Variation in fatty acid composition of milk and cheese from cows grazed on two alpine pastures

Abstract

-The aim of this study was to verify the variation in fatty acid composition of milk, and derived cheese, when dairy cows were grazed on different alpine vegetation types. An experimental design was developed to highlight the effect of pasture composition on milk and cheese fatty acid profiles, thereby mitigating the other variables (altitude, animal physiology, and animal management). Two dairy cow groups were grazed on two different key alpine vegetation types (Type 1: Trifolium alpinum, Nardus stricta, and Carex sempervirens and Type 2: Festuca nigrescens, Alchemilla xanthochlora, and Phleum alpinum). Bulk milk was collected separately from each group for 6 days, from which 12 artisanal cheeses were produced and ripened for 60 days. The fatty acid (FA) composition of the bulk milks and cheeses varied with the type of vegetation. Milk and cheese derived from cows that were grazed on Trifolium alpinum-dominated pastures were richer in long-chain FAs, unsaturated and monounsaturated FAs (particularly oleic acid), and odd-chain saturated FAs (such as C15:0 pentadecanoic and C17:0 heptadecanoic acids) while those from Festuca nigrescens pastures contained more short-and medium-chain FAs, saturated FAs, and α-linolenic acid. Furthermore, our results showed that in alpine grazing systems, milk and cheese FA profiles changed when cows were grazed on pastures with a different botanical composition, probably due to differences in forage quality and concentration of bioactive secondary metabolites. These results have to be taken into account for the valorization of the nutritional characteristics and for the traceability of grass-fed dairy products.fatty acid / milk / cheese / grassland biodiversity / alpine pasture / grazing acide gras / lait / fromage / biodiversité des pâtures / pâture alpine / pâturage

Maîtrise par l’alimentation des teneurs en acides gras et en composés vitaminiques du lait de vache

“…Généralement, les laits de vaches pâturant des prairies permanentes de montagne ont des concentrations plus élevées en C18:3n-3 et C18:1-c9, et plus faibles en AGS. Ces prairies se caractérisent par une biodiversité floristique plus importante que les prairies de plaine du fait de l'abondance de diverses plantes dicotylédones (Falchero et al 2010). La présence de certains métabolites secondaires tels que les terpènes ou polyphénols associés à ces plantes pourraient inhiber la BHR des AGPI, et expliquer la teneur plus élevée en C18:3n-3 (Chilliard et al 2007).…”

H, C, N and O stable isotope characteristics of alpine forage, milk and cheese

“…Studies of the literature on beef, lamb and pig (as examples: Camin et al, 2007;Harrison et al, 2011;Horacek & Min, 2010;Knobbe et al, 2006;Molkentin, 2009;Molkentin & Giesemann, 2007Tuross, Warinner, Kirsanow, & Kester, 2008) did not highlight a great influence of breed on the variability of stable isotope ratios of bioelements. At the AV site (details on AV vegetation are reported in Falchero et al, 2010) they fed on an oligotrophic type mainly made up of Trifolium alpinum, Nardus stricta, and Carex sempervirens (AV-T), and a mesophilous type with Festuca gr. rubra, Alchemilla xanthochlora, and Phleum alpinum (AV-F).…”

Hydrocarbon and Fatty Acid Composition of Cheese As Affected by the Pasture Vegetation Type

“…42 The highest values of C15, C17, and C17:1 observed in cheese samples of category T were in accordance with the highest values of the same fatty acids previously detected in T pasture samples. 25 The GC operative conditions applied allowed the separation of interesting isomers of both linoleic and conjugated linoleic acid. The tentative identification of these compounds was made according to the data published by different authors who used the same type of GC column and, for CLA isomers, compared the GC results with those obtained by argentation chromatography.…”

“…Fresh green forage, having higher levels of polyunsaturated fatty acids with respect to silage, allows the production of milk with a high content of polyunsaturated fatty acids. 20,22 The effect of Trifolium alpinum and Festuca nigrescens on the FA composition of milk and cheese has been recently tackled by Falchero et al, 25 who detected a significantly higher content of odd-chain (C15, C17, and C17:1) FAs in dairy samples deriving from T. alpinum-dominated pasture and a significantly higher content of α-linolenic acid in those deriving from F. nigrescens-dominated pasture. That paper reported the results of the first year of experimentation of the research project "Pro-Alpe" aiming at the characterization and protection of typical dairy products through the detailed definition of the terroir of the Italian Alpine mountains.…”

“…25 For this purpose all of the cheese samples were analyzed by applying analytical procedures useful to detect and quantify branched and trans fatty acids, as well.…”