Nonpregnancy Diagnosis Research Articles

Strategies for improving fertility in the modern dairy cow

The high producing dairy cow of the 21st century is subfertile during lactation. Our objectives are to characterize physiological periods limiting reproductive performance and to describe integrated management strategies to improve pregnancy rates. Ovarian recrudescence with normal re-occurring estrous cycles and restoration of fertility to first service are associated with a reduced occurrence of periparturient metabolic and reproductive disorders. Marked negative changes in energy balance and reduced immunocompetence influence gonadotropic and metabolic hormones. Induced ovarian inactivity was associated with enhanced uterine involution. Post-partum health and reproductive performance were improved when by-pass lipids enriched in polyunsaturated fatty acids were fed in the pre- and post-partum periods. Pharmaceutical control of follicle, CL, and uterine function with PGF, GnRH and intravaginal progesterone releasing inserts, has permitted development of more optimal timed-insemination programs for first service. Likewise, resynchronization of nonpregnant cows coupled with the use of ultrasound for early pregnancy diagnosis provides the opportunity for a second timed-insemination within 3 days of a nonpregnant diagnosis. Bovine somatotropin (bST) increases embryo development and embryo survival when coupled with a timed-insemination program or cows detected in estrus. Presence of a conceptus alters endometrial expression of genes and proteins in response to bST and nutraceuticals (i.e., unsaturated fatty acids such as eicosapentaenoic and docosahexaenoic acid in by-pass lipids) to improve pregnancy rates. Postovulatory increases in progesterone may enhance pregnancy rates in targeted populations of lactating dairy cows, but timing and magnitude of the progesterone increases are pharmaceutically dependent.

Resynchronization of ovulation and timed insemination in lactating dairy cows: III. Administration of GnRH 23 days post AI and ultrasonography for nonpregnancy diagnosis on day 30

The objective was to compare pregnancy rates to resynchronization and timed AI (TAI) protocols in lactating dairy cows that received GnRH at 23 d and were diagnosed not pregnant at 30 d after the pre-enrollment AI. Nonpregnant cows (624) at ultrasonography on day 30 (study day 0) were classified as diestrus (74.8%), metestrus (5.6%) and without a CL (19.5%). Cows in diestrus were assigned either to the GnRH group (PGF 2α on day 0, GnRH on day 2 and TAI 16 h later, n = 238) or the estradiol cypionate (ECP) group (PGF 2α on day 0, ECP on day 1, and TAI 36 h later, n = 229). Cows in metestrus were assigned to the Modified Heatsynch Group (GnRH on day 0, PGF 2α on day 7, ECP on day 8 and TAI on day 9, n = 35). Cows without a CL ( n = 122) were classified either as proestrus (10.6%), ovarian cysts (7.5%) or anestrus (1.4%), and assigned to factorial treatments (i.e., use of GnRH versus CIDR) to either the GnRH group (GnRH on day 0, PGF 2α on day 7, GnRH on day 9 and TAI 16 h later, n = 28), the CIDR group (CIDR insert from days 0 to 7, PGF 2α on day 7, GnRH on day 9 and TAI 16 h later, n = 34), the GnRH + CIDR group (GnRH on day 0, CIDR insert from days 0 to 7, PGF 2α on day 7, GnRH on day 9 and TAI 16 h later, n = 32), and the control group (PGF 2α on day 7, GnRH on day 9 and TAI 16 h later, n = 28). For cows without a CL, plasma P 4 concentrations were determined on days 0, 7, 10 and 17 and ovarian structures determined on days 0, 7 and 17. Pregnancy rates were evaluated at 30, 55 and 90 d after the resynchronized AI. For cows in diestrus, there were no differences in pregnancy rates on days 30, 55 and 90 for cows in the GnRH (27.5, 26.5 and 24.2%) or ECP (29.1, 25.5 and 24.1%) groups. In addition, there were no differences in pregnancy losses between days 30 and 55 and 55 and 90 between the GnRH (7.0 and 8.6%) and ECP (9.8 and 5.4%) groups. For cows without a CL, GnRH on day 0 increased the proportion of cows with a CL on days 7 and 17 and plasma P 4 concentration on day 17 in cows with ovarian cysts but not for cows in proestrus. The CIDR insert increased pregnancy rate in cows with ovarian cysts but reduced pregnancy rate for cows in proestrus.

Resynchronization of ovulation and timed insemination in lactating dairy cows: I: use of the Ovsynch and Heatsynch protocols after non-pregnancy diagnosis by ultrasonography

The objective was to compare pregnancy rates and pregnancy losses in lactating dairy cows that were diagnosed not pregnant and re-inseminated following either the Ovsynch ® or Heatsynch protocols. Also evaluated were the effects of stages of the estrous cycle, ovarian cysts and anestrus on pregnancy rates for both treatments. Non-pregnant cows ( n = 332) as determined by ultrasonography on day 27 post-AI (study day 0) were divided into two groups. Cows in the Ovsynch group ( n = 166) received GnRH on day 0, PGF 2α on day 7, GnRH on day 9, and timed AI (TAI) 16 h later (day 10). Cows in the Heatsynch group ( n = 166) received GnRH on day 0, PGF 2α on day 7, estradiol cypionate (ECP) on day 8, and TAI 48 h later (day 10). Cows detected in estrus on days 8 and 9 were inseminated and included in the study. On day 0, cows were classified according to different stages of the estrous cycle, or presence of ovarian cysts or anestrus. Pregnancy rates were evaluated 27, 45 and 90 days after resynchronized AI. Overall, there was no difference in pregnancy rates on days 27, 45 and 90 between cows in the Ovsynch (25.2, 17.5, and 13.9%) and Heatsynch (25.8, 19.9, and 16.1%) groups. There was no difference in pregnancy losses from days 27 to 45 and days 45 to 90 for cows in the Ovsynch (25.0 and 17.9%) and Heatsynch (14.7 and 10.3%) groups. However, pregnancy rates were increased when cows in metestrus were subjected to the Heatsynch protocol and cows with ovarian cysts were subjected to the Ovsynch protocol.

Reproductive Management of Dairy Cows in High Milk-Producing Herds

Challenges limiting reproductive efficiency of high milk-producing cows include interrelationships among body condition, dry matter intake, transition from the dry period to lactation, onset of normal estrous cycles, detection of estrus, and embryonic survival. Attention is required to details associated with diet formulation; feed bunk management; cow comfort in free stalls, holding pen, and milking parlor during extremes of temperature and humidity; proper hoof care; milking management and mastitis prevention; control of ovulation and estrus; and early nonpregnancy diagnosis. Intensive management of transition cows should involve monitoring key metabolic markers using hand-held devices. This should allow early detection of illnesses that can be followed by proven interventions to alleviate their residual effects. Body condition should be monitored more closely to reduce dry cow and transition problems and prevent prolonged anestrus by maximizing early postpartum dry matter intakes. Cow comfort should be monitored more closely to minimize standing time for milking, maximize standing time for estrus and feed intake, and maximize resting time for rumination and more efficient milk synthesis. Estrus may be detected using automated techniques such as pedometry, rump-mounted pressure-sensitive radio-telemetric devices, and in-line parlor tests for milk progesterone or estrogen. More highly fertile heifers may be impregnated using sexed semen, sexed embryos, or clones to provide more replacement heifers because of declining fertility of lactating cows. Strategies to impregnate high-producing cows will require more ovulation control before first and subsequent services without detection of estrus. Because of high rates of embryonic death, more pregnancies may be achieved by using sexed or cloned embryos. Many reproductive technologies used today, including programmed breeding, will be refined and incorporated into the management of cows on fewer dairy farms with more cows per farm. Despite trends for longer lactations associated with bST and lesser pregnancy rates, renewed lactations following parturition will continue to be essential for herd longevity of cows.

Pregnancy diagnosis in sows: direct ELISA for estrone in feces and its prospects for an on-farm test, in comparison to ultrasonography

The usefulness of fecal estrone (E 1) measurement as a tool for pregnancy diagnosis was investigated. Concentrations of E 1 were measured in feces from pregnant and nonpregnant sows by a direct ELISA without extraction. Highly significant differences in E 1 concentrations were found in feces from nonpregnant and pregnant sows (P = 0.016 to < 0.001). Pregnancy diagnosis on Days 26 to 32 after insemination, based both on fecal E 1 concentrations as measured by ELISA and ultrasonography using a 5.0 MHz linear-array transducer, was performed in a group of 496 gilts and sows. The fecal E 1 test had a sensitivity (correct diagnosis of pregnancy) of 96.5% and a specificity (correct diagnosis of nonpregnancy) of 93.6%, using 3.65 ng E 1/g feces as a cut-off value. For ultrasonographic pregnancy diagnosis the test sensitivity and specificity were 99.3 and 92.5%, respectively. Although an increase of fecal E 1 concentrations was noticed for increasing litter sizes, the results indicated that these concentrations could not be used to predict litter size. It is concluded that the distribution of fecal E 1 concentrations in both nonpregnant and pregnant sows offers a suitable basis for the development of a simple, sow-side pregnancy test.

Cocaine abuse during pregnancy: Psychiatric considerations

Cocaine abuse is an increasing problem in the obstetric population. It not only poses a health risk to the pregnant woman, but can precipitate premature labor and abruptio placentae, and has been associated with a number of physical and behavioral problems in the newborn. Evaluation and management of the pregnant cocaine abuser is similar in most respects to that of nonpregnant adults, but diagnosis, psychotherapy, and pharmacotherapy is strongly influenced by the pregnancy. This article describes the risks of cocaine use during pregnancy and outlines the evaluation and management of the pregnant cocaine abuser.

Milk progesterone determination in buffaloes post-insemination

Milk progesterone levels were studied in 17 buffaloes between post-insemination and 30 days thereafter. Six animals were confirmed pregnant. Seven of 10 animals took > 24 days to return to oestrus and the pattern of change of progesterone levels indicated a steady increase from 1 ng/ml on day 2 to 20 ng/ml on day 14 post-insemination, falling subsequently to about 5 ng/ml, 2 days prior to oestrus. In pregnant buffaloes, the milk progesterone levels showed a continuous increase up to 20 days post-insemination but did not decline thereafter. In individual buffaloes returning to oestrus, a cut-off milk progesterone level of > 10 ng/ml was considered for pregnancy diagnosis, 20, 22 and 24 days post-insemination. The test was 60, 75 and 75% accurate for detection of pregnancy on days 20, 22 and 24 respectively and 100% for non-pregnancy diagnosis on all three days. Individual animals showed a highly variable oestrous cycle length, which has been suggested as a contributory factor for false pregnancy diagnosis by milk progesterone test in this species. Milk progesterone assay may also identify silent heats, and clinical disorders.

Application of plasma and milk progesterone assay in pregnancy diagnosis in White Fulani (Zebu) cattle

In order to investigate in the zebu cattle the applicability of the technique of pregnancy diagnosis based on determination of plasma progesterone (P) concentration, White Fulani (Bunaji) cows were sampled for milk and blood on days 18 to 23 and on day 42 post-service. P was determined by radioimmunoassay (RIA) in skim milk and plasma. Confirmation of pregnancy was done by rectal palpation on days 42 and 60 post-service. Error in positive pregnancy diagnosis by the laboratory method decreased from 25 to 4.5% from days 18 to 22, respectively; this was a result of differences in estrous cycle length following unsuccessful service. Diagnosis of non-pregnancy was highly accurate (100%).

Stéroïdes sexuels et diagnostics de gestation chez les bovins — Tests en ferme

The peripheral blood and milk contain two steroids, whose concentrations can be monitored and used as a tool for pregnancy diagnosis in cattle: (1) Progesterone of maternal origin, which must be assayed between days 21-24 after Al, allows very early diagnosis of non pregnancy or of gestation onset, (2) Oestrone sulfate secreted by the feto-placental unit is a good means for confirming pregnancy over 110 days after Al. Both steroids have been assayed in a very high number of samples by RIA in so-called centralized diagnosis laboratories. These have many advantages and usually are of a very high standard. Accuracy of these diagnoses has been evaluated in a large number of experimental series and is well known (93-100% for early non pregnancy diagnosis). EIA kits for progesterone have been on the market for 2-3 years. But a more simple test to be used by the farmer himself is now available. It is a so-called dipstick test (Bovitest - ND - Clonatec), including control and test pads on the stick itself plus the conjugate and a soluble substrate. Reading and interpretation ar made by single observation according to the intensity of the blue colour on the test pad compared to that on the control. There is a good agreement between the results of the RIA procedure (used as a reference) and those of this dipstick test. A field study on a quite large basis was undertaken to evaluate the accuracy of the diagnosis made according to this on the farm test. It was very similar to that found by RIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Milk Progesterone Enzyme Immunoassay: Modifications and a Field Trial for Pregnancy Detection in Dairy Cows1,2

A milk progesterone enzyme immunoassay was modified to shorten the antibody :antigen incubation time and tested in a field trial. Coupling the antibody to paper fibers at pH 7 increased the binding activity of the paper-antibody conjugate to allow incubation for 3h at room temperature with no significant loss of competitive binding of progesterone. The relationship between progesterone concentrations measured by the modified and original enzyme immunoassays was r=.94 (n=80 pairs). Milk samples (n=67) collected 21 d after artificial insemination were classified by the original and modified methods as being from pregnant or nonpregnant cows using both spectrophotometric and visual evaluations. Comparison to subsequent rectal palpation or return to estrus showed that the two methods were comparable. A field trial was conducted involving 622 cows and 40 producers using the modified enzyme immunoassay method. The overall field trial accuracy of the enzyme immunoassay in diagnosing the cow's reproductive status for a single sample on d 21 after breeding was 71% for correct diagnosis of pregnancy and 81% for correct diagnosis of nonpregnancy. It was concluded that the modified method is a valuable technique for rapid monitoring of milk progesterone concentrations.

Serum progesterone levels as an index of pregnancy in buffaloes

Higher levels of serum progesterone on the 20th or 23rd day following impregnation were indicative of establishment of pregnancy in buffaloes. Buffaloes with serum progesterone levels of 1 ng/ml or more on these days were taken as pregnant. The accuracy of this test for diagnosing pregnancy was 75% on the 20th and 83.3% on the 23rd day after artificial insemination. The non-pregnancy diagnosis by this test was 100% accurate on both days of the test. Subclinical endometritis and/or early embryonic deaths seem to interfere with the exact diagnosis of pregnancy.

Diagnosis of pregnancy and number of foetuses in sheep by real-time ultrasonic imaging. I. Effects of number of foetuses, stage of gestation, operator and breed of ewe on accuracy of diagnosis

The adaptation of real-time imaging technology for the diagnosis of pregnancy and number of foetuses in ewes was examined. Two experiments were conducted and a total of 5530 scans were completed. Overall accuracy was 97.1% (5371 correct scans/5530 total scans). Specific accuracy rates, which describe correct diagnoses as a percentage of actual numbers in each class and diagnosed numbers in each class were as follows. Pregnancy diagnosis 99.4% (5006/5038) and 99.9% (5006/5007), non-pregnancy diagnosis 99.8% (491/492) and 93.9% (491/523), singles 98.7% (3577/3626) and 97.7% (3577/3661), twins 93.8% (1280/1363) and 97.1% (1280/1318), triplets 52.3% (23/44) and 82.1% (23/28) and quadruplets 0% (0/4) and 0% (0/4). The classification of multiple foetuses, i.e. two or more, had accuracy rates of 94.1% (1328/1412) and 98.7% (1328/1346). When errors were made, they were mostly underestimates of litter size due to failure to see foetuses actually present. Accuracy of diagnosis was affected only in early pregnancy, there being a small but significant decrease prior to 45 days gestation. Differences in accuracy between operators were small and mostly non-significant. High levels of accuracy within operators were repeatable over time. Differences in accuracy due to breed of ewe were without obvious explanation, but are likely to be caused by anatomical features and require further examination.

The use of progesterone and oestrogen concentrations in the diagnosis of pregnancy, and in the study of seasonal infertility in sows

Plasma concentrations of progesterone and oestrogen in sows 18 days after mating were examined, firstly, as a method of pregnancy diagnosis, and secondly, for indication of any abnormal endocrine patterns that may have been involved in the aetiology of seasonal infertility in sows. Progesterone levels were the most relevant indicator of ovarian function. For the diagnosis of pregnancy, progesterone levels were accurate (97 %), but for the diagnosis of non-pregnancy, especially where a high degree of early embryonic death and/or cystic follicles was suspected, as in this trial, progesteronc levels were not as accurate (60%). Oestrogen levels were of use only in confirming the type of infertility suffered by non-pregnant sows. This study shows that seasonal infertility in mated sows is a complex of several forms of infertility, each manifest in a common physical symptom of delayed return to oestrus after a normal mating to a fertile boar. The forms of infertility involved appear to be early embryonic death, luteinized ovarian cysts, small ovarian cysts and silent oestrus.

Early Diagnosis of Non-Pregnancy in Cattle: The First Eighteen Months of a Commercial Service

Feasibility studies on routine pregnancy diagnosis in cattle are reported and the commercial service resulting from them described. 4 nonpregnant cycling cows were sampled every 3 days for 30 days to establish the variation during the estrous cycle. 150 cows were then sampled at various stages up to 90 days after insemination. Pregnancy diagnosis was made by rectal palpation between 60-90 days. These results were variable because of storage techniques. In a 2nd study 700 commercial dairy cows were sampled up to 90 days after insemination. Whole milk samples from the afternoon milking were taken and preserved with a dichromate/mercuric chloride preservative. Nonpregnancy could be predicted by radioimmunoassay of progesterone with 95% success. The commercial service was offered initially below cost to farmers to encourage its use. Sample vials and preservative were given free. The major problem at the beginning of the service was in persuading the farmer to take the correct sample 21-23 days after insemination. The farmers have found the service beneficial but would like to see fewer doubtful diagnoses.

Ultrasonics in the demonstration of fetal heart movements

A new method for determining fetal heart movements by means of pulsating ultrasonics is described. Fifty patients were examined at various stages of pregnancy. from the tenth to the thirty-ninth week. Three were examined because of a suspicion of fetal death. No heart movement was demonstrable, and all 3 patients were delivered of stillborn infants. Two patients were examined because of a suspicion of “false pregnancy” in the nineteenth and thirtieth weeks, respectively. A diagnosis of nonpregnancy was made by means of ultrasonics in both cases, and both diagnoses were later confirmed. One patient, examined in the nineteenth week of pregnancy because of recurrent hemorrhages, exhibited no heart movement on ultrasonic examination, and 15 days later abortion occurred. The remaining 44 patients make up a presumed normal material, and in all these cases ultrasonic examination disclosed fetal heart movements. It is concluded that the method is particularly well suited for demonstrating fetal life from the twelfth week to the termination of pregnancy.