الفهرس 
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Abstract
This study was conducted at the Nutrition and Veterinary Clinical Nutrition Department, Faculty of Veterinary Medicine, Alexandria University, Egypt and started at 14th December 2016 until 25th January 2017, to investigate the impact of dietary supplementation of some amino acids and coccidial infection on growth performance, some blood parameters, immune response, carcass characteristics and intestinal morphology of broiler chickens.
Three hundred and twenty, one-day old of Cobb 500 broiler chicks were used in this experiment. They were obtained from Al -Watania Poultry Company (a local hatchery). The broiler chicks were randomly allotted into 10 equal groups (32 chicks /group). group No. 1 was fed on the basal diet containing requirement of lysine (Lys), methionine (Met) and threonine (Thr) according to the recommended catalog of the Cobb-500 breed. group 2 – 4 were fed on the basal diet with 30% extra lysine, methionine or threonine than the recommended requirement, respectively. group 5 fed on the basal diet with extra combination of lysine, methionine and threonine. Groups 6 – 10 were fed on the same d as dietsescribed for groups 1 – 5 but with coccidial infection. The obtained results are summarized in the following:
1. It was observed that extra lysine or methionine supplementation non-significantly (P≥0.05) increased final body weight and total weight gain, while extra threonine alone or combined with lysine and methionine supplementation non-significantly (P≥0.05) reduced final body weight and total body weight gain compared with the control group which was fed on the basal diet containing recommended requirement of these limiting amino acids.
2. Regarding coccidial infection, it was observed that, standard amino acids, excess Lys and excess Met supplementation with coccidial infection exhibited the same final weight and total weight gain compared with broiler chick group fed on the same diet without infection, while extra Thr alone or combined with other amino acids supplementation with infection non-significantly (P≥0.05) reduced final weight and total body weight gain.
3. The extra lysine and combination of amino acids increased the average daily feed intake, while extra methionine and extra threonine decreased the average daily feed intake compared with the control group.
4. Regarding coccidial infection, it was observed that extra lysine and extra threonine non- significantly decreased the average daily feed intake, while extra methionine and combination of amino acids non-significantly increased average daily feed intake compared with the control group.
5. The extra methionine and extra threonine non-significantly improved the feed conversion ratio (FCR), PER and EEU when compared with the control.
6. Regarding coccidial infection, it was observed that extra lysine and extra threonine were non-significantly improved the feed conversion ratio (FCR). PER and EEU.
7. It was observed that extra lysine, extra methionine and extra threonine non-significantly improved the performance index. Regarding coccidial infection, it was observed that extra lysine, extra methionine and extra threonine non-significantly improved the performance index.
8. The extra amino acids supplementation improved total RBCs, WBCs, Hb% and PCV% compared with broiler chick group fed on the basal diet with the recommended level of different limiting amino acids. The highest values of the mentioned parameters were recorded by broiler chicks fed on the basal diet with 30% extra of Thr supplementation.
9. It was observed that supplementation of extra (30% more than the recommended levels) Lys, Met, Thr or their combination with coccidial infection increased total WBCs counts compared with broiler chicken fed on the same diet without coccidial infection. Moreover, it was observed that extra Lys, Met, Thr or their combination with coccidial infection had no clear effect on RBCs counts, Hb% or PCV% compared with broiler chicken fed on the same diet without infection.
10. Extra Lys, Met, Thr or their combination with or without coccidial infection increased the serum total protein, globulin and glucose concentrations when compared with broiler chicken group fed on the basal diet with recommended level of the mentioned amino acids but non-significantly reduced the serum albumin level.
11. The extra supplementation of Lys, Met, Thr or their combination increased serum Ca and P concentration when compared with broiler chicken group fed on the basal diet with recommended level of the mentioned amino acids. Moreover, it was observed that extra Lys, Met, Thr or their combination with coccidial infection had no significant effect on blood serum Ca or P concentrations compared with broiler chicken group fed on the same diet without coccidial infection.
12. Extra Lys, Met, Thr or their combination and or coccidial infection decreased blood serum carotenoids at 20 and 42 days of broiler age compared with control group fed on the basal diet with recommended levels of the mentioned essential amino acids.
13. On the other hand, it was observed that extra Lys, Met, Thr or their combination had no significant effect of blood serum nitric oxide (NO2) at 20 or 42 days of age and MDA at 42 days of broiler age concentrations compared with broiler chick group fed on the basal diet with recommended levels of the mentioned essential amino acids.
14. Serum NO concentration and MDA increased in broiler chickens at 20 or 42 days with coccidial infection. Extra amino acid supplementation with coccidial infection significantly reduced blood serum NO2 and MDA concentrations compared with broiler chicks fed on recommended level of amino acids with coccidial infection, while still higher than non-infected groups.
15. The extra Ly, Met, Thr alone or their combination in broiler chicken ration had no significant (P≥0.05) effect on blood serum uric acid and creatinine concentrations compared with broiler chicken group fed on the basal diet containing standard level of the mentioned amino acids according to the recommended levels of the breed. The obtained data indicated that standard amino acids in broiler diet adequate for chick’s growth and metabolic activity.
16. It was observed that the extra amino acid supplementation and or coccidial infection deteriorated the liver function.
17. The extra Lys, Met, Thr or their combination and or coccidial infection had no significant effect of blood serum lipid profile at 20 or 42 days of broiler chickens age.
18. Extra dietary Ly, Met, Thr or their combination in broiler diet without coccidial infection increased antibody production against Newcastle disease vaccine at 14th, 21st, 35th and 42th day old of chick age. Meanwhile, the coccidial infection reduced (P≥0.05) at 2nd and 3rd weeks post infection by about 24.9% and 10.0% respectively, compared with broiler chicks group fed on the same diet without coccidial infection.
19. Extra lysine and methionine supplementation decreased the thymus and spleen weights and their relative weights percent, but increased the bursa weight and relative weight compared with the control group. Vice versa, extra threonine and combination of amino acids increased the thymus wt and relative wt % and decreased the bursa relative wt compared with control group.
20. Regarding coccidial infection, it was observed that extra supplementation of amino acids had no significant effect on the thymus wt and relative wt %, while they increased the spleen wt and relative wt % of spleen.
21. The extra methionine increased the dressing wt, and extra lysine and methionine increased the dressing relative wt % . While threonine and combination of amino acids decreased the dressing wt and relative wt %. Extra lysine increased the abdominal fat wt by about (15.3%) compared with control group, and extra lysine and combination of amino acids increased the relative wt % of abdominal fat. Supplementation of amino acids increased the gizzard wt and relative wt %.
22. Regarding coccidial infection, it was observed that control group which fed on the basal diet containing standard amino acids no significant effect on dressing wt and relative wt %, except extra lysine increased the dressing relative wt %.
23. It was observed that the excess Lys, Met, Thr and their combination supplementation reduced the numbers of oocyst in cecal tissue and in the feces at 14th or 28th days post-infection.
24. The 30% extra Lys supplementation more effective than other mentioned amino acids to ameliorate the severity of oocyst shedding in coccidia challenged broiler chicken followed by Thr and then Met supplementation.
25. No lesions score was found in the intestine or ceca of the unchallenged groups. In the challenged groups, no lesion scores were found at upper part, mid intestine or ceca for extra lysine, extra methionine, extra threonine and combination of amino acids at cecum at 6 days’ post-infection. At 28 days’ post-infection, no lesion scores were found for control, extra lysine and extra methionine at upper part, mid intestine and cecum, while extra threonine and combination of amino acids had no effect on mid intestine and cecum
26. Extra lysine, methionine, threonine and combination of amino acids increased the mucosal length, villi length and crypt depth except extra lysine was decreased the crypt depth of jejunum. Extra threonine increased the villi width and decreased the C/V ratio of jejunum, while extra lysine, methionine and combination of amino a.