Table 5.

Effects of level and source of fat in the diet of beef cows during gestation, time and treatment × time interaction on milk fat polyunsaturated fatty acid profiles during the first 42 d of lactation

	Treatment1				Days			P-value 2
Fatty acid, % of total	LF (n = 10)	CAN (n = 10)	FLX (n = 10)	SEM	21	42	SEM	LF vs. HF	CAN vs. FLX	d	trt × d
∑PUFA	2.93	2.90	2.93	0.16	3.06	2.78	0.16	0.88	0.65	<0.01	0.72
∑n-3	1.19	1.20	1.30	0.07	1.38	1.08	0.07	0.23	0.09	<0.01	0.95
18:3n-3	0.82	0.82	0.89	0.06	0.94	0.74	0.05	0.39	0.22	<0.01	0.94
20:3 + 20:4 + 20:5n-3	0.17	0.16	0.19	0.01	0.20	0.14	0.01	0.49	< 0.01	<0.01	0.90
22:5 + 22:6n-3	0.20	0.22	0.23	0.02	0.23	0.20	0.02	<0.01	0.07	<0.01	0.16
∑n-6	1.74	1.71	1.63	0.11	1.68	1.70	0.11	0.10	0.13	0.45	0.82
18:2n-6	1.25	1.24	1.23	0.11	1.19	1.29	0.11	0.63	0.82	<0.01	0.93
18:3n-6	0.04	0.04	0.03	0.00	0.04	0.04	0.00	<0.01	0.01	0.17	0.24
20:2 + 20:3 + 20:4n-6	0.37	0.35	0.30	0.01	0.36	0.31	0.01	<0.01	<0.01	<0.01	0.02
22:2 + 22:4n-6	0.08	0.08	0.08	0.00	0.09	0.07	0.00	0.85	0.03	<0.01	0.22
∑CLnA	0.07	0.08	0.11	0.01	0.09	0.08	0.01	<0.01	<0.01	0.03	0.48
c9,t11,t15-18:3	0.04	0.03	0.05	0.00	0.04	0.04	0.00	<0.01	<0.01	0.68	0.70
c9,t11,c15-18:3	0.04	0.04	0.06	0.00	0.05	0.04	0.00	0.02	0.01	<0.01	0.53
∑AD	0.37	0.40	0.58	0.09	0.43	0.47	0.09	<0.01	<0.01	<0.01	0.07
c9,t14- + c9,t13-18:2	0.11	0.14	0.20	0.02	0.14	0.16	0.02	<0.01	<0.01	<0.01	0.04
c9,t15-18:2	0.05	0.06	0.08	0.01	0.05	0.07	0.01	<0.01	<0.01	<0.01	0.02
t11,c15-18:2	0.14	0.13	0.21	0.03	0.18	0.15	0.03	<0.01	<0.01	0.03	0.55
∑CLA	0.65	0.69	0.88	0.08	0.72	0.77	0.08	<0.01	<0.01	<0.01	0.42
c9,t11- + t7,c9-18:2	0.55	0.60	0.76	0.07	0.61	0.67	0.07	<0.01	<0.01	<0.01	0.62
c11,t13-18:2	0.04	0.04	0.05	0.00	0.04	0.04	0.00	0.89	0.15	0.32	0.43
t11,c13- + c11,c11-18:2	0.02	0.02	0.04	0.01	0.03	0.03	0.01	<0.01	<0.01	<0.01	0.41
t,t-CLA	0.03	0.03	0.03	0.00	0.03	0.03	0.00	<0.01	<0.01	0.38	0.78
n-6:n-3 ratio	1.53	1.50	1.29	0.04	1.29	1.59	0.04	<0.01	<0.01	<0.01	0.98
Total, mg/g	35.9	36.5	40.6	2.74	38.9	36.4	2.72	<0.01	<0.01	<0.01	0.43

¹LF = cows fed a low-fat diet; CAN = cows fed a high-fat diet including a canola seed based–pelleted feed; FLX = cows fed a high-fat diet including a flaxseed-based pelleted feed.

²HF = average of CAN and FLX.

c = cis; t = trans; ΣPUFA = sum of polyunsaturated fatty acids (Σn-6 + Σn-3); Σn-3 = sum of n-3 fatty acids; Σn-6 = sum of n-6 fatty acids; ΣCLnA = sum of conjugated linolenic acids; ΣAD = sum of atypical dienes; ΣCLA = sum of conjugated linoleic acids. Total = ΣPUFA + ΣCLnA + ΣAD + ΣCLA.