Validation of two immunoassays for oxytocin measurements in human saliva.

The objective of this research was to develop and validate two immunoassays for oxytocin measurement in human saliva, one using a monoclonal and the other a polyclonal antibody against oxytocin, whose affinity for oxytocin was tested by an antibody mapping epitope analysis. These assays were analytically validated and used to compare oxytocin concentrations with those obtained with a commercial kit before and after the extraction or reduction/alkylation (R/A) treatments to saliva samples. The assays were also used to evaluate changes in salivary oxytocin concentrations following a physical effort and an induced psychological stress, which have previously been described as situations that cause an increase in salivary oxytocin. Both assays showed to be precise and accurate in the validation studies, and the antibodies used showed a defined binding region in case of the monoclonal antibody, whereas the polyclonal antibody showed binding events through all the oxytocin sequence. Although the monoclonal and polyclonal assays showed a positive correlation, they give results in a different range of magnitude. Both assays showed significant increases in oxytocin concentrations when applied after the physical effort and the psychological stress. This study shows that a variability in the reported values of oxytocin can occur depending on the assay and indicates that the use of different types of antibodies can give a different range of values when measuring oxytocin in saliva.

Comparison of the Effect of Two Different Handling Conditions at Slaughter in Saliva Analytes in Pigs.

In this report, different handling conditions at slaughterhouse were studied to assess changes in salivary biomarkers. For this purpose, finishing pigs were divided into two groups, one in which handling was improved to minimize stress (Group A, n = 24, transported and stabled at the slaughterhouse at low density without mixing with unfamiliar animals throughout the whole process) and another one in which animals had a more stressful handling process (Group B, n = 24, transported and stabled at high density with unfamiliar animals). Saliva samples were taken the day before transport to the slaughterhouse at 8:00 a.m. (B0) and 12:00 a.m. (B4), and the day of slaughter just after unloading animals at the slaughterhouse at approximately 8:00 a.m. (S0) and after 4 h of lairage at approximately 12:00 a.m. (S4). Group B showed significantly higher cortisol, total esterase activity, oxytocin, adenosine deaminase and haptoglobin levels than the Group A at both S0 and S4 sampling times, and higher levels of calprotectin and creatine kinase at S4 sampling time. This report indicates that differences in the way in which the pigs are handled at the slaughterhouse can lead to changes in salivary biomarkers and opens the possibility of the use of biomarker at slaughter to monitor handling conditions.

Saliva Sampling Material Matters: Effects on the Results of Saliva Analysis in Pigs.

The use of saliva as a biological sample from pigs is of high practical interest because blood collection from pigs is difficult and stressful. In this study, the influence of two different materials, a cotton roll and a polypropylene sponge, in porcine saliva collection was evaluated. For this purpose, the effect of the material used for sampling was evaluated in a panel of 13 analytes, including those related to stress (cortisol and oxytocin), inflammation and immunity (adenosine deaminase, haptoglobin and myeloperoxidase), redox homeostasis (the cupric reducing ability of saliva, the ferric reducing activity of saliva, and the Trolox equivalent antioxidant capacity), and sepsis (procalcitonin), as well as other routine analytes related to metabolism and different tissues and organs, such as lactate dehydrogenase, creatine kinase, urea, and total protein concentration. The polypropylene sponge provided a higher sample volume than the cotton roll. Although the results of some salivary analytes were equivalent for both materials, other analytes, such as creatine kinase, haptoglobin and total proteins, showed significant differences depending on the material used for saliva collection. Therefore, the type of material used for salivary collection in pigs should be considered when interpreting the results of analyses of the salivary analytes.

Gaining knowledge about biomarkers of the immune system and inflammation in the saliva of pigs: The case of myeloperoxidase, S100A12, and ITIH4.

An assay for the measurement of myeloperoxidase (Mpx) in porcine saliva was developed and validated, and factors influencing Mpx and another two biomarkers of inflammation and immune system, the protein S100A12 and the inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), were studied. The spectrophotometric method for Mpx measurement validated in this assay showed an adequate analytical performance including precision and accuracy. When a group of twenty healthy pigs was sampled every 4 h from 8 a.m. until 8 p.m., Mpx and S100A12 showed significant increases at 4 p.m., whereas ITIH4 concentration showed a significant decrease at 12 a.m. Increases were also seen in salivary Mpx, S100A12, and ITIH4 levels 24 h after the intramuscular administration of Escherichia coli lipopolysaccharide in five pigs; whereas in a non-septic inflammation after the subcutaneous administration of turpentine oil to five pigs changes were seen in S100A12 at 3 h and in ITIH4 at 48 h. When a stressful situation consisting of the transportation and stay of 4 h to a slaughterhouse of 24 pigs was performed, all analytes were increased after 4 h of lairage in the slaughterhouse compared with the values that were obtained the day before at the same time of the day. Mpx can be measured in the saliva of pigs with the automated assay described in this report. Mpx, S100A12, and ITIH4 salivary levels can change depending on the hour of the day in which the sample is taken, and increases can be produced due to sepsis, non-septic inflammation and stress.

Changes in cortisol and cortisone in hair of pigs reared under heat stress conditions.

Heat stress accounts for millions of dollars in losses for swine producers worldwide. The aim of the present study was to determine and evaluate cortisol and cortisone in hair as indicators of thermal stress in growing pigs reared under high environmental temperatures. The study was carried out in two independent batches of commercial crosses of Lean Duroc and Pietrain in trials 1 and 2, respectively, during the growing period (from 40 to 100 kg; 81 days in trial 1 and 77 days in trial 2) in the same commercial farm in Spain during the summers of 2020 and 2021. In both cases, four rooms were used. In Trial 1, Room 1 had cooling and 11 pigs per pen; Room 2 had no cooling and 13 pigs per pen; Room 3 had no cooling and 11 pigs per pen, and Room 4 had cooling and 13 pigs per pen. In Trial 2, Rooms 2 and 3 had cooling and rooms 1 and 4 had no cooling, and all of them had 13 pigs per pen. Mean THI value was higher (p < 0.0001) in rooms without cooling systems (75.0 trial 1; 74.9 trial 2) than with them (71.3 trial 1; 71.7 trial 2). A total of four pens per room (16 in total) was selected for analysis of hair corticoids and all pigs inside were sampled at the end of the study. Fifty percent of the pigs were males (castrated and intact in trial 1 and 2, respectively) and 50% females. In total, 44, 52, 44, and 52 pigs, respectively, were sampled in four rooms from the first trial and 52 for each of four rooms in Trial 2. Cortisol concentrations in hair did not show any significant change in relation to cooling-non-cooling in any trial. However, hair cortisone concentration was 172.3 pg./mg and 105.8 pg./mg less (p < 0.001) in pigs housed with cooling systems compared to those without them in Trial 1 and 2, respectively. In addition, the cortisone/cortisol ratio, which is an estimator of the activity of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) type 2, was also greater in rooms without cooling than in rooms with cooling in both trials (p < 0.0001 and p = 0.0105 for Trials 1 and 2, respectively). In relation to the sex effect, the results showed greater levels in females than in castrated males both in cortisone and the cortisol/cortisone ratio while cortisol hair levels were greater in intact males than in females. Therefore, the use of cortisone and the estimation of 11ß-HSD type 2 activity in hair is recommended to evaluate the chronic stress produced by high environmental conditions in pigs instead of using hair cortisol concentrations alone.

Reducing Stocking Densities and Using Cooling Systems for More Adapted Pigs to High Temperatures When Reared in Intensive Conditions.

This study is aimed at evaluating the effect of reducing stocking density and using cooling systems to mitigate the negative effects of high temperatures in growing pigs (females and castrated males) reared in intensive conditions (from 25 to 100 kg) during summer (June to October 2020). The experimental design was a 2 × 2 factorial where pigs were provided with an evaporative cooling system and/or raised at regular or at lower stocking densities (i.e., 0.68 to 0.80 m2/animal). Treatments were distributed in four different rooms containing sex-balanced pens with either castrated males or females. Temperature and humidity were recorded throughout the experiment, and the temperature-humidity index was calculated. Heat stress (HS) on pigs was measured through changes in animals' performance, animal-based indicators (dirtiness and activity budget) and physiological indicators (neutrophil/lymphocyte ratio and hair cortisol). The use of cooling, lowering stocking density and the combination of both strategies had positive effects on pigs' final body weight (+5 kg, +3 kg, +9 kg, respectively; p < 0.001). The prevalence of dirtiness was similar at the stocking densities tested, and no clear effect of the cooling system was found. Both mitigation strategies lowered the physiological indicators of stress, although only hair cortisone can be considered an indicator of HS. In conclusion, both mitigation strategies are effective in improving pig welfare and performance, especially when both are combined. The severity of the stocking density effect may depend on the severity of the temperature.

Oxytocin measurements in saliva: an analytical perspective.

Oxytocin has traditionally been known for its physiological effects on muscle contraction associated with birth and lactation, but in the last years is widely used as a biomarker of "positive experiences" in psychology and behavior. Different types of samples have been used for oxytocin measurements with saliva samples having the particular advantage of an easy and non-stressful collection. However, the low concentration of oxytocin in saliva can represent a limitation for its use. For this reason, sensitive assays and even a previous sample treatment in some cases are required for saliva oxytocin quantification. In addition, the lack of standardized and generally agreed-upon approach to peripheral oxytocin measurement leads to large discrepancies between different laboratories, that use different sample treatment protocols and different assays. The main objectives of this review are to describe the current status of the use of saliva for oxytocin measurement, provide details of the different sample processing techniques that can be applied and inform about the analytical techniques and assays available in different animal species, and also in humans for comparative purposes. It is expected that this information can contribute to an increase in the knowledge about the measurements of oxytocin in saliva and to its wider use in the future.

Changes in salivary biomarkers of stress, inflammation, redox status, and muscle damage due to Streptococcus suis infection in pigs.

BACKGROUND: Streptococcus suis (S. suis) is a Gram-positive bacteria that infects pigs causing meningitis, arthritis, pneumonia, or endocarditis. This increases the mortality in pig farms deriving in severe economic losses. The use of saliva as a diagnostic fluid has various advantages compared to blood, especially in pigs. In this study, it was hypothesized that saliva could reflect changes in different biomarkers related to stress, inflammation, redox status, and muscle damage in pigs with S. suis infection and that changes in these biomarkers could be related to the severity of the disease. RESULTS: A total of 56 growing pigs from a farm were selected as infected pigs (n = 28) and healthy pigs (n = 28). Results showed increases in biomarkers related to stress (alpha-amylase and oxytocin), inflammation (haptoglobin, inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), total protein, S100A8-A9 and S100A12), redox status (advanced oxidation protein producs (AOPP)) and muscle damage (creatine kinase (CK), CK-MB, troponin I, lactate, aspartate aminotransferase, and lactate dehydrogenase). An increase in adenosine deaminase (ADA), procalcitonin, and aldolase in infected animals were also observed, as previously described. The grade of severity of the disease indicated a significant positive correlation with total protein concentrations, aspartate aminotransferase, aldolase, and AOPP. CONCLUSIONS: This report revealed that S. suis infection caused variations in analytes related to stress, inflammation, redox status, and muscle damage in the saliva of pigs and these can be considered potential biomarkers for this disease.

Measurement of Calprotectin (S100A8/A9) in the Saliva of Pigs: Validation Data of A Commercially Available Automated Assay and Changes in Sepsis, Inflammation, and Stress.

Calprotectin (CALP, S100A8/A9), also named myeloid-related protein 8/14, is a dimer complex of S100A8 and S100A9 that belongs to the S-100 protein family. It is involved in inflammation and has a wide range of proinflammatory functions, such as cytokine production and regulation of leukocyte adhesion, migration, and phagocytosis. In humans, CALP traditionally can be measured in faeces, serum, and saliva as a biomarker of inflammation and sepsis. The objective of this study was to validate an automated assay for CALP measurements in the saliva of pigs, having the advantage of the use of a non-invasive sample that is easy to collect. The assay was precise and accurate. CALP in saliva measured by this assay showed significant changes depending on the hour of the day. It also showed significant increases in the saliva of pigs after the administration of lipopolysaccharide (LPS), and showed a rise, although with increases of lower magnitude, after a stressful stimulus. Further studies should be made to gain knowledge about the possible practical applications of the measurements of CALP in the saliva of pigs as a biomarker to evaluate the animals' health and welfare.

Trace Elements and Ferritin in Pig Saliva: Variations during Fattening, Time of Sampling, Effect of Dirtiness and Stability under Different Storage Conditions.

The objective of this study was to evaluate the possible changes of zinc (Zn), copper (Cu), iron (Fe) and ferritin during the entire productive cycle in fattening pigs and at different diurnal sampling times. Moreover, the possible effects of the presence of pen contaminants and storage stability at different temperature conditions were assessed. The analytes changed along the different phases of the fattening productive cycle, showing, in general, higher values at the initial phases. In addition, statistically significant variations were found in Zn and Cu measurements at different sampling times of the day. In the spectrophotometric assays, the values of all analytes significantly increased after adding high concentrations of feces or feed. However, when low concentrations of feces or feed were added, only Cu showed a significant increase. Overall, the salivary levels of Zn, Cu, Fe and ferritin in pigs can change during different fattening phases and the different hours of the day. These analytes were more stable at -80 °C and, if saliva is contaminated with feces or feed, it can lead to an increase in these analytes.

Multiomics reveals glutathione metabolism as a driver of bimodality during stem cell aging.

With age, skeletal muscle stem cells (MuSCs) activate out of quiescence more slowly and with increased death, leading to defective muscle repair. To explore the molecular underpinnings of these defects, we combined multiomics, single-cell measurements, and functional testing of MuSCs from young and old mice. The multiomics approach allowed us to assess which changes are causal, which are compensatory, and which are simply correlative. We identified glutathione (GSH) metabolism as perturbed in old MuSCs, with both causal and compensatory components. Contrary to young MuSCs, old MuSCs exhibit a population dichotomy composed of GSHhigh cells (comparable with young MuSCs) and GSHlow cells with impaired functionality. Mechanistically, we show that antagonism between NRF2 and NF-κB maintains this bimodality. Experimental manipulation of GSH levels altered the functional dichotomy of aged MuSCs. These findings identify a novel mechanism of stem cell aging and highlight glutathione metabolism as an accessible target for reversing MuSC aging.

Different Types of Glucocorticoids to Evaluate Stress and Welfare in Animals and Humans: General Concepts and Examples of Combined Use.

The main glucocorticoids involved in the stress response are cortisol and cortisone in most mammals and corticosterone in birds and rodents. Therefore, these analytes are currently the biomarkers more frequently used to evaluate the physiological response to a stressful situation. In addition, "total glucocorticoids", which refers to the quantification of various glucocorticoids by immunoassays showing cross-reactivity with different types of glucocorticoids or related metabolites, can be measured. In this review, we describe the characteristics of the main glucocorticoids used to assess stress, as well as the main techniques and samples used for their quantification. In addition, we analyse the studies where at least two of the main glucocorticoids were measured in combination. Overall, this review points out the different behaviours of the main glucocorticoids, depending on the animal species and stressful stimuli, and shows the potential advantages that the measurement of at least two different glucocorticoid types can have for evaluating welfare.

Fecal Microbiota and Hair Glucocorticoid Concentration Show Associations with Growth during Early Life in a Pig Model.

Identifying characteristics associated with fast or slow growth during early life in a pig model will help in the design of nutritional strategies or recommendations during infancy. The aim of this study was to identify if a differential growth during lactation and/or the nursery period may be associated with fecal microbiota composition and fermentation capacity, as well as to leave a print of glucocorticoid biomarkers in the hair. Seventy-five commercial male and female pigs showing extreme growth in the lactation and nursery periods were selected, creating four groups (First, lactation growth, d0−d21; second, nursery growth, d21−d62): Slow_Slow, Slow_Fast, Fast_Slow, and Fast_Fast. At d63 of life, hair and fecal samples were collected. Fast-growing pigs during nursery had higher cortisone concentrations in the hair (p < 0.05) and a tendency to have a lower cortisol-to-cortisone ratio (p = 0.061). Both lactation and nursery growth conditioned the fecal microbiota structure (p < 0.05). Additionally, fast-growing pigs during nursery had higher evenness (p < 0.05). Lactation growth influenced the relative abundance of eight bacterial genera, while nursery growth affected only two bacterial genera (p < 0.05). The fecal butyrate concentration was higher with fast growth in lactation and/or nursery (p < 0.05), suggesting it has an important role in growth, while total SCFA and acetate were related to lactation growth (p < 0.05). In conclusion, piglets' growth during nursery and, especially, the lactation period was associated with changes in their microbiota composition and fermentation capacity, evidencing the critical role of early colonization on the establishment of the adult microbiota. Additionally, cortisol conversion to cortisone was increased in animals with fast growth, but further research is necessary to determine its implications.

Novel saliva biomarkers for stress and infection in pigs: Changes in oxytocin and procalcitonin in pigs with tail-biting lesions.

There is a need for feasible and reliable measures to improve and evaluate production animal health and welfare. Oxytocin is a promising novel stress-related biomarker and procalcitonin may be a measure of sepsis. Both have potential for use in pigs and can be measured from saliva, which allows on-farm sampling with minimal impact on the animals. The current study sought to further validate these measures using a spontaneous situation that causes both stress and an increased risk for infections in pigs, namely a tail-biting outbreak. Grower pigs on a commercial farm belonging to three different phenotype groups were selected: control pigs from control pens (CC, N = 30), control pigs (CTB, N = 10), and pigs with tail lesions from pens with a tail-biting outbreak (LTB, N = 27). A single sample of saliva was collected from each pig and analysed for a range of biomarkers related to stress, infection, inflammation, and immune activation. Oxytocin tended to be higher in CC pigs than in LTB pigs, while cortisol was higher in CTB than CC pigs. Procalcitonin tended to be higher, and haptoglobin was higher in LTB than in CC pigs. Adenosine-deaminase levels were similar between phenotypes. These results provide further evidence for the link between stress and tail biting, and indicate that tail-biting lesions are potential routes for systemic spread of bacteria. Further research into saliva oxytocin as a stress biomarker and saliva procalcitonin as a sepsis biomarker in pigs is warranted.

Effects of pen faeces and feed contamination in biomarkers determination in oral fluid of pigs.

The present study aims to evaluate the possible effects of the presence of pen faeces and feed on the measurement of a panel of biomarkers in porcine oral fluid. For this, clean porcine oral fluid was pooled and incubated with two different concentrations of pen faeces or feed representing a high or low level of contamination with each material. In addition, these pools were aliquoted and subjected to centrifugation, filtration or chemical clarification to evaluate if these techniques could revert the effects of those contaminants in biomarker evaluation. A panel of 21 biomarkers that assessed stress, inflammation, immune system and redox homeostasis among others, were measured for all aliquots. Changes of statistical relevance (p < 0.05) in oral fluid contaminated with pen faeces or feed versus untreated samples were observed for all methods employed with the exception of adenosine deaminase (ADA) and creatine kinase (CK) in oral fluid contaminated with pen faeces or feed. Pen faeces did not affect the measurement of haptoglobin, superoxide dismutase, CK, lactate dehydrogenase (LDH), ADA and cortisol (when the latter is measured by chemiluminescence); while uric acid, LDH, CK, ADA, and hydrogen peroxide methods were not affected by the presence of feed in oral fluid. The effects of centrifugation, filtration or chemical clarification with chitosan in these contaminated samples were modest and for most cases did not caused baseline levels on the measured biomarkers. In conclusion, the presence of pen faeces or feed in porcine oral fluid can interfere with the results obtained when analytes are measured.

Evaluation of the Effect of Sampling Time on Biomarkers of Stress, Immune System, Redox Status and Other Biochemistry Analytes in Saliva of Finishing Pigs.

This study aims to evaluate the possible variations due to the sampling time in the day in 26 analytes of pigs' saliva, related to stress, the immune system, redox status and other biomarkers related to metabolism and selected tissues and organs, in order to know the possible effects of the hour of the day in their interpretation. These analytes were measured in saliva obtained from a population of 40 clinically healthy pigs from 8 a.m. to 8 p.m., every 4 h in the same day. In our experimental conditions, daily variations were observed in cortisol, salivary α-amylase, total esterase activity, butyrylcholinesterase, lipase, adenosine deaminase isoenzyme 1, uric acid, superoxide dismutase, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatine kinase, lactate dehydrogenase, lactate and triglycerides. These changes appeared in both sexes, except for adenosine deaminase isoenzyme 1 and superoxide dismutase which only showed differences in females. In conclusion, this report indicates that, in the experimental conditions of this trial, the time of the day and sex can influence the values obtained in various salivary analytes in pigs. These variations should thus be taken into consideration for an adequate interpretation of these analytes when used for the evaluation of health and welfare in this species.

Changes in a Comprehensive Profile of Saliva Analytes in Fattening Pigs during a Complete Productive Cycle: A Longitudinal Study.

A comprehensive panel of 29 salivary analytes was measured in fattening pigs to evaluate its possible changes along their productive cycle. The identification of those changes would allow a better interpretation of the results according to the productive phase of the animal. Saliva samples were obtained from 49 Large-White pigs (24 females, 25 males) in suckling phase, at the beginning and the end of the nursery phase, and at the beginning and the end of the growing phase. Several analytes changed according to the phase of the productive cycle, with most of the analytes showing higher values at lactation and at the beginning of nursery. Additionally, differences were seen due to sex. When possible relations between performance parameters and analytes were evaluated, significant positive but weak relationships were found between weight at birth and salivary γ-glutamyl transferase, and between back-fat thickness and salivary lactate dehydrogenase. In conclusion, differences in the values of salivary analytes can be found in fattening pigs depending on the productive phase and sex of the animals.

Response to Treatment with Melatonin and Clonazepam versus Placebo in Patients with Burning Mouth Syndrome.

Objective: to evaluate the efficacy of melatonin and clonazepam versus placebo in patients with burning mouth syndrome (BMS). Methods: a prospective double-blind study was carried out in patients with BMS and randomized to three groups: melatonin (1 mg once a day), clonazepam (0.5 mg/twice a day), or a placebo once a day, for 8 weeks. The clinical changes were evaluated, including xerostomia, the Oral Health Impact Profile 14 (OHIP-14) score, Pittsburg Sleep Quality Index, and the Hospital Anxiety and Depression Scale (HADS). Oxygen saturation and heart rate were recorded, with an analysis of salivary biomarkers in the forms of oxytocin, ferritin, adenosine deaminase (ADA), total proteins, and alpha-amylase. Results: a total of 64 patients were analyzed. A significant decrease in burning sensation was recorded with melatonin (7.8 ± 1.54 pre-treatment, 5.78 ± 2.54 post-treatment; p < 0.001) and clonazepam (8.75 ± 1.2 pre-treatment, 5.5 ± 3.6 post-treatment (p < 0.01). With regard to quality of life (OHIP-14), significant improvements were observed before and after the administration of melatonin (p < 0.001) and clonazepam (p = 0.001). On the other hand, with regard to the changes in salivary biomarkers following treatment, negative correlations were found between oxytocin and drainage (r = −0.410; p = 0.009) and between the HADS-D score and ferritin (r = −0.312; p = 0.05). While salivary amylase showed positive correlation with heart rate (r = 0.346; p = 0.029) and oxygen saturation (r = 0.419; p = 0.007). Conclusions: melatonin and clonazepam were shown to be effective at reducing the burning sensation and improving quality of life. Both drugs were found to be safe, with no major adverse effects in patients with BMS. Melatonin may be regarded as an alternative treatment for patients with BMS, though further studies are needed to confirm its effectiveness.

Tubastatin A maintains adult skeletal muscle stem cells in a quiescent state ex vivo and improves their engraftment ability in vivo.

Adult skeletal muscle stem cells (MuSCs) are important for muscle regeneration and constitute a potential source of cell therapy. However, upon isolation, MuSCs rapidly exit quiescence and lose transplantation potency. Maintenance of the quiescent state in vitro preserves MuSC transplantation efficiency and provides an opportunity to study the biology of quiescence. Here we show that Tubastatin A (TubA), an Hdac6 inhibitor, prevents primary cilium resorption, maintains quiescence, and enhances MuSC survival ex vivo. Phenotypic characterization and transcriptomic analysis of TubA-treated cells revealed that TubA maintains most of the biological features and molecular signatures of quiescence. Furthermore, TubA-treated MuSCs showed improved engraftment ability upon transplantation. TubA also induced a return to quiescence and improved engraftment of cycling MuSCs, revealing a potentially expanded application for MuSC therapeutics. Altogether, these studies demonstrate the ability of TubA to maintain MuSC quiescence ex vivo and to enhance the therapeutic potential of MuSCs and their progeny.

Oxytocin in pig seminal plasma is positively related with in vivo fertility of inseminated sows.

BACKGROUND: Identification of relevant in vivo biomarkers for fertility remains a challenge for the livestock industry. Concentrations of the small peptide hormone oxytocin (OXT), involved in male reproductive function and present in the seminal plasma (SP) of several species could be a robust one. This study characterized concentrations of SP-OXT in ejaculates from boars used in artificial insemination (AI) programs aiming to evaluate its relationship with sperm quality variables and in vivo fertility of their liquid-stored AI-semen. Seminal OXT concentrations (ng/mL) were measured in 169 ejaculates from 61 boars of the Duroc, Pietrain, Landrace and Large White breeds using a direct competitive immunoassay test based on AlphaLISA® technology. Ejaculate (ejaculate volume, sperm concentration, total sperm count) and sperm parameters (motility, viability, intracellular generation of reactive oxygen species, plasma membrane fluidity) were assessed at 0 h and 72 h in AI-semen samples stored at 17 °C. In vivo fertility included only 18 Large White and Landrace boars whose AI-semen was used to inseminated > 100 sows and evaluated both farrowing rate and litter size of 3,167 sows. RESULTS: The results showed that SP-OXT differed between boars and between ejaculates within boar (P < 0.05) but not between breeds (Duroc, Pietrain, Landrace and Large White). Ejaculates with higher SP-OXT concentration/mL (hierarchically grouped; P < 0.001) had larger volume and came from younger boars (P < 0.05). Ejaculates of boars showing positive farrowing rate deviation exhibited higher (P < 0.05) SP-OXT concentration/mL than those with negative farrowing rate deviation. CONCLUSION: The SP concentrations of OXT are boar, ejaculate and age dependent, and positively related with ejaculate volume and farrowing rates of liquid-stored semen AI-doses.