Dietary treatment with omega fatty acids mediates in vitro rumen fermentation kinetics and reduce methane emission in water buffalo

Mengwei Li,Chengjian Yang,Kaiping Peng,Fang Xie,Faiz-Ul Hassan,Hossam Mahrous Ebeid,Zhenhua Tang,Lijuan Peng

doi:10.4314/tjpr.v20i9.4

Abstract

Purpose: To investigate the effect of dietary supplementation of two omega fatty acids on in vitro rumen fermentation, microbial populations, total gas and methane (CH4) production．Methods: Both linoleic and linolenic acids were supplemented at 0 (control), 1, 3, 5 and 7 % of dry matter (DM) in a ration with a high roughage to concentrate ratio (70: 30). Total gas and CH4 were measured at 3, 6, 9, 12 and 24 h of fermentation while pH, volatile fatty acids (VFA), and ammonia nitrogen (NH3-N) concentrations were measured at 24 h using buffalo rumen fluid in an in vitro batch culture system. Microbial populations were determined using 16S-rDNA gene primers by RT-PCR.Results: The results revealed that linoleic acid at 3, 5 and 7 % decreased the concentration of NH3-N (p< 0.05) but linolenic acid at 5 and 7 % increased NH3-N (p < 0.05). A linear decrease (p <0.001) in acetate and butyrate, coupled with linear increase (p <0.001) in propionate was observed in response to treatment. Furthermore, supplementation of 3, 5 and 7 % of both fatty acids linearly (p < 0.001) decreased total gas and CH4 production when compared to the control. The addition of linoleic acid linearly (p < 0.001) decreased the number of protozoa without affecting methanogens, while linolenic acid linearly and quadratically (p < 0.001) reduced the population of both protozoa and methanogens (p < 0.05).Conclusion: Linolenic acid is more effective at a 3 % level in reducing methane production (up to 63 %) in high roughage diets.

Highlights

Ruminants are vital for human life because they provide nutritious food products by utilizing tons of crop byproducts and agricultural wastes
Vegetable oils rich in unsaturated fatty acids (C-18 fatty acids), have shown to shift rumen fermentation kinetics leading to reduced methanogenesis [4]
Studies have shown that the degree of unsaturation in long-chain fatty acids plays an essential regulatory role in rumen fermentation and volatile fatty acids (VFA) concentrations [13,16]. These findings revealed that supplementation of linoleic and linolenic acid mediates rumen fermentation to reduce the production of acetic acid while increasing propionic acid, which was beneficial for the rumen fermentation process and microbial growth while reducing H2 availability for methanogenesis

Summary

Introduction

Ruminants are vital for human life because they provide nutritious food products (milk and meat) by utilizing tons of crop byproducts and agricultural wastes. Nature has bestowed ruminants with a robust consortium of microbes that degrade highly cellulosic fibrous feedstuffs in the rumen to provide energy and essential nutrients to the host. Dietary supplementation with vegetable oils and fatty acids has been conceived as a promising strategy to reduce methane emanation from livestock owing to their potential to shift rumen biohydrogenation and toxic effects on protozoa and methanogens. Vegetable oils (like rapeseed, sunflower, linseed, and moringa) rich in unsaturated fatty acids (C-18 fatty acids), have shown to shift rumen fermentation kinetics leading to reduced methanogenesis [4]. Quantity and fatty acids composition of dietary fat determine the extent of inhibitory effect on rumen biohydrogenation and methanogenesis [5]

Objectives

Results

Discussion

Conclusion