Effects of dietary orange peel essential oil supplementation on milk yield and composition, and blood and milk antioxidant status of dairy ewes

Abstract Twenty eight lactating Chios ewes were used in an experiment to determine the effects of dietary orange peel essential oil (OEO) supplementation on milk yield, composition and fatty acid profile, as well as on antioxidant status in blood and milk. In the experiment, ewes after weaning, on day 43 postpartum, were allocated according to their milk yield and lactation number, into 4 treatment groups, being OEO0, OEO150, OEO300, and OEO450, of 7 ewes each and accommodated in individual pens. For a period of 60 days ( i.e. , days 43–102 postpartum), ewes were fed a concentrate (crude protein 175 g/kg, dry matter – DM basis; net energy for lactation 7.72 MJ/kg, DM basis) and alfalfa hay, with a concentrate-to-forage ratio of 57:43. The concentrate for treatment OEO0 (control) had no OEO, while that for treatments OEO150, OEO300 and OEO450 contained 150, 300 and 450 mg OEO/kg concentrate, respectively, after spraying OEO onto the concentrate of treatment OEO0. In the 60-day experimental period, DM intake quadraticaly (P   0.05). Milk fat fatty acid (FA) analysis showed a quadratic increase (P  4:0 , C 11:0 , C 14:0 and C 16:0 concentrations, while a quadratic decrease (P  17:1 , C 18:0 , cis- 9 C 18:1 , trans- 10 C 18:1 , C 18:2n-6c , C 18:3n-3 and C 20:3n-3 concentrations, with increasing dietary OEO inclusion levels. Overall, monounsaturated FA (MUFA), polyunsaturated FA (PUFA) and unsaturated FA (UFA) quadraticaly decreased (P  -9 desaturase activity index (C 14:1 /C 14:0 ) quadraticaly increased (P