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

Abstract

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.

Development, Regeneration, and Evolution of Feathers

“…At the end of the breeding season or during egg incubation, HPG axis activity is suppressed, as evinced by gonad regression. Luteinizing hormone and gonadal steroid hormone (e.g., testosterone, estradiol, progesterone) levels are reduced in response to natural or artificial molting (82, 88–90). Experimentally increasing plasma testosterone levels with subcutaneous implants postpones the prebasic molt (91, 92), whereas suppressing pituitary gonadotropin-releasing hormone (GnRH) receptors with a GnRH agonist can induce a molt (93).…”

Assessment of age‐related morphological changes in the testes of post‐hatch light ecotype Nigerian indigenous chicken

“…Pre‐pubertal testicular changes are considered essential as the potential for pubertal development and normal adult fertility depends on the successful completion of these pre‐pubertal changes (Chemes, 2001; Ohmura et al., 2008; Brilhante et al., 2012). These changes may be influenced by the plasma and testicular luteinizing hormone (stimulates Leydig's cell production) and androstenedione (precursor of testosterone) levels (Culbert et al., 1977; Jacquet et al., 1993). The significant increases in the seminiferous tubular diameter, germinal epithelial height and luminal diameter with age show increasing and peak cellular activities at sexual maturity.…”