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International audience; Decreasing enteric CH4 emissions is important in mitigating the environmental impact of livestock farming. The present meta-analysis examined effects of nutritional mitigation practices on absolute CH4 emissions (g/animal/d) and CH4 yield [g CH4/kg dry matter intake (DMI)] as well as on DMI (kg/d), average daily gain (kg/d), milk production (kg/d), and neutral detergent fiber digestibility (%). The database for this analysis consisted of over 400 studies. Only studies that reported statistical variance were included in the analysis (295 studies and 644 treatment mean comparisons). A standard random-effects meta-analysis weighted by inverse variance was carried out. The effects of the standardized mean difference (SMD) were classified as small (≤-0.2 and >-0.5), medium (≤-0.5 and >-0.8), and large (≤-0.8). Of the analyzed treatments, inclusion of chemical inhibitors, electron sinks, and lipids had a large effect on absolute CH4 emissions (-2.1 ± 0.5, -1.6 ± 0.2, and -1.3 ± 0.2 SMD ± SE, respectively; P 0.15), whereas electron sinks and lipids led to a small decrease in DMI (-0.2 ± 0.1, and -0.4 ± 0.1 SMD ± SE, respectively; P ≤0.01) without affecting animal productivity (P >0.05). Although these nutritional strategies effectively reduced CH4 emissions without compromising animal productivity, their adoption will largely depend on their economic feasibility.

6 páginas, 1 tabla.-- Contributed to: Innovation for Sustainability in Sheep and Goats, 2nd Joint Seminar of the Subnetworks on Nutrition and on Production Systems of the FAO-CIHEAM Network for Research and Development in Sheep and Goats. Ruiz R., López-Francos A., López Marco L. (Eds). Vitoria-Gasteiz (Spain), 3-5 October 2017. Marine lipid supplements have been used to inhibit the ruminal saturation of trans-11 18:1, with the final goal of enhancing cis-9 trans-11 conjugated linoleic acid (CLA) concentration in milk and meat. This response would be largely explained by the effects of n-3 very long chain polyunsaturated fatty acids (PUFA) on the last step of biohydrogenation (BH). In cows, docosahexaenoic acid (DHA, 22:6n-3) has been suggested to be a stronger inhibitor of trans-18:1 hydrogenation than eicosapentaenoic acid (EPA, 20:5n-3), but information about changes in individual 18:1 isomers is very limited, and no reports are available in sheep. This in vitro study was therefore conducted to compare the impact of EPA and DHA on the BH of 18-carbon fatty acids in ovine, using batch cultures of rumen microorganisms and cannulated ewes as inocula donors. The two PUFA were added at a dose of 2% incubated DM and effects were examined after 24 h of incubation. The DHA treatment led to the greatest concentration of trans-18:1 in digesta, but this was mainly accounted for by accumulation of metabolites from alternative BH pathways (e.g, trans-9, -10, -12 and -15 18:1), while the inhibition of trans-11 18:1 saturation was comparable with both PUFA. The saturation of cis-18:1 was constrained too, particularly by DHA, whereas EPA seemed to have specific effects on 18:3n-3 metabolism. Changes in oxo-FA concentrations suggested that ruminal hydration (an alternative metabolic pathway to BH) was also affected by PUFA treatments. The work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MEIC; AGL2014-54587-R). P. G. Toral and D. Carreño received Ramón y Cajal and FPI contracts from the MEIC. Co-funding by the European Regional Development Fund is also acknowledged.

Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emission factors. There is also significant uncertainty associated with enteric CH4 measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF6) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH4 emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH4 emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH4 prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH4 emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH4 prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH4 emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.

3 pag. 1 tabla.--Trabajo presentado a las XVII Jornadas sobre Producción Animal AIDA (Zaragoza, 30 y 31 de mayo, 2017)., Despite the established differences in ruminal biohydrogenation (BH) between cows and small ruminants fed vegetable oils, it has been suggested that differences would be less clear when it comes to marine lipids (rich in very long-chain n-3 PUFA). Thus, this study was conducted simultaneously in bovine and ovine to compare the in vitro BH of C18 fatty acids (FA) to 22:6n-3 (DHA). Batch cultures of rumen microorganisms were carried out using cannulated cows and ewes as inocula donors, and DHA was added at a dose of 2% incubated DM. Although DHA had a similar impact on 18:0 accumulation in cows and sheep, greater increases in t11-18:1 concentration were found in bovine, whereas alternative BH pathways that lead to the accumulation of minor trans 18:1 isomers were further promoted in ewes. These relevant specificities may probably derive from interspecies differences in rumen microbial composition. The saturation of cis 18:1 and 18:2 isomers was also inhibited in both species. Changes in oxo-FA concentrations suggested that ruminal hydration (an alternative metabolic pathway to BH) was affected to a different extent in cows and ewes., Este trabajo forma parte de los proyectos AGL2014-54587 (MINECO, cofinanciado por el FSE) y PIE201540E104 (CSIC). P.G. Toral disfruta de un contrato Ramón y Cajal y D. Carreño de uno predoctoral FPI, ambos del MINECO con FSE.

3 pag. 1 tabla.--Trabajo presentado a las XVII Jornadas sobre Producción Animal AIDA (Zaragoza, 30 y 31 de mayo, 2017). Despite the established differences in ruminal biohydrogenation (BH) between cows and small ruminants fed vegetable oils, it has been suggested that differences would be less clear when it comes to marine lipids (rich in very long-chain n-3 PUFA). Thus, this study was conducted simultaneously in bovine and ovine to compare the in vitro BH of C18 fatty acids (FA) to 22:6n-3 (DHA). Batch cultures of rumen microorganisms were carried out using cannulated cows and ewes as inocula donors, and DHA was added at a dose of 2% incubated DM. Although DHA had a similar impact on 18:0 accumulation in cows and sheep, greater increases in t11-18:1 concentration were found in bovine, whereas alternative BH pathways that lead to the accumulation of minor trans 18:1 isomers were further promoted in ewes. These relevant specificities may probably derive from interspecies differences in rumen microbial composition. The saturation of cis 18:1 and 18:2 isomers was also inhibited in both species. Changes in oxo-FA concentrations suggested that ruminal hydration (an alternative metabolic pathway to BH) was affected to a different extent in cows and ewes. Este trabajo forma parte de los proyectos AGL2014-54587 (MINECO, cofinanciado por el FSE) y PIE201540E104 (CSIC). P.G. Toral disfruta de un contrato Ramón y Cajal y D. Carreño de uno predoctoral FPI, ambos del MINECO con FSE.

6 páginas, 1 tabla.-- Contributed to: Innovation for Sustainability in Sheep and Goats, 2nd Joint Seminar of the Subnetworks on Nutrition and on Production Systems of the FAO-CIHEAM Network for Research and Development in Sheep and Goats. Ruiz R., López-Francos A., López Marco L. (Eds). Vitoria-Gasteiz (Spain), 3-5 October 2017., Marine lipid supplements have been used to inhibit the ruminal saturation of trans-11 18:1, with the final goal of enhancing cis-9 trans-11 conjugated linoleic acid (CLA) concentration in milk and meat. This response would be largely explained by the effects of n-3 very long chain polyunsaturated fatty acids (PUFA) on the last step of biohydrogenation (BH). In cows, docosahexaenoic acid (DHA, 22:6n-3) has been suggested to be a stronger inhibitor of trans-18:1 hydrogenation than eicosapentaenoic acid (EPA, 20:5n-3), but information about changes in individual 18:1 isomers is very limited, and no reports are available in sheep. This in vitro study was therefore conducted to compare the impact of EPA and DHA on the BH of 18-carbon fatty acids in ovine, using batch cultures of rumen microorganisms and cannulated ewes as inocula donors. The two PUFA were added at a dose of 2% incubated DM and effects were examined after 24 h of incubation. The DHA treatment led to the greatest concentration of trans-18:1 in digesta, but this was mainly accounted for by accumulation of metabolites from alternative BH pathways (e.g, trans-9, -10, -12 and -15 18:1), while the inhibition of trans-11 18:1 saturation was comparable with both PUFA. The saturation of cis-18:1 was constrained too, particularly by DHA, whereas EPA seemed to have specific effects on 18:3n-3 metabolism. Changes in oxo-FA concentrations suggested that ruminal hydration (an alternative metabolic pathway to BH) was also affected by PUFA treatments., The work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MEIC; AGL2014-54587-R). P. G. Toral and D. Carreño received Ramón y Cajal and FPI contracts from the MEIC. Co-funding by the European Regional Development Fund is also acknowledged.

Comunicación oral presentada al: 2017 ADSA Annual Meeting #260. Pittsburgh, Pennsylvania (Estados Unidos), 25-28 de junio de 2017., Marine lipid supplements are rich in very long chain n-3 polyunsaturatedfatty acids (PUFA) that inhibit the ruminal saturation of trans-11 18:1 and,consequently, may enhance the concentration of cis-9,trans-11 conjugatedlinoleic acid (CLA) in milk and meat. In this regard, docosahexaenoic acid(DHA, 22:6n-3) has been suggested to increase total trans-18:1accumulation in the rumen to a greater extent than eicosapentaenoic acid(EPA, 20:5n-3), but information about changes in individual 18:1 isomers isvery limited. Furthermore, although EPA and DHA are accepted to be themain responsible for this modulatory effect on ruminal biohydrogenation(BH), the contribution of docosapentaenoic acid (DPA, 22:5n-3), the thirdmost abundant n-3 PUFA in marine lipids, remains unknown. The aim of thisstudy was to compare the impact of EPA, DPA and DHA on the BH of dietaryC18 fatty acids, using batch cultures of rumen microorganisms andcannulated cows as inocula donors. The 3 PUFA were added at a dose of 2%of incubated substrate (the TMR fed to the animals; 50:50 forageconcentrate ratio) and effects were examined after 24 h of incubation. Datawere subjected to ANOVA using the MIXED procedure of SAS 9.4. Overall,EPA and DHA were equally effective to increase the concentration oftrans-11 18:1 (on average, +79% compared with the control; P < 0.001),suggesting that supplements containing differing EPA/DHA ratios (e.g., fishoils or marine algae) would have comparable effects at the same PUFAlevel. However, DHA further promoted alternative BH pathways that lead totrans-10 18:1 accumulation (+205% relative to the control; P < 0.01). Thesaturation of cis-18:1 and non-conjugated 18:2 isomers was alsoconstrained, particularly by DHA in the former case and by EPA in the latter.Increases in trans-11 cis-15 + trans-10,cis-15 18:2 and in trans-9,trans-1418:2 (P < 0.001) may indicate that EPA had specific effects on 18:3n-3metabolism. Only minor variations in ruminal BH intermediates wereobserved in response to DPA (e.g., increments in trans-10,trans-13 andcis-15 18:1; P < 0.05), which suggests a low contribution of this PUFA tothe action of marine lipids.

The potential of the spot urine sampling technique to assess urinary pseudouridine excretion was evaluated. Twelve multiparous Holstein-Friesian cows were fed two experimental diets in a complete change-over design with two 14 day experimental periods. Diets were either silage fed ad libitum with a concentrate supplement offered as a single meal (SF), or a complete diet formulated from the same ingredients (CD). Total urine collections were performed for 24h at 2 h intervals on days 11 and 14. Pseudouridine and creatinine excretion during each 2h interval depended on time of collection (pseudouridine, P, Tutkimuksessa arvioitiin lyhytaikaisen virtsankeruun soveltuvuutta kokonaispseudouridiinierityksen määritykseen virtsassa. Kaksitoista useamman kerran poikinutta holstein-friisiläislehmää ruokittiin ristikkäiskokeessa kahdella eri koedieetillä kahden 14 päivän koejakson ajan. Toisella ruokinnalla lehmät saivat vapaasti säilörehua ja väkirehutäydennys annettiin kerta-annoksena (SF). Toisella ruokinnalla sama rehuannos syötettiin seoksena (CD). Virtsan kokonaiskeräykset tehtiin 24 tunnin ajan 2 tunnin välein koejaksojen päivinä 11 ja 14. Pseudouridiinin ja kreatiniinin eritys kullakin 2 tunnin jaksolla oli yhteydessä keräämisen vuorokaudenaikaan (pseudouridiini, P

1 página.-- Trabajo presentado al: 15th Meeting of the European Society of Veterinary and Comparative Nutrition (ESVCN) ( Zaragoza, España, del 14 al 16 de septiembre de 2011)., Dietary inclusion of sunflower oil (SO) plus marine algae (MA) is known to enhance the concentration of some potentially beneficial fatty acids (FA) in ovine milk, such as trans-11 18:1 and cis-9 trans-11 18:2, but under certain conditions may also promote a shift towards other biohydrogenation (BH) intermediates e.g. trans-10 18;1. Changes in milk FA composition are related to alterations in ruminal BH of unsaturated FA and associated ruminal microbiota, but the specific bacterial species involved remains unclear. Ruminal fluid from lactating ewes fed SO plus incremental levels of MA was used to investigate the concomitant variations in trans 18:1 FA and rumen bacterial community.

1 página, 1 figura.-- Trabajo presentado al 8th International Symposium on the Nutrition of Herbivores (Aberystwyth, Reino Unido, del 6 al 9 de septiembre de 2011), Dietary supplements of sunflower oil (SO) in combination with marine lipids (fish oil or marine algae; MA) are known to increase the concentration of potentially beneficial bioactive lipids, including cis-9, trans-11 conjugated linoleic acid in ovine milk (Toral et al. 2010a). Changes in milk fat composition are related to diet-induced alteratios in ruminal biohydrogenation (BH) of unsaturated fatty acids (FA) and associated ruminal microbiota. Inclusion of SO with fish oil also promotes the accumulation of oxygenated 18-carbon saturated FA in ruminal digesta in sheep (Toral et al. 2010b). However, the bacterial species responsible for the formation and accumulation of keto and hydroxyl FA in the rumen are not well characterised. In the current study, ruminal fluid from lactating ewes fed a diet supplemented with SO plus incremental amounts of MA was used to investigate the association between the formation and accumulation of 18-caron saturated keto FA and the variations in the rumen bacterial community., This work was supported by the Spanish Ministry of Science and Innovation (MICINN; AGL2008-04805-C02-02) and the Spanish National Research Council (CSIC; 200940I034). P. G. Toral was granted by the CSIC (I3P Program).

2 pages, 2 tables.--Contributed to: XIth International Symposium on Ruminant Physiology. (Clermont-Férrand (Francia), Sep 6-9, 2008)., Fish oil (FO) in the diet alters milk fatty acid (FA) composition, enhances milk fat conjugated linoleic acid content (CLA), and also induces milk fat depression (MFD) in lactating cows (Loor et al., 2005). Even though ewes appear less prone to MFD, there is some evidence that supplementing high-concentrate diets with 10 g FO and 20 g sunflower oil (SO)/kg resulted in transient increases of milk fat content (+12%) after 3 d of supplementation, followed by a sustained decrease (up to -27%; Toral et al., unpublished). Under these circumstances, MFD in ewes was not explained by an increase in milk fat t10 c12-CLA concentration. Changes in milk FA composition were characterized by a severe reduction in 18:0 together with an increase in trans-18:1 content. Furthermore, the addition of SO and FO decreased DM intake (-19%) and reduced milk yield (-14%) which may indicate a negative impact of lipid supplements on ruminal fermentation in sheep fed high-concentrate diets. The current experiment was therefore designed to examine the effect of a mixture of SO and FO in the diet on ruminal FA profile and fermentation characteristics in ewes., This work was supported by Projects AGL2008-04805-C02-02 (MICINN) and CSI01B08 (Council of Castille and Leon).

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