Influence of maternal flock age, maternal trace mineral nutrition and incubation temperature on bone development of embryos and chicks

At hatch, the skeleton of the chick is a well formed miniature of that in the adult bird; this is the end result of 21 days of development in the egg. In order to build a strong and healthy skeletal frame, the embryo relies on trace minerals (TM) deposited in the egg by the hen. The temperature at which the embryo grows is also a key factor influencing skeletal development. The overall purpose of this research was to understand the effects of maternal trace mineral nutrition on embryonic and post-hatch bone development and to investigate the relationship between temperature and bone characteristics. Mineral content in the egg and embryonic and post-hatch bone characteristics of embryos and chicks from Young (32 week), Mid (45 week) and Old (59 week) hens were not influenced when hens were supplemented with low levels of organic (OTM) copper, zinc and manganese relative to TM sulfates (ITM) at industry levels (Control). High ITM levels increased bone strength at hatch relative to Control but not relative to OTM; at hatch OTM widen bones from Young hens relative to all diets. Therefore, an opportunity exists for industry to reduce TM levels by supplementing OTM. As hens aged, the yolk Zn and Cu content increased and embryos from Young hens had reduced proportion of calcified tibia and femur relative to those from Older hens at day 20th of incubation and weaker bones at hatch. In another study, an incubator temperature of 36.0°C applied from the 15th day of incubation until hatch increased bone strength relative to 37°C. High eggshell temperature is negatively associated with bone calcification and strength. If the stronger bones at placement in the barn increased chick mobility then water consumption and access to nutrients important for post-hatch bone growth could be increased and this might decrease future bone problems. In summary, considerable maternal age and incubator temperature variation existed on skeletal growth of the progeny, demonstrating that there may be opportunities to use maternal nutrition and hatchery management to increase skeletal health in chicks at hatch, especially those from young flocks.