The effect of grazing on the composition of conjugated linoleic acid isomers and other fatty acids of milk and cheese in goats

The effect of grazing on the fatty acid profile of milk and cheese was evaluated on 20 goats divided into two groups. The goats in the first group were kept indoors and fed with lucerne hay, the goats from the second group were kept on a natural pasture. Utilization of native pasture has been on a low level (extensive) for years in order to avoid over-grazing of the grassland. The milk from grazed goats had significantly higher contents of fat, protein and total solids without fat (P<0.001) as well as lower lactose content than goats kept indoors (P<0.01). Grazing considerably increased the total conjugated linoleic acid content in milk (0.59 vs 0.77%; P<0.001) and cheese (0.52 vs 0.84%; P<0.01). The distribution of n-3 and n-6 was much better in the grazed goats, i.e. the values of series n-3 fatty acids were higher in milk (0.52 vs 0.69%; P<0.01) and cheese (0.64 vs 1.07%; P<0.01). In addition, the n-6/n-3 ratio was also more favourable in the grazed group (milk: 6.10 vs 3.44; cheese: 4.19 vs 2.51; P<0.01). It is concluded that the milk and cheese from goats kept on the natural pasture were better in terms of nutraceutical parameters, which are advantageous in human nutrition, than the milk produced by animals kept indoors and fed with hay.