EFFET DE DIFFERENTS REGIMES PHOTOPERIODIQUES SUR LA PUBERTE DU PIGEONNEAU MALE COLUMBA LIVIA

Ce travail a pour but l’etude de l’influence du regime photoperiodique sur l’activite reproductrice de jeunes pigeons domestiques Columba livia a la puberte : poids corporel, volume testiculaire et certains parametres biochimiques et endocriniens. Les pigeonneaux ont ete repartis en 3 lots exposes a differents regimes photoperiodiques : jours courts (8L : 16D), eclairement continu (24L : 00 D), photoperiode naturelle de printemps (lot Temoin). Les animaux du lot temoin (photoperiode naturelle) presentent en fin d’experimentation un developpement testiculaire temoignant du declenchement de la spermatogenese, et une augmentation des taux plasmatiques de testosterone, proteines, cholesterol, triglycerides et thyroxine, contrairement au taux de glucose qui baisse. D’autre part, une regression testiculaire rapide chez les pigeonneaux soumis a des jours courts (8L : 16D) a ete observee. Les taux plasmatiques de proteines et de glucose augmentent, mais la testosterone, le cholesterol, les triglycerides et la thyroxine diminuent. Enfin, chez les oiseaux exposes a un eclairement continu (24L : 00 D), les gonades se developpent rapidement, les taux de testosterone, proteines et thyroxine augmentent ; les taux de glucose, de cholesterol et de triglycerides diminuent. Mots cles : reproduction; thyroxine; photoperiode; pigeon. The aim of the present investigation has been to study the influence of various photoperiodic regimes on the reproductive activity of immature male domestic pigeon Columba livia , namely: body weight, testicular volume and some biochemical and hormonal profiles. Immature birds have been divided into 3 groups held under short days (8L: 16 D), continuous light (24L: 00 D), and natural photoperiod (control group). In the control group we see a significant gonadal development, an increase in plasma levels of testosterone, proteins, cholesterol, triglycerides and thyroxin, and a decrease in plasma glucose concentrations. A rapid involution of testes in individuals exposed to short days (8L: 16D) is recorded. Plasma protein and glucose levels increase, while those of testosterone, cholesterol, triglycerides and thyroxin showed a decline. At last, there was an increase, in testicular volume of birds exposed to continuous light (24L: 00 D), testosterone, proteins and thyroxin levels, while those of glucose, cholesterol and triglycerides showed a considerable decline. Keywords: reproduction; thyroxin; photoperiod; birds.