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Fatty acid composition of ewe milk as affected by solar radiation and high ambient temperature

Published online by Cambridge University Press:  06 September 2002

AGOSTINO SEVI
Affiliation:
Istituto di Produzioni e Preparazioni Alimentari, Facoltá di Agraria di Foggia, Via Napoli, 25, 71100 Foggia, Italy
TADDEO ROTUNNO
Affiliation:
Istituto di Produzioni e Preparazioni Alimentari, Facoltá di Agraria di Foggia, Via Napoli, 25, 71100 Foggia, Italy
ROBERTO DI CATERINA
Affiliation:
Istituto di Produzioni e Preparazioni Alimentari, Facoltá di Agraria di Foggia, Via Napoli, 25, 71100 Foggia, Italy
ANTONIO MUSCIO
Affiliation:
Istituto di Produzioni e Preparazioni Alimentari, Facoltá di Agraria di Foggia, Via Napoli, 25, 71100 Foggia, Italy

Abstract

Forty lactating Comisana ewes were either exposed to or protected from solar radiation and fed either in the morning or afternoon during summer in a Mediterranean climate. Individual milk samples were taken on days 7, 21 and 42 of the study period to determine fatty acid composition by gas chromatography. Exposure to solar radiation resulted in higher proportions of short-chain and saturated fatty acids in milk, primarily because of increased contents of caproic, capric, lauric, myristic and stearic acids (by 3–18%), and decreased contents of oleic, linoleic and linolenic acids (by 2–9%). As a consequence, the long to short chain and the unsaturated to saturated fatty acid ratios were significantly higher by 4 and 13% respectively in the milk of the protected ewes compared with that of the exposed animals. Provision of shade also led to an increase in the 18[ratio ]0+18[ratio ]1 to 16[ratio ]0 ratio, and to a decrease in the 12[ratio ]0+14[ratio ]0+16[ratio ]0 fatty acid group, which are regarded as reliable indexes of the nutritional property of dietary fat in reducing cholesterol levels in human plasma. Feeding time had little impact on milk fat. Our findings suggest that high ambient temperature may markedly modify the lipid composition of ewe milk and that provision of shade, but not feeding management, can improve the milk fatty acid profile in dairy sheep raised in hot climates.

Type
Research Article
Copyright
© Proprietors of Journal of Dairy Research 2002

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