Search

SUPPLEMENTARY MATERIAL - Please download it using the following link: http://dx.doi.org/10.20350/digitalCSIC/13779 (OPEN ACCESS), This work was supported by the Junta de Castilla y León (JCyL, Spain; project CSI276P18). P. G. Toral benefited from a Ramón y Cajal research contract from the Spanish Ministry of Economy and Competitiveness (MINECO; RYC-2015-17230) and C. Fernández-Díez from a postdoctoral research contract from JCyL. Co-funding by the European Regional Development Fund (ERDF/FEDER) and the European Social Fund (ESF) is also acknowledged.

14 páginas, 2 figuras, 4 tablas., A major proportion of milk rumenic acid (RA; cis9,trans-11 CLA) is synthesized through mammary Δ9 -desaturation of vaccenic acid (VA; trans-11 18:1). Diet composition may determine the relative contribution of this endogenous synthesis to milk RA content, with effects that might differ between ruminant species. However, this hypothesis is mostly based on estimated values, proxies of stearoyl-CoA desaturase (SCD) activity, and indirect comparisons between publications in the literature. With the aim of providing new insights into this issue, in vivo Δ9 -desaturation of 13C-labeled VA (measured via milk 13C-VA and -RA secretion) was directly compared in sheep and goats fed a diet without lipid supplementation or including 2% of linseed oil. Four Assaf sheep and 4 Murciano-Granadina goats were used in a replicated 2 × 2 crossover design to test the effects of the 2 dietary treatments during 2 consecutive 25-d periods. On d 22 of each period, 500 mg of 13C-VA were i.v. injected to each animal. Dairy performance, milk fatty acid profile, including isotope analysis, and mammary mRNA abundance of genes coding for SCD were examined on d 21 to 25 of each period. Supplementation with linseed oil improved milk fat concentration and increased the content of milk VA and RA. However, the isotopic tracer assay suggested no variation in the relative proportion of VA desaturated to milk RA, and the percentage of this CLA isomer deriving from SCD activity would remain constant regardless of dietary treatment. These results put into question a major effect of lipid supplementation on the endogenous synthesis of milk RA and support that mammary Δ9 -desaturation capacity would not represent a limiting factor when designing feeding strategies to increase milk RA content. The lack of dietinduced effects was common to caprines and ovines, but inherent interspecies differences in mammary lipogenesis were found. Thus, the higher proportions of VA desaturation and endogenous synthesis of milk RA in sheep supported a greater SCD activity compared with goats, a finding that was not associated with the similar mRNA abundance of SCD1 in the 2 species. On the other hand, transfer efficiency of the isotopic tracer to milk was 37% higher in caprine than in ovine, suggesting a greater efficiency in mammary fatty acid uptake from plasma in caprine., This work was supported by the Spanish Research State Agency (Agencia Estatal de Investigación, AEI), by the European Regional Development Fund (project AGL2017-87812-R, AEI/FEDER, EU), and by the Spanish National Research Council (CSIC; PIE 202040E100). P. G. Toral benefited from a Ramón y Cajal research contract (RYC-2015-17230), from the Spanish Ministry of Economy and Competitiveness (MINECO), co-funded by the European Social Fund. The authors thank V. Peiró from the Stable Isotopes Laboratory of the Interdepartmental Research Service (SIdI, Autonomous University of Madrid, Spain) for her assistance with isotope analysis. The authors have not stated any conflicts of interest.

14 páginas, 6 tablas., Lipids of different unsaturation degree were added to dairy ewe diet to test the hypothesis that unsaturated oils would modulate milk fatty acid (FA) profile without impairing or even improving feed efficiency. To this aim, we examined milk FA profile and efficiency metrics (feed conversion ratio (FCR), energy conversion ratio (ECR), residual feed intake (RFI), and residual energy intake (REI)) in 40 lactating ewes fed a diet with no lipid supplementation (Control) or supplemented with 3 fats rich in saturated, monounsaturated and polyunsaturated FA (i.e., purified palmitic acid (PA), olive oil (OO), and soybean oil (SBO)). Compared with PA, addition of OO decreased milk medium-chain saturated FA and improved the concentration of potentially healthpromoting FA, such as cis-9 18:1, trans-11 18:1, cis-9 trans-11 CLA, and 4:0, with no impact on feed efficiency metrics. Nevertheless, FA analysis and decreases in FCR and ECR suggested that SBO supplementation would be a better nutritional strategy to further improve milk FA profile and feed efficiency in dairy ewes. The paradox of differences observed depending on the metric used to estimate feed efficiency (i.e., the lack of variation in RFI and REI vs. changes in FCR and ECR) does not allow solid conclusions to be drawn in this regard., This research was funded by the Junta de Castilla y León (JCyL, Spain; project CSI276P18). P. G. Toral benefited from a Ramón y Cajal research contract from the Spanish Ministry of Economy and Competitiveness (MINECO; RYC-2015-17230), C. Fernández-Díez from a postdoctoral research contract from JCyL and A. Della Badia from a FPI predoctoral contract from the Spanish Ministry of Science and Innovation (MICINN; PRE2018-086174). Co-funding by the European Regional Development Fund (ERDF/FEDER) and the European Social Fund (ESF) is also acknowledged.

13 páginas, 1 figura, 6 tablas., Both sheep and goats can display very different individual degrees of milk fat depression (MFD), which might explain some apparent contradictions in the literature. Because the antilipogenic effect of certain fatty acids (FA) is the most likely origin of MFD, characterizing the milk FA profile of animals showing different degrees of MFD seems a helpful step to understand the physiological basis of the tolerance or susceptibility to the syndrome. Analyzing whether specific traits may predetermine a particular responsiveness would also be of relevance to meet this aim. However, information about these aspects is scant, not only in goats and sheep but in ruminants in general. This study was conducted with 25 Murciano-Granadina does and 23 Assaf ewes that were fed a total mixed ration without lipid supplementation for 3 wk (control period). Then, all animals received the same basal diet supplemented with 2% of fish oil (FO) for 5 additional weeks (MFD period). At the end of this second period, and on the basis of the extent of FO-induced decreases in milk fat concentration, the 5 most responsive (RESPON+) and the 5 least responsive (RESPON−) animals were selected within each species, 20 in total. Milk yield and composition, including a comprehensive FA profile, were examined at the end of each period. By design, between-group variation in milk fat concentration and yield was substantial, but no significant interaction with the effect of species was detected. Reductions in these 2 performance traits averaged 6% in RESPON− and 26% in RESPON+. Results do not allow suggesting that responsiveness to MFD would be clearly predetermined neither by the studied performance traits nor by milk FA profile, although a certain relationship with energy balance might exist. Furthermore, variations in ewes and does displaying different individual degrees of MFD may be associated with changes in certain candidate milk fat inhibitors, such as trans-10 18:1 and cis-9 16:1, whereas trans-10,cis-12 conjugated linoleic acid would only have a minor role in determining MFD severity. Alterations in the molar yield of de novo and preformed FA suggest relevant differences in the mechanisms underlying MFD in RESPON+ and RESPON−, with interspecies effects being observed only in more tolerant animals. Further research is still required to elucidate key determinants of responsiveness to MFD., This work was supported by the Spanish Research State Agency (Agencia Estatal de Investigación) and the European Regional Development Fund (project AGL2017-87812-R, AEI/FEDER, EU). A. Della Badia benefited from an FPI predoctoral contract (PRE2018-086174) and P. G. Toral from a Ramón y Cajal research contract (RYC-2015-17230), from the Spanish Ministries Science and Innovation (MICINN) and of Economy and Competitiveness (MINECO), respectively. Co-funding by the European Social Fund is also acknowledged. The authors have not stated any conflicts of interest.

14 páginas, 5 tablas, 2 figuras., The causative relationship between ruminal biohydrogenation alterations known as the trans-10 shift and marine lipid-induced milk fat depression (MFD) has been questioned in dairy ewes, but the large intra- and inter-experiment differences in the levels of trans-10 shift indicators precludes firm conclusions. This meta-analysis was conducted to quantify the relationship between trans-10 shift milk indicators [i.e., trans-10,cis-12 conjugated linoleic acid (CLA), trans-10 18:1 or trans-10:trans-11 18:1 ratio] and lactation performance, mainly milk fat traits, in Assaf dairy ewes. A database comprising of 17 experiments including 50 dietary treatments was compiled. The diets were grouped into 2 dietary conditions: (1) non-MFD condition, which included 14 diets supplemented with plant oils and tannins that modified the milk fatty acid profile without lowering milk fat concentration and yield, and 12 respective control diets, and (2) MFD condition, which included 15 diets supplemented with marine lipids that induced the low fat-milk syndrome, and 9 respective control diets. The overall levels of milk trans-10 shift indicators did not differ between dietary conditions, but significant increments were found in the supplemented diets relative to their respective controls. A similar linear and negative (slope: −7.28 ± 2.816) relationship between milk fat concentration and trans-10,cis-12 CLA was found in both dietary conditions. However, the quadratic negative response of milk fat content to trans-10 18:1 concentration was greater in MFD than in non-MFD conditions. In the two dietary conditions, the relationship between milk trans-10,cis-12 CLA or trans-10 18:1 and de novo fatty acid concentration in milk was negative, whereas the relationship with preformed fatty acid proportion was positive. The magnitude of changes in both milk fatty acid groups in response to changes in these trans-10 shift indicators were greater in non-MFD compared with MFD conditions. Milk fat yield and trans-10 shift indicators were only negatively related in ewes that were fed marine lipid supplements, because reductions in de novo fatty acid yield with increased shift indicator levels were not counteracted by concomitant increments in preformed fatty acid secretion. The best-fit (lower root mean squared error, higher R2 and no prediction biases) equations of milk fat or major milk fatty acid groups, as concentration or yield, were based on milk trans-10 18:1 concentration. In conclusion, different responses between the two conditions to similar shift indicator levels support that the trans-10 shift would not be a major factor explaining the diet-induced low-fat milk syndrome in dairy ewes., This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO; AGL2017-87812-R), co-funded by the European Regional Development Fund. P. G. Toral benefited from a Ramón y Cajal research contract from the MINECO (RYC-2015-17230), co-funded by the European Social Fund, and a researcher mobility grant from the University of León.

13 páginas, 5 tablas, 3 figuras., The lactational effects of shearing (CO, control unshorn; SH, shorn) were investigated in 48 dairy ewes of 2 breeds (Lacaune, LC, n = 24; Manchega, MN, n = 24) having a similar stage of lactation (120 ± 6 d in milk) and body frame (65.1 ± 1.5 kg of body weight and 2.4 ± 0.1 body condition score), but differing in fleece and milk production. Ewes were penned indoors, adapted to the diet (alfalfa hay ad libitum and fixed amount of concentrate), and allocated for 30 d in 8 balanced groups to which the experimental treatments were applied. All ewes were sheared on the same day. Feed intake by pen and milk yield by ewe were recorded daily. Individual samples of milk (d −3, 3, 5, 7, and 15) and blood (d −7, 3, 7, and 15) were collected, as well as body weight and body condition score measured (d −15, 0, and 15), related to shearing. Pooled milk samples per pen were also collected before and after shearing for milk fatty acid analysis (d −3 and 15). Average temperatures in the barn before (12.6 ± 0.7°C) and after (13.7 ± 0.4°C) shearing were mild. Fleece was heavier in MN than in LC (1.04 ± 0.10 vs. 0.75 ± 0.09 kg/ewe) and tended to cover more body surface in MN than in LC ewes. Responses to shearing varied according to breed, the rectal temperature after shearing only decreasing significantly in the MN (−0.36 ± 0.09°C). Feed intake increased in the LC-SH (5%), when compared with LC-CO, but did not vary in the MN ewes. Ingestibility of the alfalfa hay, expressed as filling units for sheep and monitored in 2 groups of 6 dry and unshorn ewes of each breed (73.0 ± 2.5 kg of body weight and 3.1 ± 0.2 body condition score), was constant throughout the experiment (0.99 ± 0.03 filling units for sheep/kg of dry matter). Regarding milk production, LC-SH ewes yielded 10% more milk (1.38 ± 0.06 vs. 1.52 ± 0.05 kg/d) than LC-CO ewes, but no differences were detected in MN ewes (0.74 ± 0.03 kg/d, on average). No differences in the concentration of major milk components by effect of the shearing treatment were detected in either breed, but LC-SH ewes yielded 9% more milk protein than did LC-CO ewes. No relevant effects of shearing were detected on milk fatty acid profiles, although MN ewes showed lower C4:0, C6:0, C14:0, trans-11 and trans-12 C18:1 contents than did LC ewes. Moreover, no changes by effect of shearing were detected in plasma glucose, nonesterified fatty acids, cortisol, or insulin values in either breed, or in body weight or body condition score. In conclusion, shearing dairy ewes during lactation under mild winter conditions is a suitable management option that may increase feed intake and milk production, without deleterious effects on milk composition., This work is part of a research project of the Plan Nacional I+D+i Retos 2013 (Project AGL2013-44061-R) funded by the Spanish Ministry of Economy and Competitiveness (Madrid, Spain) and was also supported by a research scholarship to Abdelaali El Hadi from the International Centre for Advanced Mediterranean Agronomic Studies (Instituto Agronómico Mediterráneo de Zaragoza, Zaragoza, Spain). The authors are also grateful to Ramon Costa and the team of the SGCE (Servei de Granges i Camps Experimentals) of the Universitat Autònoma de Barcelona (Bellaterra, Barcelona, Spain) for the care of the animals and to Charles (Chuck) Simmons, native English-speaking university instructor (Cerdanyola, Barcelona, Spain) for the English language and style revision of the manuscript

16 páginas, 5 figuras., Tannins are a large, diverse and complex group of phenolic compounds that may be detrimental, innocuous or beneficial to animal nutrition and health depending on a number of factors (e.g., type, amount ingested, consumer animal species or the basal diet). The ability of tannins to modulate ruminal biohydrogenation and, consequently, the fatty acid (FA) composition of milk and meat is a relatively recent finding that has attracted interest among ruminant nutritionists. In this review, we take a close look at the effects of tannins on the broadest possible range of FA, including less abundant compounds that have previously received little attention. Tannins are able to improve the concentrations of potentially beneficial FA, such as 18:3n-3, 18:2n-6, trans-11 18:1 and conjugated linoleic and linolenic acids, both in milk and meat, which may contribute to meeting consumer demand for health-promoting foods. These positive responses to tannins can be explained by their modulatory action on specific biohydrogenation steps and pathways. Thus, higher contents of dietary polyunsaturated FA in ruminant-derived products, as well as increased or decreased accumulation of other biohydrogenation intermediates (e.g., cis and trans 18:3, 18:2 and 18:1 isomers) and changes in lipids of bacterial origin (odd- and branched-chain FA and dimethylacetals), are somewhat common findings when the effects of tannins are examined. In contrast, de novo synthesized FA are less frequently affected by these plant secondary metabolites, which also applies to other FA (e.g., trans-10 18:1) that might be detrimental to animal performance (i.e., milk fat synthesis) and perhaps to human health. However, further studies are required to unravel the reasons for certain erratic responses to tannins. This paper reviews the roles of tannin chemical and structural diversity, dosage, interaction with other dietary ingredients, differences among ruminant species and variations over time in the reaction of rumen microbiota in the influences of these phenolic compounds on milk and meat FA profiles., P. G. Toral benefited from a Ramón y Cajal research contract from the MINECO (RYC-2015-17230), co-funded by the European Social Fund.

1 página.--Trabajo presentado al Proceedings of the Fifth Dairycare Conference 2018, p. 21 (#9). Thessalonika (Grecia),19-20 de marzo de 2018., Requirements of high producing ruminants can only be covered by diets of high nutritive value that can induce subacute rumen acidosis (SARA), but not for all animals at the same time and with the same intensity. A challenge is to find noninvasive biomarkers to detect animals suffering from SARA. Milk fatty acids composition is a good candidate as it is partly linked to rumen metabolism. The aim of this work was to compare two methods of measure of milk fatty acids composition: gas chromatography (GC) considered as a “standard”, but a time-consuming and expensive method and medium infrared analysis (MIR), a rapid and cheap method which can be applied on field. Eight rumen cannulated dairy goats adapted to a low concentrate diet (20 %) were abruptly switched to a high concentrate diet (50 %). Samples of milk were taken individually on the morning for 2 days before the change, the 4 days following the change and once weekly for 3 weeks. 91 fatty acids were detected by GC and 58 were estimated by MIR. Rumen fluid was sampled simultaneously before the morning feed (T0) and 1, 2, 4 and 6 hours after. Rumen samples were analysed for pH and volatile fatty acid (VFA) composition. A principal component analysis (PCA) was used to examine the relationships among milk fatty acids percentages measured by GC. The projection of the saturated fatty acids on the first two components showed an opposition between the short and medium fatty acids (SMFA) up to 13C and the long (L) chain fatty acids (LFA). An index was calculated as the ratio of SMFA/LFA. It was positively linked to the pH values and negatively to [VFA] ones. A similar ratio was calculated from the MIR estimation. Even if both ratios were correlated (r = 0.60, n = 72), the MIR ratio was higher (0.72 ± 0.06) than the GC ratio (0.50 ± 0.05) and was not correlated with pH and only poorly with VFA. MIR overestimated SMFA and underestimated LFA. In conclusion, GC is a useful tool to detect SARA in dairy goats from milk composition, but MIR is not a relevant method due to the inaccuracy in the prediction of FA.

13 páginas, 4 figuras, 2 tablas., A great deal of uncertainty still exists about intermediate metabolites and pathways explaining the biohydrogenation (BH) of 20- and 22-carbon polyunsaturated fatty acids (PUFA). Therefore, this study was conducted to provide further insight into the ruminal metabolism of 20:5 n-3 (EPA), 22:5 n-3 (DPA), and 22:6 n-3 (DHA), the main n-3 PUFA present in the marine lipids used in dairy ruminant feeding, and to examine potential differences between bovine and ovine. To meet this aim, we investigated the 20- and 22-carbon metabolites accumulated during in vitro incubation of EPA, DPA, and DHA with rumen inocula from cows and ewes. The PUFA were added at a dose of 2% incubated dry matter and digesta samples were analyzed after 24 h of incubation using complementary gas-liquid chromatography of fatty acid methyl esters and gas chromatography-mass spectrometry of 4,4-dimethyloxazoline derivatives. Results suggested that the main BH pathway of EPA and DPA would proceed via the reduction of the double bond closest to the carboxyl group (cis-5 in EPA and cis-7 in DPA); curiously, this mechanism seemed of much lower importance for DHA. Thus, DPA would not be a major intermediate product of DHA and their BH might actually follow separate pathways, with the accumulation of numerous unique metabolites in each case. A principal component analysis supported this hypothesis, with a clear separation between PUFA treatments in the score and loading plots. Within EPA and DPA groups, cow and ewe samples loaded separately from each other but not distant. No conjugated 20:5, 22:5, or 22:6 isomer compatible with the initial product of EPA, DPA, or DHA metabolism, respectively, was identified in the ruminal digesta, although this would not unequivocally exclude their transient formation. In this regard, results from DPA incubations provided the first indication that the metabolism of this very long chain PUFA may involve the formation of conjugated double bond structures. The BH of EPA, DPA, and DHA resulted in the appearance of several tentative trans-10-containing metabolites, showing a general trend to be more abundant in the digesta of ewes than in that of cows. This finding was speculated to have some relationship with the susceptibility of dairy sheep to marine lipid-induced milk fat depression. Differences in the relative proportion of intermediate products would also suggest an influence of ruminant species on BH kinetics, with a process that would likely be slower and less complete in cows than in ewes. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved., This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO; AGL2014- 54587-R). P. G. Toral benefited from a Ramón y Cajal research contract from the MINECO. Co-funding by the European Regional Development Fund is also acknowledged.