It was hypothesized that Safflower seed (SS) can be effectively fed to improved performance and milk CLA of cows. The Objective of first study was to compare SS and cottonseed (CS), soybean and canola. Second experiment was conducted to investigate effects of feeding diets containing SS and CS on cows' performance and in final research objective was to determine effects of feeding roasted SS combined with fish oil (FO) on performance and CLA concentration of milk. Gas production was used in experiment 1 and nine and eight multiparous early lactation cows were used in experiment 2 and 3, respectively. Results of experiment 1 suggested that the gas production parameters were similar between SS and CS. Dietary inclusion of SS did not affect DM intake, rumen pH and concentrations of ammonia and VFA, blood concentrations of insulin, NEFA, urea and triglycerides, and milk production (P 0.10). Adding SS linearly reduced glucose (P=0.05) and BHBA (P 0.05), and increased cholesterol (P 0.01) and LDL (P 0.05). In vivo experiment was demonstrated that SS as an economical and rich source of essential fatty acids can be included up to 5% dietary dry matter (DM) alongside CS without affecting dairy cows' performance. In experiment 3 adding fish oil reduced milk fat and feed intake (p 0.01), but feeding diets with roasted SS increased dry matter intake. Dietary inclusion of 2.5 % roasted SS and 1% FO affected CLA content and improved Cis9 trans 11, CLA content in milk of dairy cattle (P 0.01). Key words : Iranian Safflower Seed, Whole Cottonseed, Fish Oil, Conjugated Linoleic Acid (CLA), Dairy Cattle
