Pregnancy associated glycoproteins (PAG) in postpartum cows, ewes, goats and their offspring

Development and evaluation of a lateral flow-based portable optical system for determination of the pregnancy status of dairy cows

Our objectives were to develop and evaluate an integrated system consisting of a lateral-flow immunoassay (LFIA) and an electronic portable imaging device for determination of pregnancy status of cows based on plasma concentrations of pregnancy-specific protein B (PSPB). Experiment 1 was conducted to test the performance of the LFIA for PSPB (PSPB-LFIA) whereas experiment 2 was conducted to evaluate the performance of the integrated system including both the LFIA and imaging device. The PSPB-LFIA strips were made of nitrocellulose membrane with polystreptavidin, anti-mouse antibody, Europium-anti-PSPB conjugates, and biotin-PSPB. After adding buffer and plasma in a 96-well plate, strips were dipped to initiate flow and were read in a fluorescence microscope to estimate PSPB concentrations based on the test-to-control line signal (T/C ratio). The T/C ratio of standards was linearly associated with PSPB (R2 = 0.99 in both experiments) concentrations. To test the ability to identify pregnant cows of the PSPB-LFIA only or the integrated system, plasma samples were collected and transrectal ultrasonography (TUS) was conducted 29 to 35 d post AI in lactating Holstein cows (Experiment 1: n = 83; Experiment 2: n = 205). A cow was considered pregnant (Preg) if concentrations of PSPB in plasma obtained by ELISA were ≥2 ng/mL or if an embryo was visible by TUS. In Experiment 1, the accuracy of the PSPB-LFIA compared with ELISA was 92.7% (91.2% Se; 96.1% Sp; 98.1% PPV; 83.3% NPV) and compared with TUS was 90.4% (100% Se; 78.9% Sp; 84.9% PPV; 100% NPV). The agreement between LFIA and ELISA (kappa = 0.84; 95%CI 0.71-0.96) or LFIA and TUS (kappa = 0.80; 95%CI 0.67-0.93) as methods to classify cows as Preg or Non-Preg was high. In Experiment 2, the accuracy of the PSPB-LFIA compared with ELISA was 96.1% (93.8% Se; 100% Sp; 100% PPV; 90.5% NPV) and compared with TUS was 92.2% (99.0% Se; 84.7% Sp; 87.6% PPV; 98.8% NPV). The agreement between LFIA and ELISA (kappa = 0.92; 95%CI 0.86-0.97) or LFIA and TUS (kappa = 0.84; 95%CI 0.77-0.92) as methods to classify cows as Preg or Non-Preg was high. We conclude that a system integrating a fluorescence-based LFIA and an optical reader was effective for classifying cows as pregnant or not pregnant based on estimations of plasma concentrations of PSPB. This novel system serves as a platform for further development of on-farm pregnancy testing tools based on measurement of biomarkers of pregnancy in bodily fluids of cattle.

Novel Approach for Evaluating Pregnancy-Associated Glycoprotein and Inflammation Markers during the Postpartum Period in Holstein Friesian Cows

We evaluated the relationship between decreased pregnancy-associated glycoprotein (PAG) levels, inflammatory parameters (serum amyloid A [SAA] and milk amyloid A [MAA]), postpartum inflammatory conditions (mastitis, ketosis, and follicular cysts), and the FOXP3 gene. Nineteen Holstein-Friesian cows were included in this study. Up to approximately eight weeks after delivery, weekly health examinations were performed for mastitis and ketosis, and reproductive organ ultrasonography was performed. The decreasing PAG rate was negatively correlated with SAA concentration (r = -0.493, p = 0.032). Cows with mastitis exhibited a slower trend of PAG decrease (p = 0.095), and a greater percentage of these cows had MAA concentrations above 12 µg/mL (p = 0.074) compared with those without mastitis. A negative correlation, although nonsignificant (r = -0.263, p = 0.385), was observed between the day-open period and decreased PAG rate. The day-open period was correlated with the presence or absence of follicular cysts (p = 0.046). Four cows that developed follicular cysts were homozygous for the G allele of the FOXP3 gene related to repeat breeders. These results indicate a relationship between a decreased PAG rate and inflammatory status during the postpartum period. Thus, suppressing inflammation during the perinatal period may improve reproductive efficiency in the dairy industry.

Serum pregnancy-associated glycoprotein profiles during early gestation in Karya and Konya Merino sheep

BACKGROUND

Reported as being expressed by mono- and binucleate placental cells, pregnancy-associated glycoproteins (PAGs) are released into the blood circulation from the ruminant placenta. Circulating gestational PAGs levels may differ between sheep breeds.

OBJECTIVE

This study was aimed at the close monitoring of the serum PAGs profiles of Karya and Konya Merino sheep during early pregnancy.

METHODS

Fifteen Karya and 15 Konya Merino ewes were synchronized by a 12-day treatment with progesterone-impregnated intravaginal sponges. After the sponges were withdrawn, the ewes were administered 400 IU of equine chorionic gonadotropin. The ewes were allowed to mate naturally, and all animals were sampled for blood as of the day of mating (day 0) at weeks 1, 2, 3, 4 and 5. Pregnancy diagnoses were made by transabdominal ultrasonography at week 5. At weeks 6, 7, 8, 9 and 11, blood samples were collected only from the pregnant ewes. The blood samples were centrifuged at 3000 × g, and extracted sera were stored at -20°C until being used for laboratory analyses. Serum PAGs levels were determined with the aid of a commercial PAG-enzyme-linked immunosorbent assay test originally developed for pregnancy diagnosis in cattle. Differences in the between the PAGs levels throughout pregnancy and the group effect (Karya and Konya Merino) were determined with a two-way mixed analysis of variance. Pairwise comparisons were made using a Bonferroni adjustment.

RESULTS

PAGs levels showed a linear increase with the advance of pregnancy in both Karya and Konya Merino sheep. No difference was detected between the breeds for serum PAGs levels. The serum PAGs levels of the pregnant and non-pregnant ewes differed as of the fourth week.

CONCLUSION

The serum PAGs levels of the Karya and Konya Merino ewes were similar during the first 11 weeks of gestation, and pregnancy diagnosis could be made based on serum PAGs levels as of the 4th week in both breeds.

Comparative evaluation of two commercial pregnancy-associated glycoproteins tests for early detection of pregnancy in dairy cattle

The aim of this study was to determine and compare the diagnostic accuracy of two pregnancy-associated glycoproteins tests (IDEXX on-farm pregnancy test [OFPT] and IDEXX rapid visual pregnancy test [RVPT]) for early pregnancy diagnosis in dairy cattle. Blood samples were collected from Holstein cows (n = 317) by coccygeal venipuncture 28-31 days after artificial insemination (AI). The OFPT and RVPT were performed on the farm within 2 h after blood collection using whole blood or blood serum. Transrectal ultrasonography (USG) was performed for pregnancy diagnosis on day 32 post-AI as a gold standard. One-hundred fourteen cows were diagnosed as pregnant and 203 were determined to be nonpregnant. Furthermore, embryonic mortality was detected in four of the nonpregnant animals, based on fragmented/dispersed embryonic membranes and the absence of heartbeat. Sixteen and 14 false positive results (13 jointly for both tests) were obtained for the RVPT and OFPT, respectively. Three false negative results were obtained for the RVPT. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for the OFPT were 100%, 93.1%, 89.1%, 100% and 95.6%, and for RVPT were 97.4%, 92.1%, 87.4%, 98.4% and 94.0%, respectively. The ability of both tests to distinguish between pregnant and open cows was very good (AUC of both tests above 0.9). The OFPT and RVPT almost perfectly agreed with each other. According to McNemar's analysis, false positive results have been caused difference between the two pregnancy tests and USG. In conclusion, both the RVPT and OFPT proved to be reliable and practical methods for pregnancy diagnosis 28-31 days after AI in dairy cows. However, the results of both pregnancy tests were affected by the occurrence of embryonic mortality around the time of their employment.

Expression profiles of an inactive aspartic protease (Bla g 2 allergen) in different tissues and developmental stages of the German cockroach (Blattella germanica)

Tergal glands are found in many insect species and contain constituents such as pheromones, sugars, proteins, and so forth. Preliminary studies have revealed that tergal gland secretions in the German cockroach (Blattella germanica L.) contain the human allergen Bla g 2 (B. germanica allergen 2), an inactive aspartic protease. Although Bla g 2 protein expression has been detected previously in various German cockroach body parts, including male tergal glands, studies that link protein expression in various life stages and tissues with mRNA and protein abundance have not been conducted. Therefore, the goal of this study was to measure the relative abundances of Bla g 2 protein and mRNA in different tissues and life stages of B. germanica using immunoblotting, quantitative PCR, and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based quantitative profiling. We found that Bla g 2 protein was detected in every sampled tissue, including the male tergal glands. Protein abundance was relatively high in adult males and their tergal glands in comparison to nymphs and virgin females. Similarly, Bla g 2 mRNA transcript levels were also comparatively higher in male tergal glands and adult males. In conclusion, this study provides new information on the relative abundance and distribution of Bla g 2 allergen, a medically significant protein, in different tissues and developmental stages of the German cockroach and lays the foundation for future studies that aim to determine the function of this protein in B. germanica development.

Using Pregnancy-Associated Glycoproteins (PAGs) to Improve Reproductive Management: From Dairy Cows to Other Dairy Livestock

Simple Summary

Pregnancy loss is a major cause of infertility in dairy animals, particularly in cattle, which affects the productivity and profitability of farms. Detecting these unsuccessful pregnancies could offer farmers the opportunity to reduce the economic damage caused by pregnancy loss. The determination of proteins secreted by the placenta and related to the presence of a viable conceptus called pregnancy-associated glycoproteins (PAGs) represents a diagnostic tool to identify pregnant or non-pregnant animals and to predict early pregnancy failures. This review describes the state of the art related to PAGs’ function, pregnancy profile, and use in reproductive management in bovine and other dairy livestock.

Abstract

Pregnancy success represents a major issue for the economic income of cattle breeders. Early detection of pregnant and non-pregnant animals, as well as the prediction of early pregnancy failure, can influence farm management decisions. Several diagnostic tools for pregnancy are currently available. Among these, pregnancy-associated glycoproteins (PAGs) have been shown to be useful for identifying the presence of vital embryos and for pregnancy follow-up monitoring. This review presents an overview of the PAGs’ functions, their pregnancy trends, and their use as a tool to improve reproductive management in bovine and other dairy livestock, such as small ruminants and buffalos.

Effect of Folic Acid Supplements on Progesterone Profile and Blood Metabolites of Heat-Stressed Holstein Cows during the Early Stage of Pregnancy

The aim was to elucidate the impact of oral folic acid (FA) supplements on progesterone profile, blood metabolites and biochemical indices of heat-stressed Holstein cows during the early stage of pregnancy. The study lasted from the day of artificial insemination through the end of the fourth week of pregnancy. The first group (CON, n = 17) received 0 μg of FA/kg BW as a control. The second and third groups received oral FA doses of 5 (FA5, n = 19) and 10 (FA10, n = 20) μg kg−1 BW, respectively. At the 2nd and 3rd weeks of pregnancy, the FA10 group had greater progesterone levels than the CON group (p < 0.05). The FA10 group had a greater progesterone level than the FA5 and CON groups at the fourth week of pregnancy (p < 0.01). The FA10 group had higher folate levels than CON group during the first three weeks of pregnancy (p < 0.01). Both FA-supplemented groups had significantly greater serum folates than the CON group by the end of the fourth week of pregnancy (p < 0.01). At the 2nd and 4th weeks of pregnancy, the FA10 group had greater levels of serum glucose and globulin than the CON group (p = 0.028 and 0.049, respectively). Both FA-supplemented groups had greater serum growth hormone (GH) levels at the 4th week of pregnancy (p = 0.020). Additionally, the FA10 group showed significantly higher levels of IGF-1 at the 2nd and 4th week of gestation (p = 0.040 and 0.001, respectively). FA supplementation decreased the levels of non-esterified fatty acid (NEFA) at the 2nd and 4th week of gestation (p = 0.020 and 0.035, respectively). Additionally, the FA10 group showed significantly higher pregnancy-associated glycoprotein (PAG) levels at the 2nd and 4th week of gestation (p = 0.005 and 0.001, respectively). In conclusion, oral FA supplementation (10 mcg kg−1) in the first month of gestation improved the progesterone profile, as well as blood folates, PAG, GH, and IGF-1 concentrations in heat-stressed Holstein cows. These findings could be useful in developing practical strategies to keep dairy cows’ regular reproductive patterns under heat stress conditions.

Establishment of a Sandwich-ELISA for simultaneous quantification of bovine pregnancy-associated glycoprotein in serum and milk

Bovine pregnancy-associated glycoproteins (boPAG) are expressed by trophoblast cells in the bovine placenta. The multigene family of boPAG belongs to the group of aspartic proteases. The accumulation and circulation in maternal blood and milk has made boPAG very useful and important for pregnancy diagnosis in cattle. The goal of the present study was to develop and validate a new Sandwich-ELISA which allows the detection of boPAG in maternal serum and whole milk. Therefore, 984 serum and 928 milk samples were collected monthly from 231 Holstein Friesian cows (Bos Taurus) from one week after insemination (p.i.) until six weeks postpartum. The ELISA is able to identify a cow as being pregnant at day 30 p.i. in serum and at day 40 p.i in milk with threshold values of 1.0 ng/ml in serum and 0.0165 ng/ml in milk. The postpartum half-life of boPAG was estimated to be 6.4 days in serum and 7.1 days in milk. The boPAG profile established during pregnancy in serum and milk showed a typical pattern. The amount of boPAG found in milk was 1.5 % of the amount of boPAG present in serum. In conclusion, a Sandwich-ELISA has been developed to quantify boPAG in serum and in whole milk simultaneously with the same test procedure. This is time saving for farmers and more efficient for laboratories.

Pregnancy-Specific Protein B in Yankasa Ewes During Pregnancy and Postpartum Periods

Pregnancy-specific protein B (PSPB) is produced by mono and binucleate trophoblast cells in the placenta of ruminants during pregnancy. This study was designed to determine the pattern of serum PSPB in Yankasa ewes during pregnancy and postpartum periods. Mature cycling Yankasa ewes were synchronized and divided into two groups A (n=11) and B (n=13). Group A was bred, while group B was unbred. Blood samples for PSPB assessment were collected from the ewes starting from the day of breeding until 4 weeks post-lambing. All pregnant Yankasa ewes lambed with singleton lambs after an average of 151.18 days. There was a significant (p<0.05) increase in PSPB in pregnant compared with the non-pregnant ewes in the period between 3 weeks post-breeding and 3 weeks post-lambing. Peaks were detected in the first (100.60 ng/ml), second (133.90 ng/ml), and third (114.82 ng/ml) trimesters at 5, 10 and 21 weeks of gestation, respectively, but steadily decreased within 4 weeks (2.38 ng/ml) postpartum. In conclusion, PSPB detected pregnancy in Yankasa ewes from 3 weeks post-breeding with peak levels at 5, 10 and 21 weeks post-breeding in the first, second, and third trimesters, respectively. PSPB decreased gradually after lambing until 4 weeks postpartum.

Temporal changes in circulating progesterone and pregnancy-associated glycoprotein concentrations in Jakhrana goats with failed pregnancy

This study aimed to evaluate the changes in circulating Progesterone (P4) and Pregnancy-Associated Glycoprotein (PAG) during pregnancy interrupted by abortion and to identify the better predictor of abortion risk in Jakhrana goats. Pluriparous goats (18) were involved in the study. Out of 15 pregnant goats, 3 goats were aborted during the third or fourth months of pregnancy. In the normal pregnancy, mean P4 concentration (13.96±0.27 ng/mL) remained unchanged throughout gestation whereas, the PAG level increased during early pregnancy and reached to the highest level (S-N=2.14±0.40) on day 51 of gestation. In non-pregnant goats, the P4 (0.3±0.03 ng/mL) and PAG (0.06±0.03) were significantly lower compared to the goats with maintained or failed pregnancy. In goats with the failed pregnancy, the PAG level started to decline about 12 days before the drop in P4 concentration (day 33.0±2.1 vs 21.3±3.5, before the occurrence of abortion). The mean PAG level in goats with failed pregnancy (0.33±0.03) was 4.8-folds lower compared to the animals with maintained pregnancy (1.58±0.08). In conclusion, the P4 and PAG concentrations in maternal circulation are changed by the pregnancy status and abortion. Plasma PAG is a more reliable predictor for the high risk of pregnancy failure than the P4 concentration in goats.

Plasmatic Profile of Pregnancy-Associated Glycoprotein (PAG) during Gestation and Postpartum in Sarda and Lacaune Sheep Determined with Two Radioimmunoassay Systems

Simple Summary

Nowadays the need to optimize and maximize the productivity of dairy sheep leads farmers to plan lambing in specific periods in order to avoid economic loss due to nonproductive animals. The goal is to diagnose pregnancy at early gestation in order to minimize the costs of unproductive animals and to properly formulate rations for the energy requirements of gestating or lactating animals at the same time. Moreover, early pregnancy diagnosis, as well as the possibility of distinguishing between single and multiple gestations, enables farmers to plan the management of lambing well in advance thus minimizing manpower requirements. This study showed, for the first time, the plasmatic profile of PAG (pregnancy-associated glycoproteins) in Sarda and Lacaune ewes during gestation and the postpartum period using two different radioimmune assay (RIA) systems, thus enhancing our knowledge regarding PAG concentrations in domestic ruminants. Moreover, it showed that for both breeds these RIA systems are capable of distinguishing pregnant from nonpregnant ewes starting from day 18 of gestation. Furthermore, the rapid disappearance of PAG concentration following lambing did not require the use of a cut-off limit in postpartum animals as a means for detecting a new pregnancy.

Abstract

This study was carried out to determine ovine pregnancy-associated glycoprotein (oPAG) levels in the plasma of Sarda and Lacaune ewes throughout gestation and in the first month postpartum, using two heterologous radioimmunoassays (RIA-706 and RIA-srPool) and to study the correlations between PAG levels and fetal gender and number. On Day 18 of pregnancy, PAG concentrations were detected in 90.1% and 80.8% of Sarda pregnant ewes with RIA-706 and RIA-srPool, respectively; and in 90% and in 75% of Lacaune pregnant ewes with RIA-706 and RIA-srPool, respectively. From Day 30, PAG concentrations were detected in all pregnant ewes by using both RIA methods. In the postpartum period, the PAG concentrations in Sarda ewes decreased rapidly reaching minimal levels (<1 ng/mL) on day 28 using both RIA-706 and RIA-srPool. In Lacaune ewes, PAG-706 levels were higher than PAG-srPool from parturition until the last day of observation (Day 28 postpartum). It was also observed that mean concentrations were higher in multiple than in single pregnancies in Sarda and Lacaune ewes. Moreover, due to the rapid disappearance of PAG concentration following lambing, a cut-off limit in postpartum animals was not required as a means for detecting a new pregnancy.

Biomarkers of fitness and welfare in dairy cattle: healthy productivity

Milk production intensification has led to several unwanted aspects, such as sustainability issues and environmental pollution. Among these, increased milk outputs that have been achieved over the last 70 years have led to several health and pathophysiological conditions in high yielding dairy animals, including metabolic diseases that were uncommon in the past. Increased occurrence of diverse metabolic diseases in cattle and other domestic animals is a key feature of domestication that not only affects the animals' health and productivity, but also may have important and adverse health impacts on human consumers through the elevated use of drugs and antibiotics. These aspects will influence economical and ethical aspects in the near future. Therefore, finding and establishing proper biomarkers for early detection of metabolic diseases is of great interest. In the present review, recent work on the discovery of fitness, stress and welfare biomarkers in dairy cows is presented, focusing in particular on possible biomarkers of energy balance and oxidative stress in plasma and milk, and biomarkers of production-related diseases and decreased fertility.

Relationship of foetal number and parity in Barbari goats to plasma profile of caprine pregnancy-associated glycoprotein (caPAG) during gestation and the early postpartum period

This study was conducted to characterise pregnancy-associated glycoprotein (caPAG) in peripheral plasma during gestation and postpartum periods of nulliparous and multiparous does with one or two foetuses using a caPAG specific two-step sandwich ELISA system. Earliest time-points for detection of pregnancy and foetal number with appropriate cut-off values were identified. Plasma samples from 15 pregnant (multiparous: n = 8; nulliparous: n = 7; during pregnancy and postpartum period) and six non-pregnant (during oestrous cycle) goats were collected and analysed. Mean caPAG concentration was greater than the threshold for pregnancy detection (S-N = 0.40) on d22, peaked on d45 and remained unchanged until parturition. From d45 until parturition, caPAG concentration in multiparous does with two foetuses was 1.4 to 1.8 fold greater (P < 0.001) than those with one foetus. For the ELISA, 0.83 (S-N) was the most appropriate cut-off to differentiate does with two from those with a single foetus with an overall sensitivity and accuracy of 88.9% and 84.7%, respectively. Circulating caPAG concentration in multiparous goats was greater (P < 0.05) compared with nulliparous goats during the early pregnancy and postpartum periods. After parturition, caPAG concentrations markedly decreased and were basal within 14 days postpartum. In conclusion, using the caPAG specific ELISA, results indicated there were unique gestational and postpartum profiles for caPAG concentrations that are affected by number of foetuses and parity of the doe. The marked decrease in concentration of caPAG following parturition indicates there would not be compromising of the detection of subsequent pregnancies in goats using this technique.

Pregnancy-associated glycoproteins (PAGs) concentrations in water buffaloes (Bubalus bubalis) during gestation and the postpartum period

For the first time in literature this study describes the pregnancy-associated glycoprotein (PAG) profile of buffalo cows during gestation and the post-partum period using antiserum raised against PAG-molecules purified from buffalo placenta (AS#860). Ninety-eight buffalo cows, belonging to a buffalo herd subjected to a synchronization and artificial insemination (AI) program, were enrolled in this study. Blood samples were taken on days 0 (AI), 23, 25, 28, 30 and then biweekly until the end of pregnancy. Pregnancy was confirmed by ultrasonography on days 28 and 45, and by rectal palpation from day 60 onwards. Blood samples were suspended for the non-pregnant cows on day 45, while the blood of 20 buffaloes that had calved was tested every five days from the day of calving until day 50 post-calving. A cut-off value of 1.0 ng/mL was used in order to discriminate between pregnant and non-pregnant buffaloes. We used Linear Mixed models after Log(x+1) transformation to analyse the PAG concentrations. Fifty-two buffalo cows had become pregnant out of 98 synchronized (53%) and 46 remained non-pregnant (47%) as shown by ultrasonography and the PAG analysis. Significant differences (P < 0.001) in PAG concentrations were observed between the pregnant and non-pregnant buffaloes from day 23 as the PAG of the non-pregnant cows was always close to zero. Conversely, the PAG of the pregnant cows increased progressively from day AI until day 105 post-insemination and then stabilized until the end of pregnancy. Regarding pregnancy diagnosis, the sensitivity of PAG-RIA 860 system (ability of the test to correctly identify pregnant buffalo) ranged from 23% on day 23-98% on day 28 post AI; the specificity (ability to correctly identify non-pregnant buffaloes) was 100% throughout the sampling period. PAG progressively decreased from parturition to day 25 post-partum; from day 30 post-partum, the concentrations fell below 1 ng/mL and were close to 0 on the last day of observation (50 d post-partum). In conclusion, our results showed that RIA-860 is highly accurate for diagnosing pregnancy in buffaloes starting from day 28 of gestation. Furthermore, the rapid disappearance of PAG concentration after calving means that a cut-off limit in post-partum for detecting a new pregnancy is not required.

Time-dependent changes in pregnancy-associated glycoproteins and progesterone in commercial crossbred sheep

The ruminant placenta functions as an endocrine and paracrine organ secreting proteins, growth factors, and steroid hormones, including pregnancy-associated glycoproteins (PAG), proteins with elusive function, which are readily detectable in maternal serum after placental attachment. In sheep, circulating progesterone beyond gestational Day 50 is predominantly of placental origin. The relationship among placental secreted factors, including progesterone, remains uncertain in sheep. The first aim of the study was to determine the relationship between gestational PAG profiles-using two commercial ELISA assays-progesterone, and fetal growth during pregnancy. The second aim of the study was to assess the presence and clearance of PAG in neonatal lambs and peripartum ewes in commercial crossbred sheep. Maternal serum samples were collected during mid-pregnancy and assayed for PAG1, pregnancy-specific protein B (PSPB), and progesterone. Maternal serum samples were also collected weekly starting 1-month prepartum until 10 weeks postpartum. Serum samples from newborns were collected at birth until Day 12 after birth and assayed for PAG1. Circulating maternal PAG1 concentrations steadily increased throughout mid-gestation, whereas PSPB exhibited a bimodal pattern of secretion. A strong positive correlation was observed between progesterone and PAG1 (r² = 0.779, P < 0.0001), but not between PSPB and progesterone. No relationship was found between placental factors (PAG1, PSPB, and progesterone) and fetal size. PAG1 concentrations were lower before and after parturition in singleton compared with twin pregnancies (P < 0.05). Maternal PAG1 concentrations began declining at parturition and continued to decline until 10 weeks after parturition (P < 0.05). In newborns, PAG1 concentrations continuously declined in both singleton and twins regardless of sex (P < 0.05) and cleared from newborn serum by 12 days after birth. Our findings reported for the first time how different assays used to determine circulating PAG concentrations display different gestational profiles in sheep and how it allows the differentiation between singleton and multiple pregnancies. In conclusion, the strong correlation between PAG1 and progesterone during gestation reports that PAG1 can be effectively used as a marker of placental function.

Methods for and Implementation of Pregnancy Diagnosis in Dairy Cows

The first part of this article defines the attributes of the ideal pregnancy test and describes the direct and indirect methods for pregnancy diagnosis in dairy cows that are currently available that have the potential to replace transrectal palpation. Second, this new technology must be practically integrated into a systematic on-farm reproductive management strategy and empirically demonstrated to exceed the status quo of the industry in reproductive performance. Finally a future direction for research and technology in the area of early pregnancy diagnosis in dairy cows is presented, and the overall conclusions of the ideas presented herein are drawn.

Factors associated with pregnancy-associated glycoprotein (PAG) levels in plasma and milk of Holstein cows during early pregnancy and their effect on the accuracy of pregnancy diagnosis

Lactating Holstein cows (n = 141) were synchronized to receive their first timed artificial insemination (TAI). Blood and milk samples were collected 25 and 32 d after TAI, and pregnancy status was determined 32 d after TAI using transrectal ultrasonography. Cows diagnosed pregnant with singletons (n = 48) continued the experiment in which blood and milk samples were collected and pregnancy status was assessed weekly using transrectal ultrasonography from 39 to 102 d after TAI. Plasma and milk samples were assayed for pregnancy-associated glycoprotein (PAG) levels using commercial ELISA kits. Compared to ultrasonography, accuracy was 92% for the plasma PAG ELISA test and 89% for the milk PAG ELISA test 32 d after TAI. Plasma and milk PAG levels for pregnant cows increased from 25 d to an early peak 32 d after TAI. Plasma and milk PAG levels then decreased from 32 d after TAI to a nadir from 53 to 60 d after TAI for the plasma PAG assay and from 46 to 67 d after TAI for the milk PAG assay followed by an increase from 74 to 102 d after TAI. Overall, plasma PAG levels were approximately 2-fold greater compared with milk PAG levels, and primiparous cows had greater PAG levels in plasma and milk compared with multiparous cows. The incidence of pregnancy loss from 32 to 102 d after TAI based on ultrasonography was 13% for cows diagnosed with singleton pregnancies, and plasma and milk PAG levels decreased to nonpregnant levels within 7 to 14 d after pregnancy loss. Both plasma and milk PAG levels were negatively correlated with milk production for both primiparous and multiparous cows. We conclude that stage of gestation, parity, pregnancy loss, and milk production were associated with plasma and milk PAG levels after TAI similarly. Based on plasma and milk PAG profiles, the optimal time to conduct a first pregnancy diagnosis is around 32 d after AI, coinciding with an early peak in PAG levels. Because of the occurrence of pregnancy loss, all pregnant cows should be retested 74 d after AI or later when plasma and milk PAG levels in pregnant cows have rebounded from their nadir.

Temporal changes in pregnancy-associated glycoproteins across different stages of gestation in the Barbari goat

The objective of this study was to characterize the temporal profile of pregnancy-associated glycoproteins (PAGs; isoforms 1-11) across different stages of gestation in the Barbari goat. Placentae were collected from local abattoir, classified according to crown rump length of the corresponding foetus into five groups (0-30, 31-60, 61-90, 91-120, and 121-150 days of gestation), and used for relative quantification of mRNA expression by Pfaffl method. In addition, adult female goats (pregnant, n = 7; non-pregnant, n = 5) were used to estimate weekly plasma PAG and progesterone (P4) concentrations. The relative mRNA expression of PAGs was greater (p<0.05) during 31-60 days of gestation, which correlated well with the temporal changes in plasma PAG concentrations. Relative expression of PAGs decreased steadily as gestation advanced with minimum expression observed just before parturition, except for PAG-4 and PAG-8 that showed constantly higher expression throughout pregnancy. Plasma PAG and P4 concentrations showed a distinct temporal pattern with a significant increase beginning at 2 weeks and return to basal levels by 20 weeks of gestation. However, PAG concentrations reached a peak earlier in gestation (8 weeks) than P4 (10-14 weeks). Correlation analysis indicated a strong positive association (r = 0.748, p<0.01) between plasma PAG and P4 concentrations. In conclusion, results of this study indicate a distinct temporal pattern of PAG expression and secretion during gestation in the Barbari goat. The temporal changes in PAGs and the positive association with P4 are suggestive of their role in maintenance of pregnancy and progressive foetal development.

Cellular localisation of the pregnancy-associated glycoprotein family (PAGs) in the synepitheliochorial placenta of the European bison

This paper describes the cellular immuno-localisation of the PAG family in synepitheliochorial (cotyledonary) placenta of the European bison (Eb). Uteri were harvested from pregnant wild Eb (n=4; 45-150 days post coitum-dpc); and additionally from cattle (30, 45 dpc) and pigs (42 dpc)--both domestic species were used as positive controls for cellular PAG immunodetection. Placentas were sectioned, fixed, dehydrated and subjected to double fluorescent immunohistochemistry (dF-IHC) with the use of Alexa 488 fluorochrom (A488) and propidium iodide (PI). Native positive EbPAG signals were detected by heterologous (ht; cross-species) dF-IHC with primary rabbit anti-PAG polyclonals against native or recombinant porcine PAG antigens (anti-pPAG); then visualised with secondary anti-rabbit goat immunoglobulins--conjugated to A488. Our htdF-IHC indicated an unequivocal localisation to the mono- and bi-nuclear trophectoderm (chorionic epithelium) cells expressing the PAGs (A488-green) among all placental cells, in which PI (red) stained nuclei. This is the first paper reporting the EbPAG family expression examined by htdF-IHC at the feto-maternal interface in wild Pecoran species. The cross-reactivity of anti-pPAG polyclonals with the EbPAGs suggests that shared epitopes are present in these molecules. It seems that the EbPAG family, which is robustly expressed in mono- and bi-nucleated trophectoderm cells, is associated with events taking place during placenta development. Our study also provided a proficient ht-system to identify various PAGs that could be useful as prenatal protein markers for pregnancy diagnoses, which is essential for effective reproductive management of endangered mammals.