Search

National audience; L’organisation et la taille d’un dispositif expérimental dans un organisme de recherche agronomique sont des questions qui conditionnent la pertinence et la qualité de ses résultats scientifiques et appliqués et les moyens qui lui sont consacrés. Pour faire évoluer une partie des unités expérimentales du département Inra « Physiologie animale et systèmes d’élevage » et les adapter au contexte futur des recherches, une prospective a été engagée en 2005. En s’appuyant sur une prospective plus large réalisée au niveau de l’Institut (Prospective « INRA 2020 »), plusieurs scénarios ont été construits puis analysés à l’horizon 2025, par un groupe de travail sous la responsabilité d’un chef de projet externe. Des consultations des partenaires professionnels, des élus locaux, et des personnels des unités concernées ont servi de base pour la construction de ces scénarios. In fine, quatre scénarios ont été proposés à la direction générale qui a retenu celui de l’infrastructure européenne de recherche. Il a ensuite été décliné en huit scénarios opérationnels alors évalués par six critères principaux concernant : i) la capacité d’expérimentation ; ii) l’efficacité du dispositif ; iii) le bilan environnemental ; iv) la faisabilité de la mise en œuvre ; v) les constructions, aménagements, démolitions nécessaires et leur coûts estimés ; et vi) les ressources humaines. Finalement, ce scénario a été mis en œuvre, dans ses dimensions sociale, foncière, immobilière et fonctionnelle, à partir de mi-2009. À chaque étape de la démarche, un travail de partage et d’explicitation des réflexions et des décisions a été réalisé, permettant d’en partager les objectifs, d’en comprendre les enjeux collectifs, et de s’inscrire dans cette mutation d’ensemble. Cette démarche prospective innovante, explorant en plusieurs étapes des scénarios construits et partagés, permettra à terme une évolution forte des unités expérimentales, appuyée sur une démarche rationnelle, chiffrée et argumentée par rapport aux évolutions externes et internes de la recherche agronomique.

The characteristics of animal products depend on a number of factors linked both to cheese-making technology and to the chemical and microbiological characteristics of the raw material used. These characteristics are themselves dependent on upstream factors (genetic, physiological, or dietary). Those upstream factors have increasingly been the focus of consumers'concern, in particular those related to animal feeding. They take special importance in the case of labelled products (Protected Designation of Origin (PDO), Protected Geographical Indication (PDI), etc.) which claim close links with production conditions. During last years, a number of works have been done to precise, in experimental conditions, the effects of each of these factors on the different dimensions of quality (sensorial, nutritional, hygienic...), as well as their integrated effects when they are observed in a more systemic approach, in the frame of farming systems. Examples from different species (poultry, pork, fish, bovine) are given to illustrate some of these effects.

L'objectif de cette etude correlationnelle etait de : (1) caracteriser la composition de fromages fermiers au lait de vache en termes de teneurs moyennes et de variabilite en acides gras, retinol, α-tocopherol, folate, β-carotene, xanthophylles, calcium, phosphore, magnesium, potassium, zinc, chlorure de sodium et potentiel antioxydant total (TAC), et (2) identifier les caracteristiques du troupeau et les pratiques alimentaires associees a des differences de composition du fromage. Trois cent six fromages fermiers a pâte pressee, produits en conditions reelles tout au long de l'annee, ont ete preleves. Les conditions de production du lait ont ete prealablement identifiees au moyen d'enquetes. Le fromage fermier se caracterise par une grande variabilite de composition. La nature de la ration fourragere (pâturage vs. fourrages conserves, en particulier) explique une grande partie de la variabilite en composes liposolubles du fromage. La matiere grasse du fromage est plus riche en C4:0, C18:0, C18:1 cis-9, C18:1 trans-11, C18:2 cis-9, trans-11 (CLA), β-carotene, xanthophylles, retinol, α-tocopherol et TAC et plus pauvre en C10:0, C14:0 et C16:0 avec les rations a base de pâturage comparees aux rations a base de fourrages conserves. En periode de pâturage, elle est la plus pauvre en C6:0 a C14:0, en β-carotene et en retinol et la plus riche en C18:1 cis-9, C18:2 n-6 et C18:3 n-3 avec un pâturage en alpage. Elle est plus riche en C18:1 trans-11, CLA, β-carotene et xanthophylles et plus pauvre en C16:0 avec un pâturage de premiere utilisation compare a un pâturage d'utilisation de rang superieur. Un pourcentage plus important de concentre est associe a des niveaux plus importants en C14:0 et C16:0 et plus faibles en C18:1 trans-11, CLA, C18:2 n-6, C18:3 n-3, xanthophylles et retinol. En hiver, la matiere grasse du fromage est la plus pauvre en C18:1 trans-11, CLA, C18:3 n-3 et β-carotene avec les rations a base de mais, tandis que la supplementation en vitamines A et E est associee a des niveaux plus importants de retinol et d'a-tocopherol, respectivement. Les caracteristiques du troupeau ont peu d'incidence sur la composition du fromage excepte la race. En particulier, les races Abondance et Montbeliarde sont associees a un pourcentage en CLA plus eleve dans le fromage que la race Holstein, alors que la teneur en carotenoides du fromage est la plus elevee avec la race Montbeliarde et la plus faible avec la race Abondance.

De facon a etudier la relation entre les conditions de production du lait et les teneurs en composes d'interet nutritionnel dans le fromage, il est necessaire de savoir dans quelle mesure la variabilite de composition du fromage depend de celle du lait d'origine. Les effets respectifs de la composition du lait et de la transformation fromagere sur la variabilite de composition du fromage en composes d'interet nutritionnel ont donc ete etudies en conditions reelles de production du fromage et en considerant quatre technologies fromageres differentes. Les caracteristiques nutritionnelles du lait a l'origine du fromage sont soumises a de grandes variations en partie dues a l'espece animale (vache vs. chevre). Mis a part les aspects lies a la teneur en matiere seche du fromage, la variabilite de composition du fromage en acides gras, en β-carotene, en xanthophylles et en vitamine E depend principalement de la composition du lait d'origine, alors que pour la vitamine A celle-ci est influencee a la fois par la composition du lait d'origine et par la transformation fromagere. Par contre, la composition en folates et en mineraux du fromage, ainsi que son potentiel antioxydant total, varient principalement avec la transformation fromagere. Par ailleurs, le type de technologie fromagere exerce un effet important sur la composition du fromage en mineraux et en folates, mais n'a aucun effet sur les autres composes influences par la transformation fromagere. En consequence, la teneur du fromage en composes liposolubles, contrairement aux composes hydrosolubles, depend directement des conditions de production du lait. Le potentiel antioxydant total des fromages a pâte pressee, a la difference de leur lait d'origine, est positivement correle avec certains composes antioxydants liposolubles. Il pourrait par consequent etre influence par les conditions de production du lait.

International audience; Six groups of six cows each, on two distinct sites, were fed on pasture and silage. Two analytical methods were employed, NMR to determine the proportions of polyunsaturated (PUFA), monounsaturated (MUFA) and saturated fatty acids (SFA) in milk fat and IRMS to measure the (18)O enrichment of milk water. The fatty acid composition was sensitive to the diet while IRMS results were more influenced by the production area. A discriminant analysis showed that high resolution NMR and IRMS are two complementary methods suitable for the authentication of milk according to the feeding diet and geographic origin.

Summary Thirty-five representative samples of milk from either a highland area of France (Auvergne region) or a lowland area of France (Brittany region) were collected in spring and summer (grazing periods), and in winter (stabling period). The monoterpenes and sesquiterpenes extracted from the milk fat were semi-quantified by dynamic headspace–gas chromatography–mass spectrometry (DHS-GC-MS). Milk samples were classified by factorial discriminant analysis. Milk collected in the Auvergne highland area was richer in sesquiterpenes than that collected in the Brittany lowland area. All the samples were correctly classified according to their geographical origin irrespective of seasonal herd management pattern. These findings show that the assay of terpene compounds can provide useful fingerprints for the characterization of dairy produce according to geographical area and production conditions.

L’influence de la nature des pâturages sur les caractéristiques des laits et des fromages a été étudiée dans la zone AOP Abondance à partir de 10 pâturages exploités par trois producteurs de lait fabriquant eux-mêmes leur fromage. L’expérimentation a débuté avant la mise à l’herbe avec une alimentation au foin commune aux trois troupeaux, afin d’estimer les variations dues au troupeau. Les caractéristiques des fourrages consommés ont été mesurées, ainsi que celles des laits et des fromages correspondants sur trois jours consécutifs. Les caractéristiques sensorielles des fromages, et en particulier leur texture, ont varié sensiblement selon la nature des fourrages consommés. La texture des fromages a pu être mise en relation avec l’activité de la plasmine et les proportions d’acides gras longs poly-insaturés, plus élevées dans les laits issus des pâturages de haute altitude (> 1500 m), et avec la vitesse d’acidification sous presse, plus faible pour certains pâturages. Des différences d’arôme des fromages ont été observées en fonction des pâturages, en relation avec la protéolyse secondaire et la composition en éléments volatils de ces fromages. Un transfert direct des terpènes des fourrages vers les laits puis les fromages a été mis en évidence, avec un rôle sans doute indirect sur l’arôme des fromages, via une modification de l’activité métabolique des microorganismes au cours de l’affinage. L’amertume de certains fromages a été associée à un retard d’acidification sous presse. Les relations entre nature des pâturages et caractéristiques des fromages ont été essentiellement indirectes.

The relation between the useful material content (protein+fat content) of milk and cheese yield was analyzed on 189 manufactures of pressed uncooked cheeses. These manufactures were realized under controlled conditions in the same experimental cheese dairy, within the frame- work of eight different experiments, from milks of high hygienic quality (cows free of clinical mas- titis) partially skimmed so as to have a fat/protein ratio of 1.15. The fat+protein content of manufactured milks varied from 55 to 85 g.kg -1 . The relation between fat+protein content and cheese yield was lin- ear for this wide range of variation. Fat+protein content accounted for 77% of fresh yield and 87% of dry matter yield variability. Once the effect of fat and protein contents have been taken into account, other milk parameters (pH, κ-casein variants) may have a significant effect on cheese yield, but in a marginal way. milk / fat and protein contents / cheese yield

The transfer of monoterpenes and sesquiterpenes from forages into milk fat was stud- ied in a group of cows fed successively with forages containing high and low amounts of these sub- stances. In a first 24-d period the cows received 11 kg of a cocksfoot hay containing low quantities of monoterpenes and sesquiterpenes. In a second 36-d period, 3 kg of the cocksfoot were replaced by 3 kg of yarrow, a plant rich in terpenoids. In a third 24-d period the cows returned to the cocksfoot- based diet they were fed in the first period. The quantities of monoterpenes and sesquiterpenes des- orbed from the milk fat were measured by dynamic headspace - gas chromatography - mass spec- trometry. Results showed that the quantities of monoterpenes had increased by the first milking carried out 8 h after ingestion of yarrow, whereas the increase in the quantities of sesquiterpenes was observed only after the third milking, 32 h after the diet change. The maximal quantities of monoterpenes and sesquiterpenes were measured after 4 d of the yarrow-enriched diet, after which the total quantities decreased, despite the constant supply of yarrow. Four days after discontinuing yarrow the amounts of monoterpenes and sesquiterpenes desorbed from the milk fat reverted to those measured during the first period. traceability / type of feeding / terpenoid analysis / purge-and-trap / gas chromatography-mass spectrometry

Forty-two multiparous dairy cows of 3 different breeds (Holstein, Montbeliarde and Taren- taise) were divided into 2 groups (A and B) according to β- and κ-casein genetic variants, and were fed 3 floristically different types of hay (cocksfoot, rye-grass-rich and native mountain grassland hay) according to a 3 〈 3 Latin-square design. The milk produced by these cows was used to make Saint-Nectaire-type cheese, using identical and controlled cheesemaking techniques. The cheeses made from cocksfoot diet milk had higher pH (P < 0.01), lower fat in dry matter ( P < 0.05), more elas- tic texture and a strong cellar odour ( P < 0.1). The cheeses produced from the milk of cows fed native mountain grassland hay exhibited a slightly gritty and yellower body, and had a pronounced vinegar and cabbage odour. Rheological analysis confirmed the beneficial effect of the B variant of β- and κ-caseins on milk rennet clotting ability. This effect did not seem to affect the cheeses because they could not be distinguished by any of their sensory characteristics. milk / cheese / genetic variant / diet

Effect of milk composition and herd management conditions on the characteristlcs of farmhouse saint-nectaire cheese. This study was performed in 23 farms producing raw milk saint-nectaire cheeses, chosen on their good processing ability. Chemical and sensory analysis were do ne on 67 cheeses made in these farms during winter. Important variability of chemical and sensory characteristics was observed between cheeses. Six main groups of cheeses were, identified, based on sensory characteristics, texture and flavour descriptors being the most discriminant. Chemical and bacteriologica1 characteristics of milk were not very different between groups. Differences between groups were associated either to processing parameters (type of starters) or feeding condi- tions of the cows (concentrate proportion in the diet). The type of roughage (hay vs fermented roughage) was not different between groups of cheeses. © Inra/Elsevier, Paris. cheese / feeding / sensory characteristic

Chez 50 vaches Holstein (15 primipares), nous avons etudie l'effet de la traite temporaire une fois par jour, a partir du velage, sur la production laitiere et l'etat nutritionnel. Les vaches primipares ont ete reparties en deux lots: un lot temoin (Pc) trait en permanence 2 fois/j et un lot experimental (P3) trait une fois/j pendant les trois premieres semaines de lactation puis deux fois par jour. Les vaches multipares ont ete reparties en trois lots: un lot temoin (Mc) trait en permanence deux fois par jour ; un lot experimental trait une fois par jour pendant les trois premieres semaines de lactation puis deux fois par jour (lot M3) ; un autre lot experimental trait une fois par jour pendant les six premieres semaines de lactation puis deux fois par jour (lot M6). L'essai s'est termine a la fin de la periode hivernale. La traite une fois par jour n'a pas semble provoquer d'inconfort chez les vaches. Elle a diminue la production laitiere de 2,7 kg.j -1 en 1 re semaine de lactation, de 8,4 kg.j -1 en 3 e semaine, et de 14,5 kg.j -1 en 6 e semaine. Son effet n'a pas ete different entre les vaches primipares et multipares (p > 10 %). Des la premiere semaine de traite deux fois.j -1 , la production laitiere des vaches experimentales a augmente de 6,8 kg.j -1 (difference non significative entre les lots P3, M3 et M6). A partir de la semaine 7 la production laitiere des lots P3 et M3 a ete, en moyenne, plus faible que celle des lots Pc et Mc de 2,4 kg.j -1 en moyenne, et celle du lot M6 a ete plus faible que celle du lot Mc de 5,4 kg.j -1 en moyenne. Le taux proteique du lait des vaches traites une fois par jour a ete plus eleve que celui des vaches temoins, de 2,4 g.kg -1 pendant les periodes experimentale et post-experimentale. Le nombre de cellules somatiques dans le lait n'a pas ete significativement different entre les lots. Les vaches traites une fois.j -1 ont perdu moins d'etat corporel et moins de poids vif en debut de lactation que les vaches temoins, et elles ont presente un bilan energetique moins negatif ou plus positif (difference significative pour le lot M6). Le profil sanguin (teneurs en glucose, acides gras libres, 3-hydroxybutyrate) a atteste un meilleur equilibre energetique des vaches traites une fois par jour en debut de lactation. Cet essai suggere que les vaches fortes productrices supportent sans inconvenient apparent d'etre traites une fois par jour pendant le debut de la lactation et qu'il pourrait etre envisageable d'alimenter ces animaux avec des regimes plus pauvres en concentres que maintenant, sans accroissement des risques sanitaires.

L’objectif de cette étude a été de préciser et de hiérarchiser les différents facteurs de variation de la proportion entre les caséines et les protéines totales dans le lait de vache. Au total 29 essais, tous effectués dans les unités de l’INRA de Rennes ou de Theix et regroupant 821 lactations ont été utilisés. Pour 551 de ces lactations, les variants génétiques des lactoprotéines avaient été déterminés. Les autres lactations faisaient partie d’essais dans lesquels les animaux étaient leurs propres témoins. Le principal facteur de variation de ce rapport est le polymorphisme génétique de la beta-lactoglobuline : toutes choses étant égales par ailleurs, les animaux de type BB présentent un rapport supérieur, de près de 3 points, à celui des vaches de type AA. Le variant B de la caséine kappa exerce aussi un effet favorable (+1,2 points à l’avantage des animaux BB). En dehors de la première semaine de lactation et des deux dernières semaines de gestation, le rapport caséines/protéines varie peu au cours de la lactation mais tend à diminuer légèrement en fin de lactation. Ce rapport est significativement diminué lorsque la numération cellulaire du lait dépasse 200 000 cellules/ml. Il diminue par ailleurs légèrement avec l’âge. Parmi les différents facteurs alimentaires étudiés (niveau et nature des apports énergétiques et azotés, mode de conservation et nature des fourrages), aucun n’a eu un effet significatif sur le rapport caséines/protéines du lait, sauf dans des conditions de sous-alimentation très prononcées. Ce rapport augmente très légèrement avec le niveau de production laitière des animaux et le taux protéique du lait. En pratique, la mesure du taux protéique du lait, chez des animaux indemnes de mammites reste donc un très bon indicateur du taux de caséines, dont il explique à lui seul 93 % des variations., The aim of this study was to identify and rank the various factors, in particular feeding ones, affecting the proportion of caseins in milk true protein. Twenty nine feeding trials involving 821 lactations were used. Lactoprotein genetic variants were known for 551 of these lactations. The main factor affecting the casein/protein ratio was the genetic polymorphism of beta-lactoglobulin: once corrected for other factors, BE type animals exhibited a ratio nearly 3 g/100 g higher than AA animals, kappa-casein variant B also had a positive effect (+ 1.2 g/100 g in favour of BE animals relative to AA animals). Except in the first week of lactation and in the two last weeks of pregnancy, the casein/protein ratio varied little during lactation. It was significantly reduced when milk cell count exceeded 200 000 cells/ml, even without clinical mastitis. It also decreased slightly with parity. Among the various dietary factors studied (level and type of nitrogen and energy supplies, forage type and preservation method), none had any significant effect on the milk casein/protein ratio, except in drastic dietary situations. That ratio increased very slightly in parallel with the animals' milk yield and milk protein content. In practice, measuring the milk protein content in animals free of clinical mastitis remains a very precise predictor of casein content, accounting for 93% of its variation.

The aim of this study was to identify and rank the various factors, in particular those involving feeding, that affect the proportion of caseins in milk true protein. Twenty-nine feeding trials involving 821 lactations were assessed, and lactoprotein genetic variants were known for 551 of these. The main factor affecting the casein: protein ratio was the genetic variant of β-lactoglobulin: once corrected for other factors, the milk of BB type animals had a ratio nearly 30 g/kg total protein higher than AA animals. κ-Casein variant B also had a positive effect (+12 g/kg in favour of BB relative to AA animals). Except in the last weeks of pregnancy and the first weeks of lactation, the casein[ratio ]protein ratio varied little during lactation. It was significantly reduced when milk cell count exceeded 200000 cells/ml, even in the absence of clinical mastitis. It also decreased slightly with parity. Among the various dietary factors studied (level and type of nitrogen and energy supplies, forage type and preservation method), none had any significant effect on the milk casein[ratio ]protein ratio, except in drastic dietary situations. That ratio increased very slightly in parallel with the animals' milk yield and milk protein content. In practice, measuring the milk protein content in animals free from clinical mastitis remains a very precise predictor of casein content, accounting for 93% of its variation.

Thirty-two cows (16 Montbeliardes and 16 Tarentaises) in midlactation were used in an experiment utilizing a 2 × 2 factorial arrangement of treatments. Throughout the trial, cows received first-cutting cocksfoot hay for ad libitum intake supplemented with a fixed amount of concentrate that was individually adapted to the milk yield of each cow. During a 23-d experimental period, one group of cows walked 9.6 km/d; the other group of cows remained in the barn. Cows that walked daily ate less hay (–1.3 and –2.1 kg/d of dry matter for Tarentaise and Montbeliarde cows, respectively) and yielded less milk (–1.7 and –2.5 kg/d for Tarentaise and Montbeliarde cows, respectively) than did cows that did not walk daily. A residual effect of walking on milk yield was observed during the 10 d following the experimental period. For both breeds, fat content and, to a lesser extent, protein content were higher (+6.4 and +1.0 g/ kg, respectively) for cows that walked. Somatic cell count was also higher for cows that walked (+115,000 cells/ml). This difference was more marked in cows that were initially infected by a minor or major pathogen (+185,000 cells/ml) than in uninfected cows (+47,000 cells/ml) and on the 1st d of walking when walking was linked to increases in pH, bovine serum albumin, and immunoglobulin G 1 contents of milk (+0.08 unit, +0.16g/L, and +0.19g/L, respectively). Throughout the experimental period, walking induced a rise in body temperature (+1°C) and in plasma nonesterified fatty acids (+0.63m M /L). On the 1st d of walking, plasma glucose, lactic acid, and cortisol contents were significantly higher for cows that walked (+0.25g/L, +0.64g/L, and +28.8ng/ml, respectively).

It has previously been shown that it is possible to distinguish milks from different geographical locations and feeding diets. The 18O enrichment values measured by isotope ratio mass spectrometry appeared to be the most discriminant parameter for both the geographic origin and the diet. The aim of this study is to examine the influence of the breed of cow on the isotopic enrichments of milk water when the animals were kept in the same environment and fed on the same diet. The present results indicate that the breed of cow influences the isotopic enrichments of milk. The effect is, however, of small magnitude and unlikely to diminish the capacity of δ18O measurements to discriminate between different diets and production sites.

L'effet d'une marche repetee sur la production et la composition du lait a ete etudie au pâturage sur 60 vaches laitieres multipares en pleine lactation de race Holstein, Montbeliarde et Tarentaise. Intrarace, trois lots de six a huit vaches ont ete constitues. Le premier lot (lot M) a marche 9,6 km/jour tous les 2 jours pendant 9 jours. Le second lot (lot T) restait sur une aire d'attente pendant la duree de la marche du lot M. Le troisieme lot (lot P) restait au pâturage pendant les marches. En moyenne sur les 9 jours, la production laitiere a ete significativement plus faible dans les lots M que dans les lots T. L'ecart a ete de 0,7 kg/jour chez les vaches Tarentaises et de 1,5 kg/jour chez les vaches Holstein et Montbeliardes. La repetition de la marche n'a entraine ni reduction ni accentuation de l'effet sur la production. Quelle que soit la race, il n'y a pas eu de difference significative entre les lots P et T. Au cours des 6 heures suivant la marche, les vaches des lots M sont restees couchees plus longtemps (+ 33 minutes, p < 0,01) et ont passe moins de temps a pâturer (-29 minutes, p < 0,01) que celles des lots T.

Au total 148 vaches laitieres ont ete utilisees au cours d'un essai a long terme s'etendant sur quatre lactations. Au cours de l'hiver, tous les animaux recevaient une ration de base composee d'ensilage d'herbe (a volonte) et de foin (4 kg/jour). Les vaches ont ete affectees a un traitement experimental en premiere lactation, et le sont restees jusqu'en quatrieme lactation ou jusqu'a leur reforme si elle intervenait avant. Cinq traitements hivernaux ont ete compares: trois niveaux d'apport de concentre (H, M et L), et, pour les niveaux M et L, deux modes de repartition du concentre (classique (S) ou uniforme (F)). Les apports de concentres ont ete predetermines individuellement a partir de la production au cours de chacune des quatre lactations experimentales, estimee a partir de la production des trois premieres semaines de la premiere lactation. Au pâturage toutes les vaches ont ete conduites ensemble. La frequence des mammites, les performances de reproduction et la longevite n'ont pas ete significativement differentes selon les traitements. Les boiteries ont ete plus frequentes dans le lot H que dans les autres lots. L'effet des traitements sur les performances de production a ete etudie sur les vaches ayant realise au moins trois lactations successives d'une duree hivernale superieure ou egale a 12 semaines. Entre la premiere et la troisieme lactation, l'augmentation de poids vif au velage a ete de respectivement 72, 44 et 36 kg dans les lots H, M et L, et celle de la production laitiere au cours des 12 premieres semaines de lactation de respectivement 8,3, 5,9 and 6,1 kg/jour (p < 0,01). Ces ecarts ont ete accentues chez les vaches les plus fortes productrices. A l'echelle des 40 premieres semaines de lactation, les differences d'augmentation de production entre la premiere et la troisieme lactation ne sont plus significatives entre lots (respectivement 1 175, 997 et 1 159 kg dans les lots H, M et L), en raison d'un rattrapage au cours de la periode estivale chez les lots M et L plus important en troisieme lactation. Il n'y a pas eu de difference significative entre les performances des vaches des lots S et F.

Mastitis occurrence within a lactation and times of mastitis onset were studied for about 1000 cows. The number of mastitis cases within a lactation was modeled through overdispersed Poisson regression with individual and herd covariants. The results emphasized the role of the herd variable. Increased production potential increased the number of cases per lactation at a rate of 1.4/10 kg. Calving month also played an important role. The incidence of mastitis was greater when calving took place in early autumn or winter, which led to an expanded housing period. The interval from calving to the first case of mastitis and the intervals between successive cases were modeled for cases occurring during lactation through random selections from fitted gamma distributions, these distributions being truncated to consider the lactation length. The results of both steps can be used to simulate mastitis occurrence in different conditions.

The effect of pregnancy on milk yield was studied on a 601 lactation sample. One hundred and sixty-nine lactations of non-pregnant cows, managed under identical conditions, served as controls. Lactations were divided into five groups according to parity (primiparous or multiparous) and production potential (two ranks for primiparous cows, three ranks for multiparous cows). The difference between the individual milk yield of each pregnant animal, and the mean production of the corresponding controls was computed weekly from the week of conception. The reducing effect of pregnancy began to be measurable from the 20th week of pregnancy, regardless of the group studied or the week of conception. Analysing the amplitude of this effect restricted the investigation to the three following groups: (i) primiparous cows, (ii) low- and medium-producing multiparous cows, (iii) high-producing multiparous cows. The effect of pregnancy was lower in primiparous than in multiparous cows. In the latter, it was higher in high-producing cows, partly because of the greater calf weight. At the 29th pregnancy week, this effect reached -17middot;5, -2·4 and -3·6 kg/day in the three groups, respectively. In each of these three lactation groups, the following non-linear modelY = −e−a[(Pw~18)e−bpw]was fitted, where Y is the difference between the milk yields of pregnant and non-pregnant cows at a given stage (week), Pw is the pregnancy week, and a and b are parameters. The overall milk yield losses over a complete lactation, as estimated from the integral of that equation, reached 89, 137 and 203 kg, respectively in the three groups.

Cinquante-quatre vaches laitieres multipares en milieu de lactation ont ete utilisees dans un essai en carre latin 3x3. Pendant chaque periode de 3 semaines, les animaux ont recu une ration de fourrage isoenergetique, a base d'ensilage de ray-grass anglais (11 kg de matiere seche/j), de foin de seconde coupe de dactyle (13 kg de matiere seche/j) ou d'ensilage de mais (11 kg de matiere seche/j). Chaque ration a ete complementee avec la meme quantite d'un melange d'orge, de tourteau de soja et d'uree dont les proportions ont ete calculees de maniere a ce que les apports azotes soient voisins et non limitants dans les 3 traitements. Les vaches recevant de l'ensilage d'herbe ont produit respectivement 0,4 (P > 0,05) et 1,9 kg/j (P < 0,01) de lait de plus que celles recevant de l'ensilage de mais ou du foin, mais leur lait a ete significativement plus pauvre en proteines et en caseines. Ce resultat est lie a un partage de l'energie ingeree plus favorable a la production de lait qu'a la reconstitution des reserves corporelles avec la ration a base d'ensilage d'herbe. Le rapport caseines/proteines, la teneur en calcium, le pH et les caracteristiques rheologiques du lait n'ont pas ete significativement differents selon le type de ration de base.

Seize vaches Tarentaises multipares en milieu de lactation ont recu a l'auge pendant 3 sem une ration composee de regain de prairie naturelle (lot R) ou d'herbe verte (lot H), distribuee de maniere isoenergetique (respectivement 10,7 et 10,6 UFL/j). Les 2 lots ont ensuite ete mis a l'herbe. La nature de la ration n'a eu d'effet ni sur la production de lait, ni sur sa composition chimique, ni sur son aptitude a la coagulation. A la mise a l'herbe, dans les 2 lots, la production laitiere et le pH du lait ont augmente fortement (respectivement de 1,8 kg/j et 0,04 unite, P < 0,01). Le taux proteique a augmente plus fortement dans le lot H que dans le lot R (respectivement + 2,8 et + 1,3 g/kg, P < 0,05). Ces modifications ont ete associees a des variations importantes du temps de coagulation du lait mesure a pH initial (+ 1,5 min, P < 0,01) et de la fermete du gel mesuree a pH standardise (respectivement + 1,5 et + 3,2 mm pour les lots R et H, P < 0,01). Ces modifications sont essentiellement a relier a l'augmentation des apports alimentaires consecutifs a la mise a l'herbe

International audience; Individual milk production curves of 542 cows with 722 cases of mastitis were compared with control curves drawn from healthy lactating cows. First, differences were classified into patterns of milk loss, and their distribution was analyzed among the patterns with regard to breed, season, lactation number, stage of lactation, and milk production. Then, individual milk losses were estimated and analyzed according to the same factors. In early lactation, almost 7% of mastitis cases necessitated culling or drying off. For 36% of the cases of mastitis occurring in early lactation, milk production was affected for an extended period, and the milk loss induced was 911 kg on average over the entire lactation. Fifty-two percent of the mastitis cases occurring after lactation peak was not accompanied by marked modifications of the lactation curves. For 38% of cases of mastitis occurring from mid to late lactation, milk production was affected for an extended period. When milk production was the most affected (26% of total cases), the average loss was 850 kg over the entire lactation. For cases in early or mid to late lactation, the production at mastitis onset was a determining factor of the amount and pattern of milk production loss induced. Results were applied in a simulation over two simulated groups of cows

In the rapidly changing context of research on animal health, INRA launched a collective discussion on the challenges facing the field, its distinguishing features, and synergies with biomedical research. As has been declared forcibly by the heads of WHO, FAO and OIE, the challenges facing animal health, beyond diseases transmissible to humans, are critically important and involve food security, agriculture economics, and the ensemble of economic activities associated with agriculture. There are in addition issues related to public health (zoonoses, xenobiotics, antimicrobial resistance), the environment, and animal welfare. Animal health research is distinguished by particular methodologies and scientific questions that stem from the specific biological features of domestic species and from animal husbandry practices. It generally does not explore the same scientific questions as research on human biology, even when the same pathogens are being studied, and the discipline is rooted in a very specific agricultural and economic context. Generic and methodological synergies nevertheless exist with biomedical research, particularly with regard to tools and biological models. Certain domestic species furthermore present more functional similarities with humans than laboratory rodents. The singularity of animal health research in relation to biomedical research should be taken into account in the organization, evaluation, and funding of the field through a policy that clearly recognizes the specific issues at stake. At the same time, the One Health approach should facilitate closer collaboration between biomedical and animal health research at the level of research teams and programmes.

Cent trente sept vaches laitières de race Pie-Noir (41), Montbéliarde (42) ou Tarentaise (54), en première ou deuxième lactation, ont reçu au cours de l’hiver deux niveaux d’alimentation énergétique (haut: H et bas : B), et ont été ensuite alimentées de manière identique au pâturage. Des mesures individuelles de la composition chimique du lait et de son aptitude à la coagulation ont été réalisées 3 fois pendant l’hiver et 2 fois au pâturage. Chez les Pie-Noir, les taux de caséines et de calcium et l’aptitude à la coagulation (temps de raffermissement et fermeté du gel) ont été inférieurs (P, One hundred and thirty Holstein (41), Montb6liardes (42) and Tarentaises (54) dairy cows in first or second lactation received during winter one of two levels (high, H ; low, L) of energy intake, and were later fed identically at pasture. Three times in winter and twice at pasture, individual measurements of milk chemical composition and coagulation properties were performed. Milk from Holstein cows had lower casein and calcium contents, and poorer coagulation properties (curd firming time and curd firmness) than that from Montbéliardes and Tarentaises (P

SummaryOne hundred and thirty-seven (Holstein (41), Montbéliarde (42) and Tarentaise (54)) dairy cows in first or second lactation received during winter one of two levels (high, H; low, L) of energy intake, and were later fed identically at pasture. Thrice in winter and twice at pasture, the chemical composition and coagulation properties of individual milks were measured. Milk from Holstein cows had lower casein and calcium contents, and poorer coagulation properties (curd firming time and curd firmness) than that from Montbéliardes and Tarentaises (P< 0·01). These differences practically disappeared when taking into account the distribution of the differentκ-casein variants and milk casein content.κ-BB milks had coagulation properties 20–50% superior, according to characteristic, to those of AA milks. In the three breeds, animals from the H group had casein contents higher by 1·4 g/l than those of the L group, which induced a significant improvement in curd firming time, curd firmness and cheese yield. Turning out to pasture induced an increase of 0·02 in milk pH, and improved milk coagulation properties. These changes did not appear to result entirely from the parallel increase in milk casein content.

Dans le contexte très évolutif de la recherche en santé animale, une réflexion sur ses enjeux, ses spécificités et ses synergies avec la recherche biomédicale, a été conduite à l’initiative de l’INRA. Affirmés au premier chef par l’OMS, la FAO et l’OIE, les enjeux en santé animale, hors des maladies transmissibles à l’Homme, sont énormes et touchent à la sécurité alimentaire, l’économie de l’agriculture et l’ensemble des activités économiques qui en découlent. S’y ajoutent les enjeux de santé publique (zoonoses, xénobiotiques, antibiorésistance), environnementaux et de bien-être animal. La recherche en santé animale présente des spécificités d’ordre méthodologique et scientifique, liées notamment aux particularités biologiques des espèces domestiques et aux pratiques d’élevage. Elle n’a pas les mêmes questionnements scientifiques qu’en biologie humaine même lorsqu’elle traite des mêmes agents pathogènes et, connectée aux autres sciences animales (génétique, physiologie, zootechnie), elle s’enracine dans une réalité agricole et économique très spécifique. Des synergies génériques et méthodologiques existent néanmoins avec la recherche biomédicale, en particulier autour des outils et des modèles biologiques. Certaines espèces domestiques (tel le porc) présentent en outre des similitudes fonctionnelles avec l’Homme, plus que le rongeur de laboratoire. Ainsi la singularité de la recherche en santé animale par rapport à la recherche en biologie humaine devrait être prise en compte dans son organisation, son évaluation et son financement, via une politique de reconnaissance des enjeux spécifiques. Simultanément, l’approche one health devrait faciliter une collaboration approfondie entre recherche en biologie humaine et recherche en santé animale, à l’échelle des équipes ou des programmes., In the moving context of research on animal health, a collective discussion has been carried out on its issues, special features and synergism with biomedical research. Strongly enhanced by WHO, FAO and OIE, the issues of animal health are important and deal with food security, agriculture economics and all economical activities that follow from it. Others are related to public health (zoonoses, xenobiotics, antimicrobial resistance), environment and animal welfare. Research on animal health has got special features concerning methodology and scientific questions, among others the particular biological nature of domestic species and breeding practices. Scientific questions are not similar to those of biomedical research, even if dealing with the same pathogens; connected to the other animal sciences (genetics, physiology, animal breeding), research on animal health takes root in a very specific agricultural and economical reality. Nevertheless, generic and methodological synergies do exist with biomedical research, particularly concerning biological tools and models. Some domestic species like pig have functional similarities with Humans, better than with mouse or rat. Thus, the peculiarity of research on animal health compared to biomedical research should be considered in its organisation, evaluation and funding, through a political recognition of specific issues. Simultaneously, the one health approach should facilitate a thorough collaboration between biomedical research and research on animal health, at the levels of research teams and research programmes.

International audience; The aim of this work was to characterize UV-absorbing compounds (UAC) in milk in relation to diet. In winter, 4 groups of cows each received a different diet: concentrate rich containing 35% cocksfoot hay (CCH), maize silage (MS), rye grass silage (RS), or rye grass hay (RH). In summer, 2 additional diets were given: mountain grassland hay (GH) and mountain grassland pasture (GP). Polyphenols were analyzed by HPLC and Folin reaction on forages and UAC were extracted from milks and analyzed by HPLC. In forages, the number of polyphenols was lowest in MS (57) and greatest in GP (85). Twenty-four peaks were identified, accounting for 28 to 47% peak area at 280 nm. Caffeoyl compounds and flavonoid glycosides were mainly found in RH, GH, and GP. Hydrolyzed compounds such as hydroxycinnamic acids and aglycones were found in MS and RS. Estimated amounts of polyphenols were lowest for MS (3.7 g/kg), roughly similar for CH, RS, and RH (about 15 g/kg), and greatest for GH and GP (21.6 and 35.3 g/kg, respectively). About 230 different peaks were separated in milks. Milks from RH and GP contained the lowest (87) and the greatest (127) numbers of peaks, respectively. Only 10 peaks were identified, accounting for 21 to 54% of the total spectra area. In addition to the major compound hippuric acid, phenylacetic acid, benzoic acid, 4-hydroxybenzoic acid benzaldehyde, catechol, and small amounts of ferulic acid were found in varying amounts depending on the diet. Flavonoids such as quercetin, luteolin, and apigenin were also present. Hippuric acid was clearly related to the presence of caffeoylquinic compounds in forages. Other identified UAC may originate essentially from forage simple polyphenols or from cell wall aromatics. Some of the several unknown compounds may also originate from the transformation of other nutrients. Estimated amounts of UAC were widely variable within each animal group. They were surprisingly high in CCH and roughly similar in all milks from preserved forages (about 3.6 mg/L), with generally greater values for GH milks, whereas the greatest amount was found in GP milks (13.3 mg/L). Hierarchical clustering clearly discriminated the 6 diets, showing that there were major differences in GP milks. Some UAC were specific to one or a group of diets. Ultraviolet-absorbing compounds are therefore a potential tool to distinguish between milks according to diet. In addition, they may have a bioactive effect on milk component conservation or on human health.

La composition chimique du lait dépend de facteurs liés à l’animal et au milieu. Parmi ces derniers, l’alimentation joue un rôle important : elle permet d’agir à court terme et de manière différente sur les taux de matières grasses et de protéines. Le taux protéique varie dans le même sens que les apports énergétiques (+ 0,6 g/kg par UFL supplémentaire aux alentours des recommandations). Il peut aussi être amélioré par des apports spécifiques en acides aminés (lysine et méthionine). Il est presque toujours diminué par l’adjonction de lipides, même protégés, dans la ration. Le taux butyreux dépend à la fois de la part d’aliment concentré dans la ration (et, quand celle-ci est élevée, de la nature de ces aliments concentrés), et du mode de présentation et de distribution de la ration (finesse de hachage, nombre de repas, mélange des aliments). Il peut être sensiblement augmenté par l’utilisation de certains aliments (ensilage de maïs, betteraves, lactosérum) ou additifs (substances tampons, monopropylène glycol). Il est donc possible de modifier sensiblement et dans des sens opposés le taux butyreux et le taux protéique. Dans l’avenir, des moyens synthétiques et objectifs d’appréciation de la qualité des rations (indice de fibrosité) devraient permettre d’améliorer la gestion des variations de ces taux.

Three main variation factors of the substitution rate (SR) between roughage and concentrates have been studied over a course of eight trials: (1) the concentrate supplementation level (low= L, medium=M, high=H, on average 2 kg of dry matter between two consecutive levels); (2) the type of roughage (maize silage, grass silage or hay); (3) the type of concentrate (a high proportion of starch=ST, of fibre of high digestibility=FH, or fibre of low digestibility=FL). In each trial, the three levels of concentrates were compared using a 3 × 3 Latin square design, repeated with three or four groups of Holstein-Friesian crossbred cows in mid-lactation, each period lasting 1 month. The eight trials corresponded to eight different diets according to the type of roughage and the type of concentrate used. The SRs increase systematically with the concentrate supplementation level, on average 0.47 between L and M and 0.67 between M and H. For a given roughage, the increase in the energy concentration of the concentrate corresponds to an increase in the SR values, mainly between L and M. The average SR values observed when using maize silage (0.7) are higher than those observed with grass silage (0.53) and also for the hay (0.44). These trials show, looking at the three variation factors in the study, that in mid-lactation, the higher the energy balance is, the more important the SR values become.

The objective of this study was to specify the relationships between animal species (cow versus goat) and the contents of fat-soluble constituents (fatty acids, carotenoids, retinol and α-tocopherol) in raw milk farmhouse cheeses. Four hundred and thirty-two farmhouse cheeses (74 farms × 6-7 cheeses), including 306 cow's milk cheeses and 126 goat's milk cheeses, produced in real herd management conditions throughout the year, were collected. The conditions of milk production were identified beforehand by means of surveys. In order to limit the confounding effects related to the management practices specific to each animal species, the effect of animal species was studied only within cheeses associated with conditions of milk production common to both animal species. Except for C8:0, C10:0 and β-carotene, and to a lesser extent C4:0, the levels of which in cheese clearly differed according to the animal species, the variability within species was higher than the variability between species. Caprine milk fat was on average richer (P < 0.001) in C8:0, C10:0, C18:2n − 6, retinol and α-tocopherol (>30% richer) and to a lesser extent C6:0, C12:0 and C18:0 (from 8 to 25% higher) than bovine milk fat. On the other hand, bovine milk fat was richer (P < 0.001) in C4:0, trans-11 C18:1, cis-9, trans-11 C18:2, xanthophylls and β-carotene (>30% richer) and to a lesser extent C14:0, C16:0 and C18:3n − 3 (from 16 to 23% richer). Caprine milk fat was completely devoid of β-carotene. In conclusion, the results of this work indicate that, under real herd management conditions, the animal species (cow versus goat) is a strong influencing factor of the nutritional composition of cheese.

Phenolics contribute to the micronutrient composition of forages, which in turn may affect animal product composition. To assess the importance of these compounds, the polyphenolic and botanical composition of a permanent mountain pasture in the Massif Central (France) were studied at three stages of growth. Phenolic fractions (acids, flavonoids and total) were analysed using HPLC and specific colorimetric methods over the whole pasture and in nine main species. On a botanical level, 43 species including 31 dicotyledons composed a mountain variant of Cynosurion grouping. Over time, the species growing on the field changed, the main plants being Festuca nigrescens and eight dicotyledons. In whole pasture, about 170 different compounds were separated by HPLC, of which only 30 were common to all stages. The total polyphenolic content was estimated as 31, 32 and 19 g kg−1 DM for the three stages. They were mainly composed of dihydroxycinnamic derivatives (3,5-di-O-caffeoylquinic, chlorogenic, 1,5-di-O-caffeoylquinic acids), and of flavonoids in lesser proportions. Some polyphenols were peculiar to a few species and others were ubiquitous. The two major dicaffeoylquinic acids were identified for the first time in Achillea millefolium and Knautia arvernensis. Colorimetric measurements of phenolic fractions were in good agreement with HPLC analysis (P < 0.01) for all species studied. Thus, on the mountain pasture studied, a cow would be expected to ingest up to 500 g of polyphenols daily, which could affect the quality of animal products. Copyright © 2007 Society of Chemical Industry

International audience; Two experiments were conducted to evaluate the effects of nature of forage on fatty acid composition and lipolytic system in cow milk to increase the nutritional quality of dairy products. Each experiment was divided into a 4-wk preexperimental and 6- or 8-wk experimental period. During the 2 preexperimental periods, 56 midlactating Montbeliarde or Tarentaise cows received a diet based on corn silage. Subsequently, in Experiment 1, 40 cows were allocated into 5 groups (4 Montbeliarde and 4 Tarentaise cows per group) and assigned to dietary treatments: corn silage (87% of dry matter intake), grass silage (86%), ryegrass hay (90%), mountain natural grassland hay (87%), or a diet rich in concentrate (CONC, 65/35% concentrate/hay). In Experiment 2, 16 cows divided into 2 groups were fed during 3 or 6 wk mountain natural pasture (100%) or mountain natural grassland hay (87%). Principal component analysis was applied to describe the relationships among dairy performances, milk fatty acids (FA), and lipolytic system. The milk 18: 0, cis-9-18:1, trans-11-18:1, and cis-9, trans-11-18:2 percentages were closely associated with 3-wk mountain natural pasture diet, whereas short- and medium-chain (mostly saturated) FA were associated with the CONC diet. Tarentaise milk fat contained a lower proportion (-3 to 4 g/100 g) of 16:0 and higher proportions of stearic acid and fewer markedly polyunsaturated FA than Montbeliarde milk fat. Milk lipolysis was lowest for CONC and corn silage groups. Milk from Tarentaise cows presented lower initial free FA and postmilking lipolysis. Diets given to cows, especially young grass, modified the milk content of FA with a putative nutritional effect on human health.

Les relations entre les conditions de production du lait et les teneurs en composés d'intérêt nutritionnel de fromages fermiers au lait de vache ou de chèvre ont été étudiées en conditions réelles de production au sein de 4 filières fromagères (Abondance, Tomme de Savoie, Salers/Cantal et Rocamadour). Au total, 432 fromages, dont 306 au lait de vache et 126 au lait de chèvre, produits tout au long de l'année par 74 producteurs fermiers ont été analysés. Dans un premier temps, les effets respectifs des conditions de production du lait et de la transformation fromagère sur la variabilité de composition du fromage ont été quantifiés. Dans un second temps, les relations entre la composition du fromage et les conditions de production du lait, préalablement identifiées au moyen d'enquêtes, ont été étudiées. Le fromage fermier se caractérise par une grande variabilité de composition qui dépend majoritairement de la transformation fromagère pour la vitamine B9 et les minéraux et des conditions de production du lait pour les acides gras (AG), les vitamines A et E et les caroténoïdes. L'espèce animale explique une grande partie de la variabilité en certains AG et en b-carotène dans le fromage. Les teneurs en micronutriments liposolubles et le potentiel antioxydant du fromage dépendent principalement de la nature de la ration fourragère (pâturage vs fourrages conservés) quelle que soit l'espèce animale. Les rations à base de pâturage sont associées à des teneurs en caroténoïdes et en vitamines A et E et à un potentiel antioxydant dans le fromage plus importants. En revanche, les facteurs de variation du profil en AG du fromage ont différé dans cette étude entre les vaches et les chèvres. Pour les fromages au lait de vache, il dépend principalement de la nature de la ration fourragère (pâturage vs fourrages conservés). Les fromages associés au pâturage sont plus riches en AG saturés et insaturés à longue chaîne (³ C18) et plus pauvres en AG saturés à courte et moyenne chaîne (C6:0 à C16:0). Le profil en AG du fromage au lait de chèvre dépend principalement de la proportion de matières grasses apportées par les concentrés dans la ration, du stade de lactation des animaux et dans une moindre mesure de la présence ou non de lin dans les concentrés. Ce fromage est plus riche en AG à longue chaîne et plus pauvre en AG saturés à courte et moyenne chaîne lorsque la proportion de matières grasses apportées par les concentrés est plus importante, les concentrés contiennent du lin et les animaux sont en début de lactation. En conclusion, ce travail a permis de collecter des données représentatives et détaillées sur les caractéristiques nutritionnelles de différentes variétés fromagères et de hiérarchiser les effets des principaux facteurs de production responsables de la variabilité de composition du fromage., The relationships between the conditions of milk production and the contents of components of nutritional interest in cow's or goat's milk farmhouse cheeses have been studied under real conditions of production in four cheese chains (Abondance, Tomme de Savoie, Salers/Cantal and Rocamadour). In total, 432 cheeses, including 306 cow's milk ones and 126 goat's milk ones, produced throughout the year by 74 farmhouse producers, were analysed. First, the respective effects of the conditions of milk production and the cheese-making process on the compositional variability in cheese were quantified. Subsequently, the relationships between the cheese composition and the conditions of milk production, beforehand identified by means of surveys, were studied. Farmhouse cheese was characterized by a great compositional variability which mainly depended on the cheese-making process for vitamin B9 and minerals and on the conditions of milk production for fatty acids (FA), vitamins A and E and carotenoids. The animal species explained a great part of the variability in some FA and b-carotene contents in cheese. The contents of fat-soluble micronutrients and the antioxidant capacity in cheese mainly depended on the nature of the fodder ration (pasture vs. preserved forages) whatever the animal species. The pasture-based rations were associated with higher levels of carotenoids, vitamins A and E and antioxidant capacity in cheese. On the other hand, the influencing factors of the FA profile in cheese differed in this study between cows and goats. As regards cow's milk cheeses, it mainly depended on the nature of the fodder ration (pasture vs preserved forages). Cheeses associated with pasture were richer in long length saturated and unsaturated FA (³ C18) and poorer in short and medium length saturated FA (C6:0 à C16:0). The FA profile of goat's milk cheese mainly depended on the percentage of fat from the concentrates in the ration, the stage of lactation of animals and to a lesser extent the presence or not of linseed in the concentrates. This cheese was richer in long length FA and poorer in short and medium length saturated FA when the percentage of fat from the concentrates was higher, the concentrates contained linseed and the animals were in early lactation. In conclusion, this work allowed to collect representative and detailed data on the nutritional characteristics of various cheese varieties and to hierarchy the main production factors responsible for the compositional variability in cheese.

Vingt-neuf élevages laitiers de la Réunion ont été suivis pendant 14 mois au cours des années 2002 et 2003. Des enquêtes et des contrôles d’alimentation ont été réalisés tous les trimestres pour caractériser les pratiques d’élevage et les rations distribuées. Sur des prélèvements de lait de troupeaux effectués tous les mois, des analyses de composition chimique (matières grasses, protéines, urée, lactose, minéraux,…) et de qualité hygiénique (germes totaux, cellules, spores butyriques) ont été réalisées. Au total 116 échantillons de lait correspondants à 4 passages ont été retenus pour construire une typologie des laits en 5 classes. Cette typologie a ensuite été analysée en fonction des pratiques d’élevage correspondantes. Les principaux facteurs de variation des caractéristiques des laits de troupeaux sont la saison, le niveau et la nature des apports alimentaires. Les laits les plus riches en matières utiles sont produits en hiver, essentiellement avec des rations à base de fourrages tempérés. Pour la qualité hygiénique, les meilleurs résultats sont obtenus en hiver et au printemps, dans les zones à faible pluviométrie. Aucune classe ne combine à la fois des laits riches en matières utiles, à faibles contaminations en spores butyriques et à faible numération cellulaire. Il existe donc une marge de progrès importante dans ces trois domaines, via des pratiques d’alimentation et/ou de conduite des animaux qui ont été identifiées dans cette étude., In order to characterise the incidence of livestock farming practices and rations distributed to the animals on milk quality, surveys and feeding controls were carried out quarterly on twenty-nine dairy farms during 14 months (2002-2003). Herds milk samples were collected and analysed for chemical composition (fat, protein, urea, lactose, and mineral contents) and for hygienic quality (total bacteria, butyric spore and somatic cell counts). The 116 milk sample data were analysed to build a five-class milk quality typology. This typology was then confronted to the management practices. The main factors influencing the variability of herd milk were the season, and the level and nature of feeding. The milks highest in fat and proteins contents were produced in the winter, particularly when the animals were fed temperate forages. Regarding hygienic quality, the best results were obtained in the winter and spring, in areas with low rainfall. None of the five milk classes combined on a same period high fat and protein contents, and low levels of butyric spore and somatic cell counts. An important margin of progress in mastering these main quality parameters appeared. This could be realised by adapting feeding practices and/or herd management techniques that were identified in the study.

Terpene profiles in cheese can be considered a ‘terroir’ fingerprint as the information contained in it should enable the pastures on which the animals were fed to be recognised. Yet a certain elasticity of the signature must be taken into account when determining authentication strategies, since products acknowledged as containing a common signature may have undergone certain procedures, such as cheese making and milk pasteurisation, that could have potentially altered their terpene profiles. In this study, Cantal and Saint-Nectaire-type cheeses were made from both raw and pasteurised milk from the same herd of dairy cows that had been grazed on natural grassland. Cheeses from raw and pasteurised milk were made from the same milking on the same days. Cantal and Saint-Nectaire-type cheeses were made on 4 different days, alternatively over four weeks. The terpenes in the cheese fat were analysed by dynamic headspace/gas chromatography/mass spectrometry. A great diversity of monoterpenes, sesquiterpenes and oxygen-containing derivatives were identified. The major terpenes identified in most cheeses were β-caryophyllene, α- and β-pinene and limonene. Milk pasteurisation did not induce changes in the terpene profile of the cheese. Significant differences (p < 0.001) were observed between Cantal and Saint-Nectaire cheeses: α-pinene, β-myrcene and β-phellandrene were, respectively, three, five and five times more abundant in Cantal cheese, while tricyclene, α-phellandrene and geraniol were found exclusively in Cantal cheese. In contrast, unidentified sesquiterpenes with retention indices (KI) = 1342 and 1511, α-cubebene, longifolene and γ-elemene were more abundant or exclusively found in Saint-Nectaire cheese. A significant relationship with the date of milking (p < 0.01) was observed for α-pinene and tricyclene in Cantal, for β-myrcene, δ-3-carene, p-cymene and α-terpinene in Saint-Nectaire cheese. Copyright © 2005 Society of Chemical Industry

Twenty-eight multiparous dairy cows were divided into 2 groups: one group (S) was fed a ray-grass silage diet and the other one (H) a hay-based diet. The milk produced by these cows was used to make Saint-Nectaire-type cheese on one day and Cantal cheese on the following day, using identical, controlled cheesemaking techniques for each model. The S cheeses, regardless of the model, had higher fat (P < 0.01) and fat in dry matter (P < 0.05) contents but lower total nitrogen content (P < 0.001) and exhibited a more yellow tone. The differences in sensory characteristics were more pronounced in Cantal cheeses: H cheeses had more "butter" and "grass" odours, "citrus fruits" - "hay" -"hazelnut" aromas and more persistent flavour than S cheeses, which showed more "alcohol" odour, "chemical" aroma and had a less "melting", "mellow" texture. The dietary effect was greater with Cantal cheese because of a diet / cheese model interaction., Effet d'une alimentation à base d'herbe ou de foin sur les caractéristiques du fromage : interactions avec le modèle technologique. Vingt-huit vaches laitières ont été divisées en deux groupes : l'un (S) a reçu un régime à base d'ensilage de ray-grass et l'autre (H) à base de foin. Le lait de ces animaux a été transformé un jour en fromage de type Saint-Nectaire et un autre jour en fromage de Cantal, dans des conditions technologiques contrôlées et identiques d'une fabrication à l'autre pour chaque type de fromage. Quelque soit le modèle fromager, les fromages S ont eu des taux plus élevés de matière grasse (P < 0,01) et d'extrait sec (P < 0,05) mais une plus faible teneur en azote total (P < 0,001) et ils ont été plus jaunes. Les différences de caractéristiques sensorielles ont été plus marquées dans le cas du Cantal : les fromages H ont été caractérisés par des odeurs " beurre " et " herbe ", des arômes " agrumes ", " foin ", " noisette ", et une flaveur plus persistante que les fromages S, qui ont révélé une odeur d'" alcool ", un arôme " chimique " et une texture moins " fondante " et " moelleuse ". L'effet régime alimentaire a été plus marqué dans le cas du fromage de Cantal révélant une interaction entre l'alimentation des animaux et le modèle fromager.

Cette revue fait le point sur les connaissances acquises au cours des 10 dernières années sur les relations entre les facteurs de conduite des animaux (génétiques, physiologiques, alimentaires) et la qualité sensorielle des fromages. Chez la vache, avec des fabrications au lait entier, la race peut modifier les caractéristiques de texture des fromages. Cet effet est essentiellement lié aux différences de composition chimique des laits et donc de gras/sec des fromages. Au sein d’une même race, des différences importantes de texture et de goût ont été observées en fonction des variants génétiques de la caséine β (espèce bovine) et surtout αs1 (espèce caprine). Le stade physiologique n’a un effet marqué sur la couleur, la texture et le goût qu’en tout début ou en toute fin de lactation. En revanche, les mammites ont un effet négatif important sur les caractéristiques sensorielles des fromages. L’utilisation d’ensilage de maïs conduit toujours à des fromages plus blancs et parfois à des différences de flaveur. Lorsqu’elle est correctement réalisée, la conservation de l’herbe sous forme d’ensilage comparativement au foin ne modifie pas ou peu les caractéristiques sensorielles des fromages, en dehors de leur couleur, plus jaune avec l’ensilage. Par contre, d’importantes différences de caractéristiques sensorielles sont observées entre des fromages selon que le lait provient de vaches recevant une ration à base d’herbe conservée ou conduites au printemps, au pâturage. Plusieurs essais récents ont mis en évidence un effet de la composition botanique des fourrages ingérés par les vaches laitières sur la texture et la flaveur des fromages. Ces différents effets sont dus à la présence dans le lait de molécules ou de structures issues directement de l’alimentation (carotènes, terpènes) ou produites par l’animal (plasmine, acides gras, structure des micelles de la caséine) en raison de ses caractéristiques génétiques ou physiologiques ou sous l’effet d’une alimentation spécifique., This review summarises the last 10 years of knowledge established on the relationships between management of the animals (genetic, physiology, feeding) and sensory quality of cheese. In the production of full fat raw milk cheese, the cow's breed can modify the texture of cheeses because of differences in fat in dry matter content, due to variations in the fat/protein ratio in milk. Within a same breed, large differences in texture and taste were observed between cheeses issued from milk differing by the genetic variant of beta-casein (in dairy cows) or alpha(s1)-casein (in goats). Except in very early or late lactation, the physiological stage had no significant effect on cheese sensory characteristics. In contrast, mastitis has a well known negative impact on cheese sensory properties. Feeding dairy cows or goats with corn silage by comparison with hay or grass silage lead to whiter cheeses and sometimes to differences in flavour. Conserving grass as silage, by comparison with hay, has no important effect on cheese sensory characteristics, except on colour, being more yellow with grass silage. Conversely, major differences in sensory characteristics were observed between cheeses made with milk produced by cows fed winter diets (based on hay and grass silage) or turned to pasture in the spring. Several recent experiments showed a significant effect of grass' botanical composition on cheese texture and flavour. These effects are due to the presence in milk of specific molecules or structures directly induced by feeding (carotenes, terpenes) or produced by the animals (plasmin, fatty acids, casein micellar structures) according to their genetic or physiological characteristics or under the effect of specific diets.

Abstract This review summarizes the recent developments in understanding of the relationships between the diet of animals and the sensory quality of dairy products. Feeding dairy cattle with maize silage by comparison with hay or grass silage leads to whiter and firmer cheeses and butter and sometimes to differences in flavour. Major differences in sensory characteristics were observed between cheeses made with milk produced by cows on winter diets (based on hay and grass silage) or turned out to pasture in the spring. Conversely, preserving grass as silage, by comparison with hay, has no major effect on cheese sensory characteristics, except on colour, the cheese being yellower with grass silage. Several recent experiments have shown a significant effect of grass botanical composition on cheese texture and flavour. These effects are due to the presence in milk of specific molecules directly introduced by feeding (carotenes, terpenes) or produced by the animals (plasmin, fatty acids) under the effect of specific diets.

National audience

International audience; This review summarises the last 10 years' knowledge established on the relationships between the management of animals (genetics, physiology and feeding) and the sensory quality of cheese. In the production of full-fat raw milk cheese, the cow's breed can modify the texture of cheeses because of differences in fat in dry matter content due to variations in the fat/protein ratio in milk. Within the same breed, large differences in texture and taste were observed between cheeses issued from milk differing by the genetic variant of $\beta$-casein (in dairy cows) or $\alpha$s1- casein (in goats). Except in very early or late lactation, the physiological stage had no significant effect on cheese sensory characteristics. In contrast, mastitis has a well-known negative impact on cheese sensory properties. Feeding dairy cows or goats with corn silage by comparison with hay or grass silage leads to whiter cheeses and sometimes to differences in flavour. Conserving grass as silage, by comparison with hay, has no important effect on cheese sensory characteristics, except on colour, which is yellower with grass silage. Conversely, major differences in sensory characteristics were observed between cheeses made with milk produced by cows fed winter diets (based on hay and grass silage) or turned to pasture in the spring. Several recent experiments showed a significant effect of grass' botanical composition on cheese texture and flavour. Those effects are due to the presence in milk of specific molecules or structures directly induced by feeding (carotenes and terpenes) or produced by the animals (plasmin, fatty acids and casein micellar structures) according to their genetic or physiological characteristics or under the effect of specific diets.; Effets des facteurs de production sur les caractéristiques sensorielles des fromages : une revue. Cette revue fait le point sur les connaissances acquises au cours des 10 dernières années sur les relations entre les facteurs de conduite des animaux (génétiques, physiologiques et alimentaires) et la qualité sensorielle des fromages. Chez la vache, avec des fabrications au lait entier, la race peut modifier les caractéristiques de texture des fromages. Cet effet est lié essentiellement aux différences de composition chimique des laits et donc de gras/sec des fromages. Au sein d'une même race, des différences importantes de texture et de goût ont été observées en fonction des variants génétiques de la caséine $\beta$ (espèce bovine) et surtout $\alpha$s1 (espèce caprine). Le stade physiologique n'a un effet marqué sur la couleur, la texture et le goût qu'en tout début ou en toute fin de lactation. En revanche, les mammites ont un effet négatif important sur les caractéristiques sensorielles des fromages. L'utilisation d'ensilage de maïs conduit toujours à des fromages plus blancs, et parfois à des différences de flaveur. Lorsqu'elle est correctement réalisée, la conservation de l'herbe sous forme d'ensilage comparativement au foin ne modifie pas ou peu les caractéristiques sensorielles des fromages, en dehors de leur couleur, plus jaune avec l'ensilage. Par contre, d'importantes différences de caractéristiques sensorielles sont observées entre des fromages selon que le lait provient de vaches recevant une ration à base d'herbe conservée ou conduites au printemps, au pâturage. Plusieurs essais récents ont mis en évidence un effet de la composition botanique des fourrages ingérés par les vaches laitières sur la texture et la flaveur des fromages. Ces différents effets sont dus à la présence dans le lait de molécules ou de structures issues directement de l'alimentation (carotènes et terpènes) ou produites par l'animal (plasmine, acides gras et structure des micelles de la caséine) en raison de ses caractéristiques génétiques ou physiologiques ou sous l'effet d'une alimentation spécifique.

International audience; Clinical mastitis in dairy cows has for many years been the subject of numerous epidemiological surveys to determine the main risk factors. In most cases this data has been analysed using a standard Poisson model without taking into consideration possible dependence between consecutive pathological events. These analyses have brought to light a great many potential risk factors without making it possible to clarify a certain amount of confusion surrounding the effects. The extension of an individual within a lactation model, considering dependence between clinical cases of mastitis within lactation so as to take into account inter-lactation dependence (which has already been published) is presented in the form of mixed distributions within the same survival model framework. By introducing new parameters, infection rate at calving and the identification of a higher exogenous infection rate indoors than at pasture, it is possible to take into consideration what had previously appeared to be a lactation stage factor, a calving month factor or even part of a parity factor. By considering these two types of dependence within the same model, it appears to be possible to obtain a simpler model in terms of the factors to be taken into account, and one that is based on generally acknowledged and easily understandable biological considerations. Lastly, a possible way of extending the model is to consider the dry period before calving and this is presented. This would make it possible to envisage developing a complete model of the animal's lifetime in the not-too-distant future. It is still necessary, however, to determine the farming system factors in the general sense of the term, which specifically affect one or the other of the different model parameters, before one can draw conclusions as to the potential extension of this type of model. A national survey is currently being carried out on approximately 600 French breeding farms that will help meet this last objective.

The effect of mastitis and related-germs on milk chemical composition (protein and lac- tose contents) and milk somatic cell count (SCC) was investigated in 501 milk quarter samples during two consecutive years in cows from three experimental herds. Each infected quarter was matched by a healthy one in the same udder, as a control. Milk protein and mineral assays were performed in a sub- sample of 128 milks. Staphylococci were the most frequently isolated germs (Staphylococcus aureus: 27%, coagulase-negative Staphylococci: 26%, Streptococci: 21%). Major milk pathogens (Staphylococcus aureus, Streptococcus uberis or Escherichia coli) associated with clinical signs of mastitis were accompanied by higher SCC (+1.6 log·mL -1 , P < 0.01), lower lactose concentration (-7.6 g·kg -1 , P < 0.01), higher protein concentration (+3.3 g·kg -1 , P < 0.01) and higher soluble protein concentrations (IgG and BSA), hence a sharp decrease in the casein/protein ratio (-10 percentage points, P < 0.01). Changes were more marked when Escherichia coli was present. Corynebacterium bovis did not alter milk chemical composition whereas coagulase-negative Staphylococci slightly re- duced lactose concentration (-1.8 g·kg -1 ) and increased SCC (+0.37 log·mL -1 ). Calcium and phos- phorus milk contents were hardly modified by the presence of microorganisms. The decrease in milk yield during clinical mastitis varied from 1.6 kg·d -1 in the presence of Staphylococcus aureus to 15 kg·d -1 in the presence of Escherichia coli.

International audience; The relationships between the flavour and composition of half-cooked pressed Abondance cheese (Haute-Savoie, France) were studied under natural cheese production conditions on the basis of different pastures exploited by 3 producers. Cheeses manufactured from milk produced from mountain pastures (M, n = 5, 1500-1850 m) were deemed to be more "fruity" , "animal" , "boiled milk" and "hazelnut" and less pungent and "propionic acid" than cheeses made from milk produced from valley pastures (V, n = 5, 850-1100 m). It was possible to partly attribute these differences in flavour to the presence of protein-based volatile compounds in the cheeses. The V cheeses had a greater variety of flavours than the M cheeses. Cheeses from gramineae-rich pastures had the most intense "cooked cabbage" odours, related to the greater amounts of sulphur compounds in these cheeses. Terpenes, which are more abundant in cheeses produced from dicotyledon-rich pastures, did not contribute directly to cheese aroma. The differences in flavour between the cheeses manufactured by the 3 producers were of the same magnitude as those observed between different pastures used by a same producer. The origin of the volatile compounds in the cheeses - whether of microbial origin or from the feed - was discussed.; Relations entre la flaveur et la composition chimique de fromages d'Abondance fabriqués à partir de laits produits sur différents types de pâturages. Les relations entre la flaveur et la composition des fromages à pâte pressée demi-cuite de type Abondance (Haute-Savoie, France), ont été étudiées dans des conditions naturelles de production du fromage à partir de pâturages différents exploités par 3 producteurs. Les fromages fabriqués à partir de laits produits sur des pâturages de montagne (M, n = 5, 1500-1850 m) ont été jugés plus "fruité " , "animal " , "lait cuit " et "noisette " et moins piquant et " propionique " que les fromages issus de laits produits sur des pâturages de vallée (V, n = 5, 850-1100 m). Ces différences de flaveur ont pu être attribuées en partie à la présence dans les fromages de composés volatils issus du catabolisme des acides aminés. Les fromages V présentaient une plus grande diversité de flaveur que les fromages M. Les fromages issus de pâturages riches en graminées étaient les plus intenses en odeur "chou cuit " , flaveur liée aux quantités plus importantes de composés soufrés dans ces fromages. Les terpènes, plus abondants dans les fromages issus de pâturages riches en dicotylédones, n'ont pas contribué directement à l'arôme des fromages. Les différences de flaveur des fromages entre les 3 producteurs ont été du même ordre de grandeur que celles observées chez un même producteur entre différents pâturages. Les origines microbienne et alimentaire des composés volatils des fromages ont été discutées.

L'influence de la nature des pâturages sur les caracteristiques des laits a ete etudiee in natura dansla zone du fromage d'Abondance (Haute-Savoie, France) sur 10 types de pâturages divers exploites par 3 producteurs. Les effets lies au troupeau ont ete controles et mesures sur une periode ou les 3 troupeaux recevaient la meme alimentation. L'activite de la plasmine et la teneur en acides gras poly-insatures a 18 carbones etaient plus elevees dans les laits des pâturages de montagne (n = 5, 1 500-1 850 m) que celles des laits de pâturages de vallee (n = 5, 850-1100 m) (respectivement P < 0,001, P < 0,05). La composition en terpenes des laits est apparue dependre de celle des pâturages. Les laits issus des pâturages les plus riches en dicotyledones, notamment en ombelliferes, contenaient plus de terpenes, tant en quantite qu'en variete, que les laits issus des pâturages riches en graminees. Les compositions en molecules volatiles non terpeniques et en caseines, les teneurs en calcium et phosphore n'ont pas semble etre influencees par le type de pâturage.

The volatile components from nine plants growing on natural grasslands in Auvergne, central France, selected for the broad qualitative and quantitative diversity of their terpenoid fractions, were analyzed by high-resolution gas-phase chromatography and mass spectrometry (HRGC-MS) after static headspace solid-phase microextraction (SHS-SPME). SHS-SPME allowed all the plant material to be analyzed under the same conditions despite its wide-ranging composition. This is not always possible with other extraction methods. Using an apolar poly(dimethylsiloxane) (PDMS) phase, numerous terpenoid hydrocarbons, together with alcohols, cyclic ethers, and esters, were extracted. Its ease of use and the high resolution of the chromatographic profiles obtained make SHS-SPME well suited to the rapid characterization of the main components of the volatile fraction of plants. Of the nine plants studied, four (Meum athamanticum, Pimpinella saxifraga, Achillea millefolium, and Thymus pulegioides) exhaled more than 60 different volatile components. Certain terpenes present in large amounts in these plants might help link dairy products to grazing pasture, thus improving food traceability.