Effects of Essential Fatty Acid Supplementation on in vitro Fermentation Indices, Greenhouse Gas, Microbes, and Fatty Acid Profiles in the Rumen

Sardar Muhammad Amanullah; Dong Hyeon Kim; Dimas Hand Vidya Paradhipta; Hyuk Jun Lee; Young Hoo Joo; Seong Shin Lee; Eun Tae Kim; Sam Churl Kim

doi:10.3389/fmicb.2021.637220

Effects of Essential Fatty Acid Supplementation on in vitro Fermentation Indices, Greenhouse Gas, Microbes, and Fatty Acid Profiles in the Rumen

Front Microbiol. 2021 Mar 11:12:637220. doi: 10.3389/fmicb.2021.637220. eCollection 2021.

Authors

Sardar Muhammad Amanullah^{1

2}, Dong Hyeon Kim³, Dimas Hand Vidya Paradhipta^{1

4}, Hyuk Jun Lee¹, Young Hoo Joo¹, Seong Shin Lee¹, Eun Tae Kim³, Sam Churl Kim¹

Affiliations

¹ Division of Applied Life Science (BK21Four), Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, South Korea.
² Biotechnology Division, Bangladesh Livestock Research Institute, Savar, Bangladesh.
³ Dairy Science Division, National Institute of Animal Science, Cheonan, South Korea.
⁴ Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta, Indonesia.

Abstract

This study estimated the effect of essential fatty acid (FA) supplementation on fermentation indices, greenhouse gases, microbes, and FA profiles in the rumen. The treatments used pure FAs consisting of C18:2n-6 FA (LA), C18:3n-3 FA (LNA), or a mixture of these FAs at 1:1 ratio (Combo). In vitro rumen incubation was performed in 50 mL glass serum bottles containing 2 mg of pure FAs, 15 mL of rumen buffer (rumen fluid+anaerobe culture medium = 1:2), and 150 mg of synthetic diet (411 g cellulose, 411 g starch, and 178 g casein/kg dry matter) at 39°C for 8 h with five replications and three blanks. In rumen fermentation indices, LA exhibited highest (P < 0.05) ammonia-N and total gas volume after 8 h of incubation. Furthermore, LA presented lower (P < 0.05) pH with higher (P < 0.05) total volatile fatty acid (P = 0.034) than Combo, while LNA was not different compared with those in the other treatments. Additionally, Combo produced highest (P < 0.05) CO₂ with lowest (P < 0.05) CH₄. In the early hours of incubation, LA improved (P < 0.005) Fibrobacter succinogenes and Ruminococcus flavefaciens, while LNA improved (P < 0.005) Ruminococcus albus. After 8 h of incubation, LNA had lower (P < 0.05) methanogenic archaea than LA and Combo but had higher (P < 0.05) rumen ciliates than LA. R. albus was higher (P < 0.05) in LA than in LNA and Combo. It was observed that the rate of biohydrogenation of n-6 and n-3 FAs was comparatively lowest (P < 0.05) in Combo, characterized by higher C18:2n-6 and/or C18:3n-3 FA and polyunsaturated FA (PUFA) concentrations with lower (P < 0.05) concentrations of C18:0 and saturated FA and the ratio of saturated FAs to PUFAs. Therefore, this study concluded that dietary C18:2n-6 could improve populations of fibrolytic bacteria and rumen fermentation indices, but dietary mixture of pure C18:2n-6 and C18:3n-3 is recommended because it is effective in reducing enteric methane emissions and resisting biohydrogenation in the rumen with less effect on rumen microbes.

Keywords: biohydrogenation; fatty acid; methane emission; rumen fermentation; rumen microbes.