Endogenous anabolic agents in farm animals.

The research article is about the roles of different steroid sex hormones in farm animals, including their sources, production rates, plasma levels, tissue concentrations, metabolism, and excretion.

Hormones Under Study

• The study focuses on three groups of steroid sex hormones – Gestagens, Androgens, and Estrogens. These hormones have been shown to have anabolic properties when used in farm animals.
• Gestagens include Progesterone and 20-dihydroprogesterones, which are mainly produced in ovaries and placenta.
• Androgens, specifically Testosterone, are secreted primary by the testes of animals. In boar tests, there are also large amounts of dehydroepiandrosterone and its sulphate.
• Estrogens, specifically 17beta-Estradiol and estrone, are produced in the ovaries and placenta. In the testes of boars and stallions, these hormones are produced in large amounts.

Production Rates of Hormones

• The production rates vary depending on the type of hormone. For instance, progesterone and 20-dihydroprogesterones are produced at rates of between 10 and 14 mg/24 hrs in pregnant goats and sheep, respectively.
• Similarly, testosterone has an estimated production rate of between 10 mg and 40–50 mg/24 hrs. in boars and bulls. For Estrogens, particularly in late pregnancy, the production rates can reach up to 10 mg oestrone/24 hrs. in goats, and 2 mg estrone and up to 28 mg 17beta-estradiol/24 hrs. in sheep.

Plasma Levels and Tissue Concentrations of Hormones

• The plasma levels and tissue concentrations also vary among hormones and animals. For example, in the luteal phase, plasma levels of Gestagens in are of the order of 2–10 ng/ml, while during pregnancy, these levels are a bit higher.
• The plasma levels of Androgens, for instance, in bulls and rams are generally around 2–10 ng/ml,
• Estrogens have considerably lower levels in non-pregnant animals but can reach up to 2–4 thousand pg/ml in sows and cows in late pregnancy.

Metabolism and Excretion of Hormones

• The metabolism and excretion of these hormones vary. For instance, progesterone in ruminants (cud-chewing animals) is metabolized mainly to androgens and excreted with feces.
• Androgens such as testosterone are metabolized into epitestosterone in ruminants, while in boars, urinary 11-deoxy-17-ketosteroids are major metabolites of testicular dehydroepiandrosterone.
• Estrogens, specifically 17 beta-estradiol and estrone, are metabolized to 17alpha-estradiol in ruminants, a compound with low estrogenic activity. In pigs, estrone dominates in blood and urine. The main elimination routes for these hormones are through feces in ruminants and urine in pigs and horses.

Conclusion

• The study concludes that all three groups of steroid sex hormones occur in significant concentrations in the plasma and tissues of the studied farm animals. These insights can help in evaluating the public health aspects of using these hormones, as it provides information on their natural occurrence and behavior within the animals’ bodies.