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Dietary supplementation with linseed, saponins and nitrate is a promising methane mitigation strategy in ruminant production. The main objective of this work was to assess the effects of these additives on the rumen microbiota in order to understand underlying microbial mechanisms of methane abatement. Two 2 × 2 factorial design studies were conducted simultaneously, which also allowed us to make a broad-based assessment of microbial responses. Eight non-lactating cows were fed diets supplemented with linseed or saponin in order to decrease hydrogen production and nitrate to deviate hydrogen consumption; also, combinations of linseed plus nitrate or saponin plus nitrate were used to explore the interaction between dietary treatments. Amplicon sequencing of 18S and 16S rRNA genes was employed to characterise rumen microbes. Nitrate fed alone or in combination in both studies dramatically affected the composition and structure of rumen microbiota, though impacts were more evident in one of the studies. Linseed moderately modified bacterial community structure with no effect on rumen methanogens and protozoa. Indicator OTU analysis revealed that both linseed and nitrate reduced the relative abundance of hydrogen-producingRuminococcaceae. Linseed increased the proportion of bacteria known to reduce succinate to propionate, whereas nitrate supplementation increased nitrate-reducing bacteria and decreased the metabolic activity of rumen methanogens. Saponins had no effect on the microbiota. Inconsistency found between the two studies, when nitrate was fed to the cows could be explained by changes in microbial ecosystem functioning rather than changes in microbial community structure.ImportanceThis study aimed at identifying the microbial mechanisms of enteric methane mitigation when linseed, nitrate and saponins were fed to non-lactating cows alone or in a combination. Hydrogen is a limiting factor in rumen methanogenesis. We hypothesised that linseed and saponins would affect hydrogen producers and nitrate would deviate hydrogen consumption thus leading to reduced methane production in the rumen. Contrary to what was foreseen, both linseed and nitrate had a deleterious effect on hydrogen producers; linseed also redirected hydrogen consumption towards propionate production, whereas nitrate stimulated the growth of nitrate reducing and hence hydrogen-consuming bacterial taxa. Fundamental knowledge of microbial mechanism involved in rumen methanogenesis, provides novel insights for the development of new or the optimisation of existing methane mitigation strategies.

12 páginas, 3 tablas., Based on the potential benefits for long-term human health, nutritional strategies have been developed in order to increase the milk fat concentrations of bioactive fatty acids (FA) in ruminants. Dietary supplements of fish oil (FO), extruded linseed (EL) or a mixture of EL and FO increase c9,t11-CLA and n-3 PUFA in milk from bovine and caprine. These supplements associated with a high level of starch from concentrates cause milk fat depression in cows, but information for dairy goats is limited. An experiment was performed to investigate the effects of addition of extruded linseed to a diet containing fish oil in interaction with the type and level of starch concentrate on dairy goat performance and milk fatty acid (FA) profile. Following a 2 × 3 factorial design, 72 goats were allocated to 6 experimental diets based on alfalfa hay and with concentrates including fish oil (40 g/d) without or with extruded linseed (360 g/d) and either rich in starch from barley grain or extruded wheat or that were low in starch from barley grain. In contrast to cows, in goats adding extruded linseed to low-or high-starch diets based on hay and containing fish oil increases milk fat content and changes the milk FA composition in particular by increasing some bioactive FA with 18 carbons. In these conditions FA changes were characterized by decreases in SFA (on average 22% decrease) and increases in 18:0, c9-18:1, t11-18:1, c9,t11-CLA and 18:3n-3. The milk t10-18:1 concentration remained low (, P.G. Toral was granted a post-doctoral fellowship from Fundación Alfonso Martín Escudero (Madrid, Spain).

International audience; In ruminants, the ability to maintain milk fat melting point within physiological values could play a role in the regulation of milk fat secretion when milk fatty acid (FA) composition varies, such as in response to feeding factors. However, the relationship between milk fat fluidity and changes in milk FA composition is difficult to study experimentally. A meta-analysis was therefore conducted to compare the magnitude of diet-induced variations in milk FA composition and the calculated melting point of milk FA (used as a proxy to estimate the variations in the melting point of milk fat) in 3 dairy ruminant species (cow, goat, and sheep). The coefficient of variation (CV), a scale-free measure of statistical dispersion, was used to compare the variability of criteria differing in their order of magnitude. The analysis of a database of milk FA profiles from cows, goats, and sheep fed different dietary treatments (unsupplemented diets and diets supplemented with lipids rich in oleic acid, linoleic acid, linolenic acid, or C20-22 polyunsaturated FA) revealed that the variability of the calculated melting point of milk FA was narrow (CV of 5%) compared with the variability of milk FA percentages (CV of 18 to 72%). The regulation of the melting point of milk fat is thus probably involved in the control of diet-induced variations in milk fat secretion. The calculated melting point of ewe milk FA was approximately 3 C lower than that of goats or cows across all types of diets, which might be linked to differences in milk fat content (higher in sheep) or the structure of milk triacylglycerides among these species. Lipid supplementation increased the calculated melting point of C18 FA in milk, whereas that of total FA was significantly reduced by supplements rich in oleic, linoleic, and linolenic acids but not C20-22 polyunsaturated FA. However, the slight effects of dietary treat-ments on the calculated melting point of milk FA did not differ between cows, goats, and ewes.

International audience; IMPORTANCE Limited data exist on clinical characteristics and outcomes of patients who had infective endocarditis after undergoing transcatheter aortic valve replacement (TAVR). OBJECTIVE To determine the associated factors, clinical characteristics, and outcomes of patients who had infective endocarditis after TAVR. DESIGN, SETTING, AND PARTICIPANTS The Infectious Endocarditis after TAVR International Registry included patients with definite infective endocarditis after TAVR from 47 centers from Europe, North America, and South America between June 2005 and October 2015. EXPOSURE Transcatheter aortic valve replacement for incidence of infective endocarditis and infective endocarditis for in-hospital mortality. MAIN OUTCOMES AND MEASURES Infective endocarditis and in-hospital mortality after infective endocarditis. RESULTS A total of 250 cases of infective endocarditis occurred in 20 006 patients after TAVR (incidence, 1.1% per person-year; 95% Cl, 1.1%44%; median age, 80 years; 64% men). Median time from TAVR to infective endocarditis was 5.3 months (interquartile range [IQR], 1.5-13.4 months). The characteristics associated with higher risk of progressing to infective endocarditis after TAVR was younger age (78.9 years vs 81.8 years; hazard ratio [HR], 0.97 per year; 95% CI, 0.94-0.99), male sex (62.0% vs 49.7%; HR, 1.69; 95% C1,1.13-2.52), diabetes mellitus (41.7% vs 30.0%; HR, 1.52; 95% Cl, 1.02-2.29), and moderate to severe aortic regurgitation (22.4% vs 14.7%; HR, 2.05; 95% Cl, 1.28-3.28). Health care-associated infective endocarditis was present in 52.8% (95% Cl, 46.6%-59.0%) of patients. Enterococci species and Staphylococcus aureus were the most frequently isolated microorganisms (24.6%; 95% Cl, 19.1%-30.1% and 23.3%; 95% Cl, 17.9%-28.7%, respectively). The in-hospital mortality rate was 36% (95% Cl, 30.0%-41.9%; 90 deaths; 160 survivors), and surgery was performed in 14.8% (95% Cl, 10.4%-19.2%) of patients during the infective endocarditis episode. In-hospital mortality was associated with a higher logistic EuroSCORE (23.1% vs 18.6%; odds ratio [OR], 1.03 per 1% increase; 95% C1,1.00-1.05), heart failure (59.3% vs 23.7%; OR, 3.36; 95% Cl, 1.74-6.45), and acute kidney injury (67.4% vs 31.6%; OR, 2.70; 95% C1,1.42-5.11). The 2-year mortality rate was 66.7% (95% Cl, 59.0%-74.2%; 132 deaths; 115 survivors). CONCLUSIONS AND RELEVANCE Among patients undergoing TAVR, younger age, male sex, history of diabetes mellitus, and moderate to severe residual aortic regurgitation were significantly associated with an increased risk of infective endocarditis. Patients who developed endocarditis had high rates of in-hospital mortality and 2-year mortality.