The objective of this study was to examine the effects of feeding fish oil and canola oil from transition period to early lactation on milk fatty acid composition. Experimental diets were supplemented with either 0% oil (Control, n = 9), or 2% oil (supplemented, 1% canola oil-1%fish oil, n = 9), and fed 2 times a day from day −21 to 50 related to calving. Cows were blocked by parity, previous 305–2x milk production and expected calving time. Milk samples of first, third and sixth week of lactation were collected for fatty acids analysis using gas chromatography. All milk fatty acid results were expressed as g/100g of total fatty acids. The data repeated in time were analyzed by using a mixed model for a completely randomized design with repeated measures. Significance was declared at P < 0.05. As revealed in table1, total short (SCFA; C4:0- C8:0) and medium (MCFA; C10:0- C16:0) fatty acids decreased and total poly unsaturated fatty acids (PUFA) increased in supplemented diet. The proportion of C16:0, C16:1 and C18:0 decreased in supplemented diet. The proportion of trans (t) 10, cis (c) 12–18:2, c9, t11–18:2, c9, c12–18:2, t9, t11–18:2, t-18:1, eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) increased in supplemented diets, but the proportion of c11–18:1 and c9–18:1 were similar between diets. The results of this study demonstrate that feeding a combination of fish oil and canola oil had significant effect on milk fatty acids composition.

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