الفهرس 
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Abstract
The present experimental work was carried out at the Poultry Research Laboratory belonging to Animal and Fish Production Department, Faculty of Agriculture (Saba Basha), Alexandria University. The present study was planned and conducted to find out the possibility effect of L-carnitine at different levels on Japanese quail (Coturnix Coturnix Japonica) performance, blood hematology and constituents, metabolism of lipids, immunity and anti-oxidative properties during both phases growing and laying periods during the summer season of Alexandria City in the period from May 2010 to September 2011.
First experiment (growing period):
A total number of 160 one-day-old unsexed Japanese quail chicks from the basic flock of Faculty of Agriculture (Saba Basha), Alexandria University were fed basal corn-soybean meal diet containing 24 %crude protein and 2904 Kcal ME/ kg for the first week of age. The 7th day post hatching birds were wing banded, individually weighed to the nearest 0.1 gram, and assigned randomly to 4 equal experimental groups, each one was further subdivided into four replicates with 10 chicks each. L-carnitine was added to the basal diet at four different levels being 0, 25, 50 and 100 mg L-carnitine /Kg diet.
The obtained results indicated the following:
1- The results obtained on body weight gain showed significant (P < 0.05) increase in body weight gain of the group received 25 mg L- carnitine/Kg diet as compared to the control group.
2- Japanese quail birds fed 50 mg L-carnitine/kg diet had numerically the highest growth rate value through the periods 3-5 and 1-5 weeks of age as compared to the control group and the other experimental groups.
3- Throughout all the experimental periods, it can be noticed that feed consumption was not statistically affected by L-carnitine supplementation; however, significant (P < 0.05) differences in feed conversion ratio were recorded during the periods 1-3 and 1-5 weeks of age.
4- Supplementation of L-carnitine to Japanese quail diets from 1 to 5 weeks of age did not significantly affect the final live body weight, carcass weight and relative carcass weight.
5- The effect of L-carnitine on meat quality indexes such as water holding capacity (WHC), pH, color, tenderness, crude protein, ether extract, ash and dry matter were not significant (P≤ 0.05).
6- The results of oxidative stability of fresh Japanese quail meat show that oxidation of the meat muscle increased with length of storage. In most sampling days (0, 48 and 96 hours) of storage in refrigerator, the higher supplemented levels of L-carnitine, 50 and 100 mg L-carnitine /Kg diet, showed lower (P < 0.05) malonaldehyde values than either the control treatment or the lowest level of L-carnitine (25 mg / Kg diet).
7- Absolute and relative weight of bursa of fabricious and thymus were significantly (p≤0.01) increased in quail fed L-carnitine treatments as compared with control treatment at 5 weeks of age.
8- The data revealed that WBCs, Hb and PCV % were not significantly affected by different treatments, however, significant (P < 0.05) increase was recorded in RBCs counts reached to 20.9 and 13.7 % than the control group for the groups given 50 and 100 mg L-carnitine / Kg diet, respectively.
9-The birds having 25, 50 and 100 mg L-carnitine / Kg diet recorded significantly (P < 0.05) the lesser Heterophils percentage in a descending order as compared to the control group.
10- RBCs, Hb and PCV % were not significantly affected by different treatments at 21 days of age, however, a numerical decrease was observed in WBCs counts reached to significant for the group given 100 mg L-carnitine / Kg diet as compared to the control group.
11- The percentage of lymphocytes, monocytes, basophiles and eosinophils were not affected by different treatments as compared to the control group, however, the birds having 50 and 100 mg L-carnitine / Kg diet recorded significantly (P < 0.05) the lesser Heterophils percentage and also, non-significant decrease was observed in the group had 25 mg L-carnitine / Kg diet compared to the control group.
12- L-carnitine (25 and 50 mg / Kg diet) under Egyptian summer conditions insignificantly improved phagocytic activity at 14 days after vaccination by 10.3 and 1.4 %, respectively, when compared to the control group.
13- It is obvious that supplement 100 mg L-carnitine / Kg diet significantly (P < 0.05) increased concentration of serum total protein and albumin, however, 25 and 50 mg L-carnitine /kg diet resulted in non significant increase in these traits as compared to the control group.
14- Serum globulin concentration numerically increased in the groups fed diets supplemented with 25, 50 and 100 mg L-carnitine / Kg and it surpassed the control one by 15.8, 18.5 and 13.6 %, respectively.
15- The results showed significant (P < 0.05) discrepancy in the concentration of serum uric acid. However, all L-carnitine treatments had insignificant effect as compared to the control group. Birds fed 25 mg L-carnitine diet were less (P < 0.05) in serum uric acid by 42.3 % as compared to birds fed 50 mg L-carnitine diet.
16- L-carnitine supplementation (25 and 100 mg / Kg diet) induced a numerical decrease of serum total cholesterol reached to 8.8 and 10.8 % as compared to the control group, while, non significant reduction in concentrations of LDL was observed in the groups given 50 and 100 mg L-carnitine / Kg diet. L-carnitine supplementation (100 mg / Kg diet) induced a marked (P ≤ 0.05) decrease of HDL levels as compared to those of control group.
17- Serum total lipids and triglycerides gradually decreased with increasing level of L-carnitine supplementation. Serum total lipids and serum triglycerides reached significant at 100 mg L-carnitine / Kg diet as compared to the control group.
18- Non-significant differences in the concentration of gama-glutamyl transferase and alkaline phosphatase were observed due to inclusion of different levels of L-carnitine in the diets of growing Japanese quail.
19- As for the antioxidative status in the serum, dietary treatment with L-carnitine significantly increased total antioxidant capacity and glutathione peroxidase activity and significantly (P ≤ 0.05) decreased malondialdehyde comparing to control group.
20- Antibody titters against avian Newcastle disease showed that using different levels of L-carnitine significantly increased antibody titters against avian Newcastle disease compared with control group at 14 and 21 days after vaccination.
21- Microscopically investigations in bursa of fabricius showed that the total number of follicles and the small follicles in Japanese quail supplemented with 25 and 50 mg L-carnitine/kg were significantly higher than control treatment (P≤ 0.05). However, supplementation of 100 mg L-carnitine/kg resulted in reducing the total number of follicles and the number of small follicles compared with control group significantly.
22- Histopathological examination of liver, bursa of fabricius, thymus and spleen sections revealed normal histological in all tested groups like control.
Second experiment (laying period):
A total number of 192 Japanese quail birds (128 females and 64 males) at 12 weeks old were used (hens selected based on egg production more than 60 % after a two-week pretest period). Quail weighed individually, randomly distributed into four groups, each group contained 48 birds (32 females and 16 males); each one was subdivided into four replicates with 12 birds (8 hens and 4 males). L-carnitine was added to the basal diet at four different levels 0, 50, 100 and 200 mg L-carnitine /Kg diet.
The obtained results indicated the following:
1- L-carnitine had significant (P < 0.01) effect on egg laying rate compared with those fed basal diet (control group) through all periods of the study. The best results of laying rate were recorded in the group receiving diet containing 100 mg L-carnitine / Kg diet, followed by the group fed 200 mg through the period from 12-16 weeks of age.
2- Dietary L-carnitine supplementation did not influence average egg weight of the laying Japanese quail through the different periods of the study, except through the period from 16-20 weeks of age.
3- The highest egg mass (g/hen/day) values were recorded with birds fed L-carnitine /kg diets compared to control group but the results were not significant.
4- L-carnitine diets had insignificant effect on feed consumption of laying Japanese quail hens through all periods of the study.
5- Egg weight, egg shape index, egg shell thickness, albumin weight % and albumin height were not affected significantly by different treatments, while, absolute egg shell weight and egg shell weight percentage and yolk weight percentage and index were significantly (P ≤ 0.05) affected by different dietary L-carnitine levels.
6- Yolk cholesterol was gradually decreased with increasing level of L-carnitine in the diet, but it reached significant (P < 0.01) only in those birds fed 200 mg L-carnitine / Kg diet. Also, the lipid content significantly (P < 0.001) lowered in the egg yolk of hens fed L-carnitine diets.
7- Fatty acid composition of the lipids in yolk egg was influenced by the dietary L-carnitine supplementation. Increasing level of L-carnitine supplementation in Japanese quail diet significantly increased the linoleic acid (C18:2 n-6) and decreased the saturated fatty acids proportion, compared to the control group.
8- The experimental results confirmed a positive effect of L-carnitine, which increased the hatching rate insignificantly by 5.2 - 7.0 % as compared to the control.
9-The results showed that WBCs, Hb and PCV % were not significantly affected by different treatments, however, significant (P < 0.05) increase was recorded in RBCs counts as compared to control group for the group fed 100 mg L-carnitine / Kg diet at 14 days after vaccination.
10- The birds having 50, 100 and 200 mg L-carnitine / Kg diet recorded significantly (P < 0.05) the lesser Heterophils percentage as compared to the control group, While, the percentage of lymphocytes was not affected by different levels of L-carnitine in the diets as compared to the control group at 14 days after vaccination.
11- Lymphocytes transformation test were significantly (P < 0.05) the lesser in the group given 50mg L-carnitine diets at 14 days after vaccination as compared to the other experimental groups and the control one.
12- WBCs, RBCs, Hb and PCV % were not significantly affected by different treatments as compared with the control group after 21 days after vaccination.
13- Supplementation of L-carnitine (50, 100 and 200 mg / Kg diet) under summer conditions significantly improved phagocytic activity at 14 days after vaccination by 23.7, 24.7 and 22.6 %, respectively, as compared to the control group. However, after 21 day of vaccination it was not affected by different levels of L-carnitine, except the group given 50 mg L-carnitine in their diet which showed significant decrease comparing with the control group.
14- The effects of L-carnitine supplementation on serum total protein, albumin and globulin showed significantly increase by inclusion L-carnitine in laying quail diets.
15- Supplementation of L-carnitine resulted in non-significant gradually decrease in the concentration of serum uric acid reached to 0.6, 14.4 and 16.4 %, respectively, for birds received 50, 100 and 200 mg L-carnitine / Kg diet, respectively. Also, non-significant decrease was observed for alkaline phosphatase with increasing level of L-carnitine in the dies. But, the concentration of gama-glutamyl transferase in serum was significantly (P < 0.001) decreased.
16- L-carnitine supplementation significantly (P < 0.001) decreased serum total lipids, triglycerides, cholesterol and high density lipoprotein with inclusion of L-carnitine in the laying Japanese quail diet, however, non-significant decrease in low density lipoprotein concentration was observed.
17- Supplementation of L-carnitine significantly (P ≤ 0.001) increased total antioxidant capacity and non-significantly increased glutathion peroxidase activity. In addition, significant (P ≤ 0.001) decrease in serum malondialdehyde was recorded in all groups given different levels of L-carnitine as compared to the control group.
18- Histopathological results of liver and spleen showed that increasing dietary L-carnitine to 100 and 200mg /kg resulted in improving the histological picture of liver which indicated normal section and dietary L-carnitine had no detrimental effect o spleen as all sections were normal.