The objective of this study was to investigate the effects of dietary supplementation with sunflower oil seed (raw- or heat-treated) in two levels (7.5 or 15%) on 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 weeks. 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% sunflower treatments with 3.18% whereas CON treatment caused 3.40%. 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/100 g 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/100 g of fat from the cow fed HS-HT, CON, LS-UT and LS-HT diets, respectively. C18:2 isomers of fatty acid 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 improve C18 UFA content in milk fat. It seems 7.5% heated sunflower oil seed can be the optimal source to increase UFA production and improve some milk performances.
Key words: Sunflower seed, milk production, fatty acid profile.
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