Effects of broiler breeder-feeding programme and feeder space change at photostimulation using maize- or wheat-based diets on eggshell properties and progeny bone development

1. The effects of diet type, feeding programme and fast- or slow-feed allocation in fast-feathering Cobb 500 broiler breeder hens on eggshell properties and broiler progeny bone development were investigated in a 2x2x2 factorial experiment.2. The birds were fed on either maize- or wheat-based diets during rearing and production and on a fast- or slow-feed allocation programme from 14 to 29weeks of age. At 22weeks, 69 females from each pen were placed in a layer house where feeder space (FS) either remained similar or was increased.3. Eggs produced at 33weeks were incubated, eggshell conductance (G) was determined and a sample of 14 chicks from each treatment combination was taken to obtain bone traits at hatching.4. Diet type did not influence G, yolk-free body weight (BW), residual yolk weight or relative asymmetry (RA) of any bilateral traits of leg bones of hatchlings. However, breeder diet type was involved on two-way and three-way interaction effects on progeny leg bone traits.5. Breeders feed restricted according to the slow-feeding programme laid eggs with greater G compared to those managed with the fast-feeding programme, but there was no effect of feeding programme on progeny bone traits at hatching.6. Eggs from breeders given more FS at photostimulation had greater G than those from breeders provided with similar FS. Maternal FS change did not influence hatchling yolk-free BW; however, breeders given more FS produced progeny with heavier tibias and shanks and longer femurs compared with those provided with similar FS, but only when breeders were fed on maize. Moreover, increased maternal FS at photostimulation was associated with an increased RA of femur length in the progeny.7. It was concluded that breeder FS change at photostimulation influenced eggshell conductance and consistently affected bone development of the broiler progeny.