Effects of High-Forage Diets Containing Raw Flaxseeds or Soybean on In Vitro Ruminal Fermentation, Gas Emission, and Microbial Profile.

Xiao-Ge Sun,Yu-Hui Zheng,Yue Wang,Zhan-Tao Yang,Wei Wang,Ya-Jing Wang,Zhong-Han Wang,Qian-Qian Wang,Tian Xie,Cheng Guo,Ji-Dong Wang,Hong-Jian Yang,Sheng-Li Li,Yan Zhang

doi:10.3390/microorganisms9112304

Abstract

Lipid metabolism plays an important role in the energy economy of ruminants. However, its interactions of fat, rumen fermentation, gas emission, and microorganisms are not yet clear. This study evaluated the effect of adding raw oilseeds to high-forage diets on in vitro ruminal fermentation, gas composition, and microbial profile. Three isoenergetic and isoproteic experimental diets were designed and used as fermentation substrate: control treatment (CON group) was the basal diet lacking oilseeds, the other two treatments were the basal diet supplemented by 100 g/kg dry matter (DM) raw whole soybean (S group) and 50 g/kg DM raw flaxseed (F group), respectively. Data showed that the acetate, butyrate, and total VFA concentration of culture fluids in the S group were lower (p < 0.05) than in the F group. There was a tendency to a higher level (p = 0.094) of propionate concentration in the F group compared with the other two groups. The gas production in the F group was higher (p < 0.05) than in the control group. There was a lower abundance of Sutterella (p < 0.05) and a greater abundance of Butyrivibrio (p < 0.05) in both of the two oilseed treatments. Methanobrevibacter (p = 0.078) in the F group was the lowest. Our results suggested that CH4 emission could be inhibited with flaxseed supplementation by propionate production metabolism, biohydrogenation of unsaturated fatty acid (FA), and toxicity to Methanobrevibacter, while regarding soybean seed supplementation, the emission of CH4 was more likely to be reduced through biohydrogenation of unsaturated FA modulated by Butyrivibrio.

Highlights

The results showed that the raw oilseed treatments had di effects on the in vitro ruminal volatile fatty acid (VFA), CH4 emission and microbial profile, while the IV
The results showed that the raw oilseed treatments had different effects on the in vitro ruminal VFA, CH4 emission and microbial profile, while the in vitro DM disappearance (IVDMD)
0.011 ab Unlike the study that showed fat supplementation might have negative effects on digestibility and fermentation parameters [30], this study found that rumen IVDMD

Summary

Introduction

Lipid supplementation in ruminant diets has been identified as an effective strategy to increase milk fat content and energy density of the ration [1]. Adding oil to ruminant feed can manipulate the microbial profile and fermentation patterns in the rumen [2]. It was suggested that oils could positively affect rumen fatty acid (FA) proportions by influencing the activity of rumen microbes. Specific microbial communities and their interactions play an important role in many aspects of animal production, such as nitrogen cycles [3], methane (CH4 ) emissions [4], meat and milk quality [5]. Different sorts of fats may have different impacts on lipid metabolism in the rumen, the type of FA absorbed in the intestine and the final animal products.

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Conclusion