الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
Abstract
The present study was carried out at Inshas Poultry Breeding Research Station, Animal Production Research Institute, Agricultural Research Center, EL-Dokki, Giza. This experiment was conducted to study the effect of different sources and levels of dietary selenium or zinc on productive performance, carcass characteristics, some blood constituents, immune response and the residues of selenium and zinc in meat of Silver Montazah male chicks.
Birds and experimental design:
A total of 675 Silver Montazah male chicks one - day old were used in this experiment. All chicks were wing-banded, individually weighed to the nearest gram and then distributed into nine equal experimental treatments (75 chicks each). Each treatment was divided into three replicates, 25 chicks per replicate. The average initial live body weight of all replicates was nearly similar. Birds of each treatment were randomly allocated in three floor pens.
The experimental treatments were as follows:
1. The first group served as a control treatment and fed the basal diet (BD).
2. Birds of the treatments 2 and 3 were fed the basal diet supplemented with 0.2 and 0.4 ppm Sodium Selenite (41.79% Se) respectively.
3. Birds of the treatments 4 and 5 were fed the basal diet supplemented with 0.2 and 0.4 ppm Selenium Yeast (2000 ppm Se/kg) respectively.
4. Birds of the treatments 6 and 7 were fed the basal diet supplemented with 100 and 200 ppm Zinc Oxide (75% Zn) respectively.
5. Birds of the treatments 8 and 9 were fed the basal diet supplemented with 100 and 200 ppm Zinc Polysaccharide (22% Zn) respectively.
The results obtained could be summarized as follows:
Effect of dietary selenium supplementation:
1- There were significant (P<0.01) increases in live body weight and body weight gain chicks that fed selenium (0.2 or 0.4 ppm) supplemented diets compared with the control group.
2- Feed intake (FI) was significantly (P<0.01) increased in chicks of the control group, while, feed conversion ratio (FCR) was significantly better with selenium addition in most periods studied.
3- There were no significant effects due to dietary supplemental selenium (source and level) on relative weights of carcass, tibia (weight and length), liver, heart, gizzard and lymphoid organs (spleen, bursa and thymus) percentages.
4- Total plasma protein and albumin were not significantly affected by different levels and sources of selenium supplementation in the diets.
5- All dietary Se treatments significantly (P≤0.01) reduced plasma liver enzymes (AST and ALT) compared to control treatment and the better value was recorded for selenium yeast treatment compared with sodium selenite and control groups.
6- Plasma glutathione peroxidase (GPX) and superoxide dismutase (SOD) concentrations were higher in chicks that fed selenium supplementation diets compared with the control ones.
7- Antibody titer against AI disease was higher for chicks received 0.4 ppm SY group. While, the treatment of 0.4 ppm SS had recorded the highest significant (P≤0.01) value of antibody titer against NDV comparing to other dietary Se treatments and control group.
8- Meat Se residues were greater in chicks fed diet supplemented with either organic or inorganic selenium compared with those of the control group.
Effect of dietary zinc supplementation:
1- There were significant (P<0.05) differences between groups in LBW of chicks at the 8th and 12th weeks and the whole of the experimental period. Similary, BWG differ significantly during the most studied periods (4-8, 8-12 wk of age) and the whole period of the study. Dietary zinc treatments significantly increased LBW and BWG than control group.
2- Dietary zinc treatments (either ZnO or ZnPS) significantly (P≤0.01) decreased feed intake (FI) and improved feed conversion ratio (FCR) compared with the control group.
3- There were no significant effects due to dietary supplemental Zinc (organic or inorganic) on carcass characteristics and relative weights of carcass. Also, there were no significant change in tibia (weight and length), and the percentages of lymphoid organs (spleen, bursa and thymus) due to zinc levels or sources.
4- Total plasma protein and albumin were not significantly affected by different levels and sources Zn supplementation in the diets.
5- Dietary Zn treatments significantly (P≤0.01) reduced plasma liver enzymes (AST and ALT) compared with the control treatment.
6- Dietary zinc treatments significantly (P<0.01) increased blood glutathione peroxidase (GPX) and superoxide dismutase (SOD) concentrations comparing with control group.
7- Avian influenza titer was not significant by dietary Zn supplementation than the control group. However, the highest value was recorded for the 200 ppm ZnPS treatment. Also, dietary Zn treatments significantly increased the values of antibody titer against NDV compared with the control un-supplemented group.
8- Meat Zn residues recorded higher values in chicks fed diet supplemented with 100 and 200 ppm ZnPS compared with those fed ZnO and control group which recorded the lowest value.
Conclusion
The results indicated that SY at levels of 0.2 or 0.4 ppm/kg diet and 100 or 200 ppm ZnPS/kg diet of Silver Montazah male chicks could be recommended to obtain the best improvement of growth performance and the highest antioxidant capacity and meat residues.