-The influence of pastures on milk characteristics was studied in natura in the Abondance cheese area (Haute-Savoie, France) on 10 diversified pastures exploited by 3 dairy farmers. The effects of the herd were controlled and measured by feeding an identical hay to herds. The plasmin activity and the concentration of long-chain poly-unsaturated fatty acids in milks produced in mountain pastures (n = 5, 1 500 and 1 850 m) were significantly higher (P < 0.001 and P < 0.05 respectively) than in milks from valley pastures (n = 5, 850 and 1 100 m). The terpene composition of milk was linked to the terpene composition of pastures. Milks from the pastures rich in dicotyledons, in particular Apiaceae, contained a greater quantity and a wider variety of terpenes, than milks from the pastures rich in Gramineae. The other volatile compounds, casein composition, calcium and phosphorus contents did not seem to be influenced by the type of pasture.pasture / milk / plasmin / fatty acid composition / volatile compound Résumé -Influence de la nature de pâturages alpins sur l'activité de la plasmine, la composition en acides gras et en composés volatils du lait. L'influence de la nature des pâturages sur les caractéristiques des laits a été étudiée in natura dans la zone du fromage d'Abondance (Haute-Savoie, France) sur 10 types de pâturages divers exploités par 3 producteurs. Les effets liés au troupeau ont été contrôlés et mesurés sur une période où les 3 troupeaux recevaient la même alimentation. L'activité de la plasmine et la teneur en acides gras poly-insaturés à 18 carbones étaient plus élevées dans les laits des pâturages de montagne (n = 5, 1 500-1 850 m) que celles des laits de pâturages de vallée (n = 5, 850-1100 m) (respectivement P < 0,001, P < 0,05). La composition en terpènes des laits est apparue dépendre de celle des pâturages. Les laits issus des pâturages les plus riches en dicotylédo-nes, notamment en ombellifères, contenaient plus de terpènes, tant en quantité qu'en variété, que les laits issus des pâturages riches en graminées. Les compositions en molécules volatiles non terpéni-ques et en caséines, les teneurs en calcium et phosphore n'ont pas semblé être influencées par le type de pâturage.pâturage / lait / plasmine / composition en acides gras / composé volatil

-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.cheese / flavour / volatile compound / proteolysis / pasture Résumé -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 diffé-rents 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.fromage / flaveur / composé volatil / protéolyse / pâturage

-Raw cow milk microflora: diversity and influence of conditions of production . The microbial composition of 158 raw cow milk samples taken from 27 farms located in the French Alps area was determined. Microbial analyses included the total mesophilic aerobic bacteria count as well as numeration of some useful cheesemaking microorganisms (lactic acid bacteria, halophilic bacteria, propionic acid bacteria…), spoilage bacteria (Pseudomonas, enterobacteriaceae, Clostridium spp.) and some of the pathogenic bacteria (coagulase positive staphylococci, Escherichia coli). Milk samples were of good overall microbial quality (mean value less than 10 000 cfu . mL -1 ) and had different contents of useful cheesemaking microorganisms or spoilage bacteria. Five different groups of milks were then separated according to their total count and to their relative contents in useful cheesemaking and spoilage microorganisms. When incubated at 37 o C for 24 h without any starters addition, milks of the different groups did not have the same ability to produce acid and to coagulate. At the farm level, milk suppliers practices were studied. Farmers differed by their way of washing the milking equipment and by their pre-milking and post-milking udder preparation. Combination of these practices influenced the microbial load and composition of the milk produced. microbial composition / raw milk / farmer practice Résumé -La composition microbiologique de 158 échantillons de laits crus de vache prélevés à la fin de la traite chez 27 producteurs des départements de Savoie et Haute-Savoie a été étudiée. Seize groupes microbiens ont été choisis parmi les groupes d'intérêt technologique (flore acidifiante méso-phile, flore halotolérante, bactéries propioniques…), les groupes d'altération (Pseudomonas, entéro-bactéries, Clostridium spp.) ou certains groupes potentiellement pathogènes (staphylocoques à coagulase positive, Escherichia coli). Si en moyenne les laits analysés renferment très peu de germes (moyenne inférieure à 10 000 ufc . mL -1 ), il est possible de distinguer 5 classes de laits qui diffèrent par leur teneur en flore mésophile aérobie revivifiable (de 1 200 à 15 000 ufc . mL -1 en moyenne) et par leur proportion en flore d'intérêt technologique et en flore d'altération. Les laits des différentes 575 * Correspondance et tirés-à-part Tél.

Summary — Differences in walking speed and milk yield were compared in dairy heifers and cows of 3 different breeds (Holstein, Montb6liarde, and Tarentaise) during 3 walking trials. Tarentaise cows walked faster than those of both other breeds. For walked distances of 5.6 and 3.2 km (trials 1 and 2, respectively) the mean walking speed of Tarentaises (1.71 and 1.43 m/s) was higher than for Montbéliardes (1.49 and 1.10 m/s) and-Holstein (1.50 and 1.23 m/s). In trial 2, the Holstein and the Montb6liarde breeds both required more encouragement to move forward (P < 0.05) than the Tarentaise breed. In trial 3, milk production, milk composition and blood metabolites were evaluated following walked distances of 0, 6.4, 9.6 and 12.8 km. Milk yield and protein decreased (P < 0.01 ) in proportion to the distance traveled by 1.9 kg/d and -51 g/d, respectively, after 12.8 km. In contrast, milk fat, milk protein and blood-free fatty acids increased (P < 0.01) by 4.6 g/kg, 1.8 g/kg and 0.4 mmolll, respectively, up to 12.8 km. Decreases in milk yield and protein were greater (P < 0.01 ) in Holstein cows than in the other 2 breeds. However, all cows regained their former level of milk yield within 3 d following the exercise. Five hours after walking, variation of glycemia was slight (P= 0.06) and the lactate level in the blood did not vary among walked distances. Only walked distances above 6.4 km brought about modifications in milk yield, milk composition and in blood-free fatty acids. These modifications were greater

-The infection of udder by a pathogen and milk somatic cell count (SCC) of 220 quarters from 55 Abondance and Tarentaise cows coming from three Northern Alps herds were analysed three times: in June when cows use a valley pasture before turning to highland pasture and in July and September, respectively at the beginning and the end of highland pasture grazing period. During the three periods, 31% of the experimental quarters were free or infection, 61% were infected by a minor pathogen and 8% were infected by a major pathogen. In quarters infected by a major pathogen, SCC was constantly high (> 1 600 000 cells/ml in the three periods). SCC of uninfected quarters remained below 60 000 cells/ml in the three periods whereas SCC of quarters infected by a minor pathogen averaged 89 000 cells/ml in June and 512 000 cells/ml in September. For the latter, SCC was all the higher as the infection was older. Results are discussed according to the highland grazing conditions that may have had an impact on SCC. milk / somatic cell count / udder infection / highland pastureRésumé -Évolution au cours de l'alpage de la concentration en cellules somatiques du lait de vache en relation avec l'état infectieux des mamelles. Le statut infectieux et la concentration en cellules somatiques (CCS) du lait de 220 quartiers issus de 55 vaches de race Abondance et Tarentaise ont été analysés à 3 reprises -avant la montée en alpage lorsque les animaux utilisent des pâturages de vallée (juin), en début de saison d'alpage (juillet) et en fin de saison d'alpage (septembre) -dans 3 troupeaux des Alpes du Nord. Les animaux ont été choisis sur la base de leur concentration en cellules somatiques hivernale (toujours inférieure à 100 000 et 500 000 cellules/ml pour respectivement 75 % et 25 % des animaux). La CCS des laits des quartiers a été mise en relation avec le statut infectieux des quartiers, la conformation des mamelles, le stade de lactation des animaux, le troupeau Ann. Zootech. 49 (2000) 45-54 45

NoteFacteurs de variation de la numeration cellulaire du lait en exploitation* C Agabriel

: The article analyses changes in the recent dynamics of AOC cheese production in Savoie, France, and examines problems related to changes in the economic and territorial context. First, through a cross-analysis of information from the Agricultural Census, examined in the context of urban development and AOC zoning, and economic data from the Réseau d'Information Agricole (agricultural information network), we show how the development of Savoyard AOC production has been positive over the last few decades. Second, we use surveys conducted among farmers to show how urban growth and the changing agricultural policy could be a threat to this favourable development, necessitating a fresh look at the AOC designation system in Savoie.

higher than fat content variations (-1.0 to +1.4 glkg) (fig 2). After 1 or 2 wk adaptation, these variations in performance from one type of hay to another were low. Protein content variations were significantly related to corresponding energy supply variations (R = 0.80, P < 0.05) (fig 3). Nethertheless, some types of hay seem to have a specific effect on milk production or milk composition. These results have to be confirmed on a larger range of hay types.