CONCENTRATIONS OF ESTRADIOL, ESTRONE, ESTRIOL IN THE BLOOD SERUM OF CHICKENS WITH DIFFERENT EGG YOLK WEIGHTS

The obtained data biologically confirm the feasibility of breeding chickens by the size of the egg yolk to increase their nutritional and biotechnological value. In the yolks of eggs of chickens of group III (with a yolk weight of M+0.5σ), the prevalence of triglycerides over group I (with a yolk weight of M-0.5σ) and II (with a yolk weight of M±0.3σ) was observed: by 24.0% (p<0.001) and 12.4%, cholesterol by 37.2% (p<0.01) and 13.5% and total protein by 22.8% (p<0.01) and 5.2%, respectively. It was established that the concentrations of estradiol, estriol and estrone change during the 6-hour period of the ovulatory cycle of chickens under study. The fluctuations of the 3 hormones in groups I and III do not coincide, in group II they coincide in two periods: 1-0 hours before laying an egg - a decline and 1-2 hours after laying an egg - an increase. In hens of groups I and II, changes in individual estrogen concentrations are subject to frequent fluctuations - declines and increases, and in hens of group III, hormone levels showed gradual decreases and increases. The predominant estrogen hormone in the blood serum of hens of the 3 groups in the studied periods of the ovulatory cycle is estriol (p < 0.001), the concentration of which is on average 1.77 ... 2.30 nmol / l for the entire period, while estradiol is 1.30 ... 1.47 nmol / l and estrone is 0.18 ... 0.23 nmol / l. The percentage of individual hormones in the sum of estrogens in the studied periods has different trends, so on average for the entire period for Group I the following percentage of estradiol, estriol and estrone in the sum of estrogens is characteristic: 37.2%, 58.2% and 4.6%, respectively, for Group II - 39.4%, 53.6% and 7.0%, and for Group III - 36.8%, 57.6% and 5.6%. Consequently, the ratios of estrogens in the groups of hens by periods of the ovulatory cycle are different. The obtained differences in the concentrations of estrogens by periods, and, consequently, the percentage of individual hormones to the sum of estrogens and their ratios to each other, are associated with differences in the synthesis of these hormones by the follicular membranes of oocytes in hens of the 3 studied groups, which affects the content of ovogenic substances of the yolk in the blood, and subsequently on the weight of the yolk of hens' eggs. Also, in the body of chickens, by changing the concentrations of estrogens and, consequently, their ratios, which are the executive mechanisms in the regulation of reproductive function in chickens in the general chain hypothalamus-pituitary-ovary, a switching of synthetic systems occurs during the ovulatory cycle, which ensure, in addition to the formation of ovogenic substances of the yolk, the formation of protein and mineral components of the shell.

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