Biodegraded hay with graded addition of Pleurotus ostreatus improves dry matter disappearance and reduces methane production of diets incubated in vitro

Figures & data

Figure 1. Experimental Procedure Flowchart.

Table 1. Ingredients and chemical composition of experimental diets, and biodegraded hay used for in vitro incubations.

Ingredients, % of DM		Low aADFom^b diet	High aADFom^b diet
Forage	Corn silage	38.00	32.00
	Clover/ryegrass hay	18.00	15.00
	Wheat straw	2.00	25.00
	Chicory stillage	1.00	6.00
Concentrate	Ground grain corn	16.00	5.00
	Wet grain corn	7.00	5.00
	Soy bean meal	6.00	1.00
	Commercial concentrate^f	11.00	10.00
	Vitamin and mineral mix	1.00	1.00
Chemical composition (% on DM)	Low aADFom^b diet	High aADFom^b diet	H-PO^d	RF Hay^e
Dry matter (DM)	94.37	91.43	14.52	91.29
Total ash	5.63	8.57	3.83	4.41
Crude protein	12.20	12.73	5.16	4.73
Ether extract	2.01	1.84	1.10	1.30
Metabolisable energy^g	2.21	2.02	2.02	2.01
aNDFom^a	35.19	42.38	64.87	68.72
aADFom^b	23.45	35.30	42.05	42.45
ADL^c	2.82	3.82	1.98	5.88

^aaNDFom: Neutral detergent fibre. ^baADFom: Acid detergent fibre without residual ash. ^cADL: Acid detergent lignin.^dH-PO: P. ostreatus biodegraded hay. ^eRyegrass-Fescue hay before solid state fermentation with P. ostreatus. ^fCommercial concentrate Cosetán ® dairy cow No. 15 (dry matter 88.7%, crude protein 19.0%, metabolisable energy 2.93 Mcal/kg DM, ether extract 1.7%, aNDFom 32.5%). ^gmetabolizable energy, expressed as Mcal/kg DM, Calculated after Bath and Marble (1989) and Khalil et al. (1986). All ingredients except H-PO were freeze dried before grinding and mixing.

Figure 2. Interaction of acid detergent fibre (aADFom) in the diet × H-PO (P. ostreatus biodegraded hay) concentration sliced by high aADFom and low aADFom diets for (A) methane (CH₄) production (mg/g DMi) and (B) CH₄ yield (mg/g DMd) at 24 h. Different letters between bars, for CH₄ production and CH₄ yield indicate significant differences (p < 0.05), for the inclusion of biodegraded hay.

Table 2. Effects of P. ostreatus biodegraded hay and acid detergent fibre in the diet on in vitro dry matter disappearance, gas production, partition factor, and methane (CH₄) output production and yield, at 24 h of incubation.

Items		Treatment	IVDMD^B %	pH	GP^C, mL/g DMi^D	PF^E mg/mL	Net CH4, mg	CH4 Production, mg/g DMi^D	CH4 Yield, mg/g DMd^F
Acid detergent fibre (aADFom)		Low	60.0^a	6.67^b	124.0^a	4.9^b	4.4^a	11.1^a	17.3^a
		High	54.0^b	6.83^a	100.6^b	5.5^a	3.1^b	8.0^b	13.6^b
		SEM^A	0.01	0.01	2.83	0.18	0.09	0.23	0.35
Biodegraded hay (H-PO)		0%	53.0^b	6.62^c	111.6	4.80	4.90^a	10.5^a	18.4^a
		3%	58.0^a	6.75^b	112.3	5.24	3.90^b	9.90^a	15.3^b
		6%	60.0^a	6.86^a	113.1	5.56	2.70^c	8.20^b	12.6^c
		SEM^A	0.01	0.02	3.50	0.22	0.11	0.29	0.43
p-Value		aADFom	<0.001	<0.001	<0.001	0.023	<0.001	<0.001	<0.001
		H-PO	<0.001	<0.001	0.957	0.062	<0.001	<0.001	<0.001
		H-PO*aADFom^G	0.901	0.064	0.614	0.523	0.747	0.020	0.006
Polynomial contrasts^H	Low aADFom	L	<0.001	<0.001	0.406	0.183	<0.001	<0.001	<0.001
		Q	0.167	0.628	0.987	0.809	0.242	0.450	0.990
	High aADFom	L	<0.001	<0.001	0.479	0.002	<0.001	<0.001	<0.001
		Q	0.379	0.872	0.996	0.976	0.511	0.018	0.938

^a–cMeans without a common superscript in a column differ (p < 0.05). ^AStandard error of mean, ^BIn vitro dry matter disappearance,^CGas production, ^DDMi: Dry matter incubated, ^EPartition factor: the ratio of degraded DM (DMd; mg) to net gas volume (mL), ^FDMd: Dry matter degraded, ^GLinear (L) or quadratic (Q) of H-PO at high and low ADFom concentration, ^HInteraction between H-PO inclusion and aADFom concentration in the substrate.

Table 3. Total short-chain fatty acids (tSCFA), and percentage of the main tSCFA according to the concentration of P. ostreatus biodegraded hay and acid detergent fibre, at 24 h of incubation.

Items		Treatment	Total short-chain fatty acids (tSCFA)
			Total, mM/L	Acetate, %	Propionate, %	Butyrate, %	A:P^B
Acid detergent fibre (aADFom)		Low	306.0	49.0^b	27.0^a	22.0^a	1.84^b
		High	279.0	54.0^a	26.0^b	19.0^b	2.14^a
		SEM^A	10.51	0.01	0.01	0.004	0.06
Biodegraded hay (H-PO)		0%	311.8	50.0^c	28.0^a	21.0	1.79^b
		3%	295.7	52.0^b	26.0^ab	21.0	2.02^ab
		6%	270.1	54.0^a	25.0^b	20.0	2.16^a
		SEM^A	12.87	0.01	0.01	0.01	0.07
p-Value		aADFom	0.076	<0.001	0.038	<0.001	<0.001
		H-PO	0.080	<0.001	0.021	0.232	0.001
		H-PO *aADFom^C	0.910	0.944	0.951	0.989	0.867
Polynomial contrasts^D	Low aADFom	L	0.101	0.000	0.001	0.090	<0.001
		Q	0.839	0.719	0.136	0.403	0.196
	High aADFom	L	0.007	<0.001	<0.001	0.095	<0.001
		Q	0.690	1.000	0.750	0.231	0.759

^a–bMeans without a common superscript in a column differ (p < 0.05). ^AStandar error of mean, ^BA:P: acetate:propionate ratio, ^CInteraction between H-PO inclusion and aADFom concentration in the substrate, ^DLinear (L) or quadratic (Q) of H-PO at high and low ADFom concentration.

Figure 3. Diagram of carbohydrate ruminal fermentation, indicating end products (tSCFA) and methane (CH₄). Some of the potential targets for decreasing CH₄ emissions from ruminants are indicated in italics. Source: Adapted from Patra (2012), Ramírez et al. (2015) and Arias-Islas et al. (2020).

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Data availability statement

The data that support the findings of this study are available from the corresponding author, J.A.S., upon reasonable request.