Induced moulting in cockerels: effects on sperm production, plasma concentrations of luteinising hormone, testosterone and thyroxine, and on pituitary sensitivity to luteinising hormone-releasing hormone.
1. The ability of a moult-inducing procedure to restore high levels of sperm production was assessed, in two experiments, using cockerels with reduced sperm production. The moulting procedure consisted of a period of food and light restriction for 6 weeks. The moulted birds were compared with control birds for 20 weeks. 2. Moult induction resulted in decreased daily sperm output (DSO) and plasma testosterone concentration, from weeks 3 to 7. In the first experiment, plasma luteinising hormone (LH) concentration in moulted birds was reduced on week 5. 3. No change in pituitary sensitivity to chicken luteinising hormone-releasing hormone-I (cLHRH-I) was detected at week 3 in moulted cockerels. In moulted birds, a transient increase in plasma thyroxine concentration was detected. 4. After the end of moult induction, testosterone concentrations increased, plasma LH showed a rebound at week 7 and the pituitary sensitivity to LHRH was increased at week 9. 5. This increased activity of the pituitary-testicular axis resulted for a short time in an increase in DSO of moulted birds compared with that of controls. Although amelioration was moderate, this result indicates the possibility of improving sperm production in the cockerel by using an induced moulting procedure.
Jacquet
J M
JM
Station de Recherches Avicoles, Institut National de la Recherche Agronomique-Centre de Tours, Nouzilly, France.
Seigneurin
F
F
De Reviers
M
M
D000818:Animals; D002645:Chickens / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D010902:Pituitary Gland / Q000502:physiology; D013076:Sperm Count; D013094:Spermatozoa / Q000502:physiology*; D013739:Testosterone / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D013974:Thyroxine