (mol/mol)	4.1 ^cy	4.18 ^cxy	4.2 ^bx	4.39 ^ay	4.62 ^ax	4.59 ^ax	4.18 ^by	4.36 ^bx	4.25 ^by	0.109	< 0.001	< 0.001	0.13
CH₄:VFA (mL/mol)	2.41	2.24 ^b	2.35	2.53	2.22 ^b	2.48	2.62	2.73 ^a	2.4	0.313	0.01	0.26	0.10

¹ VEG: vegetative; Start-F: start of flowering; End-F: end of flowering; ² residual standard deviation; ³ degraded organic matter. Within a parameter, means with different superscript (a,b,c) differ at P < 0.05 for the substrate effect in each stage of maturity; with different superscript (x,y,z) at P < 0.05 for the stage of maturity effect in each substrate.