Document Type : Research Paper
M. Sc. Student, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
Associate Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
The objective of this study was to determine the effects of different sources of fatty acids on the performance and liver activity indices of Holstein cows during the transition period. Thirty-five cows were randomly assigned (from 21 days prepartum to 21 days postpartum) to 5 dietary treatments consisting of a diet containing palm oil (T1) as control, CLA fat supplement (T2), extruded flaxseed (T3), mixes of CLA fat supplement and extruded flaxseed(T4), and sesame oil and sesame meal (T5). The amounts of dry matter intake and milk yields were measured daily and milk composition was measured weekly. Blood samples were collected weekly to determine the concentration of plasma parameters. Feed intake, milk yields and milk composition were generally similar among treatments (P>0.05). Among blood parameters, the levels of urea and total protein affected by treatment in postpartum (P <0/05). The concentration of total protein in group T3 was higher than group T1. The urea concentration in group T5 was higher as compared with group T3. Amount of aspartate aminotransferase in prepartum had a significant tendency between treatments (P<0.1) and the highest amount was observed for group T1. The results of this study showed that CLA supplementation and extruded flaxseed increased total protein and reduced blood urea and has a beneficial effect on the health of the liver during the transition period.