Subject(s)
Animals , Bacterial Proteins/isolation & purification , Biodegradation, Environmental , Chickens , Endopeptidases/isolation & purification , Feathers/drug effects , Goats , Hair/drug effects , Humans , Hydrolysis , Industrial Microbiology , Insect Proteins , Keratins/drug effects , Proteins/drug effects , Silk , Soil Microbiology , Streptomyces/enzymology , Wool/drug effectsABSTRACT
Various doses of testosterone propionate (TP) were administered for 10 days to refractory male redheaded buntings exposed to 15L:9D in last week of June, shortly before the onset of molt, to determine the effect of exogenous male hormone on the testes, body weight and plumage regeneration in photorefractory birds. While 5-, 10-, or 25 micrograms of TP bird-1 day-1 did not affect the testes, body weight or feather regeneration, testicular growth was stimulated but body weight declined and plumage regeneration prevented in birds that received 150- or 250 micrograms of TP bird-1 day-1. In contrast, a 50 micrograms treatment, although unable to induce the growth of the testes, caused loss in body weight and feather regeneration. Also, a 25 micrograms dose of TP administered to photostimulated birds induced complete testicular atrophy. These results suggests that testosterone exerts dose-dependent effects on the testes, body weight and plumage regeneration in buntings. A positive correlation is found between the amount of hormone and the testes growth, while the increasing amount of hormone has negative effect on the body weight and regeneration of feathers.