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 (UFA) in milk fat and performances of high-yielding lactating cows. Twenty early lactating Holstein cows were used in a complete randomized design. Treatments included: 1) CON, control (without sunflower oil seed). 2) LS-UT, 7.5% raw sunflower oil seed. 3) LS-HT, 7.5% heat-treated sunflower oil seed. 4) HS-UT, 15% raw sunflower oil seed. 5) HS-HT, 15% heat-treated sunflower oil seed. Experimental period lasted for 4 wk. Supplementation with 7.5% raw sunflower seed (LS-UT) tended to decrease milk yield, with 28.37 kg/d compared with the control (34.75 kg/d). Milk fat percentage was increased with the HS-UT that obtained 3.71% compared with CON that was 3.39% (P>0.05). Milk protein percent was decreased by 15% level sunflower treatments with 3.18% whereas CON treatment is caused 3.40% protein. The cows fed added LS-HT produced milk with the highest content of total UFA with 32.59 g/100g of milk fat compared with the HS-UT with 23.59 g/100g of milk fat. Content of C18 UFA in milk fat increased from 21.68 in the HS-UT to 22.50, 23.98, 27.39 and 30.30 g/100g 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 UFA content was significantly higher in milk of animal fed added 7.5% heat-treated sunflower. In all, results showed that diet cow's supplementation with sunflower oil seed tended to reduce milk production of lactating cows but can improve C18 UFA content in milk fat. It seems that 7.5% heated sunflower oil seed can to be the optimal source to increase UFA production.
