H. S. ALI1 and N. A. TODOROV2
1 Research Institute of Mountain Stockbreeding and Agriculture, BG – 5600 Troyan, Bulgaria
2 Thracian University, Faculty of Agriculture, BG – 6000 Stara Zagora, Bulgaria
Twenty dairy cows divided in two equal groups, 10 cows each, were used in short term Latin square experiment to test two type of supplements. All cows grazed the same natural hilly pasture containing 9% crude protein in dry matter during experimental period, lasting from 18 August to 23 September in 2006. The first supplement was 6 kg of compound feed with 15% crude protein, and the second one was 5 kg of sunflower expeller with 26% crude protein. The cows supplemented with sunflower expeller during grazing on a low protein natural pasture had higher milk yield, compared to cows receiving as a supplement compound feed. There was tendency of increasing fat percentage of milk, and significant (P < 0.05) higher percentage of protein in milk of the cows supplemented with sunflower expeller, than those receiving compound feed. Urea content of milk was higher in cows supplemented by sunflower expeller. There were not significant differences in fatty acid profile of milk fat depending on type of supplementation. However trends exist for increase of long chain fatty acids and conjugated linolic acid in milk of cows receiving sunflower expeller.