Age-related changes in gonadal and serotonergic axes of broiler breeder roosters

• Published in: Domestic animal endocrinology 2013-04, Vol.44 (3), p.145-150
• Main Authors: Avital-Cohen, N., Heiblum, R., Argov-Argaman, N., Rosenstrauch, A., Chaiseha, Y., Mobarkey, N., Rozenboim, I.
• Format: Article
• Language: English
• Subjects: Age Factors; Aging; Animals; broiler breeders; Chickens - blood; Chickens - physiology; ejaculation; estradiol; Estradiol - blood; Follicle Stimulating Hormone - biosynthesis; Follicle Stimulating Hormone - genetics; follicle-stimulating hormone; gene expression; Gonadotropin-Releasing Hormone - biosynthesis; Gonadotropin-Releasing Hormone - blood; Gonadotropin-Releasing Hormone - genetics; hypothalamus; Hypothalamus - metabolism; Hypothalamus - physiology; luteinizing hormone; Luteinizing Hormone - biosynthesis; Luteinizing Hormone - blood; Luteinizing Hormone - genetics; Male; messenger RNA; Pituitary Gland - metabolism; Pituitary Gland - physiology; Prolactin; Prolactin - blood; Real-Time Polymerase Chain Reaction - veterinary; Reproduction; Reproduction - physiology; Reverse Transcriptase Polymerase Chain Reaction - veterinary; RNA, Messenger - chemistry; RNA, Messenger - genetics; roosters; semen; Semen - physiology; Semen quality; Serotonergic Neurons - physiology; sperm concentration; testes; Testis - anatomy & histology; Testis - physiology; testosterone; Testosterone - blood; Vasoactive intestinal peptide; Vasoactive Intestinal Peptide - biosynthesis; Vasoactive Intestinal Peptide - blood; Vasoactive Intestinal Peptide - genetics; White Leghorn
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2013.01.002

Fertility of domestic roosters decreases at ∼50 wk of age. In a previous study on aging white leghorn roosters, low fertility was accompanied by low levels of both hypothalamic vasoactive intestinal peptide (VIP) and pituitary prolactin (PRL) mRNA expression; however, their role in aging broiler breeder rooster reproduction is still unclear. In this study we compared reproductive activities of young (35-wk-old) and aging (73-wk-old) broiler breeder roosters. Weekly semen volume; concentration and ejaculation grade; and concentrations of plasma testosterone, estradiol, and PRL were examined. Every other week, 10 roosters from each group were euthanized, their testes weighed, and hypothalamus and pituitary removed to determine mRNA expression of hypothalamic GnRH-I, pituitary FSH, pituitary LH, hypothalamic VIP, and pituitary PRL. Aging roosters had significantly lower testis weight and semen volume, sperm concentration, ejaculation grade and plasma testosterone and low hypothalamic GnRH-I, pituitary FSH, and pituitary LH mRNA expression than young roosters (P ≤ 0.05). Aging roosters had higher concentrations of plasma estradiol and PRL and higher hypothalamic VIP and pituitary PRL mRNA expression than young roosters (P ≤ 0.05). We suggest that PRL, which is known to inhibit the gonadal axis, and its releasing factor, VIP, play an important role in the reproductive failure associated with age in broiler breeder roosters.