A total number of 180 Sinai laying hens at 25 weeks – old were used, weighed and divided into six treatments of three replicates each and housed in individual layer cages to investigate the effect of using two levels of energy (2760 or 2660 Kcal/Kg diet) and synthetic (s) or natural source (n) of Coenzyme Q10 (CoQ10) at levels of (0, 7.5 mg/kg diet CoQ10(s) or 7.5 mg/kg diet CoQ10 (n) ) in 2x3 factorial design on the productive performance, profile fatty acids in egg yolk, nutrients digestibility and economical efficiency of local laying hens. Resulted obtained could be summarized in the following:
1- Egg weight of hens fed diet contained low ME significantly increased (P≤0.05) as compared to control diet. While, no significant influence (P≥0.05) of dietary CoQ10 and interaction between CoQ10 and ME on egg weight.
2- Egg production % and egg mass for hens with low ME was significantly (P≤0.05) higher than hens fed diet with the control diet.
3- Hens fed 7.5 mg CoQ10(s) had significantly higher (P≤0.05) egg mass by about 5.76% than CoQ10 (o) (control diet). The best egg mass was recorded by the interaction between 2660 Kcal / Kg and 7.5 mg CoQ10(s).
4- Feed intake was increased by about 7.49% for hens fed the low level of ME (2760Kcal/Kg) as compared the control diet. While, the diet with CoQ10(s) was the highest amount of feed intake comparing with CoQ10 (n).
5- Feed conversion was improved by 6.20% for hens fed diets with 2660 Kcal /Kg compared to 2760 Kcal /Kg. But, no significant influence of dietary CoQ10 and interaction between CoQ10 and ME on feed conversion ratio.
6- The dietary supplemented with CoQ10(s) and the interaction between dietary CoQ10(s) or (n) + the low level of ME resulted in a significant increase (P≤0.05) in shell thickness compared to the control diet.
7- The diet contained low level of ME caused a significant decrease (P≤0.05) in heterophil (H) % and heterophil / lymphocyte (L) compared to the control diet.
8- The percentage of C18:2ω6 and C18:2ω3 with7.5 mg/Kg CoQ10 (n) is significantly higher (P≤0.05) than those of the control diet. On the other hand the percentages of C20:4ω6 was significantly reduced (P≤0.05) in response to the diet contained with7.5 mg/Kg CoQ10(s) comparing with the control and CoQ10 (n).