Multiple Effects of Egg Weight, in Ovo Carbohydrates, and Sex of Birds on Posthatch Performance in Broilers

SIMPLE SUMMARY: Future technologies in poultry nutrition must support the growth, gut health, and energy status of the birds. One of these technologies is in ovo nutrition, in which nutrients enter the egg by a needle puncture without any harm to the embryo. Amino acids, vitamins, and even carbohydrates can be injected into various parts of the egg, mainly during the last days of hatch. Carbohydrates, as a primary energy source, are crucial for the avian body, especially on the day of hatch, when the carbohydrate resources of the egg yolk do not meet the needs of the embryo. In our study, a carbohydrate mixture composed of disaccharides and glucose was tested to examine the performance and carcass characteristics of broiler chickens. It can be concluded that a carbohydrate mixture tends to reduce hatchability; however, the correct quantity of fluids, injection day, and osmolality of the mixture still need to be specified. In addition, many other factors can determine performance, such as the hatching day, sex, and the size or weight of the egg. On the other hand, this technique may improve carcass traits. Further studies are needed to refine the method to avoid embryo death. ABSTRACT: Chickens raised for their meat (Gallus gallus domesticus) tend to have a critical phase of life right after hatching due to the management of modern production systems. Early nutrition strategies such as in ovo intervention can be an alternative means to support growth and gut health by compensating for the energy deficit after pipping out of the egg. In the current study, 1200 Ross 308 eggs were used to examine the effects of a complex carbohydrate solution of disaccharides and glucose applied in ovo on hatchability, the hatching time of different-sized eggs, and the development, performance, and carcass characteristics of broilers of both sexes. The eggs were divided into three treatment groups: intact (NT), in ovo saline (ioS), and in ovo carbohydrate mixture (ioCH). The incubation protocol was performed according to the recommendations of Aviagen (2019), and the in ovo process was carried out on day 17 by manually injecting 0.5 mL of the solutions into the amniotic fluid. After hatching, the birds were kept in floor pens until day 35 and fed ad libitum in a three-phase feeding program. Body weight, average daily weight gain, feed intake and conversion, and carcass characteristics were measured during the trial. In ovo carbohydrates reduced hatchability by 15%, while growth performance and the weight of thigh and breast muscle were enhanced significantly (p < 0.05) compared with ioS as a possible outcome of carbohydrate-to-muscle satellite cell proliferation and protein accumulation. However, further study is needed to refine the in ovo carbohydrate supplementation method to minimize the mortality of embryos during hatching.