The relationship of the interval from breeding to uterine palpation for pregnancy diagnosis with calving outcomes in holstein cows

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.

Influence of an Exercise Program, Muscle Strength, Proprioception, and Arm Length on Veterinary Students' Bovine Pregnancy Diagnosis Accuracy

Bovine pregnancy diagnosis (PD) by transrectal palpation (TRP) is an important skill for veterinary graduates. Factors influencing students' PD accuracy were investigated to optimize bovine PD by TRP training without increasing live animal exposure. The objective was to determine whether arm length and strength, proprioception, and exposure to a 6-week exercise training program were significantly associated with students' PD accuracy. Veterinary students (n = 128) who had previously received formal theoretical and practical training in bovine TRP and PD (live cows and TRP simulators) were assessed for PD accuracy on live cows. Prior to assessment, arm muscle strength measurement, an exercise program, and additional TRP sessions on Breed'n Betsy^® simulators and live cows were offered to the students. Seventy-eight students volunteered to participate in the arm length measurement, muscle strength, and proprioception testing. Of these, 35 randomly allocated students completed a 6-week exercise program, after which muscle strength was reassessed. Each student performed PDs on six cows of which the pregnancy status, ranging from 6 weeks to 9 months pregnant or not pregnant, was predetermined by an experienced veterinarian. PD accuracy was measured as sensitivity and specificity, being defined as the proportion of pregnant or nonpregnant cows, respectively, correctly identified by the student. It is concluded that hand grip strength and participation in an exercise program are significant predictors of veterinary students' PD accuracy. Implementation of an exercise program aimed at improving grip strength in the veterinary curriculum is a novel approach to improve bovine TRP and PD training.

Effect of a high-intensity one-week training programme and student-level variables on the bovine transrectal palpation and pregnancy diagnosis skills of final-year veterinary students

BACKGROUND

To improve bovine transrectal palpation (TRP) and pregnancy diagnosis (PD) training, the effect of a high-intensity one-week training programme for veterinary elective students (N=59) with an interest in production animal practice was evaluated.

METHODS

Training consisted of exposure to rectal examination simulators, abattoir organs, theory materials and live cow PDs supervised by experienced large animal practitioners. Palpation skills were assessed before and after training using a validated TRP Objective Structured Clinical Examination (OSCE) in non-pregnant cows. Each student then performed PDs (n=12) on cows of known pregnancy status. Students' PD accuracy was measured as sensitivity and specificity, being respectively defined as the proportion of pregnant and non-pregnant cows correctly identified.

RESULTS

Students' scores improved from the first to the second OSCE (P=0.03), mostly as a result of improved ability to identify uterine symmetry/asymmetry and the presence/absence of a corpus luteum on the right ovary (P<0.01 and P=0.03, respectively). Overall student sensitivity and specificity of PD were 89.1 per cent (95 per cent CI 78.1-92.2 per cent) and 67.7 per cent (95 per cent CI 60.1-74.5 per cent), respectively.

CONCLUSION

This prospective cohort study describes a strategy to improve students' TRP skills with the potential to reduce training time and animal use at teaching institutions by outsourcing student training to private practitioners.

Effect of student transrectal palpation on early pregnancy loss in dairy cattle

Transrectal palpation of the reproductive tract is the most common method for pregnancy determination in cattle and is considered a veterinary skill that new veterinary medicine (DVM) graduates should perform proficiently. However, using privately owned cattle to train students can be difficult because producers may believe that transrectal palpation by inexperienced students increases the risk of pregnancy wastage compared with examination by an experienced clinician. We used a randomized field trial of 1,216 healthy Holstein and Jersey cattle in 2 commercial dairy herds to estimate the effect of veterinary student transrectal palpation on early pregnancy loss. All cattle were determined to be pregnant using transrectal ultrasonography at approximately 37 d after artificial insemination. Cattle were then allocated into 2 groups based upon their ear tag number (study group = 598; control group = 618). Cattle in the study group were immediately palpated after ultrasonography by a fourth-year veterinary student, whereas control cattle were not subject to any additional pregnancy assessment. For analysis, the student palpators were divided into 2 groups: students who had previously had formal palpation training via an elective bovine palpation class (n = 30) and students who had not had palpation training (n = 134). All cattle were reevaluated using transrectal ultrasonography approximately 70 d after artificial insemination. A total of 53 (4.36%) animals lost their pregnancy between the first and second pregnancy assessments. Of the animals that lost their pregnancy, 26 (4.35%) were study group cows and 27 (4.37%) were control cows. Of the 26 cows documented to have had pregnancy loss within the study group, 20 out of 378 (5.3%) had been palpated by students who had not taken the palpation elective and 6 out of 220 (2.7%) had been palpated by students who had completed the elective. We found no difference in pregnancy loss between student-palpated and clinician-ultrasounded cattle, supporting the safety of using privately owned animals for student bovine palpation and pregnancy diagnosis training without affecting early pregnancy loss.

Ability of a bovine transrectal palpation objective structured clinical examination to predict veterinary students' pregnancy diagnosis accuracy

Bovine pregnancy diagnosis (PD) by transrectal palpation (TRP) is one of the most frequently performed procedures in bovine practice, and an important competency for veterinary graduates. It is currently not known if pre-existing TRP skills on non-pregnant cows can be used to predict students' future PD accuracy. The study objective was to evaluate if TRP objective structured clinical examination (OSCE) scores can predict students' future PD accuracy.Fourth year (of a six-year programme) veterinary students (n=128) received TRP and PD training on Breed'n Betsy (BB) simulators and live cows. Students' TRP skills were assessed using a live cow TRP OSCE after completion of the fourth year training. The same students received additional TRP (BB and live cows) and PD (BB) training sessions in the first semester of their fifth year. PD accuracy was assessed after the additional TRP and PD training, five months after the TRP OSCE assessment and measured as sensitivity and specificity (the ability to correctly identify the presence and absence of pregnancy, respectively). Each student palpated six cows transrectally to diagnose pregnancy status and stage for the PD assessment. The TRP OSCE results were analysed as predictors for students' PD accuracy.Students with 'competent palpation skills' on the TRP OSCE had higher PD specificity. The individual OSCE components that were predictive of higher PD accuracy were students' ability to estimate ovarian size, identify uterine position and exclude intrauterine fluid. It was concluded that a TRP OSCE has the ability to predict students' future PD accuracy.

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.

Training Method and Other Factors Affecting Student Accuracy in Bovine Pregnancy Diagnosis

To optimize bovine pregnancy diagnosis (PD) training, factors influencing student performance were investigated. The objective was to determine whether training method, gender, background (farm, urban, or mixed), previous experience in bovine PD, and current career interest influenced the accuracy of bovine PD by trans-rectal palpation (TRP). Fourth-year (of a 6-year program) veterinary students (n=138) received one PD training session in groups using either simulator training on Breed'n Betsy (BB) or training on live cows (C). Students completed a questionnaire on gender, background, and career interest. Students' PD accuracy (pregnancy status and stage) was determined after training when each student palpated six cows with known pregnancy status. Students' accuracy in determining pregnancy status was measured as sensitivity and specificity (the ability to correctly identify the presence and absence of pregnancy respectively). Factors that influenced overall accuracy with a higher student sensitivity of bovine PD by TRP were training method, farming background, an interest in a mixed animal career, and stage of gestation. Gender of students and previous experience in bovine PD did not have an influence. Training on BB simulators was associated with lower student sensitivity for pregnancy detection in cows <6 months pregnant. Student sensitivity for pregnancy detection in cows >6 months pregnant was similar for training on BB simulators and live cows. No evaluated factors were significantly associated with specificity of PD. Teaching efforts focusing on specificity of PD and repeated simulator-based training in conjunction with live cow exposure are recommended.

Comparison between allantochorion membrane and amniotic sac detection by per rectal palpation for pregnancy diagnosis on pregnancy loss, calving rates, and abnormalities in newborn calves

The objectives of the present investigation were to evaluate the pregnancy diagnosis by detection of either the allantochorion membrane (FMS) or amniotic sac (ASP) by per rectum palpation (PRP) during late embryonic or early fetal period on pregnancy loss (PRL) at reexamination, calving rates, and abnormalities in newborn calves. A controlled randomized blind design with 800 lactating dairy pregnant cows diagnosed by transrectal ultrasonography (TRUS) between Days 35 and 57 of gestation from one dairy farm were included. The cows were randomly divided according to detection of allantochorion membrane (FMS group; n = 264), detection of amniotic sac (ASP group; n = 266), and TRUS (control [CON] group; n = 270). TRUS was considered as the criterion standard method of comparison. The entire PRP was performed by one experienced veterinarian. Then, all the cows were reexamined only by TRUS between 2 and 4 weeks later by two independent veterinarians to assess PRL. The calving rate one (number of cows calved divided by the number of cows initially pregnant) and calving rate two (number of cows calved divided by the number of cows pregnant at reexamination) for each group was calculated. All abortions and stillborns were necropsied, and calves alive were followed for 5 days. The overall initial PRL (between initial pregnant cows and reexamination) for FMS, ASP, and CON groups was 7.4% (19/258), 8.8% (23/262), and 9.2% (24/260), respectively (P = 0.75). The overall late PRL (between reexamination and calving) for FMS, ASP, and CON groups was 4.2% (9/213), 5.7% (12/209), and 4.2% (9/216), respectively (P = 0.71). The calving rate one for FMS, ASP, and TRUS groups was 79.1% (204/258), 75.2% (197/262), and 79.6% (207/260), respectively (P = 0.63). The calving rate two for the same groups was 85.4% (204/239), 82.4% (197/239), and 87.7% (207/236), respectively (P = 0.27). The number of fetuses aborted late, premature, and mature dead from FMS, ASP, and CON groups was 6, 4, and 5, respectively (P = 0.85), and no abnormalities at necropsy were detected. One stillborn male calf with atresia coli after 281 days of gestation from a cow examined by ASP at Day 51 was diagnosed. It was concluded that the use of either FMS or ASP for pregnancy diagnosis during late embryonic or early fetal period did not increase the PRL, affect calving rates, or produce calves with congenital abnormalities.

Effect of early pregnancy diagnosis by per rectum amniotic sac palpation on pregnancy loss, calving rates, and abnormalities in newborn dairy calves

The objectives of the present study were to evaluate the effect of per rectal amniotic sac palpation (ASP) for pregnancy diagnosis during the late embryonic period on pregnancy loss, calving rates, and abnormalities in newborn calves. A controlled, randomized, blocked, blind experiment containing 680 lactating pregnant dairy cows with a viable embryo diagnosed by transrectal ultrasonography was performed. Two dairy operation sites (farm A and farm B) were selected. At each farm, the cows were randomly divided into control (CON) and ASP groups. The CON group was not subjected to pregnancy diagnosis via per rectum palpation. The ASP examinations were performed by one experienced veterinarian between Days 34 and 45 after breeding. All cows were reevaluated by transrectal ultrasonography only between 2 and 4 weeks later. Two calving rates were calculated: calving rate 1 (cows that calved from the initial number of pregnant cows) and calving rate 2 (cows that calved from cows pregnant at reexamination). In farm A, the percentages of early pregnancy loss were 11.5% (19 of 165) and 13.2% (24 of 182) for the CON and the ASP groups, respectively (P = 0.64). In farm B, the percentage of early pregnancy loss was 11.2% (19 of 170) for the CON group and 8.8% (14 of 159; P = 0.48) for the ASP group. In farm A, the percentage of late pregnancy loss was 7.6% (11 of 145) for the CON group and 5.5% (8 of 155; P = 0.39) for the ASP group. In farm B, the percentage of late pregnancy loss was 3.7% (5 of 137) for the CON group and 6.3% (8 of 127; P = 0.32) for the ASP group. In farm A, early pregnancy loss was higher than late pregnancy loss (12.4% vs. 6.3%; P = 0.01), and in farm B, the same tendency was detected (10.0% vs. 4.9%, for early and late pregnancy loss, respectively; P = 0.02). In farm A, calving rate 1 was 81.2% (134 of 165) for the CON group and 80.8% (147 of 182; P = 0.92) for the ASP group. Calving rate 2 for the same groups was 92.4% (134 of 145) and 94.8% (147 of 155), respectively (P = 0.68). In farm B, calving rate 1 was 77.7% (132 of 170) for the CON group and 74.8% (119 of 159; P = 0.55) for the ASP group. Calving rates 2 for the same groups were 87.4% (132 of 151) and 82.1% (119 of 145), respectively (P = 0.20). Two female calves with atresia coli were diagnosed only in the CON group. It was concluded that ASP during the late embryonic period for pregnancy diagnosis did not increase the pregnancy loss, affect calving rates, or produce abnormalities in calves.

Management of Pregnant Heifers in the Feedlot

Pregnant heifers in the feedlot pose many economic and management issues to the producer. Heifers that enter the feedlot pregnant will have increased costs associated with them regardless of the management strategy implemented. It is imperative that practitioners be aware of management concerns associated with pregnant heifers in order to provide sound recommendations for their clients. The purpose of this article is to provide the bovine practitioner with a summary of current literature and present common options for managing pregnant heifers in a feedlot setting.

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

The aim of this study was to compare the reproductive performance of dairy cows subjected to early (ER) or late (LR) resynchronization programs after nonpregnancy diagnoses based on either pregnancy-associated glycoproteins (PAG) ELISA or transrectal palpation, respectively. In addition, the accuracy of the PAG ELISA for early pregnancy diagnosis was assessed. Lactating Holstein cows were subjected to a Presynch-Ovsynch protocol with timed artificial insemination (AI) performed between 61 and 74 DIM. On the day of the first postpartum AI, 1,093 cows were blocked by parity and assigned randomly to treatments; however, because of attrition, 452 ER and 520 LR cows were considered for the statistical analyses. After the first postpartum AI, cows were observed daily for signs of estrus and inseminated on the same day of detected estrus. Cows from ER that were not reinseminated in estrus received the first GnRH injection of the Ovsynch protocol for resynchronization 2d before pregnancy diagnosis. On d 28 after the previous AI (d 27 to 34), pregnancy status was determined by PAG ELISA, and nonpregnant cows continued on the Ovsynch protocol for reinsemination. Pregnant cows had pregnancy status reconfirmed on d 46 after AI (d 35 to 52) by transrectal palpation, and those that lost the pregnancies were resynchronized. Cows assigned to LR had pregnancy diagnosed by transrectal palpation on d 46 after AI (d 35 to 52) and nonpregnant cows were resynchronized with the Ovsynch protocol. Blood was sampled on d 28 after AI (d 27 to 34) from cows in both treatments that had not been reinseminated on estrus and again on d 46 after AI (d 35 to 52) for assessment of PAG ELISA to determine the accuracy of the test. Cows were subjected to treatments for 72d after the first insemination. Pregnancy per AI (P/AI) at first postpartum timed AI did not differ between treatments and averaged 28.9%. The proportion of nonpregnant cows that were resynchronized and received timed AI was greater for ER than for LR (30.0 vs. 7.6%). Cows in ER had a shorter interval between inseminations when inseminated following spontaneous estrus (21.7±1.1 vs. 27.8±0.8d) or after timed AI (35.3±1.2 vs. 55.2±1.4d). Nevertheless, the ER did not affect the rate of pregnancy (adjusted hazard ratio=1.23; 95% confidence interval=0.94 to 1.61) or the median days postpartum to pregnancy (ER=132 vs. LR=140). A total of 2,129 PAG ELISA were evaluated. Overall, sensitivity, specificity, and positive and negative predictive values averaged 95.1, 89.0, 90.1, and 94.5%, respectively, and the accuracy was 92.1%. In conclusion, PAG ELISA for early diagnosis of pregnancy had acceptable accuracy, but early resynchronization after nonpregnancy diagnosis with PAG ELISA did not improve the rate of pregnancy or reduce days open in dairy cows continuously observed for estrus.

Accuracy of transrectal palpation for early pregnancy diagnosis in Egyptian buffaloes

The present study was undertaken to evaluate the accuracy of transrectal palpation (TRP) for diagnosing early pregnancy in buffaloes and the false diagnoses of the TRP test by using the pregnancy-associated glycoprotein radioimmunoassay (PAG-RIA) test. Pregnancy was diagnosed in 168 buffalo-cows once by TRP and PAG-RIA test between days 31 and 55 after breeding. The sensitivity of TRP for detecting pregnant buffalo-cows was 37.5% at days 31-35, increased to 93.8% at days 46-50 and reached 100% at days 51-55 (P < 0.01). All cases of false negative diagnoses (n = 10) had PAG concentration higher than the threshold (≥1.8 ng/mL) for diagnosing pregnancy. The specificity of TRP for detecting non-pregnant buffalo cows ranged between 90.9%, and 100% between days 31 and 55. All cases of false positive diagnoses (n = 5) made by TRP had PAG concentrations lower than the threshold for diagnosing pregnancy. It could be concluded that TRP is an accurate method for diagnosing pregnant and non-pregnant buffalo cows from day 46 after breeding.

Early pregnancy diagnosis by palpation per rectum: influence on embryo/fetal viability in dairy cattle

The objective was to estimate the effect of palpation per rectum (for early pregnancy diagnosis) on embryo/fetal viability in dairy cattle. A controlled, randomized block-design experiment with two blocks, one by category, and the other by number of embryos, was conducted. Five-hundred-and-twenty pregnant dairy cows and heifers with a viable embryo detected by transrectal ultrasonography (TRUS) between days 29 and 32 after AI were included. The pregnant females were randomly allocated into two nearly equal groups: palpation per rectum (PAL group; n=258) and no palpation per rectum (NPAL group; n=262). The PAL group was submitted to palpation per rectum (PPR) using the fetal membrane slip (FMS) technique once between days 34 and 41 of pregnancy. The fetal membrane slip consisted of compressing the pregnant uterine horn and allowing the chorioallantoic membrane to slip between the fingers. Both groups were submitted to two additional TRUS at days 45 and 60 of pregnancy, to monitor the potential immediate and delayed deleterious effects of PPR on embryo and fetal viability, respectively. A diagnosis of embryo/fetal death was made when there was no embryo/fetal heart beat or the absence of positive signs of pregnancy in an animal previously diagnosed pregnant, or the presence of signs of embryo/fetal degeneration. The overall rate of embryo/fetal death was 14.0% (73/520). Embryonic death (10%; 52/520) was higher than fetal death (4.5%; 21/468; P<0.001). Embryo/fetal mortality was higher in cows (16.4%; 59/360) than in heifers (8.8%; 14/160; P<0.025) and in cattle with twin (25.5%; 12/47) versus singleton pregnancies (12.9%; 61/473; P<0.025), but was not different (P>0.05) between PAL (14.7%; 38/258) and NPAL (13.4%; 35/262). In conclusion, PPR between days 34 and 41 of pregnancy using the fetal membrane slip technique did not affect embryo/fetal viability.

Early pregnancy diagnosis by transrectal ultrasonography in dairy cattle

The objective of the present study was to determine differences in time of detection of pregnancy between heifers and cows and the interval after insemination at which the maximum sensitivity and negative predictive value of transrectal ultrasonography were obtained. One-thousand-four-hundred transrectal ultrasonographies (TRUS-1; 1,079 in cows and 321 in heifers) were performed using a 5-MHz linear-array transducer. The cattle were randomly assigned to have TRUS performed once between days 24 and 30 (estrus=day 0) in cows or between days 21 and 27 in heifers. Every TRUS diagnosis was subsequently compared with a second TRUS diagnosis (TRUS-2), performed 3-8 days later, after day 30 (range 31-38) for cows and after day 27 (range 28-35) for heifers. The sensitivity and specificity between cows and heifers for the common days of TRUS (from 24 to 27) were compared. In cows, sensitivity increased gradually from 74.5% at day 24 to 100% at day 29 (P<0.01). Specificity increased from days 24-25 and reached a plateau of 96.6% on day 26 (P<0.01). In heifers, sensitivity increased from 50% at day 21 to 100% at day 26 (P<0.01). Specificity increased from 87.5% at day 21 and remained steady at 94% starting on day 23 (P>0.05). The sensitivity for cows and heifers was 89.2 and 96.8%, respectively (P<0.05) and the specificity was 93.0 and 93.4% (P>0.05). In this study, heifers were diagnosed pregnant earlier than cows, and the maximum sensitivity and negative predictive value were obtained 3 days earlier in heifers than cows (days 26 and 29, respectively).

The establishment of an ELISA for the detection of pregnancy-associated glycoproteins (PAGs) in the serum of pregnant cows and heifers

The pregnancy-associated glycoproteins (PAGs) are a large gene family expressed in trophoblast cells of ruminant ungulates. The detection of PAGs (more specifically, PAG-1) in maternal serum has served as the basis for pregnancy detection in cattle. Unfortunately, PAG-1 and/or antigenically-related PAGs exhibit a long half-life in maternal serum (>8 d) and can be detected 80-100 d post-partum, thereby producing false positives in animals bred within 60-d of calving. The goal of the present studies was to develop a monoclonal-based assay that targeted early-pregnancy PAGs whose persistence in maternal serum post-partum might be relatively short-lived. Three anti-PAG monoclonal antibodies that recognized distinct subsets of PAGs were selected and used as trapping reagents in a 'sandwich' type of enzyme-linked immunosorbant assay (ELISA). A polyclonal antiserum with broad specificity was used for detecting bound PAGs. A total of 42 cows and heifers were bled daily on day 15, days 22 to 28, and then weekly throughout pregnancy and for 10 weeks (approximately 70 d) into the post-partum period. The ELISA was able to detect PAG in maternal serum of all animals unambiguously by day 28 post-insemination (PAG concentration: 8.75 +/- 3.04 ng/mL). In maternal serum, PAG concentrations peaked during the week of parturition at 588.9 +/- 249.9 ng/mL, and after calving, PAG was completely cleared (half-life: 4.3 d) by eight-week post-partum in 38 of 40 of the animals tested and was at very low concentrations in the remaining two (1.4 and 4.9 ng/mL, respectively). In summary, a monoclonal-based assay has been established that is sensitive enough to detect PAG in maternal serum by the forth week of pregnancy, but does not suffer from carry-over of antigen from a previous pregnancy.

Epidemiology of bovine abortions in Israeli dairy herds

Routine monitoring of abortions is carried out on most Israeli Kibbutz dairy herds. The reports include both descriptive epidemiology and multivariable analysis. Data are presented according to parity, trimester, abortion curves and sire. Results are produced in the form of abortions per 10000 cows-days-at risk, proportion of aborted cows by 260 days of gestation, abortion per confirmed pregnancy, and adjusted odds ratios. For 58048 pregnancies from 111 herds in 1995, the respective abortion density, proportion of aborted cows, and abortions per confirmed pregnancy were 4.2, 5.9%, and 10.2%. Among parities, heifers had the lowest, and cows of second parity the greatest risk of fetal death (respective odds ratios 0.6 and 1.3) compared to all other parities pooled together. The greatest risk of fetal death was observed in the first, and the lowest in the second trimesters of pregnancy (odds ratios 1.9 and 0.6, respectively). Recurrent risk ratio for abortion in the same lactation was high (odds ratio 2.7). Respective proportions of aborted cows with and without a previous abortion were 17.5% and 5.9%. Odds of aborting after twinning in multiparous cows was 1.3 greater than for those having a single calf. Risk of abortion in the autumn and early winter was greater than that in the summer months. Increased risks of abortion were associated with eight sires out of the 233 used (odds ratios of mates to abort ranged from 1.9 to 3.9). One, two and three peaks of abortions were established in 53.2%, 24.3%, and 0.9% of the 111 herds studied in 1995. None were detected in 21.6% of the herds.

Effect of reproductive disorders previous to conception on pregnancy attrition in dairy cows

This study was undertaken to determine whether reproductive disorders previous to conception influence pregnancy attrition in dairy cows. Reproductive disorders were registered and pregnancy diagnoses were performed as a part of a reproductive health program at 9 commercial dairy herds in northeastern Spain. Data from 3022 diagnosed pregnant lactating cows were used. Pregnancy diagnosis by palpation per rectum was performed from 33 to 70 d post insemination. Pregnancy attrition was registered when the pregnancy diagnosis was negative at the second palpation carried out between 120 and 150 d following insemination. Data analysis was performed by multiple logistic regression methods. Pregnancy attrition rates were 2.6 and 1.8 times higher in cows with previous pyometra and retained placenta, respectively, than in cows without these disorders. No effect of endometritis, ovarian cysts and repeat breeding was shown on pregnancy attrition. Our results suggest that additional efforts to reduce the risk of retained placenta and pyometra should decrease the incidence of pregnancy attrition in dairy cows.