Low-temperature exposure in early embryogenesis as a way of increasing the resistance of chicks to infectious diseases

The article is devoted to the problem of increasing the resistance of chicks from hatching to the age of 3 weeks to infectious diseases by technological methods. Dosed low-temperature exposure to the embryo during the sensitive period of early embryogenesis was proposed as an impact factor; influenza vaccine virus was used as a test virus for experimental infection of embryos. It was found that in the embryos after cooling, the titer of the virus was significantly lower by 1.5-12.0 times (p<0.001) compared with the control. This fact indicates a decrease in the replicative activity of viral strains in embryos of this group. In chicken embryos of Russian Snow-White breed after cooling, there was a decrease in the infectious activity of the influenza A virus by 11.5 %, as well as a decrease in the infectious activity of the infectious bronchitis virus by 3.6-6.9 %, depending on the breed of the embryos. The level of chick resistance in the experimental group to diseases of bacterial etiology was also higher, as evidenced by the higher safety of 3-week-old chicks (0.8-1.1 % higher than in the control) and a higher bursa index in 12-day-old chicks (8.5-9.0 % higher than in the control). The hatchability of eggs of the experimental group was also 4.5 % higher than in the control. The effects obtained as a result of hypothermic exposure during this sensitive period of embryogenesis can be explained by inducing the production of heat and cold shock proteins by the embryo, which, in turn, activate innate antiviral reactions caused by major histocompatibility complex. However, this issue requires additional study with the involvement of molecular genetics methods, since the supposed mechanisms that cause an increase in resistance in response to low-temperature exposure in early ontogenesis need to be confirmed.