These studies were conducted to investigate effects of dietary 25 hydroxy vitamin D3 (25-OH-D3) and phytase supplementation on performance and nutrient digestibility in poultry. The customized fertilizers for crops were producted to reduce the problem of environmental pollution. In experiment 1, the objective of this experiment was to evaluate the effects of dietary 25-OH-D3 with different Ca levels on the performance, blood composition and nutrients digestibility of laying hens. A total of five hundred forty, sixty one weeks old Lohmann brown laying hens were randomly allotted in a 3 × 3 factorial arrangement, consisting of three vitamin D3 sources (cholecalciferol+25-OH-D3: 600mg+0μg, 400mg+25μg and 200mg+50μg) and three dietary Ca levels (3.5, 4.0 and 4.5%). The basal diets contained 3,000 IU/kg of vitamin D3 with the ME 2,800 kcal/kg and CP 16%. The results showed the interaction (P<0.05) between dietary Ca (3.5, 4.0 and 4.5 %) and 25-OH-D3 (0, 25 and 50μg) on the serum parathyroid hormone (PTH) and interleukin-6 (IL-6). Egg production and weight presented significant increase (P<0.05) in 4.5% Ca group compared with other treatments. In addition, egg shell thickness and tibia length were a linear increase (P<0.05) in groups fed high Ca diet (4.0 to 4.5%). There was a significant effect (P<0.05) the P digestibility increased with 4.5% Ca diets. Among the tested vitamin D3 sources, the hens fed 25-OH-D3 showed the higher (P<0.05) egg production and tibia thickness than cholecalciferol treatment. Moreover, hens fed 25-OH-D3 addition exhibited significantly (P<0.05) higher Ca digestibility and serum Ca content than cholecalciferol treatment. As dietary 25-OH-D3 increased, it was significantly increased in serum (P<0.05). The results of this experiment indicated that 4.0 to 4.5% Ca with 50μg 25-OH-D3/kg diets supplementation improved the performance of laying hens from the 61 to 68 weeks of age. In experiment 2, The purpose of this study was to investigate the effect of dietary phytase supplementation on growth performance, blood parameters, nutrient digestibility and P excretion of broilers fed available P and Ca deficient diet. Total three hundred seventy five, one-day-old Cobb 500 broiler chicks were randomly allotted to five treatments with five replicates of fifteen chicks in each. Treatments were consisted of a positive control (PC) diet with adequate avP and Ca; negative control (NC) diet with low in avP and Ca, and 500, 1000 and 1500 FTU/kg phytase supplementation to NC diet. Results indicated that birds fed the NC diet resulted in a significantly (P<0.05) decreased weight gain and feed intake compared with PC diet. However, the supplementation of phytase into the NC diet improved (P<0.05) those parameters and became similar to the PC diet feeding treatment. Serum interleukin-2 (IL-2) and interleukin-6 (IL-6) increased (P<0.05) by phytase addition (500, 1000 and 1500 FTU/kg) in NC diet to be a similar ones with PC treatment. Serum P observed lower (P<0.05) in NC group, but improved chicks fed PC diet and NC + 1000, 1500 FTU/kg phytase treatments. Serum Ca and plasma inositol were higher (P<0.05) with the supplementation of 1500 FTU/kg phytase group compared to that of others in broiler chicks. Furthermore, decreased P content in excreta was similar between NC diet and phytase addition treatments, but the lowest (P<0.05) excretion were found at 1500 FTU/kg phytase treatment. Broilers fed NC diet added to 1500 FTU/kg phytase significantly (P<0.05) spent time in more walking and preening behaviors and less pecking behavior than other groups. It can be concluded that 500 FTU/kg with avP and Ca deficient diets was able to improve birds performance, but 1000 or 1500 FTU/kg diets increased blood Ca, P and inositol contents and walking and preening behavior due to the more efficient phytate destruction. Experiment 3 was conducted to investigate the characteristics of customized fertilizer from hens feces after feeding dietary phytase in laying hens. A total of thirty, sixty weeks old laying hens were randomly assigned to three treatments in individual cage for eight weeks. Phytase was added at 0, 1,000, and 2,000 FTU/kg to the commercial diets. There was no consistent difference in total amount of feces excretion by dietary phytase levels. However amount of dried feces, N, K2O, P2O5 seemed to be decreased in 2,000 FTU/kg treatment compared with other ones. Hens manure could be manufactured as a general type fertilizer as well as K2O and P2O5 reinforced one by the addition of single ingredients as a carrier. As the results, it is possible to manufacture customized fertilizers to be optimum nutrient needs of crops.