Evaluation of the effects of different diets on microbiome diversity and fatty acid composition of rumen liquor in dairy goat

Abstract

Fat supplementation plays an important role in defining milk fatty acids (FA) composition of ruminant products. The use of sources rich in linoleic and α-linolenic acid favors the accumulation of conjugated linoleic acids isomers, increasing the healthy properties of milk. Ruminal microbiota plays a pivotal role in defining milk FA composition, and its profile is affected by diet composition. The aim of this study was to investigate the responses of rumen FA production and microbial structure to hemp or linseed supplementation in diets of dairy goats. Ruminal microbiota composition was determined by 16S amplicon sequencing, whereas FA composition was obtained by gas-chromatography technique. In all, 18 pluriparous Alpine goats fed the same pre-treatment diet for 40±7 days were, then, arranged to three dietary treatments consisting of control, linseed and hemp seeds supplemented diets. Independently from sampling time and diets, bacterial community of ruminal fluid was dominated by Bacteroidetes (about 61.2%) and Firmicutes (24.2%) with a high abundance of Prevotellaceae (41.0%) and Veillonellaceae (9.4%) and a low presence of Ruminococcaceae (5.0%) and Lachnospiraceae (4.3%). Linseed supplementation affected ruminal bacteria population, with a significant reduction of biodiversity; in particular, relative abundance of Prevotella was reduced (-12.0%), whereas that of Succinivibrio and Fibrobacter was increased (+50.0% and +75.0%, respectively). No statistically significant differences were found among the average relative abundance of archaeal genera between each dietary group. Moreover, the addition of linseed and hemp seed induced significant changes in FA concentration in the rumen, as a consequence of shift from C18 : 2n-6 to C18 : 3n-3 biohydrogenation pathway. Furthermore, dimethylacetal composition was affected by fat supplementation, as consequence of ruminal bacteria population modification. Finally, the association study between the rumen FA profile and the bacterial microbiome revealed that Fibrobacteriaceae is the bacterial family showing the highest and significant correlation with FA involved in the biohydrogenation pathway of C18 : 3n-3.

Metagenomic profiles of the rumen microbiota during the transition period in low‐yield and high‐yield dairy cows

“…B. hungatei is able to ferment glucose to formate, acetate, and butyrate and to biohydrogenate unsaturated fatty acids for the production of butyrate (Cremonesi et al, ; Kopečný et al, ). In this study, M. elsdenii was highly associated with butyrate production in the HY group.…”

NMR Lipid Profile of Milk from Alpine Goats with Supplemented Hempseed and Linseed Diets

“…Goat milk samples were collected under the experimental design reported [13]. Briefly, in the period from February to September, 18 selected Alpine goats were divided into three groups and randomly assigned to three different dietary treatments (diets in Table S1) identified as follows: (1) control diet (group C), (2) diet supplemented with linseed (group L), and (3) diet supplemented with hempseed (group H).…”

“…1D 13 C-NMR experiments were acquired on a Bruker 400 MHz spectrometer with a spectral width of 36 KHz, a relaxation delay of 16 s, and 90 • pulse of 11.0 µs at −5.0 dB. The spectra were then referenced to the residual solvent signal at 77.1 ppm.…”

“…Recent studies established that the introduction of flaxseed in an animal's diet positively impacted the n-3 FA content of milk from cows, [4][5][6], goats [7][8][9][10], and sheep [11,12]. In contrast to linseed, hempseed supplementation offers a well-balanced linoleic acid/linolenic acid ratio of about 3:1 and contains both stearidonic acid (C18:4 n-3) and γ-linolenic acid (C18:3 n-6) [13]. The supplementation of ruminants' diet with hempseed and hempseed oil has been tested and a higher milk fat content with larger proportions of linoleic acid, rumenic acid (C18:2 cis-9, trans-11), and linolenic acid were observed in both sheep [14] and goats [15].…”

An overview on the use of hemp (Cannabis sativa L.) in animal nutrition

“…Besides, feeding ewes with HSC is more prone to increasing concentration of CLA and vaccenic acid (VA) in milk compared to HS diets. The efficiency of the fatty acid transfer from diet to milk depends on several factors, including nature of the fat supplementation and the interaction between fat source and rumen microbes, when fatty acids are converted in C18:0 by lipolysis and biohydrogenation process (Cremonesi et al, 2018).…”