The aim of this study was to evaluate the effect of supplements on ω-3 and ω-6 fatty acid profile of grazing ewes. Forty-eight dairy sheep (DIM 88 + 10, BCS 2.42 + 0.24, BW 42.9 + 4.73 kg, and milk yield 1624 + 235 mL) were randomly assigned to the following dietary groups: only pasture (PAS), non-fat enriched supplementation (NFS, sheep, supplemented with 900 g of cereal based concentrate with 3.01% EE DM basis), moderate linolenic acid (ALA) supplementation (C183M, sheep supplemented with 900 g of linseed based concentrate with 6.01% EE DM basis) and high ALA supplementation (C183H, supplemented with 900 g of linseed based concentrate with 10.35% EE DM basis). All sheep grazed an Italian ryegrass paddock with an allocation of 22 h/d (PAS) or 3 h/d (all supplemented groups). Fatty acid methyl esters from milk fat were measured on one occasion using base-catalysed methanolysis. ANCOVA model with orthogonal contrast was used to test the effect of dietary treatment (Treat). Contrasts were performed to test the effect of supplementation level (SUPP), FAT enrichment and ALA level in the fat enriched concentrate (ALAL) on ω-3 and ω-6 milk FA profile. Overall treatment affect total ω-3, EPA, DHA and total ω-6 content (P<0.05). Pasture supplementation affected (P<0.05) total ω-3 and LNA content without effects on EPA and DHA (table 1). The ω-3 FA profile was mainly represented by ALA and C18:2 t11c15 whereas in ω-6 the main FA was LNA and C18:2c9t12t8c12.

Table 1. Adjusted least square means of ω-3 and ω-6 fatty acids

	Treatments											Treat				Contrast
	PAS	NFS	C183M	C183H											SUPP		FAT	ALAL
Tot ω-3 (mg/g fat)	20.1	16.7	28.3	27.9							*				*		*	ns
C18:3c9c12c15 (%ω-3)	47.6	42.3	45.6	48.9							ns				ns		ns	ns
C18:2t11c15 (%ω-3)	43.8	48.4	47.2	43.0							ns				ns		ns	ns
DPA (%ω-3)	4.7	4.6	3.6	3.9							*				ns		*	ns
C18:2c9c15 (%ω-3)	1.5	2.0	1.9	1.8							ns				ns		ns	ns
EPA (%ω-3)	1.2	1.0	0.7	0.7							*				ns		*	ns
DHA (%ω-3)	1.1	1.5	1.0	1.4							*				ns		ns	*
Tot ω6 (mg/g fat)	12.9	22.0	23.8	25.6							*				ns		*	ns
C18:2c9c12 (%ω-6)	53.2	80.6	75.0	81.1							*				*		*	ns
C18:2c9t12t8c12 (%ω-6)	23.1	9.2	10.9	10.2							ns				ns		*	ns
CLA t10c12 (%ω-6)	6.0	1.8	2.0	2.1							*				ns		*	ns
C20:3c8c11c14 (%ω-6)	5.1	2.5	0.6	0.6							*				ns		*	ns
C18:2t9c12 (%ω-6)	3.9	1.8	3.9	2.4							*				*		ns	*
C20:4 c5c8c11c14 (%ω-6)	3.5	3.2	2.9	2.7							ns				ns		ns	ns
C18:2t9t12 (%ω-6)	1.6	2.3	4.9	2.3							*				ns		ns	*

* P≤0.05; ns P>0.05