Effects of a Rearing Dietary Protein Regimen on Productive Performance, Egg Quality, and Bone Quality of Laying Hens.

The pullet phase is an important stage in the development of laying hens when the development of organs, including reproductive organs and bones, is rapid. However, in recent years, few studies have focused on this crucial stage. The purpose of this study was to evaluate the effect of a dietary crude protein (CP) regimen during the rearing period (9-21 weeks (wks) of age) on pullet development and the subsequent performance, egg quality, and bone quality of Hy-Line Brown laying hens. A total of 256 pullets were randomly assigned to two treatments. Each treatment was replicated eight times with 16 pullets per replicate (n=8), which were fed ad libitum using either of the two CP regimens: (1) 14%-18% CP (fed with 14% and 18% CP from 9-17 wks and 18-21 wks, respectively); (2) 16% CP (fed with 16% CP from 9-21 wks of age). At 21 wks of age, eight birds per treatment were randomly selected to evaluate body composition and ovarian development. For quality analysis, eggs were collected at 28, 32, 36, and 70 wks. At 70 wks of age, eight hens per treatment were selected to evaluate bone quality. There were no treatment differences in pullet performance, body composition, and ovarian development at 21 wks. The dietary CP regimen during the rearing period (9-21 wks) did not influence laying performance during the laying period. There were no treatment differences in tibial and femoral quality at 70 wks. Egg quality results showed an inconsistent trend. It was concluded that the pullets fed with the low CP grower diet (14%) during the pullet period and a high CP pre-lay diet (18%) from 18-21 wks of age developed properly and had satisfactory laying performance. However, the rearing diet did not enhance bone quality.