Effect of early or late resynchronization based on different methods of pregnancy diagnosis on reproductive performance of dairy cows

Evaluation of a Commercial Pregnancy Test Using Blood or Plasma Samples in High-Producing Dairy Cows

This study evaluated a commercial pregnancy-associated glycoproteins (PAGs)-based pregnancy test using whole blood or plasma samples during early pregnancy (28-55 days of gestation) in high-producing dairy cows. Transrectal ultrasonography was used as the gold standard method. The study population constituted of 284 cows. False positive diagnoses were recorded from Day 60 to 89 and from Day 60 to 99 postpartum in blood and plasma samples, respectively. In early pregnancy screening, correct positive diagnoses were recorded in 75% and 100% of blood and plasma samples, respectively. High milk production was associated with negative results in blood samples and with the lowest test line intensity in plasma samples. False positive or negative diagnoses were recorded in 0% of both types of samples in cows previously diagnosed as pregnant and showing signs of estrus. In conclusion, the use of plasma was more effective than the use of blood in early pregnancy diagnosis. In cows previously diagnosed as pregnant and showing signs of estrus, both types of samples showed the same results. Because of large individual variations, normal single pregnancies could not be differentiated from twin pregnancies, from pregnancies with a recently dead conceptus, or from pregnancies that experienced subsequent pregnancy loss.

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.

Associations of inflammatory and reproductive tract disorders postpartum with pregnancy and early pregnancy loss in dairy cows

Our objective was to describe associations of postpartum health with pregnancy and pregnancy loss (P-LOSS) from d 19 to 40 after first postpartum artificial insemination (AI) in lactating Holstein cows. In 2 commercial dairy herds in Ontario, Canada, 468 Holstein cows were enrolled 21 ± 3 d before expected parturition when body condition score (BCS) and lameness were assessed. Serum total Ca, haptoglobin (Hp), and nonesterified fatty acids (NEFA) were measured at 2 and 6 ± 2 d in milk (DIM). Blood β-hydroxybutyrate (BHB) measurement and metritis detection were done at 4, 8, 11, and 15 ± 2 DIM. Cows were examined for endometritis (ENDO; ≥11.5% polymorphonuclear cells in endometrial cytology) and purulent vaginal discharge (PVD) at 35 ± 3 DIM. Lameness was assessed again at 21 and 49 ± 3 DIM and BCS at 63 ± 3 DIM. First postpartum AI occurred primarily (86%) based on detection of estrus by activity monitors, on average (± standard deviation) at 65 ± 9 DIM, and the remaining cows received timed AI at 86 ± 18 DIM. Serum progesterone (P4) was measured on d 8 and 12 after AI, and pregnancy at first AI (P/AI) was estimated by the expression of ISG15 in peripheral blood leukocytes at d 19 after AI and by pregnancy-associated glycoprotein in serum at d 29, 33, and 40 after AI. Each metabolite (Ca, Hp, NEFA, and BHB) was categorized above or below a cut-point identified with receiver operating characteristic curve analysis associated with P/AI confirmed by ultrasound at d 33 from a larger data set. Data were analyzed using multivariable mixed logistic regression models, accounting for parity, health variables, covariates (season at calving and at AI, milk yield at first Dairy Herd Improvement Association test [categorized into terciles], AI method, and DIM), and herd. The proportions of cows classified pregnant at d 19, 29, 33, and 40 after AI were 64%, 54%, 50%, and 45%, respectively. At d 19 after AI, P/AI was less likely in cows diagnosed with ENDO (52% vs. 69%) or PVD (54% vs. 67%). At d 29, P/AI was less likely in cows with Hp ≥1.54 g/L at 2 DIM (38% vs. 55%) or PVD (35% vs. 56%). Both metritis and ENDO were associated with decreased P/AI at d 40 after AI. Cows diagnosed with metritis had greater risk of P-LOSS from d 19 to 29 (43% vs. 22%) or from d 33 to 40 (37% vs. 7%) than cows without metritis. From d 29 to 33, the risk of P-LOSS was greater in cows with NEFA ≥0.73 mM at 2 DIM (13% vs. 5%) or BCS ≤2.75 at 63 DIM (14% vs. 5%). The concentration of P4 on d 8 after AI was positively associated with P/AI at d 29, 33, and 40, and negatively associated with P-LOSS from d 19 to 29. Postpartum health disorders, particularly reproductive tract disease, can have detrimental effects on early pregnancy establishment and on pregnancy maintenance from d 19 to 40 after AI.

Proteomics approach reveals urinary markers for early pregnancy diagnosis in buffaloes

This study aimed to compare urine proteomics from non- and pregnant buffaloes in order to identify potential biomarkers of early pregnancy. Forty-four females underwent hormonal ovulation synchronization and were randomly divided into two experimental groups: inseminated (n = 30) and non-inseminated (n = 14). The pregnant females were further divided into two groups: pregnant at Day 12 (P12; n = 8) and at Day 18 (P18; n = 8) post-ovulation. The non-pregnant group was also subdivided into two groups: non-pregnant at Day 12 (NP12; n = 7) and at Day 18 (NP18; n = 7). Urine was collected from all females on Days 12 or 18. The samples were processed for proteomics. A total of 798 proteins were reported in the urine considering all groups. The differential proteins play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that some proteins from our study can be considered biomarkers for early pregnancy diagnosis, since they were increased in pregnant buffaloes. SIGNIFICANCE: Macromolecules have been studied for early pregnancy diagnosis, aiming to increase reproductive efficiency in cattle and buffaloes. Direct methods such as rectal palpation and ultrasonography have been considered late. Thus, this study aimed to compare urine proteomics from non- and pregnant buffaloes to identify potential biomarkers of early pregnancy. The differential proteins found in our study play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that these proteins can be considered possible biomarkers for early pregnancy diagnosis since they were increased in the pregnant buffaloes.

Recent advances in treatments for resynchronization of ovulation in small ruminants: a review

Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.

Performing Early Pregnancy Tests in Milk and Their Effect on Cow Welfare and Reproductive Performance Compared to Rectal Pregnancy Tests 40 to 45 Days Post Insemination

The main pregnancy test method for dairy cows is rectal palpation performed around 40–45 days from last insemination. This is an invasive examination that disrupts the cow’s routine, potentially affecting its well-being. We examined the effectiveness of a commercial kit for performing pregnancy tests on milk samples compared to rectal palpation at 28- and 42-days post insemination. Accordingly, the purpose of the current study was to check if performing early pregnancy test instead of rectal palpation would result in better welfare and improvement of the reproductive performance, at least in part, of the cows. At 28 days, we examined the effect of early pregnancy testing on reproductive performance, especially number of days open. At 42 days, we determined the pregnancy test methods’ effects on cow welfare measures and milk production. For the day 28 experiment, cows on one farm were divided into two groups: one milk-tested for pregnancy on 28 to 30 days after insemination, and the other tested by routine veterinary examination (42 to 45 days after insemination). The milk test resulted in a 16-day reduction in days open for cows identified as non-pregnant on day 28 compared to day 42 (rectal examination), potentially improving reproductive performance on the dairy farm. For the day 42 experiment, test effects on cow welfare as seen in pedometer data and milk production were examined on two large dairy farms. Test-day milk production did not differ significantly between milk-tested and rectally palpated groups, but well-being indices of milk-tested cows improved, especially in winter months. The reason for this can be because, in the summer, cows are interrupted due to colling activities. In addition to fewer days open and economic improvement, early milk tests for pregnancy can free up the practitioner for other tasks on the dairy farm.

Using commercial enzyme immunoassay for measuring pregnancy-associated glycoproteins to diagnose pregnancy in dairy cows under field conditions in Algeria

The purpose of the present work was to study effectiveness for early pregnancy diagnosis in cattle of the new enzyme immunoassay (EIA) sandwich kit commercially available based on the measurement of pregnancy-associated glycoproteins (PAGs). 120 Holstein-Friesian cattle of mixed age and parity were comprised from different dairy herds. The pregnant females (n = 68) were diagnosed by ultrasonography at day 35-40 after artificial insemination and confirmed by transrectal exploration at 2-3 months after AI. The non-pregnant females (n = 52) were housed in the absence of males during the experimental period. Blood samples were collected from coccygeal vessels of females into EDTA tubes. The serum was obtained by centrifugation and the serum was stored at - 20 C until assay. The PAG concentrations in pregnant and non-pregnant females were determined in serum by EIA kit. The reproducibility inter- and intra-assay of the PAG-EIA is satisfactory (2.78 and 13.19 %, respectively). The accuracy ( 94.8 %) and the test of parallelism were largely acceptable. No cross-reaction was observed with the different hormones tested at different dilutions. PAG-EIA system gave 100 % sensitivity and negative predictive values. Whereas, specificity and positive predictive value were 91.93 and 71.15 %, respectively. The accuracy of pregnancy diagnosis by PAG-EIA was 87.5 %. In conclusion, the present study shows clearly that the EIA kit can be used to measure PAG in serum cows for the detection of gestation in Algeria. Therefore, this alternative technique could be recommended to replace the radioactive methods in immunoassays to improve the reproductive performances and an efficient tool for reproductive management of dairy cattle.

Recent Possibilities for the Diagnosis of Early Pregnancy and Embryonic Mortality in Dairy Cows

Simple Summary

Pregnancy diagnosis plays an essential role in decreasing days open in dairy farms; therefore, it is very important to select an accurate method for diagnosing early pregnancy. Besides traditional pregnancy diagnoses made by rectal palpation of the uterus from 40 to 60 days after AI and measuring the serum or milk progesterone concentration between 18 to 24 days after AI, there are several new possibilities to diagnose early pregnancy in dairy farms. However, it is very important to emphasize that before introducing any new diagnostic test, we need to make sure the accuracy of that particular test to be able to decrease the rate of iatrogenic pregnancy losses caused by prostaglandin or resynchronization treatments. This review focuses on the diagnostic possibilities and limitations of early pregnancy diagnosis in the field.

Abstract

One of the most recent techniques for the on-farm diagnosis of early pregnancy (EP) in cattle is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from Days 25 to 30 post-AI. The reliability of the test greatly depends on the frequency of the transducer used, the skill of the examiner, the criterion used for a positive pregnancy diagnosis (PD), and the position of the uterus in the pelvic inlet. Non-pregnant animals can be selected accurately by evaluating blood flow in the corpus luteum around Day 20 after AI, meaning we can substantially improve the reproductive efficiency of our herd. Pregnancy protein assays (PSPB, PAG-1, and PSP60 RIA, commercial ELISA or rapid visual ELISA tests) may provide an alternative method to ultrasonography for determining early pregnancy or late embryonic/early fetal mortality (LEM/EFM) in dairy cows. Although the early pregnancy factor is the earliest specific indicator of fertilization, at present, its detection is entirely dependent on the use of the rosette inhibition test; therefore, its use in the field needs further developments. Recently found biomarkers like interferon-tau stimulated genes or microRNAs may help us diagnose early pregnancy in dairy cows; however, these tests need further developments before their general use in the farms becomes possible.

Characterization of pregnancy-associated glycoproteins and progesterone as a predictor of twins and conceptus loss in high-risk-pregnancy Holstein cows

The objective of this study was to characterize plasma concentrations of pregnancy-associated glycoprotein (PAG) and progesterone (P4) as predictors of twins and pregnancy loss in Holstein cows with high-risk pregnancies. High-risk pregnancy was characterized using transrectal ultrasonography 37 d after artificial insemination (AI) based on the following criteria: small embryo size <15 mm, n = 10), slow heartbeat (<60 beats per minute, n = 11), and extra-amniotic membrane (additional amniotic membrane, n = 3). A cohort of twins (n = 41) diagnosed at d 37 post-AI was also enrolled. Each high-risk and twin pregnancy cow was paired with a cow of the same parity carrying a normal singleton at d 37 post-AI (control, n = 65). Blood samples were collected to measure PAG and P4 at d 37, 44, and 51 post-AI. Statistical analysis was performed using ANOVA, logistic regression, and receiver operator characteristic (ROC) curve with JMP software (SAS Institute Inc., Cary, NC). Pregnancy loss at d 51 post-AI was greater in high-risk pregnancies than in controls and twins (control = 1.5%; high-risk = 87.5%; twins = 12.2%). Concentration of PAG at d 37 post-AI did not differ among groups (control = 5.3 ± 0.7; high-risk = 4.8 ± 1.2; twins = 4.0 ± 0.9 ng/mL). Concentration of P4 at d 37 post-AI was greater in twins than in high-risk pregnancies and control, and lesser in high-risk pregnancies than in controls (control = 7.0 ± 0.3; high-risk = 5.9 ± 0.4; twins = 8.4 ± 0.3 ng/mL). Regression and ROC analysis for PAG at d 37 post-AI did not find a threshold to predict pregnancy loss or twins. Regression and ROC analysis for P4 at d 37 post-AI found that a threshold of 6.5 ng/mL predicted pregnancy loss with an area under the curve (AUC) of 0.64, and a threshold of 7.2 ng/mL predicted twins with AUC of 0.71. In summary, pregnancy loss and twins were predicted with only moderate accuracy by P4 concentration at d 37 post-AI, and the variability in PAG concentrations at d 37 post-AI was not sufficient to generate a threshold to predict pregnancy loss and twins in Holstein lactating cows.

Efficacy of a commercial test kit to determine early pregnancy in cows using whole blood and blood serum

The objective of this study was to determine the efficacy of the Fassisi®BoviPreg visual test kit (Fassisi®BoviPreg) in determining early pregnancies in cows by measuring the pregnancy-associated glycoprotein (PAG) in whole blood and blood serum. The study was conducted on 50 cows, the artificial insemination (AI) dates of which were designated as day 0. Pregnancy diagnosis was performed with transrectal ultrasonography (USG), and serum samples were simultaneously collected and used with Fassisi®BoviPreg to determine pregnancies on 30 days after AI. The results of the Fassisi®BoviPreg test on serum and whole blood samples, respectively, on 30 days after AI were as follows: sensitivity, 61.54% and 50.0%; specificity, 79.17% and 75%; accuracy, 70.0% and 62.0%; positive predictive values, 76.2% and 68.4%; negative predictive values, 65.5% and 58.1%; false-positive diagnoses, 23.8% and 31.6%; and false-negative diagnoses, 34.5% and 41.9%. On day 50 after AI, sensitivities were 63.64% and 50.0%, specificities were 100.0% and 100.0%, and accuracies were 75.0% and 65.62% in serum and whole blood, respectively. Higher pregnancy rates were obtained using Fassisi®BoviPreg in cows with ≥ 5 ng/mL P4 (P < 0.001). In conclusion, the results from the Fassisi®BoviPreg tests on cows on 30 and 50 days after AI showed that the use of blood serum is more accurate and suitable than that of whole blood. The results also showed a higher confidence level in specificity 50 days after AI.

Early pregnancy diagnoses based on physiological indexes of dairy cattle: a review

With the development of standardization and scaling in the dairy farming industry, timely and accurate pregnancy diagnosis is required to improve the benefits of breeding by shortening the calving interval. However, the current pregnancy diagnostic methods cannot meet the requirements of the industry. Here, we review changes in the physiological indexes and in the function and morphological status of the reproductive organs of dairy cows at the early stages of pregnancy. In addition, the corresponding pregnancy diagnostic methods based on certain indexes are well development, and the pregnancy diagnostic approaches based on remote sensing and automation technology have become inevitable trends in the industry. These applications will reveal physiological regularities in pregnancy and benefit the detailed management of dairy cows during early pregnancy.

Development of the Timed Re-Insemination (TRI-synch) program re-inseminating 24 days after the initial service in dairy cows

For the timed re-insemination at the minimal interbreeding interval, cows were treated with a progesterone (P4 )-releasing intravaginal device from Days 13-15 to 21 post-insemination (Day 0 = estrus), followed by plasma P4 assay on Day 23 and then subjected to the Experiments 1 and 2. In Experiment 1, of 18 cows, 6 cows were determined as luteolysis with low (<1 ng/ml) plasma P4 concentrations on Day 23 and ovulated on Days 24 (3 cows), 25 (1 cow), and 26 (1 cow) except a cow affected by ovarian quiescence. In Experiment 2, all cows were treated with GnRH on Day 23. Cows with low (<1 ng/ml) plasma P4 concentrations on Day 23 were diagnosed as non-pregnant and subjected to the re-insemination in the morning of Day 24 irrespective of estrous signs. Of 36 cows, 15 cows were diagnosed as being non-pregnant on Day 23. Fourteen cows of the non-pregnant animals were re-inseminated in the morning of Day 24 irrespective of estrous signs and the pregnancy rate of re-insemination was 36%. The conception rates of initial and re-inseminations were 50% (18/36) and 36% (5/14), respectively. The overall pregnancy rate by adding the rates of initial and re-inseminations was 64% (23/36).

A shortened resynchronization treatment for dairy cows after a nonpregnancy diagnosis

We hypothesized that a shortened version of a modified Ovsynch program (OVS: GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) that excluded GnRH-1 to resynchronize ovulation in cows bearing a corpus luteum (CL) after a non-pregnancy diagnosis (NPD) or including progesterone supplementation with the OVS treatment for cows without a CL would produce shorter inter-insemination intervals and pregnancy per AI (P/AI) not different from that of cows treated with the OVS treatment. Of the 1697 lactating Holstein cows enrolled in this experiment, complete data were available for only 1584 cows because the remainder was not treated, inseminated per treatment design, left the herd before pregnancy diagnosis, or some other outcome was missing. Cows were enrolled in the study and assigned to either of three treatments at NPD (32 ± 3 d after AI [Day 0]). Cows with a detected CL were assigned randomly to: (1) a modified Ovsynch (OVS; GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) or (2) Short Synch (SS; PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI). Cows with no CL were assigned to OVS plus a progesterone insert (CIDR). Blood was collected at NPD to measure progesterone concentration and determine accuracy of treatment assignment (progesterone ≥ 1 ng/mL for a functional CL). Overall progesterone concentration at NPD was less in OVS + CIDR cows (1.5 ± 0.3 ng/mL) than in OVS (5.2 ± 0.2 ng/mL) or SS cows (3.7 ± 0.3 ng/mL). No differences in luteolytic risk (progesterone < 0.5 ng/mL at 72 h after PGF_2α-1) were detected after PGF_2α (>96.7%) and ovulation risk after GnRH-2 was 93.8, 91.7, and 86.2% for SS, OVS, and OVS + CIDR, respectively. Mean and median inter-insemination interval were less in SS (mean = 34.3 ± 0.05 d [median = 35 d] than OVS cows (40.2 ± 0.05 d [42 d]), but that in OVS cows did not differ from OVS + CIDR cows (41.4 ± 0.05 d [42 d]). Technicians were more accurate in visually detecting a functional CL than a non-functional CL (81.2 vs. 61.1%). Sensitivity of detecting a functional CL by technicians averaged 91.2%, but specificity was 39.8%. Pregnancy per AI at 32 ± 3 d after AI was less for SS (16.5% [n = 115]) than OVS (29.3% [n = 133] when a functional CL was inaccurately detected, but did not differ when a functional CL was detected accurately (27.6% [n = 561] vs 30.3% [508]). Pregnancy per AI did not differ between OVS and OVS + CIDR cows regardless of CL status. Short synch is an alternative to the entire modified Ovsynch program to produce similar P/AI when the CL status was detected accurately, and regardless of functional CL status, SS reduced inter-insemination intervals by 7 d.

Duplex Quantitative Polymerase Chain Reaction of ISG15 and RSAD2 Increases Accuracy of Early Pregnancy Diagnosis in Dairy Cows

Early diagnosis of pregnancy is important in livestock production, but there is no reliable technology used for pregnancy diagnosis within the first three weeks after insemination. During early pregnancy, the expression of interferon-stimulating genes (ISGs) in peripheral blood leukocytes (PBL) is significantly increased. However, due to different strains, detection sample types, detection methods, threshold value, etc. the specific effectiveness of early pregnancy diagnosis using ISGs is worth further study. The purpose of this study was to test interferon-stimulated protein 15 (ISG15), 2'–5'-oligoadenylate synthetase 1 (OAS1) and radical S-adenosyl methionine domain containing 2 (RSAD2) for early pregnancy diagnosis in dairy cows. The expression of ISG15, OAS1, and RSAD2 in PBL of pregnant and non-pregnant heifers on days 0, 14, 18, 21 and 28 after artificial insemination (AI) was detected by fluorescence quantitative polymerase chain reaction (PCR). The sensitivity and specificity of the pregnancy diagnosis was analyzed using expression of these three genes separately or in combination by receiver operating characteristic curve. The combination with the highest accuracy used probe primers and duplex fluorescence quantitative PCR. The single quantitative PCR results showed that expression of ISG15, OAS1 and RSAD2 on day 18 after AI was significantly higher in pregnant than in non-pregnant cows. When these three genes were used separately, or in combination, for early pregnancy diagnosis, the sensitivity for the RSAD2 gene was 100%, and the combination of ISG15 with RSAD2 was 94.7%. The duplex quantitative PCR showed that, although the sensitivity of ISG15 alone was 100%, its specificity was only 88.2% (cut-off value 1.402). The sensitivity of RSAD2 alone was 89.5%, and the specificity was 88.2%; however, when the two genes were used in combination, the sensitivity, specificity and diagnostic cut-off value were consistent with the results of single quantitative PCR. These results indicated that a duplex quantitative PCR assay system for early pregnancy diagnosis in cows using ISG15 and RSAD2 was established. Simultaneous detection of expression of ISG15 and RSAD2 by duplex quantitative PCR can effectively improve the diagnostic accuracy for dairy cows.

Hormonal protocols for early resynchronization of ovulation in ewes: The use of progestagens, eCG, and inclusion of early pregnancy diagnosis with color Doppler ultrasound

This study aimed to evaluate 1) the effect of inserting an intravaginal sponge containing medroxyprogesterone during the late luteal phase on the corpus luteum (CL) function and endogenous production of P4; 2) the effectiveness of two different equine chorionic gonadotrophin (eCG) doses on synchronization of ovulations for a resynchronization treatment; and 3) the inclusion of an early pregnancy diagnosis in an early resynchronization protocol for ovulation in ewes. For all studies, the synchronization protocol was based on a short-term protocol of six days of progestogen treatment plus one dose of prostaglandin F2alpha, one dose of eCG, and gonadorelin acetate after sponge withdrawal. For the first study, the ewes were mated with fertile rams; a second sponge was inserted in half of these ewes 12 days later, and blood samples were collected daily for six days, until sponge withdrawal. For the second study, the ewes were not mated, and received a second sponge during the same period, after which they were divided into three groups according to eCG dose (0, 200, or 300 IU). In the third study, all ewes were artificially inseminated and received the second sponge during the same period. At sponge withdrawal, pregnancy was diagnosed by color Doppler ultrasonography (DUS) of the CL, and only non-pregnant ewes were re-inseminated two days later. In the first study, serum progesterone values were similar regardless of whether an intravaginal sponge had been inserted. In the second study, the ovulation time was more concentrated in those ewes which received 200 IU of eCG. In the third study, there was no difference between the experimental groups (with or without a previous pregnancy diagnosis) in pregnancy rate at the first insemination, accumulated pregnancy rate, and pregnancy loss. The insertion of an intravaginal sponge impregnated with medroxyprogesterone acetate did not affect the endogenous production of P4. The application of 200 IU of eCG provided the best result with regard to the synchronization of ovulations in the resynchronization treatment. Also, the inclusion of an early pregnancy diagnosis with DUS is useful and improves the general results of resynchronization programs, shortening the total working period.

Resynchronisation as an Element of Improving Cattle Reproduction Efficiency

Oestrus resynchronisation (RES, Resynch) programmes for non-pregnant cows allow shortening the period between an unsuccessful insemination and the next attempt on the same cow. The protocol of oestrus RES may be started after ruling out pregnancy by means of ultrasonography carried out 28 days after insemination or after performing a test for pregnancy-specific glycoproteins (PAG) in blood or milk. The Resynch protocol can be based on a double application of prostaglandins, the OvSynch protocol, or hormonal therapy with exogenous sources of progesterone (CIDR intravaginal devices). The efficiency of the method depends on the functional state of the ovaries, the diameter of the corpus luteum, external factors, and the health and maturity of the cows. The present paper constitutes a comparison of research findings concerning the effectiveness of RES programmes.

Recombinant interferon stimulated protein 15 (rISG15) as a molecular marker for detection of early pregnancy in Bubalus bubalis

Early and accurate diagnosis of pregnancy in animals is important for improving the reproductive management of livestock. The buffalo (Bubalus bubalis) is the most important dairy animal in India, but there are reproductive problems resulting from extended calving interval and ovulation occurring in the absence of behavioral estrus. The lack of simple methods for early pregnancy diagnosis intensifies these problems. The present study, therefore, was conducted to ascertain the role of the interferon-stimulated gene, (ISG), 15 in pregnancy detection. The anti-ISG15 Mab based ELISA was developed that could be used for detecting pregnancy at 18 to 20 days after artificial insemination (AI). The ISG15 protein was isolated from a pregnant buffalo and was amplified, and cloned in Escherichia coli by using coding region primers. The ISG15 gene was expressed in the host Escherichia coli BL21 (DE3), and the protocol was standardized for optimum gene expression. Using immortal hybridoma (fused myeloma and B cells) cells, a highly specific and sensitive antibody, anti-ISG15 mAb, for detecting ISG15 (protein) in the serum of pregnant buffaloes was obtained. A blocking ELISA was developed using the anti-ISG15 mAb to detect pregnancy in buffalo within 18 to 21 days after AI. The ISG15 gene was upregulated (P <  0.05) in pregnant buffalo at 18 to 21 days of pregnancy. This assay has an overall diagnostic accuracy of 75.0%. It, therefore, is concluded that recombinant ISG15 retains the potential for detecting pregnancy in B. bubalis and may have applications in ELISA kits for pregnancy detection in closely related species.

Could a bovine pregnancy rapid test be an alternative to a commercial pregnancy-associated glycoprotein ELISA test in dairy cattle?

The aim of the present study was to compare a Bovine Pregnancy Rapid Test (Ubio quickVET; BPRT) with a commercial ELISA-PAG test (Bovine Pregnancy Test DG29®) for early pregnancy diagnosis based on the presence of the PAG (pregnancy-associated glycoprotein) in dairy cattle between 30 and 40 days after artificial insemination (AI). Blood samples were collected from 212 cows between 30 and 40 days after artificial insemination (AI) to quantify the concentrations of PAG in each sample. Transrectal ultrasonography (TRUS) diagnosis of pregnancy was conducted at day 45 ± 3 after AI as the reference standard for the two PAG tests. The results indicated the sensitivity (Se) of the BPRT and DG29 for diagnosing pregnant cattle were 89.4% and 100%, respectively while the specificity (Sp) of the two tests for diagnosis of non-pregnant animals was 89.8% and 81.3%, respectively. Based on these results, the BPRT has a slightly lesser sensitivity and greater specificity than the DG29 test. Moreover, the accuracy of both tests was 94% and 90% respectively for DG29 and BPRT. This implies that the BPRT test could be considered an accurate test when compared to PAG-ELISA test and TRUS at days 30-40 after AI. The BPRT test, therefore, can be used as an alternative to the PAG-ELISA test with some constraints that need to be considered with its use.

A resynchronization of ovulation program based on ovarian structures present at nonpregnancy diagnosis reduced time to pregnancy in lactating dairy cows

Our objective was to evaluate time to pregnancy after the first service postpartum and pregnancy per artificial insemination (P/AI) in dairy cows managed with 2 resynchronization of ovulation programs. After first service, lactating Holstein cows were blocked by parity (primiparous vs. multiparous) and randomly assigned to the d 32 Resynch (R32; n = 1,010) or short Resynch (SR; n = 1,000) treatments. Nonpregnancy diagnosis (NPD) was conducted 32 ± 3 d after AI by transrectal ultrasonography. Nonpregnant cows in R32 received the Ovsynch protocol: GnRH, PGF_2α 7 d later, GnRH 56 h later, and timed AI (TAI) 16 to 18 h later. Cows in SR with a corpus luteum (CL) ≥15 mm and a follicle ≥10 mm at NPD received PGF_2α, PGF_2α 24 h later, GnRH 32 h later, and TAI 16 to 18 h later. Cows in SR without a CL ≥15 mm or a follicle ≥10 mm at NPD received a modified Ovsynch protocol with 2 PGF_2α treatments and progesterone (P4) supplementation (GnRH plus CIDR, PGF_2α and CIDR removal 7 d later, PGF_2α 24 h later, GnRH 32 h later, and TAI 16 to 18 h later). Blood samples were collected from a subgroup of cows at the GnRH before TAI (R32 = 114; SR = 121) to measure P4 concentration. Binomial outcomes were analyzed with logistic regression and hazard of pregnancy (R32 = 485; SR = 462) with Cox's proportional regression in SAS (SAS Institute, Cary, NC). For P/AI analysis, the TAI service was the experimental unit (R32 = 720; SR = 819). Models included treatment and parity as fixed effects and farm as random effect. The hazard of pregnancy was greater for the SR treatment (hazard ratio = 1.18; 95% confidence interval: 1.01-1.37). Median time to pregnancy was 95 and 79 d for the R32 and SR treatments, respectively. At NPD, 71.3 and 71.2% of cows had a CL for the R32 and SR treatments, respectively. Treatment did not affect overall P/AI 32 ± 3 d after AI (R32 = 31.0% vs. SR = 33.9%) or for cows with a CL at NPD (R32 = 32.7% vs. SR = 32.8%). For cows with no CL at NPD, P/AI was greater for the SR treatment (36.9%) than for the R32 treatment (28.6%). Pregnancy loss from 32 to 63 d after AI was similar for all services combined (R32 = 8.3% vs. SR = 10.4%) and for cows with no CL at NPD (R32 = 13.2% vs. SR = 7.2%) but tended to be affected by treatment for cows with a CL at NPD (R32 = 6.8% vs. SR = 11.9%). Treatment affected the proportion of cows with P4 ≤0.5 ng/mL at the GnRH before TAI for all cows (R32 = 68.4% vs. SR = 81.8%), tended to have an effect among cows with a CL (R32 = 70.0% vs. SR = 81.8%), and had no effect for cows with no CL (R32 = 64.7% vs. SR = 81.8%). We concluded that the SR program reduced time to pregnancy because of a reduction of the interbreeding interval for cows with a CL at NPD and greater P/AI in cows with no CL at NPD.

Short communication: Optimization of a timed artificial insemination program for reproductive management of heifers in Canadian dairy herds

Pregnancy per AI (P/AI) following the use of 1 of 2 timed AI (TAI) protocols and 2 different intervals between TAI and resynchronization were compared in heifers that were inseminated with either conventional or sex-sorted semen. Holstein heifers (n = 317; 527 inseminations) were submitted to a 5-d Cosynch protocol with (+) or without (-) GnRH at the time of controlled internal drug release (CIDR) insertion on d 0, CIDR removal and a single PGF_2α treatment on d 5, and TAI plus GnRH on d 8 (72 h later). Visual estrus detection (ED) was conducted on d 6 in the afternoon and d 7 in the morning and heifers observed in estrus were artificially inseminated on d 7 in the afternoon. Heifers were alternately assigned conventional or sex-sorted semen. Pregnancy was diagnosed by ultrasound 27 and 42 d after AI, and heifers diagnosed as nonpregnant were resynchronized, up to 3 times, starting on d 27 or 34 to provide an interbreeding interval of 35 or 42 d. Overall, TAI protocol had no effect on P/AI at 27 or 42 d after artificial insemination or on pregnancy loss, but P/AI following the first service tended to be higher in the -GnRH TAI group (66.3 vs. 56.8%). Pregnancy per AI at 27 d (61.9 vs. 55.5%) tended to differ between conventional and sex-sorted semen. Heifers artificially inseminated based on ED tended to have a greater P/AI (67.6 vs. 58.2%) and had decreased pregnancy loss (0.0 vs. 4.1%) than those submitted to TAI. A greater number of heifers in the -GnRH TAI protocol were artificially inseminated on ED than the +GnRH TAI protocol (21.5 vs. 13.7%). No difference in P/AI was observed between the 35- and 42-d interbreeding intervals; however, more heifers in the 42-d group were artificially inseminated based on ED than in the 35-d group (22.7 vs. 7.8%). A 5-d Cosynch+CIDR TAI protocol without the initial GnRH and with a single PGF_2α at CIDR removal is an acceptable alternative to achieve high P/AI when either conventional or sex-sorted semen is used in Holstein heifers. Breeding heifers based on detected estrus increases labor, but has the potential to increase fertility.

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.