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Title: CHARACTERIZATION OF GOSSYPOL-INDUCED SPERM ABNORMALITIES IN BULLS

Author
item CHENOWETH, P. - KANSAS STATE UNIVERSITY
item Chase, Chadwick - Chad
item RISCO, C. - UNIVERSITY OF FLORIDA
item LARSEN, R. - UNIVERSITY OF FLORIDA

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/1999
Publication Date: 3/15/2000
Citation: N/A

Interpretive Summary: Gossypol is a toxic compound present in the pigment glands of the cotton plant. Cottonseed meal (CSM) is a common feed ingredient fed to cattle that can contain gossypol. Work with humans and laboratory animals indicates that gossypol can affect the male reproductive system causing lowered sperm production and reduced sperm motility. Previous studies conducted in bulls have demonstrated that gossypol can affect testicular tissue morphology, ejaculated sperm quality, and spermatogenesis, but less is known about the specific site of action of gossypol. Eight Brahman bulls received either CSM (T; 8.2 g free gossypol/bull/d) or soybean meal (C; no gossypol) for 11 wk. At sacrifice, semen was collected from different extragonadal sites reflecting sperm passage and sperm were examined by microscopy. In T bulls, some specific sperm abnormalities increased with extragonadal passage. Electron micrographs of T bull sperm indicated similar abnormalities as have been reported in nonruminants fed gossypol. The increase in midpiece abnormalities with sperm passage might suggest that spermatoxic effects of gossypol are being expressed extragonadally in bulls. However, the categories of abnormality that caused most of this increase suggest otherwise. Here, the conclusion is that the pattern reflects one of structural failure caused by the stress of nascent sperm motility upon weakened structures.

Technical Abstract: Young Brahman bulls (n=8) received either cottonseed meal delivering 8.2 g free gossypol/bull/d (T) or soybean meal (C) for 11 wk. At sacrifice, semen was collected from the mediastinum/rete testis (site 1), caput (site 2), corpus (site 3) and cauda epididymis (site 4) and ductus deferens (site 5). At least 200 fixed sperm per site were examined via DIC microscopy with electron microscopy being employed with select samples. Sperm midpiece abnormalities were characterized as aplastic, fragile and asymmetric, with detached heads being tabulated separately. In treated bulls, midpiece abnormalities generally increased with extragonadal passage. Increases occurred with midpieces in the fragile and asymmetric categories, but not with aplastic defects or detached sperm heads. Control bulls did not show such increases. Electron micrographs of bull sperm midpiece lesions induced by gossypol showed that these were ultrastructurally similar to those observed in nonruminant species. The increase in midpiece abnormalities with sperm passage might suggest that spermatoxic effects of gossypol are being expressed extragonadally in bulls. However, the categories of abnormality that caused most of this increase suggest otherwise. Here, the conclusion is that the pattern reflects one of structural failure caused by the stress of nascent sperm motility upon weakened structures.