Effect of vibration emissions during shipping of artificial insemination doses on boar semen quality

Vibration Emissions Reduce Boar Sperm Quality via Disrupting Its Metabolism

Artificial insemination (AI) with liquid-preserved semen has recently become common in pig breeding. The semen doses are produced in a centralized manner at the boar stud and then subsequently distributed and transported to sow farms. However, vibration emissions during transportation by logistic vehicles may adversely affect the quality of boar sperm. Therefore, this study aimed to explore the impact of vibration-induced emissions on sperm quality and function under simulated transportation conditions. Each time, ejaculates from all 15 boars were collected and then pooled together to minimize individual variations, and the sample was split using an extender for dilution. Different rotational speeds (0 rpm, 80 rpm, 140 rpm, 200 rpm) were utilized to simulate varying intensities of vibration exposure using an orbital shaker, considering different transportation times (0 h, 3 h, and 6 h). Subsequently, evaluations were conducted regarding sperm motility, plasma membrane integrity, acrosome integrity, mitochondrial function, adenosine triphosphate (ATP) levels, mitochondrial reactive oxygen species (ROS) levels, pH, glycolytic pathway enzyme activities, and capacitation following exposure to vibration emissions. Both vibration time and intensity impact sperm motility, plasma membrane integrity, and acrosomal integrity. Vibration exposure significantly reduced sperm ATP levels, mitochondrial membrane potential, and the levels of mitochondria-encoded proteins (MT-ND1, MT-ND6) (p < 0.05). After vibration emission treatment, the pH value and mitochondrial ROS levels significantly increased (p < 0.05). Inhibition of sperm glycolysis was observed, with reduced activities of hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH), along with decreased lactate levels (p < 0.05). Additionally, sperm tyrosine phosphorylation levels were significantly reduced by vibration emissions compared to the control group (p < 0.05). After the vibration emission treatment, the number of sperm bound to each square millimeter of oviduct explants decreased significantly compared to the control group (p < 0.05). Similarly, compared to the control group, using semen subjected to vibration stress for AI results in significantly reduced pregnancy rates, total born litter size, live-born litter size, and healthy born litter size (p < 0.05).

Artificial insemination and optimization of the use of seminal doses in swine

The optimization of processes associated with artificial insemination (AI) is of great importance for the success of the pig industry. Over the last two decades, great reproductive performance has been achieved, making further significant progress limited. Optimizing the AI program, however, is essential to the pig industry's sustainability. Thus, the aim is not only to reduce the number of sperm cells used per estrous sow but also to improve some practical management in sow farms and boar studs to transform the high reproductive performance to a more efficient program. As productivity is mainly influenced by the number of inseminated sows, guaranteeing a constant breeding group and with healthy animals is paramount. In the AI studs, all management must ensure conditions to the health of the boars. Some strategies have been proposed and discussed to achieve these targets. A constant flow of high-quality and well-managed breeding groups, quality control of semen doses produced, more reliable technology in the laboratory routine, removal of less fertile boars, the use of intrauterine AI, the use of a single AI with control of estrus and ovulation (fixed-time AI), estrus detection based on artificial intelligence technologies, and optimization regarding the use of semen doses from high genetic-indexed boars are some strategies in which improvement is sought. In addition to these new approaches, we must revisit the processes used in boar studs, semen delivery network, and sow farm management for a more efficient AI program. This review discusses the challenges and opportunities in adopting some technologies to achieve satisfactory reproductive performance and efficiency.

Boar semen cryopreservation: State of the art, and international trade vision

Biosecurity is a major concern in the global pig production. The separation in time of semen collection, processing and insemination in the pig farm is a few days for chilled semen but it can be indefinite when using cryopreserved semen. Field fertility results of boar cryopreserved semen are close to chilled semen, which makes it a valuable resource for the establishment of semen genebanks, long-distance semen trade, and the implementation of other technologies such as the sex-sorted semen. But cryopreserved semen is far from being routine in pig farms. The most recent research efforts to facilitate its implementation include the use of additives before freezing, or in the thawing extender. Long-term preserved semen trade is a biosecurity challenge. To harmonize international trade of germplasm, the World Organization of Animal Health (WOAH) established a regulatory framework for all member countries. The present paper aims to review the latest advances of boar semen cryopreservation with special focus on the benefits of its inclusion as a routine tool in the pig industry. We also review recently reported field fertility results of cryopreserved semen, its international trade compared to chilled semen, and the regulatory framework involved. Boar cryopreserved semen is a valuable tool to control biosecurity risk, implement other technologies, and facilitate international trade. Research already demonstrated good field fertility results, but it still represents less than 0.1 % of the international trade. As boar cryopreserved semen gets closer to implementation, the correspondent authorities are reviewing the trade rules.

Vibration emissions affect the quality of liquid-preserved AI doses in stallions

Artificial insemination (AI) with liquid-preserved stallion semen is a widely used reproductive technology. As the demand for AI doses of high-class stallions is transnational, they are frequently exposed to long-distance transport. Since recent studies in boars indicated that vibration emissions caused by transport negatively affected sperm quality in vitro, this study questioned whether sperm quality in stallions is similarly impaired. Furthermore, we investigated stallion and extender-related differences in the spermatozoa's resistance to transport-related quality loss. Stallion ejaculates (n = 30) were collected at a German AI center, split in half, and subsequently diluted to a final sperm concentration of 50 × 106 sperm/mL using the semen extenders EquiPlus or Gent (both Minitüb GmbH, Germany). Four 12 mL aliquots of each sample were filled in plastic syringes according to a split-sample design and exposed to vibration (Displacement index Di = 3.0 ± 0.1) at 5 °C for 0 h (control), 3 h, 6 h or 9 h. All samples were stored for four days at 5 °C after transport simulation and analyzed for total sperm motility, thermo-resistance, membrane integrity, and mitochondrial activity determined by flow cytometry as well as the pH. After calculating generalized linear mixed models for each sperm quality trait, a negative impact of the duration of transport simulation could be shown on total sperm motility (P = 0.001), thermo-resistance (P = 0.030), and the pH (P = 0.001). Simulated transport for 6 h and 9 h diminished sperm quality (P ≤ 0.01), with 9 h reducing thermo-resistance by 5 ± 2.2% points (PP) for EquiPlus and sperm motility by 2.2 ± 1.7 PP for Gent compared to the control group. In contrast, samples exposed to vibration for 3 h showed no decline in sperm quality (P > 0.05). The individual stallion influenced every semen trait (P < 0.05) and transport-related losses in sperm thermo-resistance of up to 15.9 PP were demonstrated. Furthermore, EquiPlus was superior to Gent in all semen assessments (P < 0.001). We conclude that in vitro sperm quality is impaired by vibration. As the quality loss depends on the transport time, we recommend keeping shipping time as short as possible especially for spermatozoa of stallions that are susceptible to vibration-induced sperm quality loss.

Effects of vibrations during boar semen transport: Low-temperature transport as a new management tool

Transport-related vibrations (TV) compromise the quality of conventionally stored (17 °C) boar semen, but knowledge about TV effects after 5 °C transport is insufficient. This study evaluates the effects of TV after novel 5 °C transport compared to a 17 °C control. Ejaculates of 18 fertile Piétrain boars, diluted in a split sample procedure using Androstar Premium® (AP, 5 °C storage) or Beltsville Thawing Solution (BTS, 17 °C storage), were subjected to transport simulation using a laboratory shaker IKA MTS 4. The timing was set according to the respective processing protocols: for 17 °C BTS samples, TV simulation was performed the day of collection, 5 °C AP samples were subjected to TV the day after collection following completion of the established cooling curve to 5 °C. Six samples per ejaculate were exposed to different TV durations (0 h, 3 h, or 6 h) to evaluate the effect on sperm quality (progressive motility (PM), thermo-resistance test (30 and 300 min incubation at 38 °C (TRT30/TRT300)), mitochondrial activity (MITO), plasma membrane and acrosome integrity (PMAI)). Generalized linear mixed models revealed TV (P = 0.021) and storage time (P < 0.001) dependent declines in PM. Direct, pairwise comparisons revealed that 5 °C samples are not affected by TV (P(3 h vs. 6 h transport) = 1.0; P(0 h vs. 6 h transport) = 1.0). They therefore showed superior quality maintenance after TV compared to 17 °C samples (P(3 h vs. 6 h transport) = 0.025; P(0 h vs. 6 h transport) < 0.001). Concluding, low-temperature transport is possible without significant semen quality loss and with better quality maintenance than standard transport.

Preservation of Simmental bull sperm at 0°C in Tris dilution: effect of dilution ratio and long-distance transport

OBJECTIVE

This study aimed to assess the impact of the dilution ratio of Tris diluent, storage at 0°C, and long-distance transportation on the spermatozoa of Simmental cattle. It also validated the feasibility of the regional distribution of fresh semen.

METHODS

In experiment 1, semen was diluted at four dilution ratios (1:6, 1:9, 1:12, and 1:15) to determine the optimal dilution ratio of Tris diluent. In experiment 2, we assessed sperm viability, progressive motility (objectively assessed by computer-assisted sperm analyzer), and acrosome intactness in Tris dilutions kept at constant 0°C for 1, 3, 6, 9, and 12 days. We compared them to Tianshan livestock dilutions (Commercial diluent). In experiment 3, semen was diluted using Tris diluent, and sperm quality was measured before and after long-distance transport. Artificial insemination of 177 Simmental heifers compared to 156 using Tianshan Livestock dilution.

RESULTS

The outcomes demonstrated that 1:9 was the ideal Tris diluent dilution ratio. The sperm viability, Progressive Motility, and acrosome integrity of both Tris and Tianshan dilutions preserved at 0°C gradually decreased over time. sperm viability was above 50% for both dilutions on d 9, with a flat rate of decline. The decrease in acrosome integrity rate was faster for Tianshan livestock dilutions than for Tris dilutions when stored at 0°C for 1 to 6 days. There was no significant difference (p>0.05) in sperm viability between semen preserved in Tris diluent after long-distance transportation and semen preserved in resting condition. The conception rates for Tris dilution and Tianshan livestock dilution were 49.15% and 46.15% respectively, with no significant difference (p>0.05).

CONCLUSION

This shows that Tris diluent is a good long-term protectant. It has been observed that fresh semen can be successfully preserved for long-distance transport when stored under 0°C conditions. Additionally, it is feasible to distribute semen regionally.

Proteomic analysis of boar sperm with differential ability of liquid preservation at 17 °C

Understanding the liquid preservation ability of boar sperm is pivotal for efficient management and breeding of livestock. Although sperm proteins play an important role in semen quality and freezability, how the levels of protein change in boar sperm with different liquid preservation abilities at 17 °C remains unclear. In this study, two groups of boar sperm with extreme difference in liquid preservation ability, namely the good preservation ability (GPA) and the poor preservation ability (PPA) groups, were selected by evaluating sperm motility parameters on the 7th day of liquid preservation at 17 °C. Quantitative proteomics based on tandem mass tag (TMT) labeling was used, sperm proteomic characteristics from two groups were analyzed, and potentially key proteins related to the fluid preservation ability of sperm were identified. A total of 187 differentially expressed proteins (DEPs) were identified among 2791 quantified proteins, including 85 upregulated, and 102 downregulated proteins. Further, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the DEPs revealed that they were enriched in GO terms associated with response to oxidative stress, enzyme activity related to oxidative stress or redox reactions, and several metabolic activities. The significant KEGG pathways included peroxisome, metabolic pathways, selenocompound metabolism, and collection duct acid secretion. In addition, analysis of protein-protein interactions further identified 8 proteins that could be used as biomarker candidates, including GPX5, GLRX, ENO4, QPCT, BBS7, OXSR1, DHRS4 and AP2S1, which may play an essential role in indicating the liquid preservation ability of boar sperm. These findings in this study provide new insights into the underlying molecular mechanisms of the liquid preservation ability of boar sperm. Moreover, the selected candidate proteins can serve as a reference for evaluating sperm quality or preservation ability in boars and their application in related biotechnologies.

Temperature Elevation during Semen Delivery Deteriorates Boar Sperm Quality by Promoting Apoptosis

Semen delivery practice is crucial to the efficiency of artificial insemination using high-quality boar sperm. The present study aimed to evaluate the effect of a common semen delivery method, a Styrofoam box, under elevated temperatures on boar sperm quality and functionality and to investigate the underlying molecular responses of sperm to the temperature rise. Three pooled semen samples from 10 Duroc boars (3 ejaculates per boar) were used in this study. Each pooled semen sample was divided into two aliquots. One aliquot was stored at a constant 17 °C as the control group. Another one was packaged in a well-sealed Styrofoam box and placed in an incubator at 37 °C for 24 h to simulate semen delivery on hot summer days and subsequently transferred to a refrigerator at 17 °C for 3 days. The semen temperature was continuously monitored. The semen temperature was 17 °C at 0 h of storage and reached 20 °C at 5 h, 30 °C at 14 h, and 37 °C at 24 h. For each time point, sperm quality and functionality, apoptotic changes, expression levels of phosphorylated AMPK, and heat shock proteins HSP70 and HSP90 were determined by CASA, flow cytometry, and Western blotting. The results showed that elevated temperature during delivery significantly deteriorated boar sperm quality and functionality after 14 h of delivery. Storage back to 17 °C did not recover sperm motility. An increased temperature during delivery apparently promoted the conversion of sperm early apoptosis to late apoptosis, showing a significant increase in the expression levels of Bax and Caspase 3. The levels of phosphorylated AMPK were greatly induced by the temperature rise to 20 °C during delivery but reduced thereafter. With the temperature elevation, expression levels of HSP70 and HSP90 were notably increased. Our results indicate that a temperature increase during semen delivery greatly damages sperm quality and functionality by promoting sperm apoptosis. HSP70 and HSP90 could participate in boar sperm resistance to temperature changes by being associated with AMPK activation and anti-apoptotic processes.

Science-based quality control in boar semen production

The ever-increasing understanding of sperm physiology, combined with innovative technical advances, continuously furthers the development of boar semen production management. These improvements pave the way for the future implementation of modified quality assurance concepts. This review provides an overview of current trends and new approaches in boar semen production, focusing on: the improvement of hygienic standards, alternatives to the use of antibiotics including the application of cold temperature storage and the utilization of antimicrobial additives, as well as the implementation of new quality control tools. Furthermore, the influence of dilution and temperature management, as well as new possibilities for an improvement of boar semen shipping and storage conditions are reviewed.

Update on artificial insemination: Semen, techniques, and sow fertility

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.

Intensity and Duration of Vibration Emissions during Shipping as Interacting Factors on the Quality of Boar Semen Extended in Beltsville Thawing Solution

Vibration emissions during the transport of boar semen for artificial insemination (AI) affect sperm quality. In the present study, the common influence of the following factors was investigated: vibrations (displacement index (D_i) = 0.5 to 6.0), duration of transport (0 to 12 h) and storage time (days 1 to 4). Normospermic ejaculates were collected from 39 fertile Pietrain boars (aged 18.6 ± 4.5 months) and diluted in a one-step procedure with an isothermic (32 °C) BTS (Minitüb) extender (n = 546 samples). Sperm concentration was adjusted to 22 × 10⁶ sperm·mL^-1. Extended semen (85 ± 1 mL) was filled into 95 mL QuickTip Flexitubes (Minitüb). For transport simulation on day 0, a laboratory shaker IKA MTS 4 was used. Total sperm motility (TSM) was evaluated on days 1 to 4. Thermo-resistance test (TRT), mitochondrial activity (MITO) and plasma membrane integrity (PMI) were assessed on day 4. Sperm quality dropped with increasing vibration intensity and transport duration, and the effect was enhanced by a longer storage time. A linear regression was performed using a mixed model, accounting for the boar as a random effect. The interaction between D_i and transport duration significantly (p < 0.001) explained data for TSM (-0.30 ± 0.03%), TRT (-0.39 ± 0.06%), MITO (-0.45 ± 0.06%) and PMI (-0.43 ± 0.05%). Additionally, TSM decreased by 0.66 ± 0.08% with each day of storage (p < 0.001). It can be concluded that boar semen extended in BTS should be transported carefully. If this is not possible or the semen doses are transported a long way, the storage time should be reduced to a minimum.

Cooled storage of semen from livestock animals (part I): boar, bull, and stallion

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques for cooled storage of semen from livestock animals. The first part describes the current state of the art of liquid semen preservation in boars, bulls, and stallions, including the diluents, use of additives, processing, temperature, and cooling of semen. The species-specific physiology and varying extents of cold shock sensitivity are taken into consideration. In addition, factors influencing the quality of cooled-stored semen are discussed. Methods, trends, and the most recent advances for improving sperm quality during cold-temperature storage are highlighted and their respective advantages and disadvantages are contrasted. There has been much progress in recent years regarding cold-temperature storage of boar sperm and there is great potential for a large-scale use to replace the current 17 °C temperature storage regime and the associated use of antibiotics in the future. For stallion sperm, there is an opposite trend away from previous low-temperature storage towards storage at higher temperatures to increase sperm viability and longevity. In bulls, liquid storage of sperm is mostly used in the seasonal dairy production systems of New Zealand and Ireland, but with further research focusing on shelf-live elongation of liquid preserved sperm, there is potential for an application in breeding programs worldwide.

Boar Semen Shipping for Artificial Insemination: Current Status and Analysis of Transport Conditions with a Major Focus on Vibration Emissions

In the modern pig reproduction system, artificial insemination (AI) doses are delivered from AI centers to sow farms via logistics vehicles. In this study, six breeding companies in three countries (Brazil, Germany, and the USA) were interviewed about their delivery process. It was found that there is currently no comprehensive monitoring system for the delivery of semen. The entire process “shipping of boar semen” was documented using Business Process Model and Notation (BPMN). Although it is not currently known which vibrations occur at all, it is suspected that vibration emissions affect the quality of boar semen. For this reason, a prototype of a measuring system was developed to calculate a displacement index (Di), representing vibration intensities. Vibrations were analyzed in standardized road trials (n = 120) on several road types (A: smooth asphalt pavement, B: rough asphalt pavement, C: cobblestone, and D: dirt road) with different speeds (30, 60, 90, 120, and 150 km/h). A two-way ANOVA showed significant differences in mean Di, depending on road surface and speed as well as an interaction of both factors (p < 0.001). A field study on a reference delivery from a German AI center to several sow farms indicated that 33% of the observed roads are in good quality and generate only a few vibrations (Di ≤ 1), while 40% are of a moderate quality with interrupted surfaces (Di = 1−1.5). However, 25% of the roads show markedly increased vibrations (Di ≥ 1.5), as a consequence of bad conditions on cobblestones or unpaved roads. Overall, more attention should be paid to factors affecting sperm quality during transport. In the future, an Internet of Things (IoT) based solution could enable complete monitoring of the entire transport process in real time, which could influence the courier’s driving behavior based on road conditions in order to maintain the quality of the transported AI doses.

Relevance of the Ejaculate Fraction and Dilution Method on Boar Sperm Quality during Processing and Conservation of Seminal Doses

During boar semen processing and distribution, maximizing the work protocols in the laboratories becomes essential for the conservation of seminal doses. One of the recent implementations in the boar studs to improve efficiency has been semi-automatic semen collection systems, which do not allow to discard fractions of the ejaculate. The objective of this work was to evaluate the dilution method and vibrations (simulating delivery transport) effect on sperm quality (motility, viability, morphology, thermo-resistance test) according to the fraction of ejaculate collected. Two different fractions of the ejaculate were obtained [rich fraction (RF); total fractions (TF)] from six boars, and two dilution methods applied [pouring the extender over the semen (control; ES); pouring the semen over the extender (reverse; SE)]. The seminal doses (2000 × 10⁶ sperm/50 mL) were preserved for 5 days. The results showed that the fraction collected affects sperm quality (better total and progressive motility, and faster sperm in TF; p < 0.05) regardless of the dilution method applied. However, these differences diminished after submitting the semen to the thermo-resistance test, with only differences in sperm viability being observed (p < 0.05). When seminal doses were subjected to vibrations, the sperm viability was more affected in the TF than in the RF group (p < 0.05). In conclusion, using the TF ejaculate leads to comparable results to the RF in sperm quality during storage regardless of the dilution method applied. However, the vibrations of seminal doses are more affected in doses prepared with TF than with RF, although more factors should be included to approach the real conditions during transport.

Factors influencing the response of spermatozoa to agitation stress: Implications for transport of extended boar semen

The shipping of liquid preserved semen is common practice in animal breeding and prior to cryopreservation for gene banking. Vibration emissions during transport may be harmful to spermatozoa. Therefore, strategies to minimize agitation-induced sperm injury are needed. The aim was to examine whether the type of semen extender, time after semen processing and the temperature in simulated transport conditions influence the response of boar spermatozoa to agitation stress. In Experiment 1, boar semen samples (n = 16) extended in Beltsville Thawing Solution (BTS) or Androstar Plus (APL) medium were filled in 90 mL tubes and shaken for 4 h at 200 rpm either at 22 °C or 17 °C. Samples were then stored at 17 °C for 144 h. In Experiment 2, semen samples (n = 11) extended in Androstar Premium were shaken either directly after filling at 22 °C or 20 h later after cooling to 5 °C. Samples were stored at 5 °C for 144 h. In Experiment 1, sperm motility and viability were lower (p < 0.05) in the shaken samples compared to the controls. The temperature, extender and the storage length had no effect on the agitation-induced loss of sperm quality. Sperm quality traits were higher in samples stored in APL compared to BTS. In Experiment 2, sperm motility at 24 h was reduced (p < 0.05) in those samples shaken at 22 °C but not at 5 °C. Sperm viability, membrane fluidity and mitochondrial membrane potential were not affected in either of the treatment groups. Extended boar semen designed for 17 °C storage and shipped on the day of collection is sensitive to agitation stress. In contrast, spermatozoa slowly cooled to 5 °C and shaken 20 h after processing are more resistant to agitation-induced shear forces and interfacial phenomena.

Effect of sperm concentration on boar spermatozoa mitochondrial membrane potential and motility in semen stored at 17 °C

The aim of the study was to assess the effect of sperm concentration in the ejaculate on the mitochondrial membrane potential and motility of Landrace boar spermatozoa during storage of diluted semen at 17 °C. The study was conducted on ejaculates collected from 10 boars aged 1.5–2 years. Based on sperm concentration measurements, two groups of boars were identified: Group 1 – boars providing ejaculates with a sperm concentration of at least 500 × 103/mm3 and Group 2 – boars providing ejaculates with a sperm concentration of less than 500 × 103/mm3. Four ejaculates were collected manually from each boar. Each ejaculate was diluted with Biosolvens Plus diluent, and insemination doses were prepared and stored at 17 °C. Mitochondrial membrane potential and motility of spermatozoa were evaluated at each insemination dose. The tests were carried out after 1, 24, 48, 96 and 168 h of storage. Based on the results, it was found that ejaculates with a sperm concentration ≥ 500 × 103/mm3 have a lower share of spermatozoa with high mitochondrial membrane potential than ejaculates with a sperm concentration below 500 × 103/mm3. A high correlation between the share of spermatozoa with a high mitochondrial membrane potential and motility of spermatozoa was demonstrated in the first 24 h and after 96 h of semen storage, which was confirmed by the calculated phenotypic correlation coefficients. Sperm cells in ejaculates with a higher sperm concentration are more sensitive to storage time than spermatozoa in ejaculates with a lower concentration.

Low temperature preservation of porcine semen: influence of short antimicrobial lipopeptides on sperm quality and bacterial load

Antimicrobial resistance is a steadily increasing problem and poses a serious threat to global public health. Therefore, it is highly necessary to advance the development of novel antimicrobial compounds and semen preservation strategies. The aim of this study was to evaluate a low temperature, antibiotic-free preservation procedure using Androstar Premium (ASP) extender (Minitüb) with antimicrobial lipopeptides. Firstly, seven lipopeptides in two concentrations (1 × minimum inhibitory concentration (MIC)/2 × MIC) were tested on their sperm-compatibility at 17 °C. Two lipopeptides, C16-KKK-NH₂ and C16-KKKK-NH₂, did not negatively affect sperm quality and were further evaluated for their efficiency of bacterial growth inhibition at 5 °C. Besides an overall diminution of colony forming units, both peptides showed a reduction of bacterial subcultures (n = 103) with a decrement in Gram-positive rods from 65 (ASP w/o supplements) to 39/52 (ASP w/ C16-KKK-NH₂/C16-KKKK-NH₂), in Gram-positive cocci from 21 to 9/10 and in Gram-negative species from 17 to 8/5 total subcultures. Furthermore, lipopeptides revealed activity towards selected bacteria of potential concern in artificial insemination like Trueperella pyogenes, Alcaligenes faecalis, Pseudomonas aeruginosa (not C16-KKK-NH₂), Pasteurella sp., Providencia stuartii, Escherichia coli (not C16-KKKK-NH₂) and Streptococcus porcinus (not C16-KKKK-NH₂). Consequently, both tested lipopeptides are promising candidates for alternative antibiotic-free preservation techniques of boar semen.

Effects of sulfanilamide on boar sperm quality, bacterial composition, and fertility during liquid storage at 17°C

Sulfanilamide (SA) is an effective broad-spectrum antibacterial agent in human and veterinary medicine. The purpose of this study was to evaluate the effects of SA on boar sperm quality during liquid storage at 17°C and determine the optimal concentration of SA and its effects on bacterial growth, microbial composition, and maternal fertility. Boar ejaculates were diluted with a basic extender, containing different concentrations of SA, and stored in a 17°C incubator for 6 days. The sperm motility, plasma membrane integrity, and acrosome integrity were measured daily. The results showed that when the concentration of SA was 0.02 g/L, the sperm quality parameters were significantly higher than those of all other treatment groups (p < .05). We also monitored the bacterial growth and compared the differences in the microbial species between the 0.02 g/L SA group and the control by 16S rDNA sequencing. The results revealed that some bacteria, such as Staphylococcus and Pseudomonas, were considerably lower in the 0.02 g/L SA group than in the control group (p < .05). In addition, preserved semen was used for artificial insemination, and results showed that 0.02 g/L SA group had a higher litter size, and its pregnancy rate was 92.5%.

New trends in production management in European pig AI centers

Reducing the number of spermatozoa per artificial insemination (AI) dose and managing semen in ways to ensure greater quality at the same time represents current challenges with sperm processing in pig AI centers. Based on a multi-year comparative analysis of process steps in different pig AI centers, and complementary experimental studies under standardized laboratory conditions, current process standards for the preservation of boar semen have been updated and new ones developed. Currently, these standards represent an integral part of the quality assurance of 29 European pig AI centers in ten different organizations in Germany, Switzerland and Austria. Improvement of hygiene management and guidelines for prudent use of antibiotics have become key issues. Furthermore, new quality control tools have been implemented in the processing and transport of boar semen: e.g. refractometry as an easy-to-use tool to estimate extender osmolarity and 'mobile sensing' apps for continuous monitoring of various environmental parameters. Moreover, based on a series of experiments under laboratory and field conditions, guidelines for optimizing the dilution process, and time and temperature management during boar semen processing, have been developed and implemented. Similarly, recommendations for the handling of semen doses during storage have been renewed. Over the years, the efficiency of the quality assurance system has been reflected by a decrease of bacterial contamination and a concomitant increase in the quality of semen doses. In conclusion, science-based quality assurance is an effective way to improve the production performance in pig AI centers, resulting in high quality and economically-priced semen for pig producers. Increasing knowledge of sperm physiology together with computational and technical innovations will continue to develop and modify quality assurance concepts in the future.