Semen processing and artificial insemination in health management of small ruminants

Impact of oestrus synchronization devices on ewes vaginal microbiota and artificial insemination outcome

Introduction

The low pregnancy rate by artificial insemination in sheep represents a fundamental challenge for breeding programs. In this species, oestrus synchronization is carried out by manipulating hormonal regimens through the insertion of progestogen intravaginal devices. This reproductive strategy may alter the vaginal microbiota affecting the artificial insemination outcome.

Methods

In this study, we analyzed the vaginal microbiome of 94 vaginal swabs collected from 47 ewes with alternative treatments applied to the progesterone-releasing intravaginal devices (probiotic, maltodextrin, antibiotic and control), in two sample periods (before placing and after removing the devices). To our knowledge, this is the first study using nanopore-based metagenome sequencing for vaginal microbiome characterization in livestock.

Results

Our results revealed a significant lower abundance of the genera Oenococcus (Firmicutes) and Neisseria (Proteobacteria) in pregnant compared to non-pregnant ewes. We also detected a significant lower abundance of Campylobacter in the group of samples treated with the probiotic.

Discussion

Although the use of probiotics represents a promising practice to improve insemination results, the election of the suitable species and concentration requires further investigation. In addition, the use of progestogen in the synchronization devices seemed to increase the alpha-diversity and decrease the abundance of harmful microorganisms belonging to Gammaproteobacteria and Fusobacteriia classes, suggesting a beneficial effect of their use.

Evaluation of lipidomic change in goat sperm after cryopreservation

The current study aimed to detect the relationship between the spermatozoa cryotolerance and the post-thawed sperm lipidome. Ejaculates from 20 goats, and performed a uniform frozen-thawed procedure in this study. According to the total motility of thawed sperm of goats, semen samples were classified into HF group (High Freezers, n = 8) with >60% total motility and LF group (Low Freezers, n = 8) with < 45% total motility. The lipidomic analysis based on UHPLC-MS/MS was utilized to investigate the relationship between sperm cryotolerance and their lipid metabolites expression. The results showed that the cryotolerance of sperm from different individual goats were in great variation. The total motility of post-thawed sperm in HF group (60.93 ± 2.43%) is significantly higher than that in LF group (34.04 ± 3.41%, P < 0.01). And the post-thawed sperm in HF group exhibited significantly higher plasma membrane (59.06 ± 2.34%) and acrosome integrity (62.93 ± 1.15%) than that in LF group (34.06 ± 4.85%, 44.92 ± 2.19% respectively, P < 0.01). The total of 29 lipid subclasses and 1,133 lipid molecules in the post-thawed goat sperm were identified by lipidomics analysis. The lipid content of thawed sperm in HF group was higher than that in LF group, the lipid profile in HF group was significantly separated from LF group, which indicated that the difference in lipid composition and lipid metabolism mode of sperm between the two groups was existed, especially the expression of phosphatidylcholine and triglyceride molecules. In conclusion, the cryotolerance of sperm from different individual goats were in great variation. Sperm with high cryotolerance may be able to uptake more lipids during cryopreservation. The increase in phosphatidylcholine and triglyceride content of thawed. Sperm may relate to more active lipid anabolic processes.

Effect of the donor´s age and type of extender (egg yolk versus clarified egg yolk) over the sperm quality of Majorera bucks preserved at 4 ºC: in vitro results and fertility trials

This study assessed the effect of donor´s age and two different extenders in the sperm quality of chilled semen in Majorera bucks. In experiment 1, semen was individually processed from 5 young (10–12 months old) and 4 mature (3–5 years old) bucks and then was diluted in two different extenders: EY (Tris‐glucose, 12% egg yolk) and CEY (Tris‐glucose, 12% clarified egg yolk) and cooled at 4°C; semen quality (sperm motility, percentages of alive spermatozoa, acrosome status and abnormal spermatozoa) was evaluated at 24, 48, 72 and 96 hr after cooling. In experiment II, 72 Majorera goats were assigned to four experimental groups: for groups 24‐EY (n = 18) and 24‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 24 hr, respectively, while for groups 72‐EY (n = 18) and 72‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 72 hr, respectively. In vitro results confirmed that only ejaculate volume and sperm concentration were significantly different between young and mature bucks. In addition, semen quality was similar between both diluents, presenting values for the first 48 hr similar to that recorded in fresh samples. The fertility rate was around 70% after 24 hr (4°C) in both groups, but the kidding rate was significantly lower (44.4%, p < .05) in goats inseminated with EY diluent preserved for 72 hr. Our results showed that the semen samples may be stored at 4°C in media with egg yolk or clarified egg yolk, and, therefore, the use of clarified egg yolk may represent a valid alternative to chill semen samples. Finally, young bucks (older than 10–12 months) of Majorera breed could be successfully used in breeding programmes with similar efficacy to older males.

Perspectives for Buck Kids in Dairy Goat Farming

To start milk production, dairy goats need to give birth at least once. While most female kids are reared to become the next generation of dairy goats, only a small proportion of male kids (buck kids) are reared with reproduction aims. The market for buck kid meat, especially within Northern European countries, is currently relatively small compared to the number of bucks born. Therefore, the purposes for buck kids are limited and a substantial proportion of buck kid meat is used for pet food. Due to the limited economic value of buck kids, farmers are faced with a dilemma. Although raising bucks costs more money than it yields, the birth of kids is a prerequisite for production of milk and should be seen as an investment for business-wise healthy dairy goat farming. In that perspective, dairy goat farmers have an ethical responsibility toward buck kids, as well. In this paper, we compare various scenarios of dealing with the issue of surplus male animals. We provide recommendations for the rearing of buck kids based on the sector‘s experience and current practice in the Netherlands. Reducing the number of surplus (male) offspring, e.g., by an optimized prolonged lactation management and/or by artificial insemination with sex-sorted semen, could alleviate the issue of low value buck kids. Killing surplus animals before or directly after birth, on the other hand, is met with increasing societal scrutiny. Initiatives to propagate a market for buck kid meat for human consumption are important to enable a suitable and sustainable production system. To maintain the health and welfare of goat kids, amongst other factors, sufficient and good quality colostrum, milk, and an appropriate diet as they grow older, needs to be provided. One option to assure the safeguarding of health and welfare of all goat kids are quality assurance schemes for milk production. These schemes make dairy farmers accountable for the health and welfare of all kids in the rearing period, including the provision of colostrum and adequate care for newborn buck kids. We conclude that the combination of reducing the number of surplus kids, increasing the demand for goat products, and quality assurance schemes that may help to safeguard the welfare of buck kids.

Cooled storage of semen from livestock animals (Part II): Camelids, goats, and sheep

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques in cooled storage of semen from livestock animals such as camelids, goats, and sheep. Facing worldwide environmental changes and a trend towards more conscious and healthy eating behaviors, the development of a stable animal breeding industry is a significant challenge for the near future. In the present review, factors influencing semen handling in camelids, goats and sheep are described and relevant methods as well as current trends to improve liquid-storage of cooled semen are discussed, including extenders, additives, cooling rates, and storage temperatures. The species-specific physiology and resulting challenges are taken into consideration. While the main problem for camelid semen processing is the relatively greater viscosity as compared with that of some other animals, the deciding factor for successful artificial insemination (AI) in goats and sheep is the site (i.e., cervical or vaginal) of semen placement in the reproductive tract. Due to the type of cervical anatomy, the penetration of the cervix when using AI instruments is rather difficult. Furthermore, the seminal plasma of small ruminants affects the interaction with milk-based extenders and egg yolk which results in species-specific regimens for cooled liquid-preservation. Comparing all three species, the greatest pregnancy rates were obtained by AI with goat semen after cooled liquid-storage for several days.

Carboxymethyl cellulose and glycerol act synergistically as cryoprotectant during cryopreservation of ram semen

Wider implementation of AI in sheep in the field condition has not been possible till date due to very poor conception rate after cervical insemination with cryopreserved semen. Poor cervical penetrability in ewe and diminished sperm functions in cryopreserved semen are considered responsible for it. In the present study, effect of carboxymethyl cellulose (CMC) on post-thaw qualities of ram semen was investigated. Ejaculates from eight adult Malpura rams were pooled and diluted (800 × 10⁶ sperm mL^-1) with TES-Tris-fructose-egg yolk extender having either 5 or 6% glycerol and supplemented with 0, 0.25, 0.5, 0.75 and 1.0% (w/v) CMC and packaged into 0.25 mL French mini straws. The straws were progressively cooled to 5 °C inside a cold cabinet (5 °C) and then equilibrated for 22 h inside a refrigerator (2-5 °C). Straws were frozen at -25 °C min^-1 up to -125 °C using a programmable cell freezer (Planer Biomed R-204, UK) and finally plunged into liquid nitrogen. The post-thaw progressive motility was higher (P < 0.05) in 0.75% CMC-treated group compared to control. Overall, both pre-freeze and post-thaw sperm kinetics was comparable between CMC-treated and control groups. The post-thaw sperm viability, acrosomal integrity and sperm with high mitochondrial membrane potential (hMMP) were relatively higher while sperm with high membrane cholesterol was significantly (P < 0.05) higher in presence of 0.25% CMC compared to the control. Both sperm having hMMP and non-capacitated sperm were significantly (P < 0.05) higher in presence of 5% glycerol than 6% glycerol. Similarly, functional membrane integrity (FMI) was higher in presence of 5% glycerol than 6% glycerol when CMC was added at 0.5% to extender. In conclusion, both 0.25% CMC and 5% glycerol resulted in improvement in several post-thaw sperm functions in cryopreserved ram semen. Thus CMC demonstrated cryoprotective effect on ram sperm in a synergistic manner with glycerol.

Trehalose modifies the protein profile of ram spermatozoa during cryopreservation

As a magical oligosaccharide, trehalose has been revealed to enhance the post-thaw quality of stock semen. However, information regarding the cryoprotective mechanism of trehalose during cryopreservation has not yet been determined. This study was designed to observe the effects of trehalose on the proteome of ram frozen spermatozoa by applying the isobaric tag for relative and absolute quantification (iTRAQ) strategy combined with parallel reaction monitoring (PRM). A total of 1269 proteins were identified. Among them, there were 21 differentially expressed proteins (DEPs), with 9 up-regulated proteins and 11 down-regulated proteins in spermatozoa frozen with trehalose. These DEPs were primarily located in nucleus, cytoplasm, and extracellular region. The Gene Ontology (GO) enrichment analysis demonstrated the involvement of the DEPs in signal transduction, ion binding, oxidoreductase activity, response to stress, and catabolic processes. Based on the STRING analysis, tight functional correlations were observed between 6-phosphogluconate dehydrogenase, fructose-bisphosphate aldolase A isoform 1, 14-3-3 protein epsilon, tyrosine-protein kinase Fer, and beta-hexosaminidase subunit alpha precursor. Furthermore, 10 DEPs were verified using PRM, confirming the accuracy of the iTRAQ data acquired in this study. In conclusion, trehalose can modify the protein profile of ram spermatozoa during cryopreservation, which may be associated with its cryoprotective effects. Additionally, trehalose may function on frozen spermatozoa through antioxidation, involvement in glycolysis, and increment of spermatozoa tolerance to various stresses.

Combination of fetuin and trehalose in presence of low glycerol has beneficial effects on freeze-thawed ram spermatozoa

BACKGROUND

Freeze-thawing process negatively affects ram spermatozoa in terms of sperm quality, DNA integrity and antioxidant defence system. Thus, antioxidant supplementation of spermatozoa during freeze-thawing is suggested to improve sperm parameters.

OBJECTIVES

The aim of this study was to determine the effects of fetuin and trehalose added into ram semen extender on sperm parameters, antioxidant parameters, antioxidant-related gene expressions and DNA integrity during the freeze-thawing process, in low glycerol concentration.

METHODS

Semen samples collected from six mature rams were pooled and splitted into equal aliquots and diluted with a tris-based extender containing different concentrations of glycerol (G5; %5 and G3; %3), fetuin (F; 2.5, 5 and 15 mg/mL) and trehalose (60 mm) as eight groups (G5F0, G5F2.5, G5F5, G5F15, G3F0, G3F2.5, G3F5 and G3F15).

RESULTS

G3F5 group resulted in the highest motility, mitochondrial activity and viability and the lowest DNA fragmentation and DNA damage (p < 0.05). Also, G3F0 displayed considerably more cryoprotective effect compared with G5F0 group (p < 0.05) in terms of motility, mitochondrial activity and viability rates. Lipid peroxidation levels decreased in G5F5 group compared with G5F0 group (p < 0.05). The levels of total glutathione increased in G3F2.5 group (p < 0.05) in comparison with the G5F0 group. NQO1 gene levels were upregulated approximately twofold in G5F5, G5F15, G3F2.5, G3F5 and G3F15 groups compared with G5F0 group (p < 0.05). The levels of GCLC gene were approximately twofold higher in G3F0, G3F2.5, G3F5 and G3F15 groups compared with G5F0 group (p < 0.05). GSTP1 gene levels were significantly higher with different levels in all treatment groups except for G5F2.5 and G3F0 groups in comparison with G5F0 group (p < 0.05).

CONCLUSIONS

Co-supplementation of tris-based extender having low glycerol (3%) with trehalose and fetuin to enhance the quality of ram spermatozoa after freeze-thawing process is recommended.

Decreasing glycerol content by co-supplementation of trehalose and taxifolin hydrate in ram semen extender: Microscopic, oxidative stress, and gene expression analyses

This study aimed to evaluate the comparative effects of taxifolin hydrate and trehalose on the quality of frozen-thawed ram spermatozoa for the first time. Ejaculates collected from six mature rams were pooled, and divided to eight equal aliquots to extend them with different concentrations of glycerol (%5 and %3), taxifolin hydrate (10, 100, and 500 μM), and trehalose (60 mM) as eight groups (G5T0, G5T10, G5T100, G5T500, G3T0, G3T10, G3T100, and G3T500). After freeze-thawing process of cryopreservation, microscopic and oxidative stress parameters, and gene expression levels were investigated for understanding of possible impacts of taxifolin hydrate and trehalose. The study showed that G3T10 resulted in the highest post-thawed viability and mitochondrial activity. Moreover, all extenders with taxifolin hydrate reduced DNA fragmentation in comparison to G5T0, but DNA damage was prevented at the highest rate in presence of G5T10. The level of LPO significantly decreased in the groups G5T500 and G3T100, and the expression levels of NQO1, GCLC, and GSTP1 genes significantly increased in the groups G5T100, G5T500, G3T10, and G3T100 compared to the group G5T0. Finally, co-supplementation of tris-based extender having 3% glycerol with 60 mM trehalose and 10 μM taxifolin hydrate in cryopreservation extender may be recommended to improve the quality of post-thawed ram spermatozoa. However, further in vivo and in vitro studies are suggested to evaluate fertility rates of frozen-thawed ram spermatozoa co-supplemented with trehalose and taxifolin hydrate.

Treatment of rams with melatonin implants in the non-breeding season improves post-thaw sperm progressive motility and DNA integrity

In the Merino ram, it is unclear whether cryopreserved sperm function and fertility is compromised when collected during the non-breeding season, when Merino ewes are seasonally anestrus. It was therefore investigated whether treatment with melatonin could improve sperm function or fertility when semen was collected during the period Merino ewes were seasonally anestrus. There were 16 Merino rams treated or not treated with melatonin implants during the non-breeding season of ewes (September). Ejaculates were collected before melatonin treatment (Week 0), during the period of melatonin release (Week 7) and subsequent breeding season (Week 23). In vitro sperm function was assessed before freezing, and at 0- and 3 -hs post-thaw. Fertility was determined through intrauterine insemination of ewes (n = 966) with frozen-thawed samples, during the breeding season. Compared to Week 0 values, spermatozoa from melatonin-treated rams had greater progressive motility at Week 7 (P = 0.019) and less DNA fragmentation (P = 0.003) at Weeks 7 and 23, whilst spermatozoa from non-treated rams were unchanged during these time-periods. There were no other treatment effects on sperm function or fertility (P > 0.05). In ejaculates collected during Week 23, there were no effects of treatment either before freezing or post-thawing. Sperm from ejaculates collected at Week 23, however, had lesser pre-freezing/post-thawing total motility and resulted in lower pregnancy rates (P < 0.05). It is concluded there are no effects of season on sperm quality or fertility of Merino rams and that melatonin treatment subtly improves quality of spermatozoa following cryopreservation.

Pre-freezing equilibration for 22 h improves post-thaw sperm functions in cryopreserved ram semen by reducing cholesterol efflux

Failure of cervical insemination with cryopreserved semen is hindering implementation of AI in sheep in field condition. Here the effect of equilibration time and catalase on post-thaw qualities of ram semen was investigated. Pooled semen was diluted (800 × 10⁶ sperm mL^-1) with a TES-Tris-fructose extender with 6% glycerol, 15% egg yolk and supplemented with 0, 50, 100 and 200 U mL^-1 catalase and packaged into 0.25 mL straws. In experiment 1, straws were equilibrated at 5 °C either for 3 h in a cold cabinet (E3) or for 10 (E10) and 22 h (E22) inside a refrigerator. In experiment 2, all straws were equilibrated for 22 h inside refrigerator. Straws were frozen at -25 °C min^-1 up to -125 °C using a cell freezer and finally plunged into liquid nitrogen. The post-thaw total and rapid motility were higher (P < 0.05) in E22 compared to E3 and E10. Sperm kinetics was comparable between E3 and E22, but lower in E10. Similarly, acrosome integrity, functional membrane integrity, percent high cholesterol (mCHO) and live-high mitochondrial membrane potential (MMP) were higher (P < 0.05) while live-high intracellular calcium and acrosome-reacted sperm were lower in E22 compared to E3 and E10. The percent rapid motile, high mCHO and live-high MMP were significantly (P < 0.05) lower in catalase-treated samples compared to the control, while the membrane integrity was comparable within the groups. In conclusion, pre-freezing equilibration for 22 h compared to 3 or 10 h resulted in higher post-thaw sperm functions while catalase had negative impact on cryopreservation of ram semen.

Cervical artificial insemination in sheep: sperm volume and concentration using an antiretrograde flow device

There has been development of an antiretrograde flow device (DARIO), for sheep cervical artificial insemination (CAI). There, however, needs to be optimization of sperm volume and concentration of insemination doses when the DARIO is used for CAI. Objectives were to compare fertility rates (proportion of ewes lambing as a result of CAI) when there was use of the DARIO for CAI: two sperm volumes containing equal numbers of spermatozoa: 0.25 mL of 1,600 × 10⁶ spermatozoa/mL and 0.50 mL of 800 × 10⁶ spermatozoa/mL (Test 1 group), and two sperm volumes with a different number of spermatozoa/AI dose: 0.25 mL and 0.50 mL of 1,600 × 10⁶ spermatozoa/mL (Test 2 group). There were 335 ewes from seven farms assigned to 60 batches (equally divided into a Control and Test 1 group). For the Test 2 group, 462 ewes from nine farms were assigned to 88 batches (equally proportioned into Control group and Test 2 groups). For the Test 1 group, proportion of ewes lambing as a result of CAI were 0.701 ± 0.2679 and 0.595 ± 0.2393 for the Control and Test 1 groups, respectively (P = 0.163). For the Test 2 group, proportions of ewes lambing were 0.550 ± 0.2598 and 0.658 ± 0.2412 for the Control and Test 2 group, respectively (P = 0.041). An inclusion of a larger number of spermatozoa per insemination in a 0.50 mL dose volume resulted improved proportion of ewes lambing as a result of CAI when there was used of the DARIO.

Influence of the Ovine Genital Tract Microbiota on the Species Artificial Insemination Outcome. A Pilot Study in Commercial Sheep Farms

To date, there is a lack of research into the vaginal and sperm microbiome and its bearing on artificial insemination (AI) success in the ovine species. Using hypervariable regions V3-V4 of the 16S rRNA, we describe, for the first time, the combined effect of the ovine microbiome of both females (50 ewes belonging to five herds) and males (five AI rams from an AI center) on AI outcome. Differences in microbiota abundance between pregnant and non-pregnant ewes and between ewes carrying progesterone-releasing intravaginal devices (PRID) with or without antibiotic were tested at different taxonomic levels. The antibiotic treatment applied with the PRID only altered Streptobacillus genus abundance, which was significantly lower in ewes carrying PRID with antibiotic. Mageebacillus, Histophilus, Actinobacilllus and Sneathia genera were significantly less abundant in pregnant ewes. In addition, these genera were more abundant in two farms with higher AI failure. Species of these genera such as Actinobacillus seminis and Histophilus somni have been associated with reproductive disorders in the ovine species. These genera were not present in the sperm samples of AI rams, but were found in the foreskin samples of rams belonging to herd 2 (with high AI failure rate) indicating that their presence in ewes' vagina could be due to prior transmission by natural mating with rams reared in the herd.

Technical recommendations for artificial insemination in sheep

Artificial insemination (AI) was the first important biotechnology applied to improve the genetics of farm animals. It allows the rapid and massive diffusion of desirable characteristics of males with high productive potential. We describe the different types of estrus induction and synchronization techniques and the use of the AI with fresh, chilled or frozen semen. Through the adequacy of the protocols of estrus synchronization and AI to the different production systems, the efficient use of reproductive techniques is possible, reaching acceptable pregnancy rates. Summary of reproductive results obtained using cervical and laparoscopic AI are presented.

Status of beta defensin-1 in Indian goat breeds

The present study was carried out to know the status of Beta Defensin-1 in goat semen before and after cryopreservation with beta defensin-1 supplemented semen diluent and in blood of different breeds of goat (Barbari, Jamunapari and Jakhrana). Goat semen (N-10) from each breed was collected by artificial vagina method. Immediately after collection, the volume, colour, consistency, and mass motility of ejaculate were assessed and were extended with Tris-Egg yolk-Fructose diluent having 10% (v/v) egg yolk and glycerol 6% (v/v). Samples were divided for estimation of beta defensin–1 and rest parts were cryopreserved with semen diluent having beta defensin-1 @ 10 ng/mL. Blood samples (N-30) were also collected from the same animal after semen collection. The samples were stored at –20°C until assayed. Plasma membrane of sperm was broken by freeze thaw followed by ultracentrifugation (20,000 × g for 5 min) at room temperature before ELISA test. The samples were diluted with Phosphate buffer (1:2) before analysis. The samples were analyzed using goat specific beta defensin–1 commercial kit (EO6D0419) as per the manufacturer’s instruction. The result showed that with supplementation of beta defensin-1 in goat semen, diluent maintains the concentration of beta defensin-1 even after cryopreservation. There was significant decrease (P<0.05) in beta defensin-1 concentration in sample which had no supplement in semen diluent after cryopreservation. The supplementation of beta defensin-1 in goat semen diluent improved the post-thaw immune modulatory properties of semen.

Laparoscopic Artificial Insemination Technique in Small Ruminants-A Procedure Review

Laparoscopic artificial insemination (LAI) is an intrauterine method of insemination, especially utilized in the small ruminant species to bypass their unique anatomically tortuous cervix. There are several advantages of LAI that include efficient use of processed semen leading to higher pregnancy rates. Success of LAI programs depends on proper implementation of estrus synchronization programs, patient selection and thorough knowledge of the reproductive physiology. In addition, proper equipment and surgical expertise help in reducing patient morbidity and mortality rates. LAI can be associated with several complications as a result of inadequate patient preparation, poor technique or equipment failure. Hence, a thorough planning is essential to carry out the procedure safely and with consistent success rates. Addition of LAI to a small ruminant/food animal practice can be quite profitable and professionally fulfilling, as long as an appropriate investment in equipment and adequate training of veterinarians and technical staff is implemented. Though the technique for performing LAI has been mentioned briefly through various research articles, this article serves as the first comprehensive review of the technique, equipment used, associated complications and useful practical tips that could serve as a guideline for clinicians interested in adding this service to their practice. The article also contains some novel research supported ideas to provide laparoscopic insufflation that have been recently developed.

Sperm kinematics and subpopulational responses during the cryopreservation process in caprine ejaculates

Sperm cryopreservation in goats has been a challenge for many years due to the detrimental effects of seminal plasma enzymes produced by the bulbo-urethral glands which catalyse the hydrolysis of lecithins in egg yolk to fatty acids and lysolecithins which are deleterious to spermatozoa. This fact implies to carry out additional processing steps during sperm cryopreservation for seminal plasma removal triggering different sperm responses which may affect sperm functionality. The objective of the present study was to determine specific sperm subpopulation responses in different handling steps during the cryopreservation process by using functional sperm kinematic descriptors in caprine ejaculates. Buck ejaculates (n = 40) were analysed for sperm concentration, viability, morphology and acrosome integrity. Moreover, sperm motility was assessed using a computer-assisted sperm analysis (CASA) system after five different handling steps (fresh sperm, 1st washing, 2nd washing, cooling and frozen-thawed sperm) during a standard cryopreservation protocol for goat semen. The results were analysed using Principal Component Analysis (PCA) and multivariate clustering procedures to establish the relationship between the distribution of the subpopulations found and the functional sperm motility in each step. Except for the 1st and 4th steps, four sperm kinematic subpopulations were observed explaining more than 75% of the variance. Based on velocity and linearity parameters and the subpopulations disclosed, the kinematic response varies among processing steps modifying sperm movement trajectories in a subpopulation-specific and handling step-dependent manner (p < 0.001). The predominant motile subpopulation in freshly ejaculated buck sperm had very fast velocity characteristics and a non-linear trajectory (41.1%). Washing buck sperm twice altered the subpopulation structure as well as cooling which resulted in a dramatic reduction in sperm velocities (p < 0.01). Frozen-thawed spermatozoa showed similar characteristics to cooled sperm except there was a further increase in linearity with a large proportion of sperm attributed to new slow, linear cluster (32.5%). In conclusion, this study confirms the variability and heterogeneity of goat sperm kinematic patterns throughout the cryopreservation process and suggests that the predominant motility pattern (assayed in vitro via CASA) of high quality spermatozoa might be typified by high speed and a non-linear trajectory. The relationships among the number and distribution of sperm subpopulations and the different handling steps were particularlly relevant, specially after the cooling and the post-thawing steps, when effects derived from these critical handling steps were evident and altered drastically the sperm motion patterns.

Risk factors associated with small ruminant lentivirus infection in eastern Poland sheep flocks

An analysis of the risk factors for ovine lentivirus infection was performed in sheep flocks located throughout the central-eastern region of Poland. Here, we report the infection details for 98 flocks with a total of 6470 ewes, 15 sheep breeds. The identification of infected animals and a review of the epidemiological status of each flock were based on an evaluation of serological tests performed on collected blood serum samples. Blood for examination was obtained from 2925 ewes of the 98 flocks under observation. Specific antibodies for Maedi Visna Virus (MVV) were detected via ELISA. Data illustrating the conditions at each sheep farm were obtained through questionnaires completed by farmers, as well as observations, measurements, and breeding records that were available. These observations were used to assess risk factors contributing to small ruminant lentivirus (SRLV) infection in sheep flocks. It was found that both sheep flock size and the type of management system had a significant effect on the increased risk of lentiviral infection. In addition, we demonstrate that there is a significant (p<0.0001) relationship between the occurrence of mastitis (OR 2.01, CI: 1.55-2.61) and diarrhea (OR 4.22, CI: 3.30-5.39) with SRLV infection in the observed sheep. Additionally, the infection rate of the animals translated directly to an impaired physical condition. Notably, the risk of infection could potentially be reduced if sheep producers are further acquainted with SRLV detection and invoke a control program based on diagnostic tests. Moreover, marketing approval should be granted for solely SRLV-seronegative animals.

Current and future assisted reproductive technologies for mammalian farm animals

Reproduction in domestic animals is under control by man and the technologies developed to facilitate that control have a major impact on the efficiency of food production. Reproduction is an energy-intensive process. In beef cattle, for example, over 50 % of the total feed consumption required to produce a unit of meat protein is consumed by the dam of the meat animal (Anim Prod 27:367-379, 1978). Sows are responsible for about 20 % of the total feed needed to produce animals for slaughter (Adv Pork Prod 19:223-237, 2008). Accordingly, energy input to produce food from animal sources is reduced by increasing number of offspring per unit time a breeding female is in the herd. Using beef cattle as an example again, life-cycle efficiency for production of weaned calves is positively related to early age at puberty and short calving intervals (J Anim Sci 57:852-866, 1983). Reproductive technologies also dictate the strategies that can be used to select animals genetically for traits that improve production. Of critical importance has been artificial insemination (AI) (Anim Reprod Sci 62:143-172, 2000; Stud Hist Philos Biol Biomed Sci 38:411-441, 2007; Reprod Domest Anim 43:379-385, 2008; J Dairy Sci 92:5814-5833, 2009) and, as will be outlined in this chapter, emerging technologies offer additional opportunities for improvements in genetic selection. Given the central role of reproduction as a determinant of production efficiency and in genetic selection, improvements in reproductive technologies will be crucial to meeting the challenges created by the anticipated increases in world population (from seven billion people in 2011 to an anticipated nine billion by 2050; World population prospects: the 2010 revision, highlights and advance tables. Working Paper No. ESA/P/WP.220, New York) and by difficulties in livestock production wrought by climate change (SAT eJournal 4:1-23, 2007).The purpose of this chapter will be to highlight current and emerging reproductive technologies that have the potential to improve efficiency of livestock production. The focus will be on technologies that manipulate male and female gametes as well as the stem cells from which they are derived and the preimplantation embryo. While technology is crucial to other interventions in the reproductive process like control of seasonal breeding, hormonal regulation of ovulation, estrous cyclicity and pregnancy establishment, feeding to optimize reproduction, minimizing environmental stress, and selection of genes controlling reproduction, these will not be considered here. Rather the reader is directed to other chapters in this volume as well as some reviews on other aspects of artificial manipulation of reproduction (Reprod Fertil Dev 24:258-266, 2011; Reprod Domest Anim 43:40-47, 2008; Reprod Domest Anim 43:122-128, 2008; Soc Reprod Fertil Suppl 66:87-102, 2009; Comprehensive biotechnology, Amsterdam, pp 477-485; Dairy production medicine, Chichester, pp 153-163; Theriogenology 76:1619-1631, 2011; Theriogenology 76:1568-1582, 2011; Theriogenology 77:1-11, 2012). Given the large number of mammalian species used for production of products useful for man and the diversity in their biology and management, the review will not be comprehensive but instead will use results from species that are most illustrative of the opportunities generated by assisted reproductive technologies.