Dietary protein levels during the pullet phase (8–18 week) influence the mortality during laying stage

An experiment was conducted to evaluate the effects of dietary crude protein levels on growth performance, serum and bone parameters, production performance, and egg quality of Hy-Line brown chicken. A total of 384 pullets were randomly allotted to one of 3 groups with 8 replicates of 16 birds each and were fed with a diet containing 14% crude protein (CP), 16% CP, or 18% CP from 8 to 18 wk. At 18 k, 8pullets from each treatment were randomly selected and sampled. The results showed that the dietary treatment did not influence the feed intake, FCR (growth performance), body weight, and body composition at the end of the pullet phase; however, at 30 wk, BW was decreased (P < 0.05) in the 14% CP group compared to other groups. At 18 wk, the dietary treatment did not influence serum concentrations of Ca, P, and calcitonin (CT); however, PTH showed a trend to increase with high protein diet. The dietary CP levels did not influence the bone characteristics. Cumulative egg production was not influenced by the dietary protein levels. Mortality during the laying period was significantly higher in the low CP group. It was concluded that a low protein diet during the rearing phase did not affect the femur and tibia parameters at the end of the pullet phase and production performance but increased mortality during the laying period.