The role of mycotoxins in pig reproduction : a review

Mycotoxins are commonly present in feed for farm animals. Sows and gilts are highly susceptible to mycotoxins. This article presents a review describing the main mycotoxins encountered in pig feed which have a negative impact on sow fertility and reproduction. Consumption of feed that is contaminated with these mycotoxins may cause a variety of symptoms, depending on the type of mycotoxin, quantity and duration of exposure, as well as the health status and condition of the animal at the time of exposure. Two types of fungi are recognized, field fungi and storage fungi. Field fungi such as Fusarium spp., Aspergillus spp. and Claviceps spp. may produce toxins that lead to disturbed reproductive performance. Storage fungi occur if the humidity during storage is too high. In daily practice, the symptoms related to mycotoxicosis can occur at toxin concentrations below the detection limit. Knowledge of the effects of mycotoxins is expanding rapidly. Mycotoxins may still be present in feedstuffs despite negative analytical findings and because of the presence of hot spots in feed and or feedstuffs. Clinical symptoms can be very pronounced, making the diagnosis for the practitioner quite easy but in many cases the symptoms are vague and not at all present at herd level on a regular basis. The practitioner is in the first line of raising awareness in all parties whenever the first indication exists of a possible mycotoxicosis problem causing reproductive failure in breeding pigs. The problems can be resolved only if all parties involved in pig herd health take the necessary preventive measures and actions. The main toxins causing reproductive failure discussed in this article are aflatoxins, ergot alkaloids, trichothecenes and zearalenone

Influence of sperm-oocyte coincubation period on porcine in vitro fertilization (IVF) efficiency

A major obstacle for successful in vitro production of porcine embryos is the polyspermic fertilization. One possibility to reduce polyspermic penetration is decreasing the number of spermatozoa added to the fertilization medium. Unfortunately, the lower rate of polyspermy is accompanied by a reduced penetration rate. A short gamete coincubation period of 10 min has been described to obtain fertilization rates similar to 6 h of coincubation and may improve IVF efficiency (number of monospermic fertilized oocytes/total number inseminated) depending on sperm-oocyte ratio (Gil, 2007, Theriogenology, 67(3), 620–626). Here we demonstrate that the optimal coincubation period in our IVF conditions is between 10 min and 6 h. In vitro matured oocytes (n = 600) were inseminated with frozen-thawed epididymal semen with 600 spermatozoa per oocyte and coincubated for 2, 4 and 6 h. At 2 and 4 h post insemination (hpi), oocytes were vortexed and transferred to fertilization medium without spermatozoa. At 6 hpi, presumed zygotes of all groups were washed three times in culture medium and cultured. At 22 hpi, zygotes were fixed overnight and stained with Hoechst 33,342 for the assessment of fertilization and polyspermy. The IVF efficiency was higher for the 4 h group (40 ± 5%) than the 2 and 6 h group (19 ± 8% and 17 ± 5%). Between 4 and 6 h of gamete coincubation, the increase in the number of polyspermic oocytes was relatively higher than the increase in penetration rate (+39% vs. +15%), resulting in a decline in efficiency. (This study was supported by Research Foundation-Flanders)

Porcine oocyte maturation in vitro : role of cAMP and oocyte-secreted factors: a practical approach

Polyspermy or the penetration of more than one sperm cell remains a problem during porcine in vitro fertilization (IVF). After in vitro culture of porcine zygotes, only a low percentage of blastocysts develop and their quality is inferior to that of in vivo derived blastocysts. It is unknown whether the cytoplasmic maturation of the oocyte is sufficiently sustained in current in vitro maturation (IVM) procedures. The complex interplay between oocyte and cumulus cells during IVM is a key factor in this process. By focusing on this bidirectional communication, it is possible to control the coordination of cumulus expansion, and nuclear and cytoplasmic maturation during IVM to some extent. Therefore, this review focuses on the regulatory mechanisms between oocytes and cumulus cells to further the development of new in vitro embryo production (IVP) procedures, resulting in less polyspermy and improved oocyte developmental potential. Specifically, we focused on the involvement of cAMP in maturation regulation and function of oocyte-secreted factors (OSFs) in the bidirectional regulatory loop between oocyte and cumulus cells. Our studies suggest that maintaining high cAMP levels in the oocyte during the first half of IVM sustained improved oocyte maturation, resulting in an enhanced response after IVF and cumulus matrix disassembly. Recent research indicated that the addition of OSFs during IVM enhanced the developmental competence of small follicle-derived oocytes, which was stimulated by epidermal growth factor (EGF) via developing EGF-receptor signaling

Clinical resistance and decreased susceptibility in Streptococcus suis isolates from clinically healthy fattening pigs

Streptococcus suis (S. suis) has often been reported as an important swine pathogen and is considered as a new emerging zoonotic agent. Consequently, it is important to be informed on its susceptibility to antimicrobial agents. In the current study, the Minimum Inhibitory Concentration (MIC) population distribution of nine antimicrobial agents has been determined for nasal S. suis strains, isolated from healthy pigs at the end of the fattening period from 50 closed or semiclosed pig herds. The aim of the study was to report resistance based on both clinical breakpoints (clinical resistance percentage) and epidemiological cutoff values (non-wild-type percentage). Non-wild-type percentages were high for tetracycline (98%), lincomycin (92%), tilmicosin (72%), erythromycin (70%), tylosin (66%), and low for florfenicol (0%) and enrofloxacin (0.3%). Clinical resistance percentages were high for tetracycline (95%), erythromycin (66%), tylosin (66%), and low for florfenicol (0.3%) and enrofloxacin (0.3%). For tiamulin, for which no clinical breakpoint is available, 57% of the isolates did not belong to the wild-type population. Clinical resistance and non-wild-type percentages differed substantially for penicillin. Only 1% of the tested S. suis strains was considered as clinically resistant, whereas 47% of the strains showed acquired resistance when epidemiological cutoff values were used. In conclusion, MIC values for penicillin are gradually increasing, compared to previous reports, although pigs infected with strains showing higher MICs may still respond to treatment with penicillin. The high rate of acquired resistance against tiamulin has not been reported before. Results from this study clearly demonstrate that the use of different interpretive criteria contributes to the extent of differences in reported antimicrobial resistance results. The early detection of small changes in the MIC population distribution of isolates, while clinical failure may not yet be observed, provides the opportunity to implement appropriate risk management steps