الفهرس 
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Abstract
This work was conducted to study the effect of dietary n-3 : n-6 ratio on growth carcass traits, immune response, some blood and biochemical parameters of broiler chickens as well as some lipid parameters and fatty acid profile of tissue.
This study depended on recording the results concerning body weight development, body weight gain, feed conversion ratio, relative growth rate, protein efficiency ratio and performance index and measuring some biochemical parameters, immune response and fatty acid profile of meat.
A total number of 192 one day old Avian48 broiler chicks were randomly allotted into 6 groups (32 chicks / group) of mixed sexes. The broiler groups were fed as follows : chicks of groups 1, 2, 3, 4, 5 and 6 fed balanced corn-soybean diets containing the following n-3 : n-6 ratios:- 1:1, 1:3, 1:5, 1:7, 1:9 and 1:11 respectively using different combinations of LO and SO allover the experimental period (42 days).
• The obtained results can be summarized as follows:
1. Results concerning final body weight, body weight gain, relative growth rate showed that there was no significant difference between different experimental groups due to variation of n-3 : n-6 ratio.
2. Feed intake recorded increase in the first three groups over the last three ones.
3. No significant difference was noticed in FCR at the end of the experimental period. However, numerical improvement was noticed in group 6 following reduction of feed intake in this group.
4. No significant difference was detected in protein efficiency ratio at the end of experimental period but group 6 recorded the best result (numerical effect).
5. The best dressing percentage was recorded in group 3 while no significant difference was noticed in weight of organs except significant increase in weight of gizzard in group 4.
6. There was variable effect of the n-3 : n-6 ratio on parameters of innate immunity (phagocytosis, lysozyme activity and bactericidal activity). The higher lymphocyte percentage was detected in group 5, while no significant difference between experimental groups in monocyte percentage.
7. Antibody titers to ND and AI increased in relatively narrow dietary n-3 : n-6 ratio groups in the fourth week but wider ratio groups tend to record higher antibody titers after that and at the end of experimental period.
8. The lower glucose level was detected in group 3 and 4 at the end of experimental period. Serum albumin and total protein decreased in group 3. However, higher serum globulin was noticed in group 2 and 3.
9. Group 2 recorded the best results in liver function parameters (GOT, GPT and ALP).
10. The lower serum urea was detected in group 2 and lower serum uric acid was recorded in group 5. While no significant difference was noticed in serum creatinine level. This indicated that kidney function parameters recorded variable results within groups.
11. The lower serum total cholesterol was detected in group 1 and increased by widening the n-3 : n-6 ratio. LDL-cholesterol was also increased from group 2 to group 5. Lower serum triglycerides was detected in group 2 while higher serum phospholipids was found in group 1. This may indicate that groups 1 and 2 had the best serum lipid profile among different groups.
12. Groups with narrow dietary n-3 : n-6 ratio tend to record higher RBCs count. Group 3 recorded the higher PCV and haemoglobin content. While no significant difference in MCHC was noticed between different experimental groups.
13. No significant difference between different groups was detected in tissue total lipid % in both breast and thigh. However, the breast lipid content was slightly higher than thigh lipid content.
14. Lower cholesterol content of breast meat was detected in group 3 and the higher content was detected in group 6. The cholesterol content of the thigh recorded opposite results.
15. Narrow dietary n-3 : n-6 groups tended to record higher n-3 PUFA content especially DHA (C22:6 n-3) in breast meat. While wider n-3 : n-6 ratio groups tended to deposit more SFA, MUFA and n-6 PUFA than narrower ratio groups.
16. The best n-3 : n-6 ratio of breast meat was recorded in group 2 received dietary n-3 : n-6 ratio of 1:3.
17. Group 6 recorded the best results in economic efficiency measures. This was attributed to recording the lowest oil cost / total cost %. This may suggest that n-3 enriched poultry meat should be sold with slightly higher price than commercially produced poultry meat.