Effect of different levels of crude protein in native hens performance of Khorasan station.

To investigate the effects of different levels of dietary crude protein (CP) on performance and quality traits eggs of native layer hens Khorasan، an experiment with 300 laying hens from the native stations in completely randomized design with six treatments، 5 replicates and 10 hens in each replicate in age 26 to 50 weeks was performed. Experimental treatments based on corn، soybean meal and wheat contain different levels of crude protein (17. 5، 16، 14. 5، 13، 11. 5، and 10%). Another nutrient including the energy was iso as possible. The results showed that the percentage of CP diet has no effect on egg weight (EW) and only at 10% CP significantly reduced (P<0. 05) EW. CP showed significant effect on egg production (EP) and in such a way that produced the highest EP observed in the diet containing 16% protein in overall of experiment. The lowest levels of protein (10%) decreased about 17 % in EP and this difference in the final weeks was clearly. Reduction of CP decreased significantly (p<0. 05) feed intake in groups receiving 13. 5، 11 and 10% CP. The best feed conversion ratio was observed at 16% CP (P<0. 05). Effect of CP levels on egg internal components showed that only in weeks 30 and 38 significant reduction (P<0. 05) in shell weight percent in 10% CP and in other weeks had no effect. Overall، the results of this study showed that 16% CP improved EP and feed conversion ratio in native hens and this level of CP was the better than other surfaces used in this study، especially this effect is clearer in the end weeks of product.