An Exploration of Current and Perspective Semen Analysis and Sperm Selection for Livestock Artificial Insemination

Artificial insemination of livestock has been a staple technology for producers worldwide for over sixty years. This reproductive technology has allowed for the rapid improvement of livestock genetics, most notably in dairy cattle and pigs. This field has experienced continuous improvements over the last six decades. Though much work has been carried out to improve the efficiency of AI, there are still many areas which continue to experience improvement, including semen analysis procedures, sperm selection techniques, sperm sexing technologies, and semen storage methods. Additionally, the use of AI continues to grow in beef cattle, horses, and small ruminants as the technology continues to become more efficient and yield higher pregnancy rates. In this review, AI trends in the various livestock species as well as cutting edge improvements in the aforementioned areas will be discussed at length. Future work will continue to refine the protocols which are used for AI and continue to increase pregnancy rates within all livestock species.

Integrity of Sperm Cell Membrane in the Semen of Crossbred and Purebred Boars during Storage at 17 °C: Heterosis Effects

The aim of the study was to assess changes in the integrity of sperm cell membranes during the storage of semen collected from Duroc × Pietrain crossbred boars and purebred boars of the component breeds. To compare the cell membrane integrity of sperm heads in crossbred and purebred boars, heterosis effects were estimated. The study was conducted on 48 ejaculates collected from Duroc × Pietrain crossbred boars and from purebred Duroc and Pietrain boars used for artificial insemination. Microscope slides were prepared from each ejaculate for the evaluation of the cell membrane integrity of the sperm, at 1, 24, 48, 72, and 96 h after collection of the ejaculate. Diluted ejaculates were stored at 17 °C. Sperm membrane integrity was analysed by two methods: SYBR-14/PI and eosin–nigrosin. Our results showed that the cell membrane integrity of sperm heads changed with storage time, but the extent of the changes varied depending on the genetic group of boars. The semen of Duroc × Pietrain crossbreds was clearly seen to be less sensitive to storage conditions than that of boars of the parent breeds, which was confirmed by the calculated heterosis effects. The percentage of sperm with an intact cell membrane was higher in crossbred boars than in purebred boars (p ≤ 0.05). In addition, significantly fewer moribund sperm spermatozoa and spermatozoa with a damaged cell membrane were observed in crossbred boars (p ≤ 0.05). In the semen of purebred Duroc and Pietrain boars, the cell membrane integrity of the sperm should be assessed more often during storage than in the semen of Duroc × Pietrain crossbred boars. This study provides valuable information for the development and implementation of semen quality monitoring in crossbred boars and boars of the parent breeds during storage at 17 °C with respect to the cell membrane structure of sperm heads. The evaluation methods used effectively identify damage to the cell membranes of the sperm during semen storage.

Factors Affecting Fresh Semen Quality in Pasundan Cattle at UPTD BPPIBTSP Ciamis

Background: Pasundan cattle are local cattle native to Indonesia. One way to conserve beef cattle genetics is to use Artificial Insemination technology. The success of Artificial Insemination can be influenced by the quality of semen. Purpose: To determine factors affecting fresh semen quality in Pasundan cattle at UPTD BPPIBTSP Ciamis. Methods: The data were obtained through observations on seven Pasundan bulls in March 2021 towards fresh semen quality and some factors influencing it. The Pasundan bulls observed were seven productive males. Results: The fresh semen quality of Pasundan cattle, such as volume, color, and pH, showed good result,s but the average consistency and concentration of spermatozoa were still below the standard. The factors that can affect the fresh semen quality are the breed of beef cattle, age, body weight, feed, season, exercise, and frequency of semen storage. Conclusion: The determining factors that can cause the consistency and concentration of Pasundan cattle’s spermatozoa at UPTD BPPIBTSP Ciamis are feed and season.

A High Incidence of Sperm with Cytoplasmic Droplets Affects the Response to Bicarbonate in Preserved Boar Semen

Retained cytoplasmic droplets (CD) are the most frequent sperm abnormality in boar semen. A high incidence of CD is associated with subfertility, but the underlaying reasons are not well understood. The storage of extended semen might augment the adverse effects of CD on essential steps towards fertilization, such as capacitation. The aim of this study was to examine whether the enhanced presence of CD in boar semen influences sperm’s response to the capacitation stimulus bicarbonate during long-term semen storage. Extended semen samples (n = 78) from 13 artificial insemination centers were analyzed using a flow cytometric calcium influx assay. Samples with >15% of CD showed a reduced specific response to bicarbonate and a higher non-specific destabilization after storage for 96 h and subsequent incubation at 38 °C in three variants of Tyrode`s medium (p < 0.05). The size of the bicarbonate-responsive sperm population was inversely correlated with the presence of CD-bearing sperm (r = −0.61, p < 0.01). Samples with ≤15% and samples with >15% of CD did not differ in motility or viability and acrosome integrity during semen storage. In conclusion, incomplete epididymal sperm maturation impairs the in vitro capacitation ability and promotes sperm destabilization in stored boar semen.

Role of Antioxidants in Cooled Liquid Storage of Mammal Spermatozoa

Cooled preservation of semen is usually associated with artificial insemination and genetic improvement programs in livestock species. Several studies have reported an increase in reactive oxidative species and a decrease in antioxidant substances and sperm quality parameters during long-term semen storage at refrigerated temperatures. The supplementation of antioxidants in extenders before refrigeration could reduce this detrimental effect. Various antioxidants have been tested, both enzymatic, such as superoxide dismutase and catalase, and non-enzymatic, such as reduced glutathione, vitamins E and C and melatonin. However, the problem of oxidative stress in semen storage has not been fully resolved. The effects of antioxidants for semen-cooled storage have not been reviewed in depth. Therefore, the objective of the present study was to review the efficiency of the supplementation of antioxidants in the extender during cooled storage of semen in livestock species

Plant Extracts as Alternative Additives for Sperm Preservation

Sperm preservation is a crucial factor for the success of assisted reproductive technology (ART) in humans, livestock, and wildlife. Irrespective of the extender and the storage conditions used, semen handling and preservation negatively affect sperm quality. Moreover, oxidative stress, which often arises during semen storage, significantly reduces sperm function and compromises the sperm fertilizing ability by inducing oxidative damage to proteins, lipids, and nucleic acids. Plant extracts have recently emerged as a cheap and natural source of additives to preserve and enhance sperm function during semen storage. The present work provides an update on the use of these natural compounds as alternative additives for sperm preservation in 13 animal species, including humans. A detailed description of the effects of 45 plant species, belonging to 28 families, on sperm function during semen storage is presented. The plant material and extraction method employed, dosage, possible toxic effects, and antimicrobial properties are provided.

PSV-8 Effects of Air Exposure and Agitation on Quality of Stored Boar Semen Samples

Recent adoption of post cervical artificial insemination facilitates lowered concentrations of semen inseminated. In order to achieve this reduced concentration, the volume of the insemination dose has been reduced and replaced with additional air in the semen storage container. The objective of this study was to investigate the effects of semen volume, air contact inside semen dose tubes, daily agitation of semen doses and extender type on semen quality, thermo-resistance and bacterial growth in extended boar semen doses over 7 days of liquid storage at 17 C. Ejaculates from 4 terminal cross-bred boars were collected for 4 weeks and used in the 3 x 2 x 2 factorial study. The effects of treatment (CON: 80ml doses sealed at the top of the tube; 40HIGH: 40ml doses sealed at top of tube; and 40LOW: 40ml doses sealed at top of the liquid), extender type (long-term vs short-term), and agitation (agitated vs not agitated) were investigated. The result of the study revealed that motility (P=0.014) and viability (P=0.007) in 40HIGH were lower than CON. pH (P&lt; 0.001) was higher in 40HIGH compared to CON. Agitation did not impact motility (P=0.541), viability (P=0.406) or morphology (P=0.970) while long-term extender maintained higher motility (P=0.034), viability (P&lt; 0.001) and normal acrosomes (P&lt; 0.001) compared to short-term extender. VAP (P=0.039) of 40HIGH was lower than CON in a thermo-resistance test. Bacteria were cultured on both sheep’s blood and MacConkey agar and neither treatment (P=0.798; 0.766) nor agitation (P=0.396; 0.476) impacted bacterial growth in this study. In conclusion, semen doses prepared with 80mL or 40mL of total volume with minimal air contact in the tubes yield more desirable semen quality, as air contact negatively impacts boar semen pH and sperm motility. Additionally, regardless of volume or air exposure, daily agitation of boar semen doses did not affect semen quality.

Characteristics and Cryopreservation of Semen of Sex-Reversed Females of Salmonid Fish

Sex reversal has been used as a breeding strategy by salmonid fish to produce genetically and phenotypically single sex populations. Production of all-female fish has great importance for the creation of monosex female triploids of salmonid fish, which are valued for their sterility, lack of female maturation, and larger commercial size. Among salmonids, the majority of rainbow trout (Oncorhynchus mykiss) production is based on all-female production with a high proportion of all-female triploid production in Europe. The main aim of this review is to present the recent knowledge regarding sex-reversed females (SRFs) of salmonid fish. We discuss the methods of sex reversal as well as their effects on the morphology and histology of the reproductive tract. We focus on the characteristics of SRF semen as well as the factors determining semen quality. The lower quality of SRF sperm compared to that of normal males has resulted in the need for the artificial maturation of semen. Most importantly, methods of semen storage—both short-term and long-term (cryopreservation)—that can improve hatchery operations are presented with the special emphasis on recent progress in development of efficient cryopreservation procedures and use of cryopreserved semen in hatchery practice. Moreover, we also address the emerging knowledge concerning the proteomic investigations of salmonid sperm, focusing primarily on the proteomic comparison of normal male and SRF testicular semen and presenting changes in SRF rainbow trout sperm proteome after in vitro incubation in artificial seminal plasma.