Dosed Exposure to Low Temperature as a Breeding Background in The Selection of Gene Pool Breeds of Chickens for Viral Vaccines Production

Abstract

Background: One of the ways to utilize the potential of local breeds is to use them as producers of raw materials for the bio-industry (production of vaccines and diagnostics for animals and humans). Methods: Breeding of Russian White (PRWC) laying hens in 5 generations was carried out with the aim of increasing the output of allantois-amniotic fluid of embryos with a selective background (cooling of hatching eggs during the sensitive period of embryogenesis). In F5, the thermoregulation capabilities of 7-day-old PRWC chickens were studied in comparison with Amrox chickens under the influence of a daily stress factor (cooling at +10oC for 30 minutes) and raising at +22oC. The level of allantois-amniotic fluid output and biological activity of the Newcastle disease virus in F5 PRWC embryos in comparison with F0 and commercial line embryos was evaluated. Results: Day-old PRWC chicks responded to exposure to low sublethal temperature with muscle shivering, but, unlike Amrox chickens, they were active and retained the reflex of searching for food. PRWC chickens raised at low temperatures up to 7 days of age maintained the same growth rate as chickens raised at a common regime but used less residual yolk, which practically did not decrease the body temperature, and change the level of thyrotrophic hormone in response to the dosed exposure at low temperatures at 7 days of age. The content of doses of the Newcastle disease virus (EID50) in the extraembryonic fluid of F5-embryos of PRWC was 32.3 times higher than that of commercial line ones. Conclusion: PRWC chicks in the early neonatal period are more reactive at low temperature and have better thermoregulation mechanisms. PRWC embryos can be recommended for use in the production of various viral vaccines as well as diagnosticums.