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In vitro ruminal biohydrogenation of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic acid (DHA) in cows and ewes: Intermediate metabolites and pathways.
J Dairy Sci. 2018 Jul; 101(7):6109-6121.JD

Abstract

A great deal of uncertainty still exists about intermediate metabolites and pathways explaining the biohydrogenation (BH) of 20- and 22-carbon polyunsaturated fatty acids (PUFA). Therefore, this study was conducted to provide further insight into the ruminal metabolism of 20:5 n-3 (EPA), 22:5 n-3 (DPA), and 22:6 n-3 (DHA), the main n-3 PUFA present in the marine lipids used in dairy ruminant feeding, and to examine potential differences between bovine and ovine. To meet this aim, we investigated the 20- and 22-carbon metabolites accumulated during in vitro incubation of EPA, DPA, and DHA with rumen inocula from cows and ewes. The PUFA were added at a dose of 2% incubated dry matter and digesta samples were analyzed after 24 h of incubation using complementary gas-liquid chromatography of fatty acid methyl esters and gas chromatography-mass spectrometry of 4,4-dimethyloxazoline derivatives. Results suggested that the main BH pathway of EPA and DPA would proceed via the reduction of the double bond closest to the carboxyl group (cis-5 in EPA and cis-7 in DPA); curiously, this mechanism seemed of much lower importance for DHA. Thus, DPA would not be a major intermediate product of DHA and their BH might actually follow separate pathways, with the accumulation of numerous unique metabolites in each case. A principal component analysis supported this hypothesis, with a clear separation between PUFA treatments in the score and loading plots. Within EPA and DPA groups, cow and ewe samples loaded separately from each other but not distant. No conjugated 20:5, 22:5, or 22:6 isomer compatible with the initial product of EPA, DPA, or DHA metabolism, respectively, was identified in the ruminal digesta, although this would not unequivocally exclude their transient formation. In this regard, results from DPA incubations provided the first indication that the metabolism of this very long chain PUFA may involve the formation of conjugated double bond structures. The BH of EPA, DPA, and DHA resulted in the appearance of several tentative trans-10-containing metabolites, showing a general trend to be more abundant in the digesta of ewes than in that of cows. This finding was speculated to have some relationship with the susceptibility of dairy sheep to marine lipid-induced milk fat depression. Differences in the relative proportion of intermediate products would also suggest an influence of ruminant species on BH kinetics, with a process that would likely be slower and less complete in cows than in ewes.

Authors+Show Affiliations

Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas s/n, 24346 Grulleros, Leon, Spain.Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas s/n, 24346 Grulleros, Leon, Spain. Electronic address: g.hervas@csic.es.Natural Resources Institute Finland (Luke), Production Systems, Milk Production, FI-31600, Jokioinen, Finland.Institute of Biological, Environmental and Rural Sciences, Animal and Microbial Sciences, Aberystwyth University, Aberystwyth, Ceredigion, SY23 3EB, United Kingdom.Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas s/n, 24346 Grulleros, Leon, Spain.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

29705425

Citation

Toral, P G., et al. "In Vitro Ruminal Biohydrogenation of Eicosapentaenoic (EPA), Docosapentaenoic (DPA), and Docosahexaenoic Acid (DHA) in Cows and Ewes: Intermediate Metabolites and Pathways." Journal of Dairy Science, vol. 101, no. 7, 2018, pp. 6109-6121.
Toral PG, Hervás G, Leskinen H, et al. In vitro ruminal biohydrogenation of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic acid (DHA) in cows and ewes: Intermediate metabolites and pathways. J Dairy Sci. 2018;101(7):6109-6121.
Toral, P. G., Hervás, G., Leskinen, H., Shingfield, K. J., & Frutos, P. (2018). In vitro ruminal biohydrogenation of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic acid (DHA) in cows and ewes: Intermediate metabolites and pathways. Journal of Dairy Science, 101(7), 6109-6121. https://doi.org/10.3168/jds.2017-14183
Toral PG, et al. In Vitro Ruminal Biohydrogenation of Eicosapentaenoic (EPA), Docosapentaenoic (DPA), and Docosahexaenoic Acid (DHA) in Cows and Ewes: Intermediate Metabolites and Pathways. J Dairy Sci. 2018;101(7):6109-6121. PubMed PMID: 29705425.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - In vitro ruminal biohydrogenation of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic acid (DHA) in cows and ewes: Intermediate metabolites and pathways. AU - Toral,P G, AU - Hervás,G, AU - Leskinen,H, AU - Shingfield,K J, AU - Frutos,P, Y1 - 2018/04/26/ PY - 2017/11/22/received PY - 2018/03/16/accepted PY - 2018/5/1/pubmed PY - 2019/3/13/medline PY - 2018/4/30/entrez KW - PUFA KW - cattle KW - mass spectrometry KW - ruminal lipid metabolism KW - sheep SP - 6109 EP - 6121 JF - Journal of dairy science JO - J Dairy Sci VL - 101 IS - 7 N2 - A great deal of uncertainty still exists about intermediate metabolites and pathways explaining the biohydrogenation (BH) of 20- and 22-carbon polyunsaturated fatty acids (PUFA). Therefore, this study was conducted to provide further insight into the ruminal metabolism of 20:5 n-3 (EPA), 22:5 n-3 (DPA), and 22:6 n-3 (DHA), the main n-3 PUFA present in the marine lipids used in dairy ruminant feeding, and to examine potential differences between bovine and ovine. To meet this aim, we investigated the 20- and 22-carbon metabolites accumulated during in vitro incubation of EPA, DPA, and DHA with rumen inocula from cows and ewes. The PUFA were added at a dose of 2% incubated dry matter and digesta samples were analyzed after 24 h of incubation using complementary gas-liquid chromatography of fatty acid methyl esters and gas chromatography-mass spectrometry of 4,4-dimethyloxazoline derivatives. Results suggested that the main BH pathway of EPA and DPA would proceed via the reduction of the double bond closest to the carboxyl group (cis-5 in EPA and cis-7 in DPA); curiously, this mechanism seemed of much lower importance for DHA. Thus, DPA would not be a major intermediate product of DHA and their BH might actually follow separate pathways, with the accumulation of numerous unique metabolites in each case. A principal component analysis supported this hypothesis, with a clear separation between PUFA treatments in the score and loading plots. Within EPA and DPA groups, cow and ewe samples loaded separately from each other but not distant. No conjugated 20:5, 22:5, or 22:6 isomer compatible with the initial product of EPA, DPA, or DHA metabolism, respectively, was identified in the ruminal digesta, although this would not unequivocally exclude their transient formation. In this regard, results from DPA incubations provided the first indication that the metabolism of this very long chain PUFA may involve the formation of conjugated double bond structures. The BH of EPA, DPA, and DHA resulted in the appearance of several tentative trans-10-containing metabolites, showing a general trend to be more abundant in the digesta of ewes than in that of cows. This finding was speculated to have some relationship with the susceptibility of dairy sheep to marine lipid-induced milk fat depression. Differences in the relative proportion of intermediate products would also suggest an influence of ruminant species on BH kinetics, with a process that would likely be slower and less complete in cows than in ewes. SN - 1525-3198 UR - https://www.unboundmedicine.com/medline/citation/29705425/In_vitro_ruminal_biohydrogenation_of_eicosapentaenoic__EPA__docosapentaenoic__DPA__and_docosahexaenoic_acid__DHA__in_cows_and_ewes:_Intermediate_metabolites_and_pathways_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022-0302(18)30385-0 DB - PRIME DP - Unbound Medicine ER -