morphologigal measurements of lymphoid tissues and intestinal development of chicks from different breeder ages and hatched under heat stress

This study was carried out to evaluate the effect of breeder age and hatching temperature variations on chick quality. The experiment was a completely randomized design in a 3x2 factorial arrangement (three breeder ages and two hatching temperatures). We used 720 eggs from three breeder ages (30, 42, or 64 weeks). The hatching temperature for control group was 37.5 °C during all the hatching period and for the elevated temperature group, it was 39.0 °C during 6h between 10 and 18 days of incubation. Five chicks per treatment were euthanized by cervical dislocation for bursal and spleen morphological measurements. The data were analyzed using ANOVA and the differences among means were compared by Tukey test (5%). Chicks from older flock had larger follicular area of bursa de Fabricius when hatched under normal temperature. The higher hatching temperature induced intestinal development because chicks hatched under high temperature had bigger crypt depth. Changes in hatching machine temperature affected young flock chick quality. Chicks from older flocks had better immune response. Keywords: broiler; bursal; hatching; intestine; spleen.