The Effects of Feed Energy Level in Pullets on the Performance and Development

This study evaluated the impact of dietary energy levels on the growth and development of laying hens during the rearing phases (starter, grower, developer, and pre-lay). A total of 504 Hy-Line Brown hens, starting at 3 weeks of age, were housed in rearing cages from 3 to 16 weeks and then transferred to laying cages from 16 to 18 weeks, with a stocking density of 0.075 m² per bird. Four dietary treatments were applied: control (Con), high energy (H; +100 kcal), low energy (L; −100 kcal), and very low energy (VL; −200 kcal), with seven replicates per treatment. The results showed that hens in the VL group had significantly lower body weights by week 5. However, no significant differences in body weight gain or feed intake were observed between the Con and H groups throughout the study. The feed conversion ratio (FCR) increased as dietary energy levels decreased in the L and VL groups. Abdominal fat was also influenced by dietary energy levels up to week 16, and the H group reached sexual maturity earlier than all other groups. These findings suggest that optimal or higher dietary energy levels enhance growth performance and development during rearing. Further studies are recommended to explore the effects on laying performance, including age at first egg, peak production, and average egg production rates.