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

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.

Milk fatty acid composition of indigenous goat and ewe breeds from Sindh, Pakistan

“…Within SAFA, palmitic acid (C16:0), myristic acid (C14:0) and stearic acid (C18: 0) accounted for the highest proportions in milk fat of both breed species with mean values 44.11% for goat and 46.26% for ewes correspondingly. Similar results were reported by Tomotake et al (2006); Bernard et al (2005); Sevi et al (2002) and Atti et al (2006) for Silico-Sarde, Comisana ewes and Alpine and JapaneseSaanen goats fed on different diets.…”

Dietary nano-chromium tripicolinate increases feed intake and decreases plasma cortisol in finisher gilts during summer

“…Circulating glucose concentrations were increased in pigs (Prunier et al 1997) and cattle (Denbow et al 1986), but decreased in sheep (Achmadi et al 1993) and cattle (Shwartz et al 2009;Wheelock et al 2010), and unchanged in pigs in another study (de Bragança and Prunier 1999) under hot conditions. Heat exposure increased plasma NEFA in sheep (Sevi et al 2002), but decreased NEFA in lactating cattle (Itoh et al 1998;Shwartz et al 2009;Wheelock et al 2010). These differences between basal hormone and metabolite concentrations may relate to differences in experimental conditions, such as ambient temperature and feeding manner, physiological status and animal species.…”

Effect of whole cottonseed v. sunflower seed on the fatty acid profile of subcutaneous fat, longissimus dorsi and blood of Thai Native and Holstein bulls

“…It has been shown by Sevi et al (2002) that in heat stressed ewes, the FA profile of milk fat had higher proportions of SFA and lower proportions of oleic acid and PUFA. Moreover, Perry et al (1998) observed an increase in C16:0 and C18:0 and a decrease in C18:1 of subcutaneous fat when steers were exposed to higher ambient temperatures.…”