Effect of Whole or Ground Flaxseed Supplementation on Fatty Acid Profile, Fermentation, and Bacterial Composition in Rumen of Dairy Cows.

Guoxin Huang,Jiaqi Wang,Nan Zheng,Wenhao Tang,Xiaofeng Chang,Yangdong Zhang,Liya Guo,Kaizhen Liu,Shengguo Zhao

doi:10.3389/fmicb.2021.760528

Abstract

Flaxseed is rich in α-linolenic acid (ALA) and can increase omega-3 polyunsaturated fatty acid in the milk of dairy cows. However, the response of rumen fermentation to different forms of flaxseed supplementation is unknown. This study aimed to investigate the effect of different forms of flaxseed on the fatty acid profile, fermentation, and composition of bacteria in the rumen of dairy cows. In total, 30 Holstein dairy cows were selected and randomly assigned into three groups (10/group). Cows were fed a basal diet (control check; CK) or basal diets supplemented with either 1,500 g per day whole flaxseed (WF) or 1,500 g per day ground flaxseed (GF). The WF group had the highest ALA content in rumen fluid, whereas no difference was found between the CK and GF groups. However, the molar proportion of acetate increased in the WF and GF groups and was the highest in the GF group, and a similar trend was shown by propionate, isobutyrate, butyrate, isovalerate, and valerate (CK < WF < GF). The abundance of Ruminococcaceae_NK4A214_group, Christensenellaceae_R-7_group, and Eubacterium_coprostanoligenes_group also showed the same trend (CK < WF < GF). Different forms of flaxseed release ALA by different mechanisms in the rumen, and the molar proportions of volatile fatty acids and the bacterial composition were potentially influenced mainly by the amount of ALA released into the rumen.

Highlights

As a source of omega-3 polyunsaturated fatty acid (n-3 PUFA), flaxseed is widely used to enhance levels of n-3 PUFA in milk production (Meignan et al, 2017; Brzozowska et al, 2018; Marino et al, 2019), α-linolenic acid (ALA; c9,c12,c15-C18:3)
This study aimed to investigate the effect of whole flaxseed (WF) or ground flaxseed (GF) supplementation on rumen formation and bacterial community
Cows were randomly assigned into three groups and provided with a basal diet or the basal diet supplemented with 1,500 g per day WF or 1,500 g per day GF, as shown in Table 1

Summary

Introduction

As a source of omega-3 polyunsaturated fatty acid (n-3 PUFA), flaxseed is widely used to enhance levels of n-3 PUFA in milk production (Meignan et al, 2017; Brzozowska et al, 2018; Marino et al, 2019), α-linolenic acid (ALA; c9,c12,c15-C18:3). Flaxseed is rich in ALA, 18% of the total seed, and 53 to 56% of total fatty acids (Mustafa et al, 2002; Petit, 2003). Previous studies reported that GF supplementation had a higher efficiency in increasing n-3 PUFA (mainly ALA) in milk. The n-3 PUFA (mainly ALA) in WF cannot be released as completely as GF because of the flaxseed shell. To release ALA from WF, cows need to crush the flaxseed by tooth. In the rumen of ruminants, ALA in WF takes longer to be released. ALA in GF could be released into the rumen in a shorter time. Compared to a short and rapid release, a long release may lead to the continuous biological hydrogenation of ALA in the rumen. The efficiency of transporting the ALA into milk is lower

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