Effect of dietary milk thistle (Silybum marianum L.) oil supplementation on animal performance and milk fatty acid composition in dairy ewes

Abstract

Supplementation of ruminant diets with oils derived from plants has proved to be a good strategy for enhancing desirable milk fatty acids (FA) profile and improving yield. The objective of this study was to determine the effect of inclusion of milk thistle oil in dairy ewes’ rations, on animal performance and milk fatty acid composition. A total of 20 Greek mountain ewes, in second lactation, were allocated into two treatments. Treatments were 1) concentrate diet (control – CON) and 2) concentrate diet supplemented with 3 % (w/w) milk thistle oil (MTSO). Individual monthly milk samples were collected throughout the lactation period of the animals to determine the milk chemical composition and fatty acid profile. Supplementation with MTSO resulted in significantly higher milk yield (576.8 g vs 439.0 g for the CON group) (P < 0.05) and did not affect fat content. Regarding milk fatty acid composition, ewes on the MTSO treatment produced milk with significantly increased concentration of monounsaturated and polyunsaturated FA, improving the nutritional value of milk. Major changes were observed in milk FA profile due to oil supplementation. Milk thistle oil significantly decreased concentration of saturated FA (SFA). Milk in ewes receiving the MTSO supplement showed an increase in milk conjugated linoleic acid (C18:2 cis-9,trans-11) concentration. In conclusion, both milk quantity and quality were favourably affected by MTSO, suggesting that dietary MTSO could serve as a practical means to modify milk composition while improving its nutritional value.