Effect of different levels of energy and protein on performance of Khazak hens during the first of laying period

The diets of laying hens can vary depending on factors such as strain, production targets, age, and climatic conditions. Due to the limitations in basic studies in estimating the requirements of native birds, it is necessary to perform studies in this field, so that the requirements are commensurate with the climatic conditions of the region and the production rate. Therefore, the present study was conducted to investigate the effect of different levels of dietary energy and protein on production performance and egg quality in early laying of Khazak hens and to select the optimal levels of energy and protein at this stage of production. In this study, 160 Khazak-laying hens aged 25 weeks were selected and in a completely randomized design as a factorial experiment with two levels of metabolizable energy (2700 and 2900 kcal ME/kg DM of diet) and two levels of crude protein (15% and 19%) with 4 replicates and 10 birds in each replication were fed for 90 days. Production yield and egg quality traits were measured during the experiment. Data were analyzed using the generalized linear model procedure and the means were compared using the Turkey’s test. Energy level had a significant effect on laying percentage, egg mass, feed intake and feed conversion ratio, and protein level had a significant effect on feed intake and feed conversion ratio (P˂0.05). Also, the interaction of energy and protein on all production traits except the average weight of eggs was significant (P˂0.05), so that egg production percentage, egg mass increase and feed consumption and feed conversion ratio decreased with increasing energy and protein levels. Although the highest quality eggs were observed from hens that consumed the diet with the lowest energy and protein, but it was not significant compared to eggs produced by hens that consumed the diet with the highest energy and protein. The results showed that diets containing 19% CP and 2900 kcal ME improved production and feed conversion ratio, and the quality of produced eggs did not differ significantly from diets containing low levels of energy and protein. Therefore, the diet with 19% CP and 2900 kcal ME is ideal for Khazak hens in the first period of laying hen.