Effect of free gossypol in whole cottonseed on the semen quality of Holstein bulls

Abstract

It is suspected that feeding large amounts of whole cottonseed and cottonseed meal to dairy cows can cause gossypol intoxication. It has also been shown that male antifertility is probably the first physiological effect of free gossypol. The objective of this investigation was to determine whether diets containing 0,185 or 0,254% free gossypol per kg dry matter would cause any spermatozoal defects at intakes of 64 or 75 mg free gossypol (as whole cottonseed) per kg live mass in two-year-old Holstein bulls. Twelve Holstein bulls were allotted to three comparable groups receiving complete diets containing 0; 27,9 and 39,1% whole cottonseed per DM which contained 0,64% free gossypol per DM. Semen was collected on days 60, 80, 100, and 120 and compared for volume, colour, motility, concentration, % spermatozoa live or dead, % spermatozoa with normal morphology, viability after deep freezing and swimming speed. Histological studies were also carried out on the testes. No parameters were influenced significantly (p < 0,05) and it was concluded that free gossypol intakes used in this study did not cause any spermatozoal defects and that the free gossypol was probably efficiently detoxified in the rumen.

Daar word vermoed dat die voeding van groot hoeveelhede heel katoensaad en/of katoensaadoliekoek aan melkkoeie moontlik tot gossipolvergiftiging kan lei. Dit is ook bekend dat manlike onvrugbaarheid die eerste fisiologiese effek van vry gossipol is. Die doel van hierdie studie was om vas te stel of diëte wat 0,185 of 0,254% vry gossipol per kg droë materiaal bevat enige spermdefekte teen innames van 64 of 75 mg vry gossipol (as heel katoensaad) per kg lewende massa in twee-jaar-oue Holsteinbulle sal veroorsaak. Twaalf Holsteinbulle is ewekansig in drie vergelykbare groepe ingedeel en vergelykbare diëte gevoer wat onderskiedelik 0; 27,9; en 39,1% heel katoensaad op 'n DM basis bevat het waarvan die vrygossipolinhoud 0,64% op 'n DM basis was. Semen is op dag 60, 80, 100, en 120 na aanvang van die proef versamel en ten opsigte van volume, kleur, beweeglikheid, konsentrasie, % sperme lewendig of dood, % morfologies normale sperme, lewensvatbaarheid na bevriesing en swemspoed vergelyk. Histologiese studies is ook op die testes uitgevoer. Geen van die gemete kenmerke het betekenisvol (p < 0,05) tussen die drie groepe verskil nie. Daar is tot die gevolgtrekking gekom dat die genoemde vrygossipolinnames geen spermdefekte veroorsaak het nie en dat die vry gossipol waarskynlik in die rumen ontgiftig is.

Keywords: Gossypol; infertility; bulls