Summary — The effect of diet on the chemical characteristics and rennet coagulation properties of milk from Brown and Friesian cows was examined with three feeding levels (normal, +7 or +14% of INRA requirements) and three forage:concentrate ratios (65:35, 57:43 and 44:56). The

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-The effect of two patterns of concentrate allocation were studied on twenty-eight Italian Brown cows (initial milk yield, 19.4 kg·d -1 ) grazing an alpine pasture. One group was supplemented at a flat rate, based on the initial milk production (Flat Supplement, FS), while the second was supplemented at a declining rate, according to the decline of lactation (Declining Supplement, DS). During an 8-week period in July and August, the cows were moved onto 8 successive sectors, ensuring a daily herbage allowance of 20 kg of dry matter per cow. The crude protein content of the herbage decreased from 19.5% at the beginning to 12.4% at the end, while the fibre fractions showed an opposite trend. The DS group showed a slightly higher, not significant, herbage intake (10.9 vs. 10.6 kg OM·d -1 ). BCS changes were in no case different from 0. The milk yield was positively affected by the FS (17.0 kg·d -1 vs. 15.2 kg·d -1 ); no difference was observed in milk composition. Coagulation properties were satisfactory without any appreciable effect of the two treatments. dairy cow / pasture / supplementation / herbage intake / milk production Résumé -Vaches laitières au pâturage alpin : effet des modalités de la distribution de l'aliment concentré sur la quantité d'herbe ingérée, l'état corporel, la production de lait et son aptitude à la coagulation. Vingt-huit vaches laitières de race Brune italienne (production moyenne initiale de lait : 19,4 kg·j -1 ), conduites sur un pâturage alpin, ont été réparties en 2 lots qui différaient par les modalités d'allocation du concentré. Dans le premier lot, les vaches recevaient une quantité constante de concentré, calculée d'après la production et la composition du lait pendant une période préliminaire d'une semaine (lot FS). Dans le second, elles recevaient une quantité de concentré dé-croissante, sur la base d'une production laitière persistante de 97 % par semaine (lot DS). Pendant l'essai, d'une durée de huit semaines (juillet-août), les animaux ont successivement pâturé 8 secteurs dans lesquels la disponibilité en herbe était d'environ 20 kg de matière sèche par jour. La teneur en matières azotées totales de l'herbe a diminué de 19,5 % (de la matière sèche) à 12,4 % pendant l'essai, tandis que celle en fractions fibreuses a présenté une évolution inverse. Le lot DS a été caractérisé par une ingestion plus faible de concentré (3,5 kg vs. 4,5 kg de matière organique par jour) et légère-ment plus élevée d'herbe (+0,3 kg MO·j -1 ; différence non significative). Les variations de la note d'état corporel n'ont pas été significativement différentes de 0. La production de lait a été augmentée avec le traitement FS (17,0 vs. 15,2 kg·j -1 ). La composition du lait n'a pas présenté de différences significatives. Les propriétés de coagulation du lait ont été satisfaisantes et n'ont pas été affectées par les traitements.vache laitière / pâturage / supplémentation / ingestion d'herbe / production laitière

The concentration of n-alkanes in the cuticular wax of plants can be used to estimate the composition of the diet selected by free-ranging animals. The aims of this study were to characterize the n-alkane profiles of developing leaves and evaluate the degree of chemical discrimination between six browsed broadleaf tree species: European ash (Fraxinus excelsior L.), flowering ash (Fraxinus ornus L.), hornbeam (Carpinus betulus L.), hazel (Corylus avellana L.), mountain ash (Sorbus aucuparia L.) and beech (Fagus sylvatica L). The effect of the stage of development was examined by considering five different vegetative stages: dormant bud (DB), late bud (LB), young leaf (YL), mature leaf (ML) and senescing leaf (SL). Five samples per each vegetative stage and species, gathered in a mixed woodland of the Italian Eastern Alps between February and October, were analysed for their n-alkane concentrations (C23-C36). The residual coefficient of variation was 15.5% on average for the individual n-alkanes considered. There were noticeable differences in individual and total n-alkanes content between species. In particular, C27 was the predominant n-alkane in beech and C33 was found in high proportions in the two species of Fraxinus; hazel and flowering ash had a higher total n-alkanes content than the overall mean, while the lowest values were found in hornbeam and beech. The n-alkane profile also underwent important changes during the vegetative development, with different extent and direction according to the species. In the three successive leaf stages, a tendency for a progressive increase in the longest chain homologues was observed. In any case, the young leaf stage differed most from the contiguous stages. Canonical discriminant analysis indicated that the n-alkane profile of buds and leaves were mathematically distinguishable and the chemical differences between species were persistent over the plant vegetative development

Abstract-The aim of this research was to measure, in terms of milk quantity and quality and variations of live weight (LW) and body condition score (BCS), the effect of offering different levels of concentrate to dairy cows grazing at high altitude. The experiment, which lasted 8 weeks, was conducted on a pasture located at an altitude of 1800-2200 m. Three groups of 10 Italian brown cows were fed different levels of concentrate offered above a production of 7 kg energy corrected milk (ECM)