The contribution of mountain pastures to the link to terroir in dairy and meat products

Publishe

Bacterial Community Profiling of Milk Samples as a Means to Understand Culture-Negative Bovine Clinical Mastitis

Inflammation and infection of bovine mammary glands, commonly known as mastitis, imposes significant losses each year in the dairy industry worldwide. While several different bacterial species have been identified as causative agents of mastitis, many clinical mastitis cases remain culture negative, even after enrichment for bacterial growth. To understand the basis for this increasingly common phenomenon, the composition of bacterial communities from milk samples was analyzed using culture independent pyrosequencing of amplicons of 16S ribosomal RNA genes (16S rDNA). Comparisons were made of the microbial community composition of culture negative milk samples from mastitic quarters with that of non-mastitic quarters from the same animals. Genomic DNA from culture-negative clinical and healthy quarter sample pairs was isolated, and amplicon libraries were prepared using indexed primers specific to the V1–V2 region of bacterial 16S rRNA genes and sequenced using the Roche 454 GS FLX with titanium chemistry. Evaluation of the taxonomic composition of these samples revealed significant differences in the microbiota in milk from mastitic and healthy quarters. Statistical analysis identified seven bacterial genera that may be mainly responsible for the observed microbial community differences between mastitic and healthy quarters. Collectively, these results provide evidence that cases of culture negative mastitis can be associated with bacterial species that may be present below culture detection thresholds used here. The application of culture-independent bacterial community profiling represents a powerful approach to understand long-standing questions in animal health and disease

Effet des systèmes de production sur les caractéristiques sensorielles du fromage de Cantal AOC.

National audienc

Effets respectifs d'une alimentation à base d'herbe et de la transformation fromagère sur la composition en acides gras d'intérêt nutritionnel de fromages de type Saint-Nectaire ou Cantal

National audienc

Extruded linseeds, vitamin E and plant extracts in corn silage-based diets of dairy cows: Effects on sensory properties of raw milk and uncooked pressed cheese

International audienceLinseed supplementation of dairy cows' diet increases unsaturated fatty acid (FA) concentrations, which could lead to oxidised off-flavours in dairy products if antioxidant content is low. The FA profiles and sensory properties of milk and uncooked pressed cheese (Saint-Nectaire type) from four groups of six cows receiving a corn silage-based diet with no additional lipid (control), or supplemented with extruded linseeds (5% of additional fat-in-dry matter intake; EL), EL and vitamin E (7500 IU per cow per day of DL-alpha-tocopherol; ELE), or ELE and plant extracts rich in carotenoids and polyphenols (1% of dry matter intake) were compared. Feeding EL decreased milk and cheese 4- to 16-carbon saturated FA, and increased 18:1 cis-9, 18:3n-3 and total trans FA concentrations. Extruded linseeds did not induce oxidised off-flavours but led to a less firm and more meltable texture in cheese. Vitamin E supplementation increased a-tocopherol concentration, but did not affect sensory properties

Feeding cows with hay, silage, or fresh herbage on pasture or indoors affects sensory properties and chemical composition of milk and cheese

International audienceIn European countries, silage-free feeding is an ancient tradition and has a particularly positive reputation among consumers. In the present study, we compared grass-based forages from the same plot conserved as hay or silage or fed fresh either on pasture or indoors, and we evaluated the differences in sensory properties of milk and uncooked pressed cheese. All herbage from the first cut of a grassland dominated by perennial ryegrass was harvested on the same day and preserved either as hay or silage. The first regrowth of the same plot was used for strip grazing or green feeding indoors. Balanced by breed, 24 Montbeliarde and 24 Holstein cows were allocated to the 4 treatments. Apart from the forages, the late-lactation cows received 3 kg/d of dry matter from concentrate. After 2 wk of dietary adaptation, the bulk milk of 3 subgroups, each with 4 cows, was collected. Part of the milk was pasteurized, and part was left raw and partly transformed to small-sized Cantal-type cheese ripened for 9 wk. Milk and cheese underwent descriptive sensory analysis by a trained sensory panel, as well as analyses of physicochemical traits. Volatile organic compounds of the cheeses were also analyzed. Raw and pasteurized milk from hay-fed cows had less intense odors of cooked milk, cream, and barnyard than milk from grazing cows, whereby the effect of pasteurization did not differ between herbage utilization methods. Cheeses obtained from cows fed fresh herbage (grazing and indoors) were clearly yellower than cheeses from silage- and hay-fed cows, which coincided with the color intensity perceived by the panelists. Moreover, cheeses from cows fed fresh herbage had more intense barnyard and dry fruit flavors, were perceived as creamier and having less lactic odor, and exhibited more fat exudation than those from cows fed conserved herbage. Only a few differences were observed in milk and cheeses from hay-fed compared with silage-fed cows, and those differences were far less pronounced than those of milk and cheeses from cows fed fresh herbage. In conclusion, the present study did not substantiate assumptions of clear sensory differences of milk and uncooked pressed cheese from hay-fed compared with silage-fed cows. For the first time, this study reports that the global flavor intensity of cheeses from indoor green-fed cows is similar to that of cheeses derived from cows fed conserved forages, whereas cheeses from grazing cows have the greatest global flavor intensity.