Browsing by Author "Alm-Packalén, Karoliina"

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  • Alm-Packalén, Karoliina (Helsingin yliopisto, 2009)
    The economic importance of a high breeding efficiency in sows and dairy cows emphasizes the benefit of accurate prediction of fertility of boar and bull semen. The artificial insemination (AI) studs need an objective and rapid, but inexpensive, method to evaluate ejaculates. We developed a new quick and easy fluorescence method for frozen-thawed bull semen that uses an automatized fluorometer and the fluorophore stain propidium iodide that stains only cells with damaged membranes. The fluorescence of the semen sample and the totally killed subsample were measured simultaneously and viability was calculated. For fertility evaluation, the non-return rates (NR%) obtained from 92,120 inseminations with the analyzed batches were recorded. The correlation between the total number of viable spermatozoa in the insemination dose and field fertility was low but significant, suggesting that plasma membrane integrity evaluation can serve as a cost-effective quality control method for frozen-thawed semen at bull AI stations. In the second study we describe a sudden, though long-lasting, drop in bull semen quality at an AI station. During five consecutive months, the number of rejected ejaculates and discarded frozen semen batches due to poor motility increased, and the number of all forms of abnormal spermatozoa increased. However, for the accepted ejaculates, a 60-day NR% was normal. The previous summer had been rainy, and the hay used in the AI station was visibly moldy. Immunoassay and gas chromatography-mass spectrometry detected Fusarium mycotoxins HT-2 and T-2, but no zearalenone in the hay. Occurrence of mycotoxins such as T-2 and HT-2 in the moldy hay coincided with, and may have been responsible for, the impaired semen quality in AI-bulls. In the third study we describe the deteriorating effects of Bovine Respiratory Syncytial Virus (BRSV) epizootics on sperm quality in young AI bulls. The disease caused by BRSV is often mild in animals older than 6 months and is therefore neglected. However, it seems to be able to cause testicular fibrosis and disturbances in sperm morphology, thus requiring attention at AI stations with valuable breeding animals. In the remaining two studies we concentrated on boars and studied the effect of altering insemination dose, sperm morphology and insemination technique (traditional vs. intrauterine insemination). The insemination dose for boars should exceed 3 x 109 spermatozoa under commercial circumstances to avoid decrease in prolificacy at farms. Morphological examination of spermatozoa requires some experience, but it is quite an easy and inexpensive method to screen-out overtly poor-quality ejaculates. Therefore, we suggest routine morphological examination of all young boars entering the AI station and regularly thereafter. The intrauterine insemination was easy and fast to perform in sows, but it did not result in marked increase in NR% or litter size when inseminating with 3 x 109 spermatozoa / dose. This thesis focuses on different aspects affecting male reproduction. In the research projects we studied the deleterious effects of trichothecenes in feed and BRSV infection on sperm quality, developed a new method for sperm viability determination as well as studied the importance of semen quality and insemination dose for reproductive success.