Background: Selenium (Se) is important for the postnatal development of the calf. In the first weeks of life, milk is the only source of Se for the calf and insufficient level of Se in the milk may lead to Se deficiency. Maternal Se supplementation is used to prevent this.
A considerable proportion of male factor infertility cases are associated with inflammatory processes. The most common sexually transmissible agents causing sexually transmitted diseases in industrial countries are Chlamydia trachomatis, genital Ureaplasma and Mycoplasma spp. This study was undertaken to investigate whether these bacterial contaminants in semen affect sperm quality parameters and particularly DNA integrity (detected by sperm chromatin structure assay) in males from infertile couples (n = 293). The results showed that semen contaminations with the investigated bacterial species were not associated with sperm DNA fragmentation. However, contaminations with Mycoplasma spp. and C. trachomatis were associated with decreased sperm concentrations. Total sperm numbers in contaminated semen samples tended to be decreased, but not significantly. Mycoplasma had the highest adverse effect on sperm quality (concentration, motility, morphology and DNA condensation). Antibiotic therapy of the selected 47 men was successful in 55%, but semen quality parameters did not improve at least up to 3 months after the therapy. The presence of pathogenic bacteria in semen is primarily associated with low sperm production. Our data showed that Mycoplasma spp. contamination of semen had the highest adverse effect on sperm quality. Sperm chromatin integrity assessed by the presence of DNA breaks was not disturbed.
Sperm chromatin status in fresh dog semen and the effect of long-term storage of chilled and frozen dog semen on sperm chromatin integrity was assessed by the sperm chromatin structure assay (SCSA). In the first experiment, the chromatin integrity of fresh semen from 60 dogs with different historiy of fertility was compared with other sperm parameters (total sperm count, sperm motility, viability, acrosomal integrity and sperm morphology). Except for 15 dogs that had never mated before, all were used in breeding as semen donors. Thirty-three of them were successful breeding males while in 12 repeated fertility problems were noted. Ejaculates were assigned to groups with good and poor quality, based on determined sperm motility and percentage of morphologically normal sperm. In the second experiment, chromatin status was measured in fresh and chilled spermatozoa (on day 0, 2, 4, 6, 8 and 10 of storage). Finally, in the third experiment, the chromatin status was measured in fresh and cryopreserved spermatozoa. Evaluating fresh dog semen, we observed that DNA fragmentation index (DFI) and percentage of cells with high DNA stainability (HDS) negatively correlated with total sperm count, percentage of total and progressively motile spermatozoa, sperm viability and percentage of morphologically normal spermatozoa, even with rather low correlation indices. Lower chromatin integrity was found in the group of dog ejaculates showing poor quality in comparison with the group of good quality ejaculates. All dogs with repeated fertility problems were classed in the group showing poor quality, and even though their DFI was significantly higher than the DFI of successful breeding males, the highest DFI we obtained was only just below 9%. We can assume that the chromatin damage level in any of the evaluated dogs was not high enough to have a significant effect on their fertility. Concerning the potential cause of reduced male fertility, the assessment of chromatin integrity in fresh dog ejaculates failed to add any additional information to the results obtained by other techniques of semen analysis. Thus, the current study indicates that neither 10-day preservation of canine sperm chilled in commercial extenders nor long-term cryopreservation in extenders recommended for canine sperm preservation produce adverse effects on sperm chromatin integrity.
AbstrAct:The aim of this study was to evaluate the effect of sex determination procedures in Day 7 to Day 8 bovine embryos of various quality. For the purposes of comparison we used high quality (HQ) as well as lower quality (LQ) embryos obtained from superovulated donors. The healthy embryonic cells isolated from HQ embryos and blastomeres protruding into the perivitelline space of LQ embryos, were analysed by polymerase chain reactions (PCR) using primers specific for the Y chromosome determinant. After microsurgical intervention and completion of sex determination, the female embryos were then transferred (ET) to synchronized recipients. A total of 310 embryos of HQ were used and gender was safely determined in 275 cases (88.7%). PCR analysis of extruded cells isolated from 170 LQ embryos was carried out with certainty only in 111 embryos (65.3%, P < 0.01). After ET of 122 HQ sex defined embryos, pregnancy was established in 69 recipients (56.6%). A similar conception rate 51.9% (27/52) was found after the ET of sex defined embryos designated as LQ. The accuracy of analysis was confirmed after calving and revealed that designated female sex coincided with 95.5% and 96.2% of calves when HQ and LQ embryos were transferred, respectively. Our results clearly show that a microsurgical technique in combination with PCR method represents a rapid and reliable approach for sex determination in HQ as well as in LQ preimplantation bovine embryos and can be used in field conditions for the regulation of the sex of progeny in selected herds.
The aim of this study was to evaluate the efficiency of sex determination after microsurgical splitting of D<sub>7</sub> (Day 7) bovine embryos and to test the conception rate after subsequent transfer of female demi-embryos. High-quality morulae (<I>n</I> = 100) and early blastocysts (<I>n</I> = 123) obtained from superovulated donors were microsurgically bisected and blastomeres biopsied from one half of bisected embryos were analysed by PCR using specific primers for the Y-chromosome determinant. The female demi-embryos were transferred (ET) in pairs (bilateral) or individually (ipsilateral) to synchronized recipients. Sex determination was successfully completed in 92% of morulae (42.4% female) and 89.4% of early blastocysts (43.6% female). Conception rates were 56.5% (30.4% identical twins) and 48.8% (19.5% identical twins) after bilateral (<I>n</I> = 46) and ipsilateral (<I>n</I> = 82) transfers, respectively. The number of foetuses in relation to the number of original embryos before splitting was 40/46 (87%) and 40/41 (97.6%) after bilateral and ipsilateral transfers of demi-embryos, respectively. The results document that the microsurgical bisection in combination with PCR sex analysis represents a rapid and reliable approach to increase an amount of sex-desired calves in embryo transfer programs.
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