The present study was conducted at the Nutrition and clinical Nutrition Department, Faculty of Veterinary Medicine, Benha, University to investigate the effect of dietary enzyme supplementation as feed additive for quail chicks on growth performance, dry matter digestibility, carcass quality, serum biochemistry, hematological parameters, and histological changes of internal organs, laying performance and economical efficiency. A total number of 240 Japanese quails were used. The quail chicks were randomly allocated into randomly and equally divided into 4 groups (60 per each, three replicates per group). These quail chicks were fed as follow: Quail chicks of group 1 were fed on basal diet without enzyme supplementation used as control group. While the Quail chicks of group 2 fed on basal diet supplemented with Kemzyme® plus dry 0.5g/kg diet, , group 3 fed on basal diet supplemented with Phytase 0.1g/kg diet, group 4 fed on basal diet supplemented with Kemzyme® plus dry 0.5g/kg diet + Phytase 0.1g/kg diet 1- addition of dietary enzymes on the diet on all experimental groups had insignificant improvement in the digestibility of DM and ether extract when compared with control group. 2- The obtained results presented that growth of Japanese quails fed dietary Kemzyme plus dry®0.5g/kg diet and Kemzyme plus dry®0.5g/kg diet + phytase0.1g/kg diet were better than other groups especially on the last two weeks (35th and 42 th day of age)of finishing period. 3- From obtained results at the end of experiment (14 th -42 th days of age), it was observed that there was a significant (P

The present study was conducted at the Nutrition and clinical Nutrition Department, Faculty of Veterinary Medicine, Benha, University to investigate the effect of dietary supplementation of probiotic (Lactic dry®) and prebiotic (Bio-Mos®) feed additives as a growth promoters for broiler chicks on the diet dry matter digestibility, growth performance, carcass quality, serum biochemistry, haematological parameters, histological changes of internal organs, and economical efficiency. A total number of 285 day-old chicks were used. The chicks were randomly allocated into randomly and equally divided into 5 groups (57 per each, three replicates per group). These broiler chicks were fed as following: Chicks of group 1 were fed on basal diet without probiotic and prebiotic supplementation as the control group. While the chick of group 2and 3 fed on basal diet supplemented with (lactic dry at 0.25g/kg and 0.5g/kg, respectively). The group 4 and 5 fed on basal diet supplemented with Bio-Mos®, at level 0.5 g/kg and 1 g/kg , respectively.1. The higher rate of inclusion of probiotic lactic dry (0.5g/kg diet) result in increase the average body weight of chicks allover the period of trail. 2-At 45th day of age feeding probiotic and prebiotic supplemented diet, result in a significant increase in body weight of broiler chick fed on 0.25g lactic dry/kg, 0.5g lactic dry /kg and 1g Bio-Mos /kg when compared with control group. 3-From obtained results at the end of experiment (from 10th to 45th days of age), it was observed that there was significant increase in BWG of, lactic dry at level of 0.25g/kg , 0.5g/kg, Bio-Mos 1 g/kg when compared with control group. 4-The analysis of variance of obtained data regarding total RGR from 0-45 days show insignificant difference between Lactic dry 0.25g/kg, and Bio Mos at 1 g/kg groups when compared with control group. There was significant increase in RGR of lactic dry 0.5g/kg group when compared with control group. 5- Analysis of variance of obtained data showed that FCR not significantly different between all dietary treatment and control group during experimental period from (0-45 days of age). 6- Chicks supplemented with lactic dry 0.25g/kg diet show significant increase in PER when compared with control group. The most likely explanation are the improvement of bioavailability. 7- The dressing percentage data show that there was insignificant increase in all dietary treatments and show insignificant difference on gizzard, and heart percentage when compared with control group, while there was significant increase in breast muscle yield compared with control group. 9- There was significant increase in diameter of small intestine among the four supplemented groups and control. 10- There was no significant effect of probiotic and prebiotic on immune organs (liver and spleen%), while there was a significant increase in thymus in group supplemented with lactic dry 0.25 g/kg, than other groups, as well as there was a significant increase in bursa in group supplemented with lactic dry 0.5 g/kg, Bio-Mos 0.5 and 1 g/kg diet. 11 - Dry matter percentage as well as crude protein showed that there was significant increase in all treated groups, while fat significantly decrease than control group. 12- It was observed that the pH significantly increase, while TVN and TBA value of meat significantly decrease in all treated groups than control group 13-There is a significant decrease in serumALT in lactic dry 0.25 g/ kg ,lactic dry 0.5 g / kg diet and Bio-Mos 0.5 g/kg diet. 14-There was significant decrease in serum creatinine level in chicks group supplemented with lactic dry at 0.5 g/kg diet when compared with control group, while there was significant decrease on serum uric acid level on chick fed on diet supplemented with lactic dry at 0.25 g/kg diet and lactic dry 0.5 g/kg diet. 15 - Significant decrease is cholestesol on chicks fed on lactic dry at 0.25 g/kg diet and 0.5 g/kg diet. 16 -There was significant decrease on serum glucose level on chick fed on lactic dry at 0.5 g/kg diet when compared with control group. 17- Small intestine in high concentration in both lactic dry (0.5 g/kg diet) and Bio-Mos (1g/kg diet) showed focal inflammatory cell infiltration in the lamina propria. 18- Economical evaluation revealed that lactic dry supplemented group at level 0.25 g/kg diet recorded the highest net revenue and economical efficiency than other dietary treatment groups. General recommendations: From the obtained results, we can conclude that: 1- The use of Lactic dry® or Bio-Mos® feed additives as growth promoters improves the digestion coefficient of dry matter, broiler performance. 2- The use of Bio-Mos® feed additive as growth promoter at a rate of 0.5 g /kg diet recorded highest significant values in the body chemical composition of broiler chicks for dry matter, crude protein, ash %, and lowest fat % than all treated groups and control. 3- Economical evaluation revealed that Lactic dry® feed additive as growth promoter at a rate of 0.25 g /kg diet recorded higher net revenue and economical effeciency compared to other supplemented and control groups.