Effect of restricted feed intake in broiler breeder hens on their stress levels and the growth and immunology of their offspring1

The prenatal environment has been shown to have significant effects on the lifelong health of offspring in humans and other species. Such effects have not been studied extensively in avian species but could prove important, especially in the case of severe feed restriction imposed on broiler breeder hens to prevent obesity and reduce rate of lay. Feed restriction can potentially affect not only nutrient supply to the embryo but stress hormone levels within the hen. This study investigated the impact of nutrient restriction of the breeder hen on growth rate and immune responses in the progeny with the objective to measure the impact of feed restriction of broiler breeder hens on growth and immune response of the progeny. Broiler breeder hens were feed restricted from 24 wk of age and maintained at three bodyweights; 3.4, 3.6, and 4.0 kg until 43 wk of age and behavioral and physiological measures of stress recorded. Chicks were hatched from each hen treatment and at day 7 vaccinated for infectious bronchitis virus (IBV) and at 16, 18, and 20 d old given an immune challenge of lipopolysaccharide. Growth and immune responses of these birds were then recorded. Sex ratio was affected by hen bodyweight, with a significantly increased proportion of males hatched from heavy hens. Growth rate from 35 to 42 d of age was reduced in male progeny from low bodyweight hens. Female progeny from heavy hens responded to an immune challenge by reduced live weight and increased heterophil: lymphocyte ratio, suggesting a more robust immune response in these birds than in the progeny from lower bodyweight hens. Overall, progeny from heavy hens had increased antibodies at day 35 to the vaccination of IBV compared with progeny of low bodyweight hens, also suggesting an improved immune response in these birds. Breeder hens restricted to the lowest feed level showed behaviors indicative of increased stress (object pecking) and an increased heterophil: lymphocyte ratio. Feed restriction of broiler breeder hens increased indices of stress in hens and resulted in offspring that have reduced growth rate and immune response in a sex-dependent way.