Fatty acid composition of milk from cows supplemented with canola oil

Abstract Text: The objective of this study was to evaluate the inclusion of canola oil in the diet of dairy cows on the fatty acid (FA) composition of milk. Eighteen lactating Holstein cows were distributed in 6 contemporary 3 x 3 Latin Square, 3 periods and 3 treatments: T1 = control diet (without oil), T2 = inclusion of 3 % canola oil and T3 = 6% inclusion of canola oil in the diet (dry matter). The cows were individually fed. The experiment was conducted during three periods of 21 days, with 14 days for adaptation and seven days to collections. The milk samples were collected to determine the fatty acid composition on the last day of each experimental period. Identification and quantification of fatty acid were done by gas chromatograph (column of 100 meters using hydrogen carrier gas). The results were analyzed using the MIXED procedure of SAS (2001). The effects of treatments were analyzed using two orthogonal polynomial contrasts: linear (L) and quadratic (Q), the significance declared at P ≤ 0.05. The inclusion of 6% of canola oil in the diet increased 53.49% of milk omega-3 concentration and reduced 53.69% of omega-6/omega-3 ratio, in compare with the control treatment. The thrombogenicity (capacity to promote heart attacks and strokes) and atherogenicity (capacity to promote atherosclerosis) decreased linearly (P<0.0001) with the inclusion of canola oil in the diet (Table 1). In conclusion, canola oil alters the fatty acid composition of milk, resulting in healthier milk with nutraceutical properties.

Table 1. Fatty acid composition (g/100g total FA) of milk from cows fed canola oil.

Fatty acid composition	Inclusion of canola oil (%)			SEM	P
	0	3	6		L	Q
Saturated	64.91	55.29	51.42	1.25	<0.0001	=0.033
Y= 63.97(1.11) – 2.1958(0.1677)X
Unsaturated	34.48	43.53	47.52	0.98	<0.0001	=0.0049
Y = 35.4756(1.1284) + 2.1664(0.1748)X
Omega-3	0.20	0.39	0.43	0.02	<0.0001	=0.0008
Y= 0.2286(0.0268) + 0.03369(0.005927)X
Omega-6	1.98	2.08	2.11	0.05	0.273ns*	0.728ns
Omega-6/Omega-3	11.51	5.52	5.33	0.06	<0.0001	=0.0002
Y= 10.49(0.6779) – 1.055(0.1728)X
Thrombogenicity	2.92	1.99	1.74	0.09	<0.0001	=0.001
Y = 2.78(0.10) – 0.1948(0.02030)X
Atherogenicity	2.43	1.52	1.25	0.09	<0.0001	=0.0002
Y = 2.32(0.096) – 0.1952(0.01845)X

ns*= not significant.

Keywords: omega-3, dairy, nutraceutical, health.