Changes in serum testosterone and anti-Mullerian hormone concentration in bulls undergoing scrotal insulation

While changes in semen quality after heat stress are well characterized in the bull, changes in endocrine function have not been critically evaluated. It was hypothesized here that scro-tal insulation results in alterations in Sertoli cell and Leydig cell function, as measured by changes in serum testosterone and anti-Mullerian hormone (AMH) concentration. Scrotal insulation bags were placed in 10 bulls for 8 d. Blood was collected on days-22 and-2, and weekly from days 5 to 96 (day 0 = first day of scrotal insulation) for measurement of serum concentration of AMH and testosterone using ELISA. The concentration of AMH de-creased on day 5, followed by an increase on day 54 ( P = 0.014). When AMH concentration was normalized to pre-insulation values, the percent increase in serum concentration of AMH was significant between days 26 and 54, with another peak at 75 d ( P = 0.031). The serum concentration of testosterone ( P = 0.0 0 01) and the percentage of change in testos-terone concentration ( P < 0.0 0 01) increased on day 5, followed by a decrease from days 33 to 96. Scrotal insulation was associated with Sertoli and Leydig cell dysfunction, as mea-sured by serum testosterone and AMH concentration. The persistently low concentration of testosterone at the end of the study suggests a long term effect of scrotal insulation on Leydig cell function. (c) 2021 Elsevier Inc. All rights reserved.