This paper illustrates the importance of the analytical method for the determination of fatty acid composition in feed. In Switzerland, not only the lipid content but also the fatty acids profile are necessary to formulate a ration that will produce an optimum quality of fat in the pig carcass. Results of this study showed that the fatty acid profile obtained by gas chromatography (GC) with in situ transesterification was more accurate and complete than that obtained by a GC method in two steps (fat extraction followed by esterification) or by a gravimetric empirical method which employed the extraction of soluble compounds in a given solvent.

Cet article illustre l�importance de la methode analytique pour la determination de la composition d�acides gras dans les aliments pour animaux. Notamment dans l�alimentation pour porcs ou, en Suisse, non seulement la teneur en lipides mais aussi le profil d�acides gras sont necessaires pour formuler une ration apte a fournir une qualite optimale de graisse dans la carcasse de porc. L�etude montre que la methode GC (chromatographie en phase gazeuse) par transesterification in situ est plus precise et complete que, d�une part, la methode GC en deux etapes (par extraction des corps gras puis esterification) et, d�autre part, la methode empirique, par gravimetrie, qui consiste en l�extraction des composes solubles dans un solvant donne.

Various raw cured meat products belong to the cultural heritage of Switzerland. The present investigation provides for the first time extensive analytical data regarding the nutritional value of dry-cured ham (Rohschinken), Coppa, dry-cured bacon (Rohessspeck), Appenzeller Mostbrockli and dried beef (Trockenfleisch) of Swiss origin. The analyses showed a high amount of protein and large differences in the fat content dependent on the variety. The pork meat products dry-cured ham, Coppa and dry-cured bacon contain substantial amounts of vitamin B 1 , niacin and phosphorus. In the beef meat products Mostbrockli and dried beef above all the content of vitamin B 12 , niacin, phosphorus, iron and zinc have to be mentioned. All products investigated had a high salt content which is due to the manufacturing process.

Un essai a ete mis en place dans le but d�etudier l�effet d�un deficit energetique de l�ordre de 15 MJ par jour pendant deux semaines sur la composition de la matiere grasse du lait. Vingt-quatre vaches en debut de phase de pleine lactation ont ete reparties en deux variantes apres avoir ete nourries selon le meme regime (foin, melange d�ensilages d�herbe et de mais, pommes de terre, concentres energetique et proteique, aliment mineral) et gardees dans les memes conditions depuis le velage. Dans la variante C (Controle), les vaches ont ete nourries selon les recommandations, alors que dans le groupe D (Deficit), les vaches ont ete mises progressivement en situation de deficit energetique pour atteindre un bilan energetique de -15 MJ/jour sur une duree de deux semaines. Cette phase a ete suivie par deux semaines de retour a un approvisionnement selon les recommandations. Durant la phase de deficit, le poids vif, le BCS (body condition score ou note d�etat corporel), la production laitiere et le taux proteique ont diminue alors que le taux de matiere grasse et d�uree dans le lait ont augmente. Tendanciellement, par rapport aux valeurs mesurees durant la phase d�adaptation, la composition de la matiere grasse du lait a ete modifiee sous forme d�une augmentation des acides gras (AG) longs (C18 et plus), parmi lesquels principalement l�acide oleique (C18:1c9 ) ainsi que la somme des AG omega 3. Proportionnellement, on observe une baisse des AG satures au profit d�AG mono- et polyinsatures. La plupart des effets constates durant le deficit sont partiellement ou entierement reversibles apres deux semaines de retour a une alimentation conforme aux recommandations.

BACKGROUND A wide range of isomer-specific health benefits have been attributed to conjugated linoleic acids (CLAs). Little information is currently available on the influence of different feed components on the concentration of CLA isomers in ruminant-derived products. The aims of this study were to compare the effect of cereal mix or dried sugar beet pulp supplementations fed to grazing dairy cows on milk CLA isomeric distribution and to examine the monthly variation of CLA isomers during the grazing season. RESULTS The concentrations of the isomers t7c9, t10c12 and t10t12 were higher in milk from cows supplemented with cereals (P < or = 0.001). The milk of beet pulp-supplemented cows showed higher levels of the isomers t11c13 (P < or = 0.05), t9t11 (P < or = 0.001) and t7t9 (P < or = 0.01). Total CLA as well as seven other minor isomers were not significantly affected by the concentrate type. Monthly variations occurred extensively for almost all detected isomers. Total CLAs showed the highest values at the beginning of the grazing season and in autumn in coincidence with plant regrowth. CONCLUSION These results show that even at low levels, supplement types can significantly influence the concentration of some CLA isomers in milk fat; an indication is given of the possibility to manipulate the animals' diet to change the CLA isomeric profile in ruminant-derived products.

Influence of an energy deficient diet on milk composition An experiment was set up to study the effect of an energy deficit of approximately 15 MJ per day for two weeks on the composition of milk fat. Twenty-four cows at the beginning of full lactation, which were fed the same diet (hay, mixtures of silage of grass and corn, potatoes, concentrates of energy, protein and minerals) and kept under the same conditions after calving, were allotted to two groups. In group C (control), the cows were fed according to the recommendations, whereas in group D (deficit), the cows were slowly introduced to a diet resulting in an energy deficit of 15 MJ/day for two weeks. This phase was followed by a two weeks return to a normal diet. During the deficit phase, the live weight, BCS, milk production and protein levels decreased whereas the urea and fat content of milk increased. Compared to the values measured during the adaptation phase, the composition of the fat content of milk tended to have increased long (C18 and more) chain fatty-acids (FA), mainly C18: 1c9 (oleic acid) as well as the sum of omega-3 FA. There was a proportional decrease in saturated FA compared to mono- and poly-unsaturated FA. The majority of the effects noted during the deficit period were partially or entirely reversed after two weeks back to a recommended diet.

A trial was carried out to investigate the influence of forage from temporary or from permanent grassland as well as permanent grassland supplemented with maize silage on the milk fat composition. The trial lasted seven weeks: two weeks of adaptation period and five weeks of experimental period. The forage was offered ad libitum in the stable. None of the cows received concentrates, only a mineral supplement was added. Both feed intake as well as milk production were recorded daily. Before the trial and three times during the trial milk samples were taken and in addition to the fat, protein and lactose content different fatty acids in the milk fat were analysed. The variant with the forage from the permanent grassland had, in comparison with the forage from the temporary grassland, higher proportions of unsaturated fatty acids and higher contents of omega-3 and of conjugated linoleic acid (CLA). With increasing age of the forage, the contents of omega-3 and CLA decreased. The addition of maize silage had a stronger influence on these fatty acids, as the lowest amounts of omega- 3 and CLA were found.

In Switzerland, cooked sausages are very popular and belong to the most often consumed meat products. The aim of the present study was to determine the detailed fatty acid composition in commercially available Swiss cooked sausages. Analyses were performed in eight sausage types (N=5): frying sausage from veal, Cervelat, Vienna sausage, Lyoner sausage, meat loaf, frying sausage from pork, pork sausage, and Lyoner sausage from poultry. The fatty acid content ranged from 15.8 to 22.6 g per 100 g edible sausage. On average, 40% of the fatty acids were saturated, 48% monounsaturated, and 9% polyunsaturated. The cooked sausages also contained small amounts of CLA and trans fatty acids. Similar patterns were found regarding the individual fatty acid composition of the sausages. However, depending on the meat and fat type (pork, poultry, beef, veal) as well as the recipes used for the different sausages, slight differences in the individual fatty acid concentrations were detected.

Typically, two different flock managements are employed by basque sheepherders in winter and spring. Thus, seasonal changes in the fatty acid (FA) composition of Idiazabal PDO farmhouse cheeses were studied. Ewe's raw milk cheeses elaborated in winter and spring were collected after 120 days of ripening from 10 Idiazabal PDO farmhouses. In winter, concentrate and conserved forages were fed, whereas a part-time grazing system was adopted from spring onward. Spring cheeses had less (P <or= 0.05) saturated FA and higher (P <or= 0.05) content of unsaturated FA, including trans-FA (mainly trans-vaccenic acid) and conjugated linoleic acid (CLA), branched-chain FA (BCFA), and n-3 FA. Principal component analysis (PCA) separated winter and spring cheeses into two groups by the combination of two principal components (84.2% of variance). Fresh pasture in the diet enhanced desirable FA and lowered atherogenicity index in cheeses, supporting the benefits of using a part-time grazing system for the consumer.

The aim of this study was to characterise mountain-produced meat. A total of 88 steers of the hardy Swiss Herens breed were compared. The animals came from extensive grassland mountain farms in the Alps (1200 and 1800 m above sea level) and in the Jura (1200 !, m) and from a lowland farm practising intensive fattening without grass. The meat produced at medium altitude (1200 m) did not have any particular sensory characteristics after maturing for two weeks. On the other hand, after three weeks maturing, the mountain-produced meat had a stronger pastoral flavour than the lowland meat. The meat produced at an altitude of 1800 m on poor, steep pasture was 30% less tender than the lowland meat and was the least acceptable in a consumer test. Grass-based feeding altered the fatty acid composition of the meat and improved its nutritional quality. By enabling the different production sites to be fully distinguished from one another, the fatty acids proved to be excellent "terroir" biomarkers, indicating the possibility of analytical traceability.

BACKGROUND: Different conjugated linoleic acid (CLA) isomers are known to have contrasting physiology or health effects and there is growing evidence that the profile of natural isomers in milk is influenced by the production system. This survey is the first to compare feeding regimes and concentrations of 14 CLA isomers in milk from three production systems in the UK.RESULTS: Total CLA and seven isomers (including C18:2 c9t11 which comprised >80% of total) were significantly higher in milk from both organically certified and non-certified low input (LI) systems compared with milk from conventional high input farms. Sampling date also affected concentrations of total CLA and nine isomers; being lowest in March and highest in August. Seasonal differences were greater in milk from LI herds, thought to be due to changes in herbage and/or stage of lactation. Multivariate analysis showed a strong positive relationship between several CLA isomers and increasing levels of fresh forage in the diet.CONCLUSIONS: These results add to the evidence on how management adjustment may improve the profile of CLA isomers in milk fat, although animal or human intervention studies are required to identify the effects of consuming milk with different CLA levels and isomer profiles on human health. (C) 2009 Society of Chemical Industry

Among consumers there is a growing demand for food products with a natural nutritional-physiological advantage over comparable conventional products. As part of an EU funded project, Agroscope Liebefeld-Posieux ALP examined the possible impact of processing on nutritionally valuable milk components. using the example of conjugated linoleic acids (CLA). Among the many benefits ascribed to CLA, it is believed to have an anticarcinogeneic effect. The extent to which processing influences the CLA content of the end product was determined by literature research and own investigations of organic and conventional butter. Furthermore, new methods to determine the oxidation stability of butter were evaluated by ALP, and the storage stability of CLA enriched and conventional butter was examined. As a third objective, a process for low-input CLA enrichment of milk fat has been developed.

The possibility of influencing the composition of milk fat during lactation has already been the subject of multiple studies. At the beginning of lactation, some of the milk fatty acids are derived not only from the diet but also from body reserves which are mobilized to make up for the energy deficit. A project was set up with the aim of studying the possibilities of influencing milk fat by altering the composition of the body reserves. Preliminary results are presented here. At the beginning of drying off 28 dairy cows of the ALP herd were divided into two groups. During the whole dry period until calving, the cows of the experimental group (S) received 2 kg per day of a feed containing 50% coarse-grind sunflower seeds, whereas the control group (K) received feed containing the same quantity of fat in the form of animal fat. After calving and in the weeks which followed, all cows received the same low fat ration. Analyses of samples of fat tissue, removed under local anaesthesia, at drying off and at calving time showed a greater increase in the concentration of linoleic acid during the dry period for the S group (P < 0.05). During the first 12 weeks of lactation, ingestion levels, milk production and milk contents (fat, protein, lactose) as well as the energy balance did not differ between the two groups. The fatty acid composition of milk was analyzed every 2 weeks after the end of the 1st week until the 11th week of lactation. The milk of the S group tended to be less rich in saturated fatty acids and contained more mono-unsaturated fatty acids than the K milk at the beginning of lactation (week I to 3). It was also more concentrated in poly-unsaturated fatty acids, especially linoleic acid C18:2 c9c12, with significant differences in the first week only. The other fatty acids analyzed in fat tissue and milk were not influenced by the diets.