Volatile fatty acids and methane production from browse species of Algerian arid and semi-arid areas

Figures & data

Figure 1. The study area.

Table 1. Total VFAs production (mmol VFA/g dry matter incubated) and molar proportions (mmol/mol total VFA) of acetate, propionate, butyrate and valerate at 24 h of incubation of Algerian browse species.

Plant family	Plant species	pH	Total VTA	Acetate	Propionate	Butyrate	Valerate	C2:C3
Dicotyledons
Chenopodiaceae	Arthrocnemum macrostachyum	6.71^a	1.61^ef	752^abc	187^bc	49.9^bc	12.2^bc	4.04^bcd
	Atriplex canescens	6.69^ab	1.94^def	726^cd	175^bc	83.1^a	12.2^bc	4.19^bcd
Asteraceae	Artemisia herba-alba	6.48^c	2.71^bcd	775^ab	156^cd	48.6^bc	14.4^bc	4.99^ab
Fabaceae – Leguminosae	Astragalus gombo	6.55^abc	3.71^a	745^bc	177^bc	56.3^bc	14.4^bc	4.25^bcd
	Calobota saharae	6.59^abc	2.97^abc	745^bc	184^bc	50.1^bc	13.0^bc	4.09^bcd
	Hedysarum coronarium	6.73^a	2.60^bcd	738^c	209^ab	39.1^c	10.8^bc	3.57^cde
	Medicago sativa	6.53^bc	3.59^a	686^e	209^ab	67.4^ab	26.8^a	3.36^de
	Ononis natrix	6.61^abc	2.24^cde	786^a	137^d	58.4^abc	17.7^b	5.81^a
Monocotyledons
Poaceae – Gramineae	Hordeum vulgare (straw)	6.29^d	3.12^ab	699^de	231^a	60.8^abc	9.0^c	3.06^e
	Stipa tenacissima	6.56^abc	1.16^f	753^abc	169^cd	54.9^bc	17.9^b	4.50^bc
	SEM	0.02	0.153	6.23	6.59	4.62	1.49	0.175
	p value	<.001	<.001	<.001	<.001	<.001	<.001	<.001

Notes: C2:C3 = acetate to propionate ratio. SEM = standard error of the mean.

^a,b,c,d,e,fMeans in a column with different superscripts are significantly different (p < .05).

Table 2. Total gas and methane production (ml/ g dry matter incubated), percentage of methane in gas and methane production per unit of VFAs production at 24 h of incubation of Algerian browse species.

Plant family	Plant species	Gas production (ml/g DM)	Methane (ml/g DM)	ml methane/100 ml gas	CH4:VFA
Dicotyledons
Chenopodiaceae	Arthrocnemum macrostachyum	57.4^e	11.5^d	20.3^b	0.325^ab
	Atriplex canescens	58.4^e	13.6^d	23.6^ab	0.313^b
Asteraceae	Artemisia herba-alba	83.8^d	15.9^cd	19.1^b	0.263^b
Fabaceae – Leguminosae	Astragalus gombo	107.4^ab	22.7^ab	21.2^b	0.269^b
	Calobota saharae	102.7^bc	20.4^bc	19.9^b	0.310^b
	Hedysarum coronarium	92.0^cd	19.6^bc	21.3^b	0.364^ab
	Medicago sativa	119.3^a	25.8^a	21.7^b	0.335^ab
	Ononis natrix	67.3^e	13.9^d	20.4^b	0.276^b
Monocotyledons
Poaceae – Gramineae	Hordeum vulgare (straw)	110.9^ab	21.8^ab	19.6^b	0.318^ab
	Stipa tenacissima	40.0^f	11.4^d	28.7^a	0.483^a
	SEM	2.44	0.83	1.26	0.031
	p value	<.001	<.001	.002	.005

Notes: CH₄:VFA = mmol of methane per mmol total VFA produced. SEM = standard error of the mean.

^a,b,c,d,e,fMeans in a column with different superscripts are significantly different (p < .05).