Effect of different pastures on CLA content in milk and sheep cheese

It is known that milk composition included conjugated linoleic acid (CLA) is affected by animal feeding system (Cabidduet al., 2001). In Sardinia dairy sheep feeding is mainly based on pastures. Most of them are characterised by self-regenerating species, like annual ryegrass (Lolium rigidumGaudin) and burr medic (Medicago polymorphaL.). Non conventional species belonging to the Compositae family such as (Chrysanthemum coronariumL.) seem interesting for sheep feeding when other herbages decrease in quality (late spring- early summer). It was observed thatC. coronariumestablishes rapidly, can be grazed early in the growing season and persist where other pasture species may disappear; for these reasons it can be considered a valuable source of food. Moreover a preliminary study with dairy sheep fed fresh forage ofC. coronariumshowed relatively high levels of CLA in milk (Molle G.pers.com.) The aim of the present work was to study the influence of different pastures on milk composition, with particular reference to CLA and its precursors.