Benoît Graulet

MicroRNAs (miRNAs) are small regulatory RNAs that regulate numerous biological processes and potentially impact human health. Despite their abundance in raw milk, little is known about their content in processed dairy products or how manufacturing affects their abundance and bioavailability. We characterized and compared the miRNA profiles of yogurt and cheese produced from the same raw milk from cows raised under agroecological or intensive systems, assessing compositional changes during processing, while accounting for farming system effects. High-throughput sequencing identified a total of 1,384 miRNAs, including 258 common to all matrices, forming a conserved milk-derived core. Processing into yogurt or cheese reduced milk-specific miRNAs while introducing microbial small RNAs from fermentation bacteria such as Lactococcus and Streptococcus thermophilus. Differential analysis revealed stable miRNomes across agroecological and intensive farming systems, but substantial processing-associated changes involving 29 and 353 miRNAs during cheese and yogurt production, respectively, and some miRNAs showed matrix-specific stability. These miRNAs were predicted to influence cell proliferation, metabolism, and protein-related pathways, suggesting shifts in the regulatory impact of milk-derived miRNAs in fermented dairy products. Overall, these findings underscore the dynamic nature of dairy miRNomes and the combined influence of processing and microbial activity in shaping miRNA composition.

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 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.

Background: Early lactation is a period at risk for mastitis. Our objective was to investigate the influence of nutritional vitamin E and plant extracts on redox and immune status at the systemic and local mammary levels during an inflammatory challenge in dairy cows. Thirty-six Holstein cows were placed in three groups: a ‘control’ group (n = 11) unsupplemented; a ‘vitamin E’ group (n = 13), supplemented with 3000 IU/d for 4 weeks before calving and 1000 IU/d for 4 weeks after calving; and a ‘plant extracts’ group (n = 14) supplemented with 10 g/d for 4 weeks before and after calving. Lipopolysaccharide (LPS) from Escherichia coli was infused into a one-udder quarter of the cows 5 weeks after calving. Blood and milk samples were collected before and 4, 7, 9, 28, and 76 h after the LPS infusion. Results: In the plant extract group, antioxidant gene ( NQO1 ), superoxide dismutase activity 4 hours after the LPS challenge and total antioxidant capacity were increased compared to the control group. In the vitamin E group, expression of the antioxidant gene ( SOD3 ) and glutathione peroxidase activity were more elevated than in the control group. Systemic immunity appeared to be reduced by antioxidant supplementations, with a higher migration of classical neutrophils in the plant extract group and less ROS production of neutrophils in the vitamin E group. However, immune capacities were increased at the local level in classical neutrophils (ROS production and phagocytosis) in both the plant extract and vitamin E groups. Following the LPS infusion, supplementation did not reveal any differences in terms of rectal temperature, milk yield or milk cell counts, but it did have a positive effect on mammary epithelium integrity (lower milk Na ⁺ :K ⁺ ratio and higher OCLN gene expression). In addition, the plant extracts stimulated the synthesis of milk constituents, with higher milk protein gene expressions ( LALBA , CSN3 , CSN1S1 ) and a tendency towards a higher lactose content in milk. Conclusion: The LPS challenge showed that vitamin E or plant extracts enhanced the local inflammatory response while preserving systemic antioxidant capacities, integrity of the mammary gland and the composition of milk, and thus possibly contributing to preventing mammary infection in early lactating dairy cows.

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 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 weeks 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 (α_S1-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.

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.