Endogenous Hormone Activity Research Articles

Hormonal Activity in Poultry Excreta Processed for Livestock Feed

Experiments were conducted to determine the kind and amount of endogenous hormonal activity present in various sources of poultry excreta processed for use as livestock feed. These experiments were conducted to determine: 1) the presence of both androgenic and estrogenic activity in poultry excreta; 2) the amount of activity found; and 3) the effect of processing methods, such as dehydration, upon the level of hormonal activity. Experiments in which chick comb growth was bioassayed showed that caged laying hen excreta processed by house fly larvae contained androgenic activity that ranged from 2.18 to 9.36 μg. of testosterone equivalents per gram of dried excreta. This activity was not present in fresh excreta and was not affected by drying times or temperatures up to 48 hr. at 100°C. In rat uterine growth assays, fresh, dried caged laying hen excreta contained up to 1.6 μg. of estradiol equivalents per gram of dried excreta. Holding excreta for 5 to 7 days under wither aerobic or anaerobic conditions reduced estrogenic activity, but drying temperatures up to 100° C. did not appear to affect the level of these hormones in excreta.

The onset of first oestrus in the guinea-pig and the effects of gonadotrophins and oestradiol in the immature animal.

SUMMARY The immature female guinea-pig approaching first oestrus and ovulation has been studied. A clear relationship between the rate of growth of the animal and the age at puberty has been found. The 'crucial period', a time just before first oestrus, when external signs of endogenous hormonal activity give an indication of the presence of ripening follicles in the ovary, has been defined. At this time premature ovulation can be regularly induced by a single injection of gonadotrophin (guinea-pig anterior pituitary homogenate, purified luteinizing hormone or follicle-stimulating hormone). Injection of oestrogen advanced vaginal opening but, in contrast to the rat, did not cause premature ovulation.

Effects of active immunization with bovine luteinizing hormone on reproduction in the female rat.

The active immunization of female rats with bovine luteinizing hormone causes an impairment of the animals’ reproductive capacity. Less than 10% of the immunized animals exhibited normal estrous cycles, accepted male partners and had what could be considered uneventful pregnancies. The impairment of the reproductive performance could be classified into 4 major categories. The animals demonstrated fertile matings but complicated complicated pregnancies, sterile matings, nonmating behavior, or they became anestrous. Booster injections of the LH preparation consistently increased the circulating antibody titer to the bovine hormone and concomitantly increased the severity of the reproductive disorder. The immunologic mechanism by which the endogenous hormone activity is diminished remains to be clarified. (Endocrinology82: 1190, 1968)