Cabiddu, A., Addis, Decandia, Piredda, G., Spada, S., Fiori, M., Sitzia, M., Fois, N., Molle, G., Pirisi, A.
The aim of this study was to evaluate the effect of feeding fresh forages on the fatty acid composition of sheep milk, with special emphasis on the content of conjugated linoleic acid (CLA) and its precursors. Three forage species were compared during flowering phase: chicory (CH, Cichorium intybus), burr medic (BM, Medicago polymorpha) and saffl ower (SA, Carthamus tinctorius). Thirty-six mature Sarda ewes in late-lactation (157±4 DIM) were blocked into three homogeneous groups (CH, BM and SA) by milk yield (1930±60 ml) and body weight (49.6±0.9 kg) and randomly allocated to the three experimental paddocks. Each paddock was divided into two plots that were rotationally grazed (grazing period 14 d). Sward height and standing biomass were evaluated at the beginning and the end of each grazing period. The botanical and chemical composition of the herbage at the beginning and the end of the grazing period were evaluated. Individual milk yield and composition were measured fortnightly from 28 April to 4 June. Milk yield and milk protein were not infl uenced by forage species. Fat content was signifi cantly lower for SA than the other forages (5.78% vs 6.37% and 6.75% for SA, CH and BM respectively, P<0.05). Milk fatty acid composition was affected by the forage species. CLA content (mg/g of fat) was signifi cantly higher in milk from SA (20.69 vs 15.98 and 15.17 for SA, CH and BM respectively, P<0.01). CLA content signifi cantly decreased at the end of the season (P<0.01) probably due to the decrease of linoleic and linolenic acid in the forages. On the basis of these results, we conclude that it is possible to manipulate the milk fatty acid composition and in particular to enhance the content of benefi cial fatty acids by the use of appropriate fresh forage-based regimens.
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