Authentication of cow feeding and geographic origin on milk using visible and near-infrared spectroscopy.

International audience; The ability of near-infrared spectroscopy to trace cow feeding systems and farming altitude was tested on 486 bulk milk samples from France and northwestern Italy. Milks were grouped into feeding systems according to the main forage in the diet. Partial least square discriminant analysis correctly classified 95.5, 91.5, and 93.3% of pasture versus maize silage, hay, and fermented herbage feeding systems, respectively. Discrimination was slightly less successful when diets with large proportions of the nondominant forage were included in each group. Near-infrared spectroscopy correctly discriminated no-pasture from pasture milk, even with only 30% of pasture in the diet (5.4% cross-validation error), and the error stabilized when pasture exceeded 70% (2.5% error). Near-infrared spectroscopy did not reliably trace milk geographic origin when the feeding system effect was isolated from the altitude effect. These findings may be usefully exploited for the authentication of dairy products

Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys

International audience; The aim of this study was to predict the fatty acid (FA) composition of bulk milk using data describing farming practices collected via on-farm surveys. The FA composition of 1,248 bulk cow milk samples and the related farming practices were collected from 20 experiments led in 10 different European countries at 44 degrees N to 60 degrees N latitude and sea level to 2,000 m altitude. Farming practice-based FA predictions [coefficient of determination (R-2) >0.50] were good for C16:0, C17:0, saturated FA, polyunsaturated FA, and odd-chain FA, and very good (R-2 >= 0.60) for trans-11 C18:1, trans-10 + trans-11 C18:1, cis-9,trans-11 conjugated linoleic acid, total trans FA, C18:3n-3, n-6:n-3 ratio, and branched-chain FA. Fatty acids were predicted by cow diet composition and by the altitude at which milk was produced, whereas animal-related factors (i.e., lactation stage, breed, milk yield, and proportion of primiparous cows in the herd) were not significant in any of the models. Proportion of fresh herbage in the cow diet was the main predictor, with the highest effect in almost all FA models. However, models built solely on conserved forage-derived samples gave good predictions for odd-chain FA, branched-chain FA, trans-10 C18:1 and C18:3n-3 (R-2 >= 0.46, 0.54, 0.52, and 0.70, respectively). These prediction models could offer farmers a valuable tool to help improve the nutritional quality of the milk they produce

Effet de la forme de présentation de l'orge sur la production et la composition du lait de vache

International audienc

The effect of feeding sequence on fat concentration in milk

International audienc

Facteurs de variations du rapport des teneurs en matières grasses et protéiques du lait de vache : étude dans les exploitations des Alpes du Nord

Soixante deux exploitations laitières des Alpes du Nord ont fait l’objet d’une enquête détaillée concernant à la fois la structure de l’exploitation et du troupeau, la qualité des fourrages et les pratiques alimentaires hivernales et estivales. Ces données ont permis d’analyser les variations de la composition chimique du lait d’une exploitation à l’autre, et en particulier du rapport taux butyreux/taux protéique. Celui-ci a présenté des variations très importantes d’une exploitation à l’autre et d’un mois à l’autre. Selon les exploitations, ces variations sont dues surtout à celles du taux butyreux (cas le plus fréquent), ou plutôt à celles du taux protéique. Les différences de niveau de ce rapport d’une exploitation à l’autre sont difficiles à expliquer par les seules données disponibles : en particulier, compte tenu du type des vaches présentes (Abondance, Tarine et Montbéliarde), l’effet de la race ne semble pas prépondérant. Ce sont les exploitations qui maîtrisent le mieux l’alimentation hivernale et estivale des animaux (et qui présentent par ailleurs des effectifs importants et stables au cours de l’année) qui ont présenté les rapports les plus stables au cours de l’année.A detailed survey was conducted on 62 dairy farms located in the northen Alpes to determine some of the factors in herd management that influence milk fat content: protein content ratio (FC/PC). Large variations were noted between farms (1.10 to 1.25) and between months in the same farm. Depending on the farms, these variations result mainly either from differences of fat content (more frequent situation) or from differences of protein content. Differences of FC/PC among farms were not well related to the different herd characteristics avalaible. Low FC/PC variations between months in the same farm were associated with good feeding practices (during winter and summer)

Facteurs de variation de la numeration cellulaire du lait en exploitation

International audienc