Abstract
Sperm morphology and the fertilizing capacity of ejaculated spermatozoa were examined in 6 Swedish Landrace boars before and after heat stress. The boars were exposed to 35° C during 100 h in a climatic room. Fertility was measured by insemination of gilts before and at various times after heat stress. Each gilt (n = 44) was inseminated with a total of 5×109 spermatozoa diluted to 10O ml with EDTA-glucose diluent and fertilization was assessed by examining recovered ova 2 days after insemination.
Changes in semen quality varied among the boars from a very weak response in 2 boars to pronounced semen alterations occurring 2–6 weeks after heat stress in the other boars. A close relationship was found between seminal changes and fertilization rates, all ejaculates which had high fertilization rates being of the same quality as the pre-exposure ejaculates. The ejaculates that had poor fertility were characterized by lowered sperm motility and increased numbers of spermatozoa with abnormal heads, proximal cytoplasmic droplets and nuclear pouch formations.
Keywords: glutathione peroxidase, Se-status, pregnant sows and gilts, weakborn piglets
Sammanfattning
Morfologi och befruktningsförmåga hos ejakulerade spermier undersöktes hos 6 stycken Svenska Lantrasgaltar, före och efter värmestress. Galtarna vistades i en klimatkammare där de exponerades för 35°C i 100 tim. Fertiliteten bedömdes genom att gyltor (n = 44) inseminerades med sperma som samlades före, och vid olika tidpunkter efter värmestressen.
Till varje insemination användes 5×109 spermier utspädda till 100 ml med EDTA-glukos lösning. Gyltorna slaktades 2 dygn efter insemination och befruktningsförmågan bedömdes genom att antal befruktade respektive obefruktade ägg räknades.
Förändringarna i spermiekvaliten varierade hos galtarna, från ringa förändringar hos 2 av galtarna till uttalade spermiemorfologiska förändringar som varade i 2–6 veckor efter värmestressen hos de övriga 4 galtarna. Ett nära samband påvisades mellan de spermiemorfologiska förändringarna och befruktningsförmägan, vilket innebar att ejakulat som gav en hög befruktningsfrekvens också uppvisade en spermiekvalite som ej avvek från de ejakulat som samlats före värmestressen. Ejakulat med lag befruktningsförmåga karakteriserades av sänkt spermiemotilitet och ökat antal spermier med patologiska huvudformer, proximala droppar och kärnsäckar.
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