Maryam Doostalivand - Department of Animal Science, Animal Science and Food Technology Faculty, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Iran
Somayyeh Salari - Department of Animal Science, Animal Science and Food Technology Faculty, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Iran
Ahmad Tatar۱ - Department of Animal Science, Animal Science and Food Technology Faculty, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Iran
Mohammad Razi Jalali - Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

This study evaluated the effects of different sources of insoluble fiber at different cage densities on egg performance, egg quality, tibia characteristics, and cecal microbial population of ۷۰-week-old Hy-Line W-۳۶ for ۱۰ weeks. A total of ۱۲۰ laying hens were allocated to six treatments, including control (CTL) and two sources of insoluble fiber (sugarcane bagasse (SB) and sunflower hulls (SFH) in ۵ % of diet) at two stock densities (۳ and ۵ hens per cage) with five replicates. Dietary inclusion of SB decreased average daily feed intake (ADFI) and egg production (EP), but improved egg weight (EW), egg mass (EM) and feed conversion ratio (FCR) compared to the birds fed SFH. High stock density reduced ADFI, EP, and EW, but increased FCR. Egg quality parameters such as Haugh unit, shell strength, shell thickness, percentage of shell, percentage of yolk, percentage of white and yolk color, and tibia characteristics of laying hens were not affected by insoluble fiber, stock density, or their interactions. High stock density–challenged hens had higher plasma corticosterone levels, but lower feather scores compared to the normal stock density hens (P < ۰.۰۵. Besides, subjecting hens to high stocking density decreased populations of Lactobacillus spp. and increased the cecal population of E. coli compared to the control group (P < ۰.۰۵). The inclusion of SFH and SB in layer diets, however, increased populations of Lactobacillus spp. and decreased the cecal population of coliforms and E. coli compared to birds in the CTL group. Therefore, dietary inclusion of insoluble fiber, especially sugarcane bagasse,  can be a useful method to improve  productive performance and cecal microbial population of old laying.

Corticosterone, Egg quality, Insoluble fiber, Laying hen, Stocking density