AbstractCondensed tannins in plants are found free and attached to protein and fibre but it is not known whether these fractions influence rumen degradation and microbial colonization. This study explored the rumen degradation of tropical tannins-rich plants and the relationship between condensed tannins fractions’ disappearance and microbial communities colonising plant particles. Leaves from Calliandra calothyrsus, Gliricidia sepium, and Leucaena leucocephala, pods from Acacia nilotica and the leaves of two agricultural by-products: Manihot esculenta and Musa spp. were incubated in situ in the rumen of dairy cows. An in vitro approach was also used to assess the effects of these plants on rumen fermentation parameters. All plants contained more than 100 g/kg of condensed tannins with a large proportion (32 to 61%) bound to proteins. Calliandra calothyrsus had the highest concentration of condensed tannins at 361 g/kg, whereas Acacia nilotica was particularly rich in hydrolysable tannins (350 g/kg). Hydrolysable and free condensed tannins from all plants completely disappeared after 24 h incubation in the rumen. Disappearance of protein-bound condensed tannins was variable with values ranging from 93% for Gliricidia sepium to 21% for Acacia nilotica. In contrast, fibre-bound condensed tannins disappearance averaged ~82% and did not vary between plants. Disappearance of bound fractions of condensed tannins was not associated with degradability of plant fractions. The presence of tannins interfered with the microbial colonisation of plants. Each plant had distinct bacterial and archaeal communities after 3 and 12 h of incubation in the rumen and distinct protozoal communities at 3 h. Adherent communities in tannin-rich plants had a lower relative abundance of fibrolytic microbes, notably Fibrobacter spp. Whereas, archaea diversity was reduced in high tannin-containing Calliandra calothyrsus and Acacia nilotica at 12 h of incubation. Concurrently, in vitro methane production was lower for Calliandra calothyrsus, Acacia nilotica and Leucaena leucocephala although for the latter total volatile fatty acids production was not affected and was similar to control. Here we show that the total amount of hydrolysable and condensed tannins contained in a plant govern the interaction with rumen microbes affecting degradability and fermentation. The effect of protein- and fibre-bound condensed tannins on degradability is less important.

Urine is a highly suitable biological matrix for metabolomics studies. Total collection for 24-h periods is the gold standard as it ensures the presence of all metabolites excreted throughout the day. However, in animal studies, it presents limitations related to animal welfare and also due to alterations of the metabolome originating from the use of acid for preventing microbial growth or microbial contamination. In this study, we investigated whether spot urine collection is a practical alternative to total collection for metabolomic studies in lactating cows. For this purpose, we collected urine samples from 4 lactating Holstein cows fed 4 diets in a 4 × 4 Latin square design. Urine was collected for 24 h using a collecting device (i.e., total collection) or collected once per day 4 h after the morning feeding (i.e., spot urine collection). Dietary treatments differed by the amount of nitrogen content (high vs. low) and by the nature of the energy (starch vs. fiber). Urine metabolome was analyzed by 2 untargeted complementary methods, nuclear magnetic resonance and hydrophilic-interaction liquid chromatography (HILIC) coupled to a time-of-flight mass spectrometer, and by 1 targeted method, HILIC-tandem mass spectrometry. Although sampling technique had an effect on the abundance of metabolites detected, spot urine samples were equally capable of showing differences in urine metabolome than samples from total collection. When considering nitrogen levels in the diet, the robustness and precision for discriminating high- and low-nitrogen diets was equally achieved with both sampling techniques. A total of 22 discriminant metabolites associated with the N level of diets were identified from untargeted HILIC coupled to a time-of-flight mass spectrometer (n = 9) and nuclear magnetic resonance (n = 11), and 2 from targeted HILIC-tandem mass spectrometry. Alternatively, starch or fiber in the diet induced less changes in the metabolome that were not clearly discriminated independently of the sampling technique. We concluded that spot urine collection can successfully reveal differences in the urine metabolome elicited by dietary N levels and be used as a substitute of total urinary 24-h collection for metabolomic studies.

In Northern Senegal, traditional cattle management systems (TRAD) which depend on natural forages coexist with intensified systems (INT) which rely on periodic supplementation with crop residues and local concentrates. This study aims to estimate the effects of seasons and management systems on the methane emissions of Gobra zebu, in relation to the diet’s chemical composition and feed intake. Six Gobra zebu cows per management system were individually monitored over 10 months, diet and faeces were sampled each season and their chemical composition and dry matter intake (DMI) were predicted by near infrared spectroscopy. Each diet was fermented in vitro to assess methane production and volatile fatty acid concentration. The DMI and digestible organic matter intake (DOMI) decreased (P < 0.0001) during the dry seasons for both systems in the same range, but INT improved the crude protein of the diets (P < 0.0001). Enteric methane production (mmol.g−1 dry matter) was lower for TRAD than INT, except during the rainy season when TRAD cows experienced a higher increase (P = 0.002). The methanogenic potential (methane production in vitro × DMI) varied with the seasons and the system with more accentuated variations for TRAD (P < 0.0001). Methanogenic potential shows true reflection of the effects of the seasons and management systems. The results highlight that enteric methane emissions varied with seasonal changes and that intensifying the diet induced no mitigating effect.

Many studies have shown that metabolic efficiency of ruminants can be significantly decreased when B-vitamin supply is insufficient. Under the present state of knowledge, the amounts of B vitamins available for intestinal absorption cannot be predicted based on diet composition. Therefore, in an attempt to increase our understanding of the effects of dietary factors, on B-vitamin supply for dairy cows, the effects of increasing amounts of extruded linseed in diets based on hay (permanent grassland hay, H; Experiment 1) or corn silage (CS; Experiment 2) on apparent ruminal synthesis (ARS) of thiamin, riboflavin, niacin, vitamin B6, folates and vitamin B12 were evaluated. In each experiment, four lactating Holstein cows fitted with cannulas in the rumen and the proximal duodenum were used in a 4 × 4 Latin square design. In both experiments, the dietary treatments consisted of an increasing supply of extruded linseed representing 0%, 5%, 10% or 15% of diet DM. The forage : concentrate ratios were 50 : 50 and 60 : 40 for Experiments 1 and 2, respectively. Duodenal flow was determined using YbCl3 as a marker. The ARS of each B vitamin was calculated as duodenal flow – daily intake. In both experiments, treatments did not affect thiamin, riboflavin, niacin and vitamin B12 duodenal flow or ARS. Increasing the dietary concentration of extruded linseed decreased folate intake in Experiment 1 and vitamin B6 intake in Experiment 2 but resulted in a greater duodenal flow of vitamin B6 and folates regardless of the forage used in basal diet. Greater dietary linseed concentrations decreased vitamin B6 apparent degradation in the rumen in CS-based diet only and increased folate ARS in both H- and CS-based diets. Increasing linseed concentration of isonitrogenous and isoenergetic diets increased vitamin B6 and folate supply to dairy cows, both with H- and CS-based diets.

The present study was carried out to determine the effect of Acacia nilotica, a tropical plant rich in hydrolyzable tannins (HT), on rumen fermentation and methane (CH4) production in vitro. We used leaves and pods from A. nilotica alone and combined. The combination of HT from A. nilotica leaves and pods and condensed tannins (CT) from Calliandra calothyrsus and Leucaena leucocephala were also evaluated to assess potential differences in biological activity between HT and CT. Four series of 24-h incubations were performed using rumen contents of 4 sheep fed a tropical grass (natural grassland based on Dichanthium spp.). A first experiment tested different levels of replacement of this tropical forage (control [CTL] without tannins) by A. nilotica leaves or pods: 0:100, 25:75, 50:50, 75:25 and 100:0. A second experiment tested the mixture of A. nilotica leaves and pods in different proportions: 100:0, 75:25, 50:50, 25:75, and 0:100. A third experiment tested the 50:50 combination of A. nilotica leaves or pods with C. calothyrsus and L. leucocephala. Acacia nilotica pods and leaves had a high content of HT (350 and 178 g/kg DM, respectively), whereas C. calothyrsus and L. leucocephala had a high content of CT (361 and 180 g/kg DM, respectively). The inclusion of HT from A. nilotica leaves and pods decreased CH4 production dose-dependently (P < 0.01). Total replacement of the CTL by A. nilotica decreased CH4 production by 64 and 55% with leaves and pods, respectively. Pods were richer in HT than leaves, but their antimethanogenic effect did not differ (P > 0.05). Although A. nilotica leaves and pods inhibited fermentation, as indicated by the lower gas production and VFA production (P < 0.01), this effect was less pronounced than for CH4. Volatile fatty acid production decreased by 12% in leaves and by 30% in pods when compared with the CTL alone. Positive associative effect was reported for VFA, when HT-rich sources and CT-rich sources were mixed. Combining the 2 sources of HT did not show associative effects on fermentation or CH4 production (P > 0.05). Hydrolyzable tannin-rich sources were more effective in suppressing methanogenesis than CT-rich sources. Our results show that HT-rich A. nilotica leaves and pods have the potential to reduce ruminal CH4 production.

Among techniques for estimating enteric methane (CH4) emission by ruminants, open-circuit respiration chambers (OC), the use of a gas tracer (SF6), and the GreenFeed (GF) device are the most commonly used. In this study, we compared these techniques in 8 dry cows receiving a diet made of 70% hay and 30% concentrates given in limited and constant amounts, in a 15-wk experiment. Two periods in free stalls for SF6 and GF and in chambers for OC were used; in addition, SF6 was determined in chambers for 1 period. Methane emission (g/d) and CH4 yield (g/kg DMI) were higher (P < 0.0001) for OC than for SF6 and GF (367, 310, and 319 g/d for OC, SF6, and GF, respectively). The difference between OC and GF was related to a difference in post-prandial rate of gas emission. The between-animal coefficient of variation of CH4 emission was higher for SF6 than for OC and GF (20.8, 13.5, and 12.0% on average, respectively). Correlation coefficients between OC and SF6 were high and significant for CH4 emission and CH4 yield (r = 0.782 and r = 0.717, respectively; P < 0.05), but not significant between OC and GF, or between SF6 and GF. Correlation coefficients were highly significant for SF6 determined either in free stalls or in chambers (r = 0.908 and 0.903 for CH4 in g/d and g/kg DMI, respectively; P < 0.01). Carbon dioxide (CO2) emission and CO2 yield were similar for GF and OC (10,003 and 9,887 g/d, 752 and 746 g/kg DMI, respectively); CO2 data obtained with SF6 were lower (7,718 g/d and 606 g/kg DMI; P < 0.0001), but this technique is not relevant for CO2 emission determination. Correlation coefficients between OC and GF were not significant for CO2 emission and CO2 yield. This set of results shows that differences between methods are minor for average values, but that individual correlations may limit their interchangeability for determining gas emissions of individual animals. This study also shows the reliability of GF on-farm determination of CH4 and CO2 emissions for groups of animals.

The aim of the study was to compare the effect of fiber- or starch-rich diets based on grass silage, supplemented or not with bicarbonate, on CH4 emissions and milk fatty acid (FA) profile in dairy cows. The experiment was conducted as a 4 × 4 Latin square design with a 2 × 2 factorial arrangement: carbohydrate type [starch- or fiber-rich diets with dietary starch level of 23.1 and 5.9% on a dry matter basis, respectively], without or with bicarbonate addition [0 and 1% of the dry matter intake, respectively]. Four multiparous lactating Holstein cows were fed 4 diets with 42% grass silage, 8% hay, and 50% concentrate in 4 consecutive 4-wk periods: (1) starch-rich diet, (2) starch-rich diet with bicarbonate, (3) fiber-rich diet, and (4) fiber-rich diet with bicarbonate. Intake and milk production were measured daily and milk composition was measured weekly; CH4 emission and total-tract digestibility were measured simultaneously (5 d, wk 4) when animals were in open-circuit respiration chambers. Sensors continuously monitored rumen pH (3 d, wk 4), and fermentation parameters were analyzed from rumen fluid samples taken before feeding (1 d, wk 3). Cows fed starch-rich diets had less CH4 emissions (on average, -18% in g/d; -15% in g/kg of dry matter intake; -19% in g/kg of milk) compared with fiber-rich diets. Carbohydrate type did not affect digestion of nutrients, except starch, which increased with starch-rich diets. The decrease in rumen protozoa number (-36%) and the shift in rumen fermentation toward propionate at the expense of butyrate for cows fed the starch-rich diets may be the main factor in reducing CH4 emissions. Milk of cows fed starch-rich diets had lower concentrations in trans-11 C18:1, sum of cis-C18, cis-9,trans-11 conjugated linoleic acid (CLA), and sum of CLA, along with greater concentration of some minor isomers of CLA and saturated FA in comparison to the fiber-rich diet. Bicarbonate addition did not influence CH4 emissions or nutrient digestibility regardless of the carbohydrate type in the diet. Rumen pH increased with bicarbonate addition, whereas other rumen parameters and milk FA composition were almost comparable between diets. Feeding dairy cows a starch-rich diet based on grass silage helps to limit the negative environmental effect of ruminants, but does not lead to greater milk nutritional value because milk saturated FA content is increased.

L’ambition de cet article est de dresser un bilan environnemental de l’élevage de bovins pour la viande en France, aussi exhaustif que possible, à partir des données scientifiques et statistiques disponibles. Les impacts environnementaux abordés sont les émissions de gaz à effet de serre, la pollution de l’eau et des sols, l’utilisation des ressources naturelles (énergie, phosphore, eau), l’utilisation des terres et la biodiversité végétale et animale. Les méthodologies d’évaluation et les indicateurs utilisés sont justifiés et discutés. Lorsque l’unité d’expression est le kg de viande, l’essentiel des impacts environnementaux provient de l’atelier naisseur en raison de la longue phase d’élevage pour obtenir un broutard. Les résultats sont très différents lorsque les impacts sont calculés par unité de surface, que le stockage de carbone dans les prairies est pris en compte et que les impacts positifs de ces systèmes sur la biodiversité et sur le paysage sont intégrés à l’analyse. Bien qu’ayant des atouts pour aborder la transition agroécologique du fait de la part importante de prairies permanentes leur permettant de tirer avantage des régulations biologiques, les systèmes naisseurs sont cependant engagés depuis 20 ans dans un processus d’agrandissement au détriment de leur durabilité.

This experiment was designed to better understand the differences in enteric methane (CH4) emissions of ruminants in tropical and temperate areas. Two double 4 x 4 Latin squares using adult sheep were evaluated simultaneously in a temperate and a tropical site. At each site, two breeds (four Texel, temperate origin, and four Blackbelly, tropical origin) and four hay types (two C3 grasses and two C4 grasses grown, respectively, in temperate and tropical sites) were tested. High-(H) and low-quality (L) grass hays were tested within each type of grass. No difference in thy matter (DM) intake (g/kg BW/d) was observed between sites. Intake of C4 grass was lower than that of C3 grass. A breed x site interaction was observed. In the tropical site, dry matter intake (g/kg BW/d) was higher in Blackbelly compared to Texel, whereas no difference was observed in the temperate site. The total-tract DM, OM (organic matter), NDF (neutral detergent fiber) and ADF (acid detergent fiber) digestibility values recorded in the temperate site were lower (P < 0.01) than those reported in the tropical site. Methane yield (g/kg DM intake) was not affected by site, whereas a breed x site interaction was observed. In the tropical site, methane emission was lower for Blackbelly compared to Texel, whereas the opposite was observed in the temperate site. Differences in methane emissions between the temperate and tropical sites could only be the result of diet and breed interactions with the environment. (C) 2018 Elsevier Ltd. All rights reserved.

Livestock is the main source of methane (CH4) emissions. It is important to accurately determine emissions from ruminants that meet standardized international guidelines for national greenhouse gas inventories. A new method to improve the accuracy of CH4 emissions that complies with IPCC rules for a Tier 3 method is described and evaluated. This method, developed by INRA (French Institute for Agricultural Research), was applied to the French inventory of CH4 emissions by ruminants and compared with the IPCC Tier 2 method. For enteric CH4, depending on the animal category, the INRA CH4 emission estimates lay between 88% and 114% of IPCC's. The INRA/IPCC ratio for enteric emission was close to unity and did not differ between methods (P = 0.43) for adult cows (i.e. most cattle). In France, feedlot manure is stored in aerobic conditions, and so the INRA/IPCC fit for manure emission was poorer (P < 0.05). The INRA/IPCC fit for enteric CH4 was very close between methods to that for total CH4 (P = 0.39), enteric CH4 representing 93% of total emissions. The main improvement is the use of a robust equation (from numerous data and diets), based on digestible organic matter intake (DOMI) corrected for the digestive interactions, to predict CH4 consistently from enteric and manure sources. It was developed for the French livestock inventory but is customizable for other countries. This new improved CH4 estimation method, based on equations from a large literature database, complies with IPCC rules for a Tier 3 method.

Modulating the assembly of the ruminal microbiota might have practical implications in production. We tested how an early-life dietary intervention in lambs influences the diversity and function of the ruminal microbiota during and after the intervention. Microbiota resilience during a repeated dietary intervention was also tested. The treatment, aiming to mitigate enteric methane emissions, combined garlic essential oil and linseed oil. Fifty-six lambs and their dams were allocated to two groups and treatment (T1) or placebo (C1) was drenched from birth until 10 weeks of life. Lambs were weaned at 8 weeks. From 16 to 20 weeks, lambs in each group were divided in two subgroups that received (T1-T2 and C1-T2) or not (T1-C2 and C1-C2) the same treatment. Measurements were done at 8, 14, and 20 weeks. Average daily gain was similar between groups. Methane production was reduced by treatment at 8 and 20 weeks but at 14 weeks it was similar between C1 and T1. Interestingly, early-life treated lambs displayed a numerical increase (P = 0.12) in methane emissions at 20 weeks compared with non-treated lambs. Concentration of VFA was not affected by the intervention at 8 or 14 weeks but a lower concentration was observed in T2 lambs compared with C2 at week 20. Metataxonomics (rRNA gene) revealed differences in archaeal communities between groups of lambs when treatment was applied (weeks 8 and 20); whereas, in accord with methane emissions, these differences disappeared when treatment was discontinued (week 14). Protozoal community structure was not affected by treatment. In contrast, bacterial community structure differed between treated and non-treated lambs during and after the intervention. Rumen and urine LC-MS and NMR metabolomics at week 20 separated C2 from T2 lambs and correlation analysis highlighted interactions between microbes and metabolites, notably that of methylated compounds and Methanomassiliicocceae methanogens. This study demonstrates that a long-term early-life intervention induced modifications in the composition of the rumen bacterial community that persisted after the intervention ceased with little or no effect on archaeal and protozoal communities. However, there was no persistency of the early-life intervention on methanogenesis indicating resilience for this function.

Optimizing milk production efficiency implies diets allowing low methane (CH4) emissions and high dairy performance. We hypothesize that nature of energy (starch v. lipids) and lipid supplement types (monounsaturated fatty acid (MUFA) v. polyunsaturated fatty acid (PUFA) mitigate CH4 emissions and can induce low milk fat content via different pathways. The main objective of this experiment was to study the effects of starch-rich or lipid-supplemented diets that induce milk fat depression (MFD) on rumen biohydrogenation (RBH) of unsaturated fatty acids (FA) and enteric CH4 emissions in dairy cows. Four multiparous lactating Holstein cows (days in milk=61±11 days) were used in a 4×4 Latin square design with four periods of 28 days. Four dietary treatments, three of which are likely to induce MFD, were based (dry matter basis) on 56% maize silage, 4% hay and 40% concentrates rich in: (1) saturated fatty acid (SFA) from Ca salts of palm oil (PALM); (2) starch from maize grain and wheat (MFD-Starch); (3) MUFA (cis-9 C18:1) from extruded rapeseeds (MFD-RS); and (4) PUFA (C18:2n-6) from extruded sunflower seeds (MFD-SF). Intake and milk production were measured daily. Milk composition and FA profile, CH4 emissions and total-tract digestibility were measured simultaneously when animals were in open-circuit respiration chambers. Fermentation parameters were analysed from rumen fluid samples taken before feeding. Dry matter intake, milk production, fat and protein contents, and CH4 emissions were similar among the four diets. We observed a higher milk SFA concentration with PALM and MFD-Starch, and lower milk MUFA and trans-10 C18:1 concentrations in comparison to MFD-RS and MFD-SF diets, while trans-11 C18:1 remained unchanged among diets. Milk total trans FA concentration was greater for MFD-SF than for PALM and MFD-Starch, with the value for MFD-RS being intermediate. Milk C18:3n-3 content was higher for MFD-RS than MFD-SF. The MFD seems more severe with MFD-SF and MFD-RS than PALM and MFD-Starch diets, because of a decrease in milk SFA concentration and a stronger shift from trans-11 C18:1 to trans-10 C18:1 in milk. The MFD-SF diet increased milk trans FA (+60%), trans-10 C18:1 (+31%), trans-10,cis-12 CLA (+27%) and PUFA (+36%) concentrations more than MFD-RS, which explains the numerically lowest milk fat yield and indicates that RBH pathways of PUFA differ between these two diets. Maize silage-based diets rich in starch or different unsaturated FA induced MFD with changes in milk FA profiles, but did not modify CH4 emissions.

The combination of linseed and nitrate is known to decrease enteric methane emission in dairy cows but few studies have been carried out in fattening cattle for animal liveweight gain, enteric methane emission, animal health and presence of residues in beef products. To address this gap, 16 young bulls received a control (C) diet between weaning at 9 months and 14 months, then were split into two groups of eight balanced on feed intake, BW gain and methane emission to receive either the C diet or a diet moderately supplemented with extruded linseed and calcium nitrate (LN) for 2 months before being slaughtered. On a dry matter (DM) basis, the C diet contained 70% baled grass silage and 30% concentrate mainly made of maize, wheat and rapeseed meal. In the LN diet, rapeseed meal and a fraction of cereals were replaced by 35% extruded linseed and 6% calcium nitrate; linseed fatty acids and nitrate supply in the LN diet were 1.9% and 1.0%, respectively. Methane emission was measured continuously using the GreenFeed system. Methaemoglobin was determined every week in peripheral blood from bulls receiving the LN diet. Nitrate and nitrite concentrations were determined in rumen, liver and tongue sampled at slaughter. Dry matter intake tended to be lower for LN diet (P = 0.10). Body weight gain was lower for LN diet (P = 0.01; 1.60 and 1.26 kg/day for C and LN diet, respectively). Daily methane emission was 9% lower (P < 0.001) for LN than C diet (249 and 271 g/day, respectively) but methane yield did not differ between diets (24.1 and 23.2 g/kg DM intake for C and LN diet, respectively, P = 0.34). Methaemoglobin was under the limit of detection (<2% of total haemoglobin) for most animals and was always lower than 5.6%, suggesting an absence of risk to animal health. Nitrite and nitrate concentrations in offal did not differ between C and LN diets. In conclusion, a moderate supply of linseed and nitrate in bull feed failed to decrease enteric methane yield and impaired bull liveweight gain but without adverse effects for animal health and food safety.

Nutritional policies recommend that animal products should be made to contain more polyunsaturated FA, especially n-3 FA. This means finding ways to limit ruminal lipolysis and/or biohydrogenation. In pursuit of this goal, we performed an in vitro study to test the ability of four feed additives, typically used for other purposes, to reduce ruminal biohydrogenation of a linolenic acid-rich substrate. The four additives tested were cinnamon essential oil, brown algae (Ascophyllum nodosum), synthetic vitamin E, and garlic essential oil. The first three additives had no effect on ruminal fermentation and biohydrogenation. Garlic essential oil led to a decrease in methane production (P<0.001), an increase in propionate (P = 0.002) and butyrate (P<0.001) production at the expense of acetate (P<0.001), and a decrease in biohydrogenation evaluated by the disappearance of linolenic acid (P = 0.083) and linoleic acid (P = 0.008). Stearic acid proportion in FA decreased, while biohydrogenation intermediates such as C18:2t11c15 and vaccenic acid proportion increased (P<0.001).Practical applications: Garlic essential oil emerges as a promising additive for decreasing biohydrogenation, but its efficiency needs to be confirmed in vivo in different dietary conditions, and possible side effects of the incorporation of garlic oil in diets will have to be evaluated.

Microorganisms in the digestive tract of ruminants differ in their functionality and ability to use feed constituents. While cecal microbiota play an important role in post-rumen fermentation of residual substrates undigested in the rumen, limited knowledge exists regarding its structure and function. In this trial we investigated the effect of dietary supplementation with linseed oil and nitrate on methane emissions and on the structure of ruminal and cecal microbiota of growing bulls. Animals were allocated to either a CTL (control) or LINNIT (CTL supplemented with 1.9% linseed and 1.0% nitrates) diet. Methane emissions were measured using the GreenFeed system. Microbial diversity was assessed using amplicon sequencing of microbial genomic DNA. Additionally, total RNA was extracted from ruminal contents and functional mcrA and mtt genes were targeted in amplicon sequencing approach to explore the diversity of functional gene expression in methanogens. LINNIT had no effect on methane yield (g/kg DMI) even though it decreased methane production by 9% (g/day; P < 0.05). Methanobrevibacter- and Methanomassiliicoccaceae-related OTUs were more abundant in cecum (72 and 24%) compared to rumen (60 and 11%) irrespective of the diet (P < 0.05). Feeding LINNIT reduced the relative abundance of Methanomassiliicoccaceae mcrA cDNA reads in the rumen. Principal component analysis revealed significant differences in taxonomic composition and abundance of bacterial communities between rumen and cecum. Treatment decreased the relative abundance of a few Ruminococcaceae genera, without affecting global bacterial community structure. Our research confirms a high level of heterogeneity in species composition of microbial consortia in the main gastrointestinal compartments where feed is fermented in ruminants. There was a parallel between the lack of effect of LINNIT on ruminal and cecal microbial community structure and functions on one side and methane emission changes on the other. These results suggest that the sequencing strategy used here to study microbial diversity and function accurately reflected the absence of effect on methane phenotypes in bulls treated with linseed plus nitrate.

The agriculture, forestry and other land use sector are responsible for 24% (10-12 Pg CO(2)e per year) of anthropogenic greenhouse gas (GHG) emissions worldwide, with concomitant opportunities for mitigation. A scientific panel used deliberative methods to identify ten technical measures comprising 26 sub-measures to reduce GHG emissions from agriculture in France. Their abatement potential and cost are compared. The proposed measures concern nitrogen (N) management, management practices that increase carbon stocks in soils and biomass, livestock diets, and energy production and consumption on farms. Results show that the total abatement potential can be divided into three parts. One third of the cumulated abatement potential corresponds to sub-measures that can be implemented at a negative technical cost. These sub-measures focus on increased efficiency in input use including N fertilisers, animal feed and energy. The second third are sub-measures with moderate cost (< (sic)25 per metric Mg of avoided CO(2)e). These sub-measures require specific investments or changes to cropping systems, but additional costs or lower incomes are partially compensated for by a reduction in other costs or by the production of other marketable products. The remaining third are high-cost sub-measures (> (sic)25 per metric Mg of avoided CO(2)e). These require investment with no direct financial return, the purchase of particular inputs, dedicated labour time or involve production losses. Assuming additivity, the cumulated abatement is 32.3 Tg CO(2)e per year in 2030, but only 10 Tg (i.e. 10% of current agricultural emissions) when calculated under current inventory rules. This study confirms that a significant abatement potential exists in the agricultural sector, with two thirds of this potential at low or even negative cost. This is likely to be an underestimated as it is based on a status quo of the current agricultural system. Results also emphasise the need to upgrade inventory rules so that efforts to reduce emissions can be accounted for.

In this paper, we used erroneous values for the molecular weight of thiamin and vitamers of vitamin B6. This error had limited effects on the overall results or statistical significance; however, several values reported in text and in tables are incorrect. The error affected statements in the Thiamin (page 2735) and Vitamin B6 (page 2737) subsections of the Results and Discussion, as well as values of thiamin and vitamin B6 reported in Table 1 (page 2732), Table 2 (page 2735), and Table 3 (page 2735), and correlation coefficients for ARS of vitamin B6 in Table 4 (page 2736). A revised version of this paper containing the corrections noted above has been published as supplementary data (see file below). The authors regret the errors. Supplementary Data: Corrected Article View File. Download .pdf (.32 MB) Help with pdf files Effects of dietary nitrogen levels and carbohydrate sources on apparent ruminal synthesis of some B vitamins in dairy cowsJournal of Dairy ScienceVol. 99Issue 4PreviewEffects of nitrogen level and carbohydrate source on apparent ruminal synthesis (ARS) of thiamin, riboflavin, niacin, vitamin B6, folates, and vitamin B12 were evaluated using 4 lactating Holstein cows distributed in a 4 × 4 Latin square design with treatments following a 2 × 2 factorial arrangement. Cows were fitted with cannulas in the rumen and proximal duodenum. The treatments were 2 N levels and 2 carbohydrate sources. The diet with the high N level provided 14% crude protein, calculated to meet 110% of the protein requirements and an adequate supply in rumen-degradable protein, whereas the diet with the low N level contained 11% crude protein, calculated to meet 80% of the protein requirements with a shortage in rumen-degradable protein. Full-Text PDF Open Archive