Dairy products are major dietary sources of B vitamins. However, the impact of cow diet and dairy processing techniques on B vitamin concentrations remains unclear. This study investigated the effects of diet composition on B-vitamin content in raw milk and, in yogurt, and Cantal-type cheese produced therefrom. Forty Holstein and Montbéliarde-breed cows were assigned to either a grass-based agroecological system or a corn-based intensive system for 19 weeks. Vitamins B1, B2, B5, and B6 were quantified by liquid chromatography, and B9 and B12 by chemiluminescence. Milk from the agroecological system contained higher vitamin B2, and lower vitamin B5 concentrations than milk from the intensive system. This same pattern was also observed in cheese, but not in yogurt, showing impacts of technological processing. Adding probiotics into yogurts increased pyridoxal (B6) concentration. This study highlighted diet-related differences in B vitamin concentrations in raw milk, and these differences transferred to cheese but not to yogurt.

In semi-mountainous grass-based dairy systems, summer droughts frequently reduce grass availability, with implications for animal performance as well as milk and cheese quality. The objective of our study was to investigate the effect of a simulated summer forage shortage in a traditional semi-mountainous grass-based system versus a corn-based system with part-time grazing. During a 19-wk experiment, 26 Prim'Holstein and 14 Montbéliarde cows were blocked in 4 balanced groups of 10 cows. During the first 8 wk, 2 groups were fed a grass-based diet (75% of grazed grass, 25% of hay and concentrates) and the remainder were fed a corn-based diet (75% mixed ration, 25% of grazed grass). During the following 11 wk, one group in each feeding system was subjected to a reduction in grazed grass intake and a corresponding increase in indoor feeding, resulting in 50% of grazed grass for grass-fed cows and removal of grazed grass for corn-fed cows. Milk yield and composition were recorded during the whole trial, in addition to indoor individual intake. Grass intake was modeled to calculate feed efficiency and estimate methane emissions. At the end of the experiment, bulk milk from each group was sampled for physicochemical and microbiological analyses and processed into Cantal-type cheeses. After 9 wk of ripening, cheeses underwent physicochemical, microbiological and descriptive sensory analyses. Results showed that the complete removal of grazed grass in corn-based system had no effect on milk production but impaired feed efficiency; grass reduction in the grass-based diet better maintained milk yield, enhanced feed efficiency, and reduced methane emission intensity. Cheese softness increased with proportion of grass in the diet, and it was positively correlated with primary proteolysis (αS1-casein and β-casein breakdown) but negatively correlated with the C16:0/C18:1 ratio and the calculated fat melting point. Cheese from cows fed with more grazed grass were the yellowest and had the most pronounced flavors, as well as higher counts of heterofermentative lactobacilli and lactic acid bacteria. Removal of grazed grass from the corn-based diet led to cheese that was less yellow and had less flavor, in line with lower levels of secondary proteolysis. In conclusion, our study suggests that maintaining fresh herbage in corn-based diets is crucial for maintaining cheese quality without impairing animal performance. In grass-based systems, complementation with indoor feeding may have limited effects on product quality but promotes the maintenance of animal performance.

In dairy cows, early lactation is a period prone to oxidative stress, inflammation and health problems. Our objective was to investigate the effects of the nutritional supplementation of early lactating cows with plant extracts or vitamin E on physiological and immunological status. Forty-five Holstein cows were divided into three groups: control group (n = 15), vitamin E group (n = 16) (3,000 IU/d for 3 weeks before and 1,000 IU/d after calving), and plant extract group (n = 14) (10 g/d only after calving). Their redox and immune status were monitored during the first 12 weeks of lactation, every four week. In week 12, plasma malondialdehyde levels in plasma were lower in the vitamin E and plant extract groups than in the control group. The vitamin E and plant extract groups had lower ex vivo plasma CCL4, IL6 and IL8 cytokine levels, lower proportions of blood regulatory neutrophils, and less ROS production by blood neutrophils than the control group. In terms of immune response, vitamin E and plant extracts down-regulated the gene expression of FABP3 in the milk mammary epithelial cells of multiparous cows. Therefore, supplementation with either vitamin E or plant extracts could prevent systemic hyper-inflammation and improve the immune response during early lactation. ### Competing Interest Statement Angelique Corset's research was financially supported by Biodevas Laboratoires and the Association Nationale de Recherche Technologique (ANRT), the Pays de Loire and Brittany regions, and BPI France in the frame of the NEOLAC project. She was remunerated as an employee of Biodevas Laboratoires as part of a PhD thesis under an industrial training through research agreement supervised by Dr Jean-Francois Ricouleau of Biodevas Laboratoires. The other authors report no potential conflicts of interest. Conseil régional de Bretagne, https://ror.org/05510z802 Conseil régional des Pays de la Loire, https://ror.org/01zsm1k25 Association Nationale de la Recherche et de la Technologie, https://ror.org/00ht2ab73

At the onset of lactation in dairy cows, inflammation and oxidative stress may occur and result in a risk of pathologies and lower milk yield. To propose an innovative management strategy for cows during this period, it is essential to better understand these physiological variations. Our objective was to evaluate the metabolic, redox and immune status of 7 primiparous and 8 multiparous Holstein cows during late gestation and the first months of lactation. Blood samples were collected between 3 weeks before calving until 12 weeks postpartum. Milk samples were also collected, but only at the time points after calving. The metabolic (nonesterified fatty acids (NEFA), BHB, glucose, urea, calcium) and redox (reactive oxygen metabolites (ROM), oxidative stress index (OSI), glutathione peroxidase activity, vitamin E) statuses were analyzed in plasma or erythrocytes. The expression of genes related to antioxidant functions was determined in leukocytes collected from milk. For immune status, plasma cytokine levels and the production of reactive oxygen species (ROS) in classical and regulatory neutrophils were measured in 2 whole blood ex vivo challenges. The data were analyzed using a mixed model that included the fixed effects of parity and week and their interaction. Milk yield, plasma NEFA and BHB in wk 2 and 4 after calving were higher in multiparous cows than in primiparous cows, whereas glucose and calcium tended to be lower. Plasma ROM and OSI levels in wk 8 were higher in multiparous than in primiparous cows. Multiparous cows also displayed higher glutathione peroxidase activity in erythrocytes, and antioxidant transcription factor and superoxide dismutase-1 expression levels in milk leukocytes. Moreover, multiparous cows had higher plasma concentrations of vitamin E but lower plasma levels of cytokines CXCL10, CCL2, IL1Rα and IFNγ. Following ex vivo whole blood stimulation with Escherichia coli, lower IL1α and TNFα levels were measured in multiparous than in primiparous cows. Intracellular ROS production by neutrophils was lower in multiparous than in primiparous cows. These results thus indicated marked physiological changes in wk 8 compared with wk 2 and 4 of lactation. These differences in the physiological status of primiparous and multiparous cows offer interesting perspectives for potential dietary strategies to prevent pathologies which take account of parity and week relative to calving.

There are a number of differences in the meat and carcass quality traits between pasture-raised and concentrate-raised lambs that may further be used to trace back the diet, but the extent to which these differences are modulated by pasture-finishing duration is unknown. In this study, we investigated the changes in longissimus thoracis et lumborum muscle and fat spectrocolorimetric properties, and dorsal fat firmness, in lambs switched from a stall-fed concentrate-based diet to grazing on lucerne for various durations (0, 21, 42, 63 days) pre-slaughter. Stall-fed lambs from the different treatment groups were managed in a single group and lucerne pasture-finished lambs from the different treatment groups also co-grazed in a single group. The level of concentrate fed to stall-fed lambs was adjusted to maintain a similar mean pattern of growth between lucerne pasture-fed and stall-fed lambs. The trial used a total of 141 lambs over two successive years. Dorsal fat was firmer in lambs finished on lucerne pasture, even for the shortest finishing duration (21 days), the difference being of commercial importance. Dorsal fat colour and carotenoid content showed changes at 21 days on lucerne pasture but did not change further for longer lucerne pasture-finishing durations. In contrast, perirenal fat lightness, yellowness, chroma and carotenoid content showed changes at 21 days on lucerne pasture and increased consistently with lucerne pasture-finishing duration. Although these changes in fat spectrocolorimetric properties were not, or barely, visible to the naked eye, they could be of interest for authenticating the duration of lucerne pasture-finishing. Muscle redness increased consistently with the duration of lucerne pasture-finishing, the change becoming significant from 42 days on lucerne pasture and being visible to the naked eye. We observed a consistent decrease in muscle hue angle and perirenal fat redness and a consistent increase in perirenal fat hue angle with lucerne pasture-finishing duration, but these changes only became significant from 63 days on lucerne pasture. The pattern of change in the lamb carcass and meat quality traits measured according to lucerne pasture-finishing duration therefore varied between the tissues and quality traits.

Understanding the mechanisms underlying desirable phenotypes in animal production is crucial for animal genetic selection and nutrition. Under the BEEFALIM 2020 program, aimed at improving the feed efficiency of suckling beef cattle, several experiments were conducted to study the digestive and metabolic mechanisms associated with the between-animal variability of feed efficiency in young Charolais cattle, heifers, and cows. To evaluate the digestive and metabolic mechanisms involved, direct measurement using reference methods were coupled with indirect measurements using indicators (proxies and biomarkers). Feed efficiency was characterized by residual feed intake, defined as the portion of measured dry matter intake not explained by the observed animal performance (live weight, body weight gain and composition). The results presented confirm that certain metabolic mechanisms, as well as the body composition of animals, would be more strongly associated with individual variations in feed efficiency than digestive mechanisms, especially when diets are rich in starch. However, the experimental setup does not exclude the possibility that appetite or feeding capacity contributes to differences in feed efficiency between individuals. Indeed, the identified mechanisms could be associated with the efficient phenotype solely because they covary with the level of feeding. Based on our results, and those of the literature, we suggest, however, that protein metabolism and turnover would be associated with between-animal variation of feed efficiency regardless of the feeding level and could be proposed as a candidate determinant of RFI variation. Further studies are needed to discern the true causality of the identified mechanisms.

Comprendre les mécanismes à l’origine des phénotypes d’intérêt en production animale est capital pour la sélection et l’alimentation des animaux. Dans le cadre du programme BEEFALIM 2020, qui visait à améliorer l’efficience alimentaire chez le bovin allaitant, plusieurs expériences ont été menées pour étudier les mécanismes digestifs et métaboliques associés aux variations individuelles de l’efficience alimentaire chez des jeunes bovins, génisses et vaches de race Charolaise. Pour évaluer les mécanismes digestifs et métaboliques impliqués, nous avons couplé des mesures directes à l’aide des méthodes de référence et des mesures indirectes à l’aide d’indicateurs (proxies et biomarqueurs). L’efficience alimentaire était caractérisée par la consommation moyenne journalière résiduelle, définie comme la partie de l’ingestion de matière sèche mesurée qui n’est pas expliquée par les performances animales observées (poids vif, gain de poids et composition du gain). Les résultats obtenus confirment que certains mécanismes d’ordre métabolique, ainsi que la composition corporelle des animaux, seraient associés de façon plus forte aux variations individuelles d’efficience alimentaire que les mécanismes d’ordre digestif, surtout lorsque les régimes sont riches en amidon. Un renouvellement des protéines tissulaires plus lent semble expliquer le meilleur taux de conversion de l’azote alimentaire en muscle chez les animaux efficients alimentés avec des régimes riches en amidon. Cependant, notre dispositif expérimental ne nous permet pas d’exclure la possibilité que l’appétit ou la capacité d’ingestion des animaux contribuent aux différences d’efficience alimentaire entre individus. En effet, les mécanismes identifiés pourraient être associés au phénotype efficient uniquement parce qu’ils covarient avec le niveau d’ingestion. D’après les résultats de cette étude et ceux de la littérature, il est suggéré néanmoins que le métabolisme et en particulier le renouvellement protéique seraient associés aux variations d’efficience alimentaire de manière indépendante du niveau d’ingestion. Ils constitueraient une première piste pour les considérer comme de vrais déterminants du phénotype d’efficience alimentaire. Des études complémentaires sont nécessaires pour établir le lien de causalité entre les mécanismes identifiés et l’efficience alimentaire.

The content, composition and variation of vitamin compounds in goat milk have been little studied. An experimental design was based on 28 commercial farms, selected considering the main feeding system (based on main forage and especially pasture access), goat breed (Alpine vs Saanen) and reproductive management (seasonal reproduction), in the main French goat milk production area. Each farm received two visits (spring and autumn) that included a survey on milk production conditions and bulk milk sampling. Milk vitamins (A, E, B2, B6, B9, B12) and carotenoid concentrations plus colour indices were evaluated. A stepwise approach determined the variables of milk production conditions that significantly altered milk indicators. The main forage in the diet was the major factor altering goat milk vitamin and carotenoid concentrations and colour indices. Bulk milk from goats eating fresh grass as forage was richer in α-tocopherol (+64%), pyridoxal (+35%) and total vitamin B6 (+31%), and b* index (characterising milk yellowness in the CIELAB colour space) was also higher (+12%) than in milk from goats eating conserved forages. In milk from goats eating fresh grass, concentrations of pyridoxamine, lutein and total carotenoids were higher than in milk of goats fed corn silage (+24, +118 and +101%, respectively), and retinol and α-tocopherol concentrations were higher than in milk of goats fed partially dehydrated grass (+45 and +55%). Vitamin B2 concentration was higher in milk of goats eating fresh grass than in milk of goats fed hay or corn silage as forage (+10%). However, bulk milk when goats had access to fresh grass was significantly poorer in vitamin B12 than when fed corn silage (−46%) and in γ-tocopherol (−31%) than when fed conserved forage. Alpine goats produced milk with higher vitamin B2 and folate concentrations than Saanen goats (+18 and +14%, respectively). Additionally, the milk colour index that discriminates milks based on their yellow pigment contents was 7% higher in milk from Alpine than Saanen herds, but milk from Saanen goats was richer in lutein (+46%). Goat milks were richer in vitamins B2 and B12 and folates, but poorer in vitamin B6 in autumn than in spring (+12, +133, +15 and −13%, respectively). This work highlights that goat milk vitamin and carotenoid concentrations and colour indices vary mainly according to the main forage of the diet and secondly according to the breed and season.

Vitamins are essential nutrients for the proper functioning of mammalian cells, but these cells are generally not able to synthesize them, or not in sufficient quantities to cover the needs of the whole organism. They are involved in most cellular biological functions and at all physiological stages of individuals. Specific needs have to be covered by regular nutritional intake, because of limited body's storage capacity. Epidemiological studies indicate that this is not the case. In addition to the well-known symptomatic pathologies of deficiencies in each of the vitamins (like xerophthalmia due to vitamin A deficiency), the links between these sub-clinical intakes and the risks of developing diseases with age are highlighted. Dairy products can be interesting vitamin sources because of the quantities they contain, their bioavailability, their regular consumption, whether daily or yearly, and their affordability. However, elements to characterize the vitamin content in these products are still far from complete. Some vitamins have not yet been studied (D, K, B-1, B-3, B-5, B-8 and C), some variation factors have been described for others. Grazing ruminants thus seem to produce milk that is richer in vitamins (A, E, B-2, B-9) than in other feeding modes, but this turns out to be to the detriment of vitamin B-12 for which dairy products are important provider in human nutrition. A more detailed knowledge of the qualitative and quantitative relationships between production conditions (species, breeds, nature of the feed in particular) would eventually make it possible to propose ways of producing milk and dairy products whose vitamin content could be optimized.

Les vitamines sont des nutriments essentiels au bon fonctionnement des cellules des mammifères mais celles-ci ne sont généralement pas capables de les synthétiser, ou pas en quantité suffisante pour couvrir les besoins de l’organisme entier. Elles participent à la plupart des fonctions biologiques cellulaires et à tous les stades physiologiques des individus. Il est important que les besoins spécifiques soient couverts par des apports nutritionnels réguliers, les capacités de stockage corporel étant parfois très limitées. Les études épidémiologiques indiquent cependant que tel ne serait pas le cas. En plus des pathologies symptomatiques bien connues des carences en chacune des vitamines (comme la xérophtalmie résultant de la carence en vitamine A), il est de plus en plus mis en lumière des liens entre ces apports subcliniques et les risques de développement de maladies en particulier avec l’âge. Les produits animaux de ruminants, les produits laitiers en particulier, peuvent être des sources d’apport intéressantes compte tenu des quantités qu’ils contiennent, de la biodisponibilité de celles-ci, de leur consommation régulière, que ce soit au niveau quotidien ou annuel, de leur bonne accessibilité (coût, transport, stockage). Cependant, les éléments de caractérisation des teneurs en vitamines dans ces produits sont encore loin d’être complets. Certaines vitamines n’ont pour le moment pas été étudiées (D, K, B1, B3, B5, B8 et C), quelques facteurs de variation ont été décrits pour les autres. Les ruminants au pâturage semblent ainsi produire des laits plus riches en vitamines (A, E, B2, B9) qu’avec les autres modes d’alimentation, mais cela s’avère être au détriment de la vitamine B12 pour laquelle les produits laitiers ont un rôle pourvoyeur important dans la nutrition humaine. Une connaissance plus approfondie des relations qualitatives et quantitatives entre les conditions de production (espèces, races, nature de l’alimentation en particulier) permettrait à termes de proposer les moyens de produire des laits et des produits laitiers dont les apports en vitamines pourraient être optimisés.

Residual feed intake (RFI) is one of the preferred traits for feed efficiency animal breeding. However, RFI measurement is expensive and time-consuming and animal ranking may depend on the nature of the diets. We aimed to explore RFI plasma biomarkers and to unravel the underlying metabolic pathways in yearling bulls fed either a corn-silage diet rich in starch (corn diet) or a grass-silage diet rich in fiber (grass diet). Forty-eight extreme RFI animals (Low-RFI, n = 24, versus High-RFI, n = 24, balanced per diet) were selected from a population of 364 Charolais bulls and their plasma was subjected to a targeted LC-MS metabolomic approach together with classical metabolite and hormonal plasma analyses. Greater lean body mass and nitrogen use efficiency, and lower protein turnover were identified as common mechanisms underlying RFI irrespective of the diet. On the other hand, greater adiposity and plasma concentrations of branched-chain amino acids (BCAA) together with lower insulin sensitivity in High-RFI animals were only observed with corn diet. Conversely, greater plasma concentrations of BCAA and total triglycerides, but similar insulin concentrations were noted in efficient RFI cattle with grass diet. Our data suggest that there are diet-specific mechanisms explaining RFI differences in fattening Charolais yearling bulls.

Malgré un net regain d’intérêt, les références techniques sur les systèmes valorisant les races locales bretonnes sont quasi inexistantes. Les éleveurs comme les restaurateurs s’intéressent à la spécificité des produits issus de ces races locales. Si leur qualité est empiriquement reconnue, elle n’a jamais été précisément décrite. Les éleveurs s’interrogent sur les qualités intrinsèques des produits laitiers (fromageabilité, crémeux du lait…), sur leurs qualités organoleptiques, et de façon plus générale, sur la notion de qualité globale des produits, à laquelle sont associées bien évidemment les pratiques de production. L’objectif de ce projet de recherche participative était de mieux connaître les qualités du lait des races locales de vaches laitières dans leurs diverses composantes : qualités intrinsèques mais aussi nutritionnelles et technologiques. Des prélèvements de laits de tank associés à des enquêtes ont été réalisés dans les exploitations participant au projet sur différentes races de vaches (6 en Bretonne Pie Noir et 4 en Froment du Léon). Nous avons effectué les prélèvements pendant trois périodes : avril, juillet et novembre 2017. Nous avons caractérisé les laits au niveau biochimique et technologique. Le lait de Bretonne Pie Noir et de Froment du Léon est plus riche en matières grasses et en protéines que le lait des principales races de vaches françaises. Les variants des protéines sont aussi assez caractéristiques de ces races. Ceci leur confère des propriétés technologiques particulières, comme une meilleure aptitude fromagère mais également une moins bonne aptitude à supporter les traitements thermiques. Ces laits sont également plus jaunes ce qui résulte de concentrations plus élevées en β-carotène et riboflavine, sans que cela soit totalement systématique. Les caractéristiques particulières de ces laits de vaches de race locales méritent d’être mieux valorisées et mises en avant dans des circuits courts de commercialisation.