Fatty acids profile of cow\u2019s milk produced from alpine grazing.

Milk from alpine grazing shows a different fatty acids profile (FA) from that produced in lowlands farms. In particular, it seems to have an increased content in Mono- and Polyunsaturated Fatty Acids (MUFA and PUFA) and a better n-6 to n-3 ratio. Conjugated linoleic acid compounds (CLA) content also seems to be enriched. The present study aimed at evaluating the effect of alpine grazing (AG), in comparison to a Total Mixed Ration (TMR) feeding system, on fatty acids profile of milk. The study took place from May to September 2006 and involved a farm which during summer move to alpine grazing (Novegno Mountain - Vicenza, North Italy). During the lowland period (P1, May, 25) animals were fed a TMR diet, whereas during the alpine periods (P2, July, 18; P3, September, 5) animals were kept at pasture and received a concentrate supplement based on maize and barley. Bulked milk samples (mix of evening and morning milking) were collected 3 times throughout one week of each experimental periods (n=9). FA profile was assessed by gas-chromatography and the obtained data (% of the total detected FAME) were submitted to a one-way ANOVA; the 3 levels of fixed effect Period/Feeding system were used to calculate two orthogonal contrasts (P1 vs P2+P3 and P2 vs P3). Results showed a significant decrease of Saturated Fatty Acids (from P1: 62.9 to P3: 56.6%; P<0.001) and an increase of MUFA (from P1: 25.3 to P3: 31.1; P<0.001) and PUFA (from P1: 4.2 to P3: 5.5; P<0.01), determining also a better n-6 to n-3 ratio (from P1: 3.6 to P3: 2.6; P<0.01), Thrombogenic (from P1: 3.1 to P3: 2.3; P<0.001) and Atherogenic (from P1: 2.6 to P3: 1.9; P<0.001) indexes and CLA content (from P1: 0.8 to P3: 2.2; P<0.001). For all of these variables contrast analysis showed a significant difference (P