Medycyna Wet. 64 (4b), 515-519, 2008
Wocławek-Potocka I., Korzekwa A., Skarżyński D. J.
Can phytoestrogens pose a danger in the reproduction of cows?
Since alpha-alpha, lucern and soy bean contain high concentrations of phytoestrogens, plant estrogens may be present in fodder for ruminants, especially dairy cattle. Although the concentration of basic flavonoids in blood plasma of cows fed soy bean rises within one hour of feeding, their active metabolites are present in the blood plasma in high concentrations for a lengthy period after feeding. Phytoestrogens are much less active than endogenous estrogens, therefore their 1000-times higher concentrations in the blood plasma enable them to act on the hormonal status of the female. They might influence the reproductive processes on many regulatory levels: on the central level as well as local and peripheral levels. It has been proved that phytoestrogens might inhibit secretion and action of pituitary LH, thus modulating the action of endogenous estrogens in the follicular phase of the estrus cycle, which may be a reason for a lack of estrus and disruption of the ovulation. Although phytoestrogens and their active metabolites do not directly influence P4 secretion in the bovine luteal cells, they may inhibit the sensitivity of the bovine CL to luteotropic factors, including LH. They may also stimulate testosterone and prostaglandin (PG)F2a secretion leading to disruption of steroidogenesis in the CL. Within the bovine oviduct and uterus, phytoestrogens modulate synthesis and action of the factors responsible for conception, embryo development and implantation. Phytoestrogens stimulate PGF2a synthesis in the bovine endometruim, leading to the disruption of the ratio of luteotropic to luteolytic arachidonic acid (AA) metabolites. Therefore, they might be one of the reasons for the disruption of early pregnancy and in the end lead to embryo mortality. In conclusion, when feeding animals with fodder containing many phytoestrogens, the fact that their high productivity might lead to low reproduction efficiency must be taken into account. Keywords: phytoestrogens, estrus cycle, early pregnancy, cow
Keywords: reproduction, estrous cycle, prostaglandins, retrograde transfer, destination transfer