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Abstract: Studies within the QLIF project reviewed in this article suggest that organic or low-input management is more likely to result in milk with fatty acid profiles that are higher in α-linolenic acid and/or beneficial isomers of conjugated linoleic acid and antioxidants with up to a 2.5-fold increase in some cases, relative to milk from conventional production. These advantages are preserved during processing, resulting in elevated contents or concentrations of these constituents in processed dairy products of organic or low input origin. Much of the literature suggests that these benefits are very likely to be a result of a greater reliance on forages in the dairy diets (especially grazed grass). Since the adoption of alternative breeds or crosses is often an integral part sustaining these low-input systems, it is not possible to rule out an interaction with genotype in these monitored herds. The results suggest that milk fat composition with respect to human health can be optimized by exploiting grazing in the diet of dairy cows. However, in many European regions this may not be possible due to extremes in temperature, soil moisture levels or both. In such cases milk quality can be maintained by the inclusion of oil seeds in the dairy diets. [Copyright &y& Elsevier]

Three groups of Holstein cows were fed concentrates with different fatty acid compositions; one high in saturated lipids, another high in unsaturated lipids and the last one simulating high de novo synthesis. The feedings resulted in milk with fat contents of 5.0%, 3.7% and 4.0%, respectively. The milk fat globules (MFGs) were significantly larger in the milk with the highest fat content. All three types of milk were pumped for 450 s at various shear rates and temperatures. Afterwards, measurement of particle size distribution showed that the highest coalescence of MFGs in the milk occurred with the largest fat globules. Moreover, the fat globules were more unstable at a pumping temperature of 31°C compared with lower temperatures. Likewise, an increase was found in free fatty acids for milk with the largest MFGs, indicating that milk with a high fat content is more unstable when exposed to mechanical stress. Xanthine oxidase activity in raw milk was not affected by pumping. The results are discussed in relation to automatic milking systems. [Copyright &y& Elsevier]