Fatty acids profile in milk of Chinampo cows (Bos taurus) fed fresh forage from sarcocaulescent shrubs or alfalfa hay

Abstract

The objective of the present study was to determine the concentration of fatty acids (FA) in the milk of Chinampo cows (Bos taurus), with emphasis on conjugated fatty acids (CLA). A sample of 10 ml was collected from 32 cows that had been lactating at least 60 days, but not longer than 120 days. A group (FV, n = 25) was free-ranged grazed on green fresh pasture (sarcocaulescent shrub semiarid area, La Paz, B.C.S.) during the wet season (September-October 2009). The second group (HA, n = 7) was penned and fed fodder of alfalfa hay. The FA analysis revealed that there were less saturated FA in the FV group (P < 0.05). This difference was basically explained by the lesser content of 14:0, 15:0, and 16:0. The concentration of total monounsaturated FA was higher in FV (P < 0.05), given by the higher concentration of 18:1 n-9 and 18:1 n-7 trans-11. The total concentration of polyunsaturated FA was similar for both groups, but there was a higher concentration of 18:2 n-6 and 18:2 n-7 cis-9 trans-11 in the FV group (P < 0.01). The proportion of omega-3 FA was similar for both groups, but the concentration of omega-6 FA was higher in FV (P < 0.01), resulting in an increased omega-6:omega-3 ratios in the FV group compared to HA. It is concluded that Chinampo cows left to free-range on fresh green pasture reduced the total saturated FA of medium chain length, and increased the concentration of 18:1 n-9, 18:1 n-7 trans-11 and 18:2 n-7 cis-9 trans-11, a benefit for human health. However, an increase in omega-3 FA is desirable in the milk of free-ranging cows in the area.