Fixed-time artificial insemination (FTAI) is a reproductive technology that aids in obtaining an appropriate time to perform single artificial insemination (AI), thus reducing the number of inseminations per sow bred. FTAI protocols can either be based on estrus detection or day of weaning, aiming to synchronize ovulation using ovulation inducers. The protocols involving estrus detection usually employ porcine luteinizing hormone (pLH) as an inducer and, in general, satisfactory reproductive performance is observed. For protocols based on weaning day, the main hormone used is analog of gonadotropin-releasing hormone such as triptorelin and buserelin. Regardless of the protocol, the number of piglets born is usually not affected by FTAI. However, a possible compromise in the farrowing rate should be considered. The FTAI in gilts requires progestogen treatment for estrus synchronization, increasing the labor requirement and cost of protocol. Some of the benefits of FTAI are a reduced number of semen doses required, advantage of planning the breeding time and; consequently, optimizing labor involved. However, the limitations include a slight reduction in the fertility index due to the compromised farrowing rate in some cases, costs incurred by following the protocol, and difficulty in measuring all the conceptual benefits under commercial conditions. The aim of this review is to approach the reproductive performance of the current protocols of FTAI, considering the benefits and limitations of this technology in swine production.
Artificial insemination is widely used in horse breeding for increased breeding success and the use of the full capacity of genetic resources (Aurich, 2012). To facilitate national and international exchange, it is necessary to store sperm in a quality-preserving manner for the duration of transport. For long-term storage, stallion semen is often cryopreserved. This method is, however, associated with greater losses in quality (Gibb & Aitken, 2016). To counteract these losses, liquid preservation at 5°C (Ijaz & Ducharme, 1995) or 15-20°C (Cuervo-Arango et al., 2015) is often used, especially for shorter storage periods (Wiebke et al., 2021), which can lead to increase in bacterial contamination. It has been shown, that bacterial contamination of ejaculates leads to a deterioration of sperm quality and impairs sperm motility, viability and fertility (Neto et al., 2015).Furthermore, the transfer of pathogens into the female reproductive tract can cause pathologies such as endometritis, disrupted fertil-
Cryopreservation of boar semen is of growing interest for breeding companies worldwide. Cryopreserved semen can be stored for many years, shipped over long distances and set into quarantine before insemination. The latter is particularly essential in times of epizootic diseases. The extender most commonly used for cryopreservation is based on egg yolk (EY). EY provides protection against cold shock to spermatozoa during the freezing process due to the low-density lipoprotein (Bergeron & Manjunath, 2006), but it also covers the risk of entering microbial contaminants (Thibier and Guerin, 2000). With the use of pasteurized egg yolk (PEY), not only that risk can be minimized, but also the time-consuming preparation of the eggs would be omitted. The aim of the present study was to investigate the in vitro effect of PEY on frozenthawed boar semen.
| MATERIAL S AND ME THODS
| Experimental Design and Semen ProcessingAll procedures involving animals were carried out in accordance with guidelines and regulations according to the European Commission Directive for Pig Welfare and were approved by the animal welfare committee of the Institute for Reproduction of Farm Animals Schönow (IFN-2021-V-08). Single ejaculates of 13 boars of different breeds (White Large, Landrace, PREMO ® ), aged from 9 months up to 2.5 years, from a single boar stud in Switzerland were included in the study (Table 1). All boars were routinely used for production and housed individually in straw-bedded pens. The sperm-rich fraction of the ejaculates was collected using the double gloved-hand method.Volume, sperm concentration, motility and morphology of the ejaculates were determined immediately after collection, followed by a
Over the years, reproductive efficiency in the swine industry has focused on reducing the sperm cell number required per sow. Recent advances have included the identification of subfertile boars, new studies in extended semen quality control, new catheters and cannulas for intrauterine artificial insemination (AI), and fixed‐time AI under commercial use. Therefore, it is essential to link field demands with scientific studies. In this review, we intend to discuss the current status of porcine AI, pointing out challenges and opportunities to improve reproductive efficiency.
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