94 research outputs found
Ruminal bacterial community change in response to diet-induced variation of ruminal trans-10 fatty acids
Trans fatty acids (FA) are produced during the biohydrogenation of linoleic acid in the rumen. Because of their healthâpromoting properties, transâ11
isomers, which are usually the most abundant biohydrogenation intermediates, are most desirable (1). However, in high yielding dairy cows, when high
concentrate diets containing fat are fed to cows, a shift from transâ11 to transâ10 FA can occur, therefore, transâ10 isomers can become the
predominant biohydrogenation intermediates, inducing milk fat depression in dairy cows(2) and having possible detrimental effects on human health(3).
The aim of this work was to study the bacterial community dynamics in response to dietâinduced transâ10 FA shift
Effect of cow diet on the ruminal microflora and its in vitro fatty acid production
The objective of this study was to investigate the effects of donorâs cow diet (hay or maize silage plus concentrates) on ruminal bacteria count, flora diversity and fatty acids profile (FA) of ruminal fluid and in vitro biohydrogenation (BH) of C18:2.
Two dry cows fitted with a ruminal canula were used in a 2x2 design. Each period included three weeks of diet adaptation and two weeks of sampling. The cows were fed twice daily either a diet (H) composed of grass (38%) and alfalfa hay (62%) or an acidogenic diet (A) composed of maize silage (38%), wheat (57%) and soybean (5%) meal. Ruminal fluid was sampled and centrifugated (150g, 5min., 39°C). The ruminal fluid (80mL) was mixed with 80mL of buffer, a fermentative substrate and grape seed oil as source of C18:2 before being incubated during 6 hours at 39°C in anaerobic and dark conditions. Biodiversity was estimated by the Simpson index modified by Haegeman et al.1 after SSCP analysis, and FA were analysed by GLC. Bacteria counting was realised according to Oblinger and Koburger2 (1975).
Total and cellulolytic bacteria contents were higher in inoculum A than in inoculum H (9.3.109 vs. 2.4.108/mL for total bacteria and 2.4.108 vs. 1.6.107/mL for cellulolytic bacteria). No difference in the biodiversity of the inoculums was noticed according to the cow or the diet, but diversity during period 1 tended to differ (P=0.09) from period 2, suggesting a time variation of flora biodiversity. Before incubation, the ruminal fluid from the cow receiving diet A contained significantly (P<0.01) more C18:2, trans-10 and trans-11 C18:1, and odd-chain FA than inoculum from the cow receiving diet H.
After incubation, inoculum A resulted in a significantly (P<0.01) greater BH of C18:2 than inoculum H, and produced more trans-10C18:1, trans-11C18:1 and odd-chain FA (P<0.01)
Trans-10 and odd-chain FA are known to be increased by a high concentrate diet, which explains that inoculum A was richer in these FA than inoculum H. The ruminal flora selected in vivo by diet A continued the production of these FA in vitro. The greater content of trans-11C18:1 and of C18:2 in the inoculum A could be explained by the greater content in C18:2 of the diet A. During incubation with added C18:2, inoculum A continued to produce more trans-11 along with a higher C18:2 BH than inoculum H, which could be due to the higher concentration of cellulolytic bacteria in the inoculum A
Temperature and duration of heating of sunflower oil affect ruminal biohydrogenation of linoleic acid in vitro
Sunflower oil heated at 110 or 150°C for 1, 3, or 6 h was incubated with ruminal content in order to investigate the effects of temperature and duration of heating of oil on the ruminal biohydrogenation of linoleic acid in vitro. When increased, these 2 parameters acted together to decrease the disappearance of linoleic acid in the media by inhibiting the isomerization of linoleic acid, which led to a decrease in conjugated linoleic acids and trans-C18:1 production. Nevertheless, trans-10 isomer production increased with heating temperature, suggesting an activation of Î9-isomerization, whereas trans-11 isomer production decreased, traducing an inhibition of Î12-isomerization. The amount of peroxides generated during heating was correlated with the proportions of biohydrogenation intermediates so that they might explain, at least in part, the observed effects. The effects of heating temperature and duration on ruminal bacteria community was assessed using capillary electrophoresis single-strand conformation polymorphism. Ruminal bacterial population significantly differed according to heating temperature, but was not affected by heating duration. Heating of fat affected ruminal biohydrogenation, at least in part because of oxidative products generated during heating, by altering enzymatic reactions and bacterial population
Random changes in the heifer rumen in bacterial community structure,physico-chemical and fermentation parameters, and in vitro fiber degradation
The variability over time of several main ruminal characteristics was studied in heifers over 15 consecutive weeks. Three heifers were assigned to a low-fiber diet (27% NDF) and three to a high-fiber diet (44% NDF). The physico-chemical (pH and redox potential) and fermentation(volatile fatty acids and ammonia contents) parameters were determined on 1 day per week for 15 consecutive weeks. On the same days the bacterial community structure was studied using a molecular fingerprint technique and the ruminal fiber degradation was studied by in vitro incubation of a withdrawn ruminal content sample. Numerous random changes were observed from week to week for all physico-chemical and fermentative parameters and in vitro fiber degradation. The redox potential was the only parameter to show a significant interaction between diet and week. Except for the ammonia content, the amplitudes of fluctuations observed were higher for the low-fiber diet. The bacterial community structure did not differ between diets or weeks. The in vitro fiber degradation was similar for both diets, with numerous random changes throughout the study. The findings of this study indicated that most of the parameters of the ruminal ecosystem had time-related changes with random fluctuations around a mean value which reflect an unstable equilibrium. This conclusion was
valid for both low- and high-fiber diets
Etude par pyrosĂ©quençage haut dĂ©bit (454) de lâimplantation des bactĂ©ries au niveau du rumen du veau laitier, de sa naissance au sevrage
Objectif : Décrire la séquence temporelle d'implantation de la
population bactérienne au niveau du rumen chez le
veau, de la naissance jusqu'au sevrage, via des
outils de microbiologie moléculaire
From high throughput 454 GS FLX data analysis process of 16S RNA gene sequences using barcoding to bacterial community exploration
From high throughput 454 GS FLX data analysis process of 16S RNA gene sequences using barcoding to bacterial community exploratio
The ruminal level of trans-10 fatty acids of dairy cows is linked to the composition of bacterial community
The ruminal level of trans-10 fatty acids of dairy cows is linked to the composition of bacterial communit
Mesure in vitro de l'activité de la communauté bactérienne ruminale
Les techniques modernes de biologie molĂ©culaire permettent une description de la micropopulation ruminale. LâĂ©tude de lâactivitĂ© de cette population sur les principaux constituants de la ration est souvent rĂ©alisĂ©e in vitro. Lâobjectif de cette Ă©tude Ă©tait de vĂ©rifier si la population bactĂ©rienne est active mais nâĂ©volue pas pendant une courte incubation in vitro, ce qui permettrait de mettre en relation le profil et lâactivitĂ© des bactĂ©ries.
La communautĂ© bactĂ©rienne mise Ă incuber in vitro nâa pas Ă©voluĂ©, ni en quantitĂ©, ni en structure ou en diversitĂ©, ce qui suggĂšre que les conditions de culture nâentraĂźnent pas une sĂ©lection de certaines espĂšces au cours des 6 premiĂšres heures. Cette communautĂ© est restĂ©e active, puisque capable de dĂ©grader les diffĂ©rents substrats : matiĂšres azotĂ©es, glucides et lipides. Une mesure in vitro de lâactivitĂ© microbienne est donc possible, et pourrait sâavĂ©rer intĂ©ressante Ă associer aux techniques de biologie molĂ©culaire afin de mieux caractĂ©riser la communautĂ© bactĂ©rienne dâun prĂ©lĂšvement
Integrating data from spontaneous and induced trans-10 shift of ruminal biohydrogenation reveals discriminant bacterial community changes at the OTU level
IntroductionMicrobial digestion is of key importance for ruminants, and disturbances can affect efficiency and quality of products for human consumers. Ruminal biohydrogenation of dietary unsaturated fatty acids leads to a wide variety of specific fatty acids. Some dietary conditions can affect the pathways of this transformation, leading to trans-10 fatty acids rather than the more usual trans-11 fatty acids, this change resulting in milk fat depression in dairy cows.Materials and methodsWe combined data from an induced and spontaneous trans-10 shift of ruminal biohydrogenation, providing new insight on bacterial changes at different taxonomic levels. A trans-10 shift was induced using dietary addition of concentrate and/or unsaturated fat, and the spontaneous milk fat depression was observed in a commercial dairy herd.Results and discussionMost changes of microbial community related to bacteria that are not known to be involved in the biohydrogenation process, suggesting that the trans-10 shift may represent the biochemical marker of a wide change of bacterial community. At OTU level, sparse discriminant analysis revealed strong associations between this change of biohydrogenation pathway and some taxa, especially three taxa belonging to [Eubacterium] coprostanoligenes group, Muribaculaceae and Lachnospiraceae NK3A20 group, that could both be microbial markers of this disturbance and candidates for studies relative to their ability to produce trans-10 fatty acids
Statistics of the French purse seine fishing fleet targeting tropical tunas in the Atlantic Ocean (1991-2013)
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