Effects of cage size on growth performance, blood biochemistry, and antibody response in layer breeder males during rearing stage.

This study was conducted to investigate the effects of cage size on growth performance, blood biochemistry, and antibody response in layer breeder males during rearing stage. 575 one-day-old Jinghong layer breeder males were randomly allocated into 3 treatments and reared in 3 cage sizes: large (160 × 160 × 62 cm; LC), medium (120 × 120 × 62 cm; MC), and small (80 × 70 × 62 cm; SC). The stocking density of birds in 3 treatments was kept identical and adjusted every 2 wk, from 45 birds/m2 during the period of 0 to 2 wk of age to 12 birds/m2 during the period of 17 to 18 wk of age. Body weight and shank length were measured every 2 wk, and then the daily weight gain and daily feed intake were calculated. Tibia length and breaking strength were determined at 8 wk of age. Blood parameters including malodiadehyde (MDA), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), alkaline phosphatase (ALP) and corticosterone (CORT), and antibody titers against avian influenza viruses H5N1 (Re-5 strain) and H9N2 (Re-2 strain) and Newcastle disease virus in response to vaccination were determined at 18 wk of age, respectively. Body weight, shank length, and daily weight gain of birds in LC were similar with those in MC, and were greater than those in SC at 18 wk of age (P < 0.05), respectively. No significant difference was found in average daily feed intake among the 3 treatments from 11 to 18 wk of age. Birds in LC and MC had the similar tibia length; however, birds in SC were smaller (P < 0.05). Tibia breaking strength of birds in LC was higher than those in SC (P < 0.05), respectively. Birds in LC showed lower plasma MDA, GSH-Px, SOD, and CORT contents than those in MC and SC (P < 0.05); however, birds in LC exhibited higher levels of serum antibody titers against H5N1 and H9N2 avian influenza viruses as compared with MC and SC (P < 0.05). Consequently, LC and MC were superior to SC and were beneficial for birds' growth and development. [ABSTRACT FROM AUTHOR]