effect of different levels of calcium and phosphorous on performance native hens of khorasan station in different production stages

this experiment was conducted to evaluate the effects of different levels of calcium (ca) and phosphorus (p) on performance native hens of khorasan province. a total of 400 native hens from khorasan station were used in a completely randomized design (factorial experiment) with 8 treatments, 5 replicates and 10 hens in each replicate of  age 26 to 50 weeks. eight experimental diets based on corn, soybean and wheat contain different levels of ca (2.5, 3, 3.5 and 4) and total p (0.5 and 0.75) per percent of diet, and levels of other nutrients such as energy and crude protein was similar. the results showed that different levels of ca and p did not show any effect on egg weight. levels of ca have significant effect on the egg production, so that the highest egg production(72.16) and egg mass was observed in the 3.5% ca, although the level 3 and 3.5 percent of the ca in the early production period (26-33 weeks) had similar effects. p levels had no effect on the egg production and egg mass. level of 4% ca showed the highest feed consumption, but p levels did not effect on feed intake. the best feed conversion ratio(3.16) was observed in the group receiving 3.5% ca. effect of  ca levels  on tibia ash  was  significantly so that the lowest of ash was observed in 2.5% ca. levels of 0.75 p was reduced ash of the tibia. overall, the results of this experiment showed that 3.5% ca improves egg production and fcr in native hens, but p levels had no effect on production traits