-The objective of this study was to relate farm feeding practices in different production systems to milk fatty acid (FA) composition on the scale of round tankers. Milks from 10 collection rounds in the French department of the Haute-Loire (10 to 36 herds per collection round) were sampled twice and three times during winter and grazing periods, respectively. The collection rounds were principally characterised by the forage system (grass or maize silage). Nine variants of milk production conditions were defined: four for the winter feeding period (W1 to W4) and five for the grazing period (G1 to G5). Over the year rumenic acid was positively correlated with vaccenic acid (r = 0.99), all the other trans and c11 isomers of C18:1, oleic acid (r = 0.79), linolenic acid (r = 0.82) and eicosapentaenoic acid (C20:5n-3, EPA). The milk fat from cows grazed on grass had a higher proportion of total trans FA (including trans C18:1, non-conjugated C18:2 and c9t11-CLA) and total cis C18:1, and a lower proportion of medium-chain saturated FA (−9.50 g·100 g −1 for C16:0 between G5 vs. W1) and monounsaturated FA (mainly c9-C16:1) than that from grass silage-based (and concentrate-supplemented) diets. Also, C18:0, c9t11-CLA (r = 0.65), t11c15-C18:2, C18:3n-3 (r = 0.68) and EPA (r = 0.64) were positively linked to permanent grassland forages (green or conserved) on the scale of the year. During winter, trans (t6+7+8, t10, t12 and t13+14) and cis (c12, c13 and t16+c14) isomers of C18:1 were positively correlated with the proportion of maize silage in the diet (r = 0.47 to 0.91). The wide range of milk FA composition from the rounds observed in this study was closely linked to the variants in feeding and husbandry conditions. Our data confirm the strong effect of nutritional factors on milk FA composition of tanker milk shown in experimental trials. round tanker milk / farm feeding and husbandry practices / trans, conjugated and n-3 fatty acids / grassland / dairy cow Résumé -Variabilité des acides gras de laits de collecte en fonction des pratiques alimentaires et des conduites d'élevage dans une zone française de semi-montagne. L'objectif de cette étude était, à l'échelle de laits de tournées, d'établir des relations entre les pratiques d'alimentation et les conduites d'élevage de différents systèmes de production et la composition en acides gras (AG) de ces laits. Les laits de 10 tournées dans le département français de la Haute-Loire (10 à 36 troupeaux par tournée) ont été prélevés, respectivement, deux et trois fois pendant l'hiver et la période de pâ-turage. Neuf variants des conditions de production des laits ont été définis : quatre pour la période hivernale (W1 à W4) et cinq pour la période de pâturage (G1 à G5). Au cours de l'année, l'acide ruménique était positivement corrélé à l'acide vaccénique (r = 0.99), à l'ensemble des autres isomères trans et c11 du C18:1, aux acides oléique (r = 0.79), linolénique (r = 0.82) et EPA. La matière grasse laitière provenant du pâturage avait une proportion plus élevée en AG...

The aim of this work was to study the variability in the composition of bulk milk mixtures of fat-soluble compounds (vitamins A and E, carotenoids, and terpenoids) and assess the links with milk production conditions. Milk from 10 collection trips in the French department of the Haute-Loire (10 to 36 herds per trip) was sampled in the tanker twice during the winter period and 3 times during the grazing season. The collection trips differed in their altitude (440 to 1,150 m) and the forage system (grass or based on corn silage). Vitamins A and E, carotenoids, and terpenoids of the 50 tanker loads of milk were analyzed. Data of milk production conditions in the 204 farms made it possible to constitute indicators for the collection trip and to define 50 mean herds. The relationships between mean herd characteristics (breed, stage of lactation, and feed) and milk characteristics were investigated. The constituents of tanker loads of milk were comparable to those observed in milk produced by groups of animals receiving contrasting diets (rich in concentrate or corn silage vs. pasture). The characteristics of the milk differed according to the period; those produced at grazing were more yellow (1.02 +/- 0.4; mean of difference) and richer in beta-carotene, lutein, vitamin E (2.0 +/- 1.2, 0.23 +/- 0.12, and 6.1 +/- 5.0 mug/g of fat, respectively), and sesquiterpenes (2.7 +/- 2.5) than winter. The variations observed for beta-carotene, lutein, and vitamin E were linked to the proportion of grazed grass or grass silage in the forage (r = 0.66, 0.69, and 0.51, respectively), unlike the vitamin A content. During grazing, 20 of the 32 terpenoids identified were associated with the proportion of permanent grassland available for grazing or cut. These results show that feeding is an effective way to modify the quality of dairy products, even in the case of bulk tank milk mixtures. Dairy plants could market different milks, which would contain specific compositions.

The first objective of the present paper was to assess the potential of both isotopic ( (18)O/ (16)O in milk water) and molecular biomarkers (terpenes, fatty acids, carotenoids, and vitamins) and milk color to discriminate the production zone (lowland or upland areas) from which 49 tanker bulk milks were collected over one year from a total of 204 farms. The milk water (18)O enrichment was higher in lowland (<500 m altitude) than in upland (>700 m altitude), but the delta (18)O values failed to discriminate systematically the production zone at the scale of the year because of its high variability related to the sampling period. In contrast with vitamins A and E, carotenoids, and milk color measurements, terpenes and fatty acids were confirmed to be relevant tracers of the production zone. The milk compounds with the strongest discriminative potential were fatty acids, which were determined by high-resolution gas chromatography. The calculation of fatty acid ratios, which permits the limitation of using fatty acid relative quantity expressed in percentage of total fatty acids to be overcome, was shown to be particularly relevant in discriminating upland from lowland milk ratios. The selection of two pairs of ratios, namely, iso-C17:0/C18:3 n-3 and iso-C15:0/iso-C14:0, enabled the authentication of 100% of the highland versus lowland milks whatever the season. The second objective was to evaluate the relevance of fatty acid composition to discriminate milks according to the proportion of corn silage in the diets of dairy cows. The selection of two fatty acids ratios, namely, trans11 cis15-C18:2/trans11-C18:1 and cis9-C16:1/iso-C16:0, enabled the correct classification of 100% of the milk samples according to the proportion of corn silage in the basic fodder rations (<25% vs >30%). The relationship between the milk production zone and the type of forage fed to the cows is discussed.

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°N to 60°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.

The aims of this work were to elucidate the potential of using milk fatty acid (FA) concentration to predict cow diet composition and altitude of bulk milk collected in 10 different European countries and to authenticate cow-feeding systems and altitude of the production area using a data set of 1,248 bulk cow milk samples and associated farm records. The predictions based on FA for cow diet composition were excellent for the proportions of fresh herbage [coefficient of determination (R2)=0.81], good for hay, total herbage-derived forages, and total preserved forages (R2>0.73), intermediate for corn silage and grass silage (R2>0.62), and poor for concentrates (R2<0.51) in the cow diet. Milk samples were assigned to groups according to feeding system, level of concentrate supplementation, and altitude origin. Milk FA composition successfully authenticated cow-feeding systems dominated by a main forage (>93% of samples correctly classified), but the presence of mixed diets reduced the discrimination. Altitude prediction reliability was intermediate (R2<0.62). Milk FA composition was not able to authenticate concentrate supplementation level in the diet (<58% of samples correctly classified). Similarly, the altitude origin was not successfully authenticated by milk FA composition (<76% of samples correctly classified). The potential of milk FA composition to authenticate cow feeding was confirmed using a data set representative of the diversity of European production conditions.

-The aim of this correlational study was to: (1) characterize the composition of cow's milk farmhouse cheeses in terms of average contents and variability in fatty acids, retinol, α-tocopherol, folate, β-carotene, xanthophylls, calcium, phosphorus, magnesium, potassium, zinc, sodium chloride and total antioxidant capacity (TAC) and (2) identify herd characteristics and feeding practices associated with differences in cheese composition. Three hundred and six farmhouse pressed cheeses, produced under real herd management conditions throughout the year, were collected. The conditions of milk production were identified beforehand by means of surveys. The farmhouse cheese was characterized by a high variability in composition. The nature of the basic fodder ration (pasture vs. preserved forages, in particular) explained a great part of the variability in the fat-soluble components in the cheese. The cheese fat was richer in C4:0, C18:0, cis-9 C18:1, trans-11 C18:1, cis-9, trans-11 C18:2 (CLA), β-carotene, xanthophylls, retinol, α-tocopherol and TAC and poorer in C10:0, C14:0 and C16:0 with the pasture-based rations compared with the preservedforage-based rations. In the grazing period, it was the poorest in C6:0 to C14:0, β-carotene and retinol and the richest in cis-9 C18:1, C18:2 n-6 and C18:3 n-3 with the alpine pasture. It was higher in trans-11 C18:1, CLA, β-carotene and xanthophylls and lower in C16:0 with a first-use pasture compared with a pasture of higher use rank. A higher percentage of concentrate was associated with higher levels of C14:0 and C16:0 and lower levels of trans-11 C18:1, CLA, C18:2 n-6, C18:3 n-3, xanthophylls and retinol. In the indoor feeding period, the cheese fat was the poorest in trans-11 C18:1, CLA, C18:3 n-3 and β-carotene with the maize-based rations, while the vitamin A and E supplementation was associated with higher retinol and α-tocopherol contents, respectively. Herd characteristics did not markedly affect the cheese composition, except the breed. In particular, Abondance and Montbéliarde breeds were associated with higher CLA percentage in the cheese than the * Corresponding author (通讯作者): jbc@clermont.inra.frArticle published by EDP Sciences and available at http://www.edpsciences.org/lait or http://dx

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.

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