Abstract: The objective of this study was to investigate the effects of dietary supplementation with sunflower oil seed (Raw-or Heat-treated) in two levels of 7.5 or 15% on unsaturated fatty acids in milk fat and performances of high-yielding lactating cows. Twenty early lactating Holstein cows were used in a complete randomized design. Treatments included: CON, control (without sunflower oil seed). LS-UT, 7.5% raw sunflower oil seed. LS-HT, 7.5% heat-treated sunflower oil seed. HS-UT, 15% raw sunflower oil seed. HS-HT, 15% heat-treated sunflower oil seed. Experimental period lasted for 4 weeks with first 2 weeks used for adaptation to the diets. Supplementation with 7.5% raw sunflower seed (LS-UT) tended to decrease milk yield with 28.37 kg day-1 compared with the control (34.75 kg day-1). Milk fat percentage was increased with the HS-UT treatment that obtained 3.71% compared with CON that was 3.39% and without significant different. Milk protein percent was decreased by high level sunflower oil seed treatments (15%) with 3.18% whereas CON treatment is caused 3.40% protein. The cows fed added Low Sunflower Heat-Treated (LS-HT) produced milk with the highest content of total unsaturated fatty acid with 32.59 g/100 g of milk fat compared with the HS-UT with 23.59 g/100 g of milk fat. Content of C18 unsaturated fatty acids in milk fat increased from 21.68 g/100 g of fat in the HS-UT to 22.50, 23.98, 27.39 and 30.30 g/100 g of fat from the cow fed HS-HT, CON, LS-UT and LS-HT treatments, respectively. C18:2 isomers of fatty acid in milk were greater by LS-HT supplementation with significant effect (p<0.05). Total of C18 unsaturated fatty acids content was significantly higher in milk of animal fed added low heat-treated sunflower (7.5%) than those fed with high sunflower. In all, results of this study showed that diet cow's supplementation with sunflower oil seed tended to reduce milk production of lactating cows but can improve C18 unsaturated fatty acid content in milk fat. About 7.5% level of sunflower oil seed that heated seemed to be the optimal source to increase UFA production.
H. Mansoori, A. Aghazadeh and K. Nazeradl, 2011. Sunflower Oil Seed (Raw-or Heat-Treated) in Lactating Dairy Cow's Diets: Effects on Milk Fatty Acids Profile and Milk Production. Journal of Animal and Veterinary Advances, 10: 470-479.