Evaluation of different levels of dietary crude protein on hatchability, chick weights and immune response of khorasan's native hens

This experiment was conducted to evaluate the effects of different levels of dietary crude protein (CP) on reproductive performance of native hens at Khorasan stations using 300 hens, in a completely randomized design with 6 dietary treatments and 5 replicates and 10 hens in each replicate from 26 to 50 weeks of age. Treatments based on corn, soybean meal and wheat with different levels of protein, including 17.5, 16, 14.5, 13, 11.5, and 10% CP levels and another nutrient including the energy was equal as possible. Results showed that the initial weight of chickens and the ratio of chicken weight to egg weight increased with CP levels upto 16% from the beginning of experimental period to 50 weeks and decreased with 17.5% CP level. The highest hatchability percentage in all periods was related to the 17.5% CP diet that showed significant difference with other treatments (P<0/05). Results on immune responses showed that treatment with 17.5 % CP, the highest titer of antibody against SRBC, IgG and IgM (P<0/05). In relation to cellular immunity (Test CBH) the result was slightly different and the highest cellular immune response to treatments containing 16% CP and higher levels of CP (17.5%) education compared to the treatment (16%). Overall, the results showed that reproductive performance and humoral immune response of native birds improved with increasing levels of CP.