Estrogen blood profile of chickens in the studied period of the ovulatory cycle
Authors: Perinek O. 
Published: November 2024

The aim: to study the dynamics of the concentrations of estradiol, estriol and estrone, their ratios in the studied period of the ovulatory cycle and the connection with the size of egg yolk.

Materials and methods. The material for the study was chickens of the Pushkin breed, in the amount of 36 birds. at 36 weeks of age. The chickens were kept in individual cages. Light mode — 14C:10T. Watering — nipple, temperature in the poultry house and feeding - in accordance with the standards adopted by the Central Collective Use Center of the All-Russian Scientific Research Institute of Growing Animals "Genetic collection of rare and endangered breeds of chickens". Over the course of 7 days, eggs from 96 chickens of 30 weeks of age were assessed by the weight of the egg, yolk, white, shell - using electronic scales Mertech M-ER 122ACF(JR) with an accuracy of 0,01 g. Eggs were counted and assessed individually: From each hen, at least 3 consecutively laid eggs were examined the next day after collection. Based on the data obtained from assessing chickens based on the quality characteristics of eggs and productivity, 36 birds with egg yolk weights M-0,5σ, M±0,45σ, M+0,5σ were selected. Blood from the studied chickens was taken in the morning and during the day on an empty stomach to simultaneously determine the concentrations of estradiol, estriol and estrone 2 hours before laying eggs and within 4 hours after laying, with an interval of 1 hour. In order to obtain serial blood samples from chickens for Dynamic studies of estrogens included the installation of peripheral venous (intravenous) catheters. The concentration of estrogen in the blood plasma of chickens was determined by ELISA.

Results. The concentrations of individual estrogenic hormones change during the 6 hours of the studied period of the ovulatory cycle, periodically increasing and decreasing, while the fluctuations coincide only in two periods after the egg is laid: after 1—2 hours — a rise and 2—3 hours — a decline. Of the six studied periods of the ovulatory cycle of chickens, the time period of practical interest is 2—1 hours before egg laying, when the ratio of estradiol:estrone was 7,4:1, estriol:estrone — 7,9:1 and estradiol:estriol — 1:1. During this period, a positive significant correlation was revealed between the estradiol:estrone ratio and the yolk mass of chicken eggs — +0,55 (p <0,05). Also, in the established period, the highest concentration of estradiol (1,52±0,12 nmol/l), estrone (0,29±0,04 nmol/l) was simultaneously observed compared to other periods, and the lowest concentration of estriol (1,67± 0,16 nmol/l). A positive correlation was determined between estradiol and estrone — +0,68 (p <0,05) and estradiol and estriol — +0,71 (p <0,05).

Conclusion. In the period 2—1 hours before laying eggs, the effect on the body of chickens of estrogenic hormones in the ratio estradiol: estrone 7,4:1, estriol:estrone – 7,9:1 and estradiol:estriol — 1:1 leads to inactivation of synthetic systems, providing intensive formation of ovogenic substances by the liver (vitellogenin, lipoproteins), and the transfer of vitellogenic material into developing follicles.