Plasma IGF-I, INSL3, testosterone, inhibin concentrations and scrotal circumferences surrounding puberty in Japanese Black beef bulls with normal and abnormal semen

• Published in: Theriogenology 2018-07, Vol.114, p.54-62
• Main Authors: Weerakoon, W.W.P.N., Sakase, M., Kawate, N., Hannan, M.A., Kohama, N., Tamada, H.
• Format: Article
• Language: English
• Subjects: Beef bull; IGF-I; Inhibin; INSL3; Puberty; Semen
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2018.03.006

The relationships between semen abnormalities and peripheral concentrations of testicular and metabolic hormones in beef bulls are unclear. Here we compared plasma insulin-like growth factor I (IGF-I), insulin-like peptide 3 (INSL3), testosterone, inhibin concentrations, and scrotal circumferences surrounding puberty in Japanese Black beef bulls (n = 66) with normal or abnormal semen. We collected blood samples and measured scrotal circumferences monthly from 4 to 24 months of age. Semen was collected weekly from 12 months until at least 18 months of age. Fresh semen was evaluated for semen volume, sperm motility, concentrations, and morphological defects. The normal fresh semen was frozen by a standard method and examined for post-thaw sperm motility and fertility. Bulls were classified as having either normal post-thaw semen (n = 45) or abnormal semen (n = 21, when at least one of the above test items was abnormal for 6 months). Abnormal semen was classified into abnormal fresh or low-fertility post-thaw which evaluated for rates of transferable embryos. The abnormal fresh was categorized as having sperm morphological defects, low motility, and morphological defects plus low motility. Scrotal circumferences were smaller for the abnormal-semen group vs. the normal-semen group at 20 and 24 months (p