Milk and cheese fatty acid composition in sheep fed Mediterranean forages with reference to conjugated linoleic acid cis-9,trans-11

Abstract

Two experiments were undertaken to evaluate the effect on milk and cheese fatty acid composition of feeding different fresh forages to dairy sheep both in winter (experiment 1, growing stage of the forages, early lactating ewes) and in spring (experiment 2, reproduction stage of the forages, midlactating ewes). Four forage species were compared: annual ryegrass (RY, Lolium rigidum Gaudin), sulla (SU, Hedysarum coronarium L.), burr medic (BM, Medicago polymorpha L.), and a daisy forb (CH, Chrysanthemum coronarium L.). The forages were cut twice daily and offered ad libitum to 4 replicate groups of Sarda dairy sheep (groups RY, SU, BM, and CH). The CH forage was particularly rich in linoleic acid in both periods, whereas BM and SU forages were rich in linolenic acid in winter and spring, respectively. Milk fatty acid composition was affected by the forage in both experiments. Milk conjugated linoleic acid and vaccenic acid contents were higher in CH and BM groups (winter) and CH group (spring) than in the other groups. No differences were observed when comparing fatty acid profile between milk, 1-d-old cheeses, and 60-d-old cheeses within experimental groups, suggesting that the fatty acid recovery rates during cheese making and ripening were not affected by the feeding regimens. After stepwise discriminant analyses of the pooled data, the milks and cheeses sourced in the different feeding regimens differed among them. Based on these results, we conclude that it is possible to manipulate the fatty acid profile of sheep dairy produce to maximize the content of beneficial fatty acids by the use of appropriate fresh forage-based regimens.