Table 5.

Fatty acids (FA) concentration in milk of cows fed stearic acid (SA) and oleic acid (OA) dietary treatments in low and high rumen-active unsaturated fatty acids (RUFA) experiments

Items (% of total FA)	LRUFA experiment1						HRUFA experiment1
	Treatments2			P-value			Treatments2			P-value
	SA	OA	SEM	Trt	Wk	Trt × Wk	SA	OA	SEM	Trt	Wk	Trt × Wk
C6:0	0.76	0.84	0.07	0.21	0.31	0.33	0.8	0.78	0.03	0.51	<0.001	0.87
C8:0	0.81	0.83	0.05	0.72	0.10	0.45	0.69	0.65	0.03	0.32	<0.001	0.95
C10:0	2.5	2.5	0.13	0.59	<0.01	0.67	1.9	1.7	0.10	0.27	<0.001	0.91
C12:0	3.3	3.2	0.15	0.17	<0.01	0.71	2.2	2.1	0.11	0.30	0.02	0.90
C14:0	11.8	11.3	0.32	0.08	<0.01	0.70	8.9	8.5	0.28	0.37	<0.01	1.00
C15:0	0.78	0.78	0.04	0.91	<0.01	0.47	0.52	0.51	0.03	0.73	<0.001	0.70
C16:0	37.3	37.7	0.60	0.47	<0.01	0.80	29.9	30.2	0.33	0.59	<0.001	0.28
cis-9 C16:1	1.8	1.9	0.09	0.30	<0.01	0.24	1.1	1.1	0.10	0.50	<0.001	0.34
C18:0	12.2	10.4	0.30	<0.01	<0.01	0.50	14.9	13.8	0.43	0.06	<0.01	0.09
cis-9 C18:1	22.4	23.8	0.80	0.05	<0.01	0.56	26.6	27.6	0.61	0.26	0.42	0.89
trans-9 C18:1	0.13	0.14	0.01	0.33	0.56	0.37	0.54	0.60	0.03	0.17	<0.001	0.62
trans-10 C18:1	0.16	0.24	0.03	0.08	0.17	0.24	1.1	0.93	0.18	0.51	<0.001	0.33
trans-11 C18:1	0.32	0.28	0.06	0.51	0.23	0.48	1.4	1.9	0.10	<0.001	<0.001	0.01
cis-9 trans-11 C18:2	0.23	0.28	0.01	<0.01	0.58	0.86	0.44	0.55	0.03	<0.01	<0.001	0.17
trans-10 cis-12 C18:2	0.017	0.005	0.005	0.07	0.08	0.17	0.01	0.01	0.001	0.65	0.91	0.40
cis-9 cis-12 cis-15 C18:3	0.47	0.49	0.02	0.32	0.64	0.50	0.46	0.47	0.02	0.84	<0.001	0.50
C20:0	0.67	1.33	0.37	0.09	0.24	0.95	3.7	3.9	0.11	0.12	<0.001	0.06
C20:4	0.11	0.15	0.01	0.03	0.22	0.66	0.13	0.13	0.01	0.73	<0.001	0.30
C22:0	0.01	0.01	0.001	0.46	0.12	0.62	0.08	0.08	0.001	0.48	<0.001	0.85
C23:0	0.09	0.09	0.01	1.00	0.30	0.74	0.11	0.1	0.01	0.35	0.02	0.28
De novo FA3	21.1	20.4	0.70	0.18	<0.01	0.65	16.2	15.5	0.55	0.29	0.01	0.10
Mixed FA3	39.0	39.6	0.6	0.38	<0.01	0.84	30.9	31.1	0.33	0.65	<0.001	0.47
Preformed FA3	38.2	38.3	1.10	0.89	<0.01	0.62	52.8	53.4	0.72	0.53	<0.001	0.91

¹LRUFA represents the diets contain low content of RUFA; HAUFA represents the diets contain high content of RUFA.

²SA dietary treatment contained approximately 0.4% more C18:0 than OA dietary treatment on DM basis; OA dietary treatment contained approximately 0.3% more C18:1 cis-9 than SA dietary treatment on DM basis.

³De novo FA are primarily synthesized in mammary gland (carbon length < 16), preformed FA are primarily absorbed from blood circulation (carbon length > 16), and mixed FA are from both sources (C16:0 + C16:1 cis-9).