Growth and ontogenetic allometry of visceral organs in cross loman brown chicken embryos at different embryogenesis stages under a standard temperature-humidity incubation regime

The article presents the study results of growth and ontogenetic allometry of visceral organs in cross Loman Brown chicken embryos at different embryogenesis stages under a standard temperature-humidity incubation regime. The research has been carried out in the scientific laboratory of the Velikie Luki State Agricultural Academy in 2019-2020. The material for the research is Loman Brown embryos (n=200). Morphometric assessment of the embryos’ body weight and visceral organs of the heart, muscular stomach and liver has been made since the 9th day up to the 20th day and the assessment of spleen - since the 13th day up to the 20th day. The specific growth rate of the visceral organ weight in chicken embryos has been determined according to the formula of I. Schmalhausen and S. Brody, and allometric growth - by the method of M. Mina and G. Klevezal using the formula of simple allometry. It is revealed that at different embryogenesis stages there are critical phases of the rise in the specific growth rate of the visceral organs in Lohmann Brown chicken embryos: heart - during the early-fetal stage - on the 10th, 11th and 12th day, during the mid-fetal stage - on the 14th day and during the late-fetal stage - on the 18th day; muscular stomach - during the early-fetal stage - on the 12th, during the mid-fetal stage - on the 13th, 16th and 17th day, during the early-fetal stage - on the 18 th 19 th day; liver - during the early-fetal stage - on the 10th, 11th day, during the mid-fetal stage - on the 15th day; spleen - during the mid-fetal stage - on the 14th day. A negative allometry of the relative growth rate of visceral organs in Loman Brown embryos has been observed during all embryogenesis stages. Allometric growth of visceral organs of chicken embryos at different stages of development is uneven, that is, there are periods of increase and decrease in their growth in relation to body weight. The heart of Loman Brown embryos grows more intensively at the early-fetal (b=0.925±0.075) and late-fetal (b=0.931±0.072) stages of development, the muscular stomach and liver - at the early-fetal stage (b=0.940±0.068 and b=0.972±0.046, respectively), the spleen - at the mid-fetal stage (b=0.772±0.126).