The objective of this book was to assess the influence of fish oil (FO) on the humoral immune response, some blood parameters as well as growing broilers rendered insusceptible to a disease such as sheep erythrocytes (SRBC) after pre-starter diet also in the other study we evaluated of different levels of fish oil and poultry oil (FO+PO) on the performance, fatty acid(FA) composition, cholesterol and triglyceride concentrations and quality of broiler Breast meat assessed. In the third study we showed the effects of 3% dietary fat contain different levels from poultry fat (PF), which is rich in omega-9 and omega-6 polyunsaturated fatty acids (n-9 and n-6 PUFA) and fish oil (FO), In the final study, The efficacy of fish oil (FO) on serum biochemical parameters and performance was investigated in streptozotocin (STZ)-diabetic rats.