Fatty acid composition of cow milk fat produced on low-input mountain farms

The fatty acid (FA) composition of bulk milk fat was examined on three mountain dairy farms in the Czech Republic. Milk samples were collected in the period of indoor grass silage feeding (November-April) and in the grazing period (May-October). In total fifty FAs were identified in the milk fat. The two-way ANOVA with factors of the farm and of the period of milk sample collection was used for the evaluation of variation in FA concentrations. Significant differences between the farms (P < 0.01) were found in the concentration of five FAs, which accounted for 30.40 g/100 g total FAs. Significant differences between the indoor and the grazing period (P < 0.01) were found in the concentration of sixteen FAs, which accounted for 63.86 g/100 g total FAs. The content of long-chain (> C16), mono- and polyunsaturated FAs in the milk fat was higher in the grazing period (49.22, 31.69 and 4.69 g/100 g total FAs) than in the indoor period (42.25, 27.55 and 4.15 g/100 g total FAs, respectively; P < 0.01). The proportion of conjugated linoleic acid (CLA) was also higher in the grazing period (1.09 g/100 g total FAs) than in the indoor period (0.74 g/100 g total FAs; P < 0.01). The medium-chain (C12-C16) and the saturated FAs were more abundant in the milk fat in the indoor period (48.91 and 67.16 g/100 g total FAs) than in the grazing period (41.31 and 62.16 g/100 g total FAs; P < 0.001 and P < 0.01; respectively). These results indicated a positive influence of seasonal grazing on the FA profile of cow milk fat as regards its potential health effects in consumers.