Dynamics of change in fermentation and fatty acid profiles in high moisture alfalfa silage during ensiling at different temperatures

Liu, Qinhua; Dong, Zhihao; Shao, Tao

doi:10.1590/0103-8478cr20170605

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ANIMAL PRODUCTION • Cienc. Rural 48 (03) • 2018 • https://doi.org/10.1590/0103-8478cr20170605 copy

Dynamics of change in fermentation and fatty acid profiles in high moisture alfalfa silage during ensiling at different temperatures

A dinâmica de mudança na fermentação e perfis de ácidos graxos em silagem de alfafa de alta humanidade durante a ensilagem a diferentes temperaturas

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT:

The objective of present study was to investigate the dynamics of change in fermentation and fatty acid profiles in high moisture (DM=232g/kg FW) alfalfa silages during ensiling at 45°C, 30°C and 15°C. After ensiling for 1, 3, 7, 21, 39 and 65 days, silages was sampled and examined. Lactic fermentation changing into butyric fermentation in silage ensiled at 30°C and 45°C occurred on ensiling for 21 and 65 days, respectively, as accompanied with high ammonia-N content ( >150g/kg N), which subsequently resulted in a sudden increase of pH (P < 0.05). In contrast, the increase of lactic acid content was observed in silage ensiled at 15°C during ensiling for 65 days (P<0.05). As the ensiling temperature rose, considerable losses in total FA, C18:2n6 and C18:3n3 increased after ensiling for 1 day as compared with alfalfa before ensiling (P < 0.05) mainly due to thermolability of polyunsaturated FA and multiplication of lactic acid bacteria. Contents of total FA, C18:2n-6 and C18:3n-3 fluctuated in silage stored at 30°C and 45°C during ensiling from 3 to 65 days (P < 0.05), but decreased at 15°C due to the intervention of aerobic bacteria, yeasts and lipoxygenase. Therefore, after ensiling for 65 days, high moisture alfalfa silage ensiling at 15°C had better fermentation quality than at 30°C and 45°C. Temperature had significant influence on dynamics of change in FA profile in alfalfa silage during ensiling.

Key words:
silage; fermentation quality; fatty acid; temperature

Universidade Federal de Santa Maria Universidade Federal de Santa Maria, Centro de Ciências Rurais , 97105-900 Santa Maria RS Brazil , Tel.: +55 55 3220-8698 , Fax: +55 55 3220-8695 - Santa Maria - RS - Brazil
E-mail: cienciarural@mail.ufsm.br

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[1] E-mail: taoshaolan@163.com. ^*Corresponding author

Ingredients	--------------------------------------pH-------------------------------
Ingredients	4.5	5.0	5.5	6.0
Lactic acid aqueous solution 85:100 (w/v, μL)	15	5	2.5	2.5
Acetic acid aqueous solution 99.5:100 (w/v, μL)	35	25	10	2.5
Butyric acid aqueous solution 98:100 (w/v, μL)	20	50	100	0
Ammonium oxalate aqueous solution 6.21:100 (w/v, mL)	5.5	8	9	1
Distilled water (mL)	14.43	11.92	10.90	19.00

Items ^a	Tem	---------------------------------ET (d)-----------------------------						Means of Tem	SEM	-----------Significance----------
		1	3	7	21	39	65	Means of Tem	SEM	Tem	ET	Tem×ET
pH	45°C	5.92	4.94	4.95	4.88	4.83	5.81	5.22	0.056	0.001	<0.001	<0.001
	30°C	6.05	5.57	5.29	5.70	5.73	5.45	5.63
	15°C	6.28	6.24	5.87	5.75	5.56	5.39	5.85
Means of ET		6.08	5.58	5.37	5.44	5.37	5.55
Lactic acid (g/kg DM)	45°C	3.43	22. 7	16.5	23.8	25.6	8.35	15.5	0.603	<0.001	<0.001	<0.001
	30°C	13.1	22.3	25.0	0.76	0.52	2.20	10.7
	15°C	0.56	9.87	13.7	10.5	12.7	14.2	10.3
Means of ET		5.70	16.1	18.4	11.7	12.9	8.26
Acetic acid (g/kg DM)	45°C	1.06	3.50	3.66	3.61	5.71	20.5	6.35 c	1.371	<0.001	<0.001	0.100
	30°C	11.2	17.8	24.7	32.1	25.6	53.9	27.6 a
	15°C	2.87	10.1	13.7	17.8	28.9	36.3	18.3 b
Means of ET		5.04D	10.5CD	14.0BC	17.8BC	20.1B	36.9A
Propionic acid (g/kg DM)	45°C	0.13	0.40	0.27	0.30	0.40	4.33	0.97	0.611	0.002	<0.001	0.010
	30°C	0.43	0.23	1.50	6.50	10.6	15.1	5.73
	15°C	0.13	0.27	0.33	0.07	0.40	1.70	0.48
Means of ET		0.23	0.30	0.70	2.29	3.80	7.04
Butyric acid (g/kg DM)	45°C	0.30	1.80	0.93	3.90	4.83	20.4	5.36	1.165	<0.001	<0.001	<0.001
	30°C	0.83	1.03	1.37	30.9	36.4	38.9	18.2
	15°C	0.07	0.20	0.80	0.37	0.01	1.30	0.46
Means of ET		0.40	1.01	1.03	11.7	13.8	20.2
Ammonia-N (g/kg N)	45°C	63.4	86.9	72.3	79.8	106	240	108	8.056	0.006	<0.001	<0.001
	30°C	88.2	154	145	197	192	197	162
	15°C	46.4	109	98.7	133	163	128	113
Means of ET		66.0	117	105	137	154	188
LAB (log₁₀ cfu/FM)	45°C	8.37	6.66	7.03	5.22	4.89	5.48	6.28	0.050	<0.001	0.001	<0.001
	30°C	7.94	7.70	7.96	7.51	7.60	6.95	7.61
	15°C	7.54	7.44	7.58	8.25	7.72	8.25	7.80
Means of ET		7.95		7.27	7.52	6.99	6.74	6.89
Aerobic bacteria (log₁₀ cfu/FM)	45°C	6.20	5.10	4.30	3.32	3.11	2.11	4.02c	0.076	<0.001	<0.001	0.071
	30°C	7.68	6.52	5.58	5.22	4.11	4.15	5.54b
	15°C	8.50	7.20	6.35	5.39	5.48	5.61	6.42a
Means of ET		7.46A	6.27B	5.41C	4.64D	4.23DE	3.96E
Yeasts (log₁₀ cfu/FM)	45°C	<2.00	<2.00	<2.00	<2.00	<2.00	<2.00	2.00	0.086	<0.001	0.008	0.002
	30°C	4.38	2.00	2.91	<2.00	<2.00	<2.00	2.55
	15°C	3.78	3.62	2.79	4.92	2.45	3.55	3.52
Means of ET		3.39	2.54	2.57	2.97	2.15	2.52

Items^a	Tem	------------------------------------ET (d)---------------------------------							Means of Tem	SEM	---------Significance----------
		0	1	3	7	21	39	65	Means of Tem	SEM	Tem	ET	Tem×ET
Total FA	45°C	33.8	20.1	23.9	20.7	22.8	23.9	23.1	24.0 b	0.616	0.007	<0.001	0.090
	30°C	33.8	25.0	26.3	27.7	25.7	30.7	26.2	27.9 a
	15°C	33.8	31.1	29.3	26.8	27.4	25.4	20.3	27.7 a
Means of ET		33.8A	25.4B	26.5B	25.1B	25.3B	26.7B	23.2C
C16:0	45°C	7.35	6.25	6.00	5.12	5.63	6.03	8.17	6.36	0.199	<0.001	0.028	<0.001
	30°C	7.35	9.30	9.73	9.30	11.10	10.13	8.77	9.38
	15°C	7.35	8.33	9.20	9.60	8.87	10.67	8.20	8.89
Means of ET		7.35	7.96	8.31	8.01	8.53	8.94	8.38
C16:1	45°C	0.70	0.22	0.42	0.34	0.32	0.37	0.57	0.42 b	0.042	0.024	0.305	0.403
	30°C	0.70	0.63	0.63	0.70	0.50	0.73	0.53	0.63 a
	15°C	0.70	0.63	0.67	0.37	0.80	0.53	0.53	0.60 a
Means of ET		0.70	0.49	0.57	0.47	0.54	0.55	0.54
C18:0	45°C	1.66	1.39	1.31	1.17	1.22	1.34	1.47	1.37	0.032	0.002	0.081	0.044
	30°C	1.66	1.47	1.50	1.70	1.47	1.80	1.37	1.57
	15°C	1.66	1.60	1.67	1.57	1.87	1.77	1.40	1.65
Means of ET		1.66	1.48	1.49	1.48	1.52	1.64	1.41
C18:1	45°C	2.16	0.77	0.88	0.69	0.82	0.80	1.03	1.02 b	0.084	0.014	0.001	0.723
	30°C	2.16	2.00	1.43	1.47	1.43	1.30	1.00	1.54 a
	15°C	2.16	1.00	1.17	1.20	0.87	1.43	0.90	1.25 ab
Means of ET		2.16A	1.26B	1.16B	1.12B	1.04B	1.18B	0.98BC
C18:2n6	45°C	5.99	4.87	5.66	5.11	5.50	5.65	4.67	5.35 b	0.125	0.007	0.057	0.186
	30°C	5.99	5.43	6.27	6.30	5.60	6.40	5.40	5.91 a
	15°C	5.99	7.80	6.50	7.17	6.10	5.90	4.13	6.22 a
Means of ET		5.99	6.04	6.14	6.19	5.73	5.98	4.73
C18:3n3	45°C	15.9	6.57	9.65	8.22	9.36	9.68	7.13	9.50a	0.334	0.049	<0.001	0.056
	30°C	15.9	8.07	7.60	8.20	8.27	9.67	9.80	9.64a
	15°C	15.9	9.77	9.30	6.90	6.10	5.70	4.13	8.26b
Means of ET		15.9A	8.13B	8.85B	7.77B	7.91B	8.35B	7.02C