Accuracy of ultrasonography for pregnancy diagnosis on days 10 to 22 in heifers

Two operators independently conducted ultrasonic pregnancy examinations on nulliparous Holstein heifers on Days 10, 12, 14, 16, 18, 20 and 22, and assigned a diagnosis (pregnant or nonpregnant) and a score for degree of certainty in the diagnosis (1, 2 or 3 for low, intermediate or high, respectively). Pregnancy was retrospectively confirmed by the ultrasonographic detection of an embryo proper and embryonic heartbeat on Day 24 in 20 25 bred heifers; the five nonpregnant heifers were excluded from the analyses. Eleven nonbred heifers were included as an unequivocal source of nonpregnant heifers. Accuracy was not significantly greater than a guess (50%) before Day 18, but reached 100% on Days 20 and 22. Mean accuracy was higher (P<0.005) for nonpregnant (65 77 , 84%) than pregnant heifers (91.5 140 , 65%). For certainty score, there were main effects of day (P<0.0001), reproductive status (pregnant or nonpregnant, P<0.003), and an interaction of day and reproductive status (P<0.0001). The certainty score increased in all heifers among days and was higher (P<0.05) in pregnant than nonpregnant heifers on Days 16 to 20. For luteal area (area of corpus luteum, excluding area of fluid filled center, if present), there were significant main effects of day, reproductive status and a day by status interaction (P<0.0001 for each). Luteal area was approximately constant in pregnant heifers, but in nonpregnant heifers it was lower (P<0.05) on Days 16 to 22 than on Days 10 to 14. Uterine echotexture was scored on a scale of 1 to 3, characteristic of a diestrus, intermediate and estrus uterus, respectively. There were main effects of day and reproductive status (P<0.0001 for each) and an interaction of day and reproductive status (P<0.025). Uterine echotexture was approximately constant in pregnant heifers, but in nonpregnant heifers it was higher (P<0.05) on Days 16 to 22 than on Days 10 to 14. Pregnancy diagnosis on Days 10 to 14 was based on detection of the conceptus; however, detection of the conceptus was not accurate prior to visualization of the embryo proper (mean Day 22, range Days 20 to 24). In nonpregnant heifers, a correct diagnosis with high certainty was made when a small corpus luteum and uterine echotexture characteristic of estrus were detected. In the absence of these changes on Days 18 to 22, a diagnosis of pregnancy was made with high accuracy and intermediate or high certainty.     

Real-time ultrasonography for determining pregnancy status and viable fetal numbers in ewes

The reproductive tracts of 26 estrus synchronized, bred ewes were scanned with a portable 5.0 MHz real-time ultrasound unit within 1 to 6 d postbreeding. Intrarectal scanning was performed on alternate days until Days 28 to 30 and twice weekly until Days 50 of gestation. Transabdominal uterine scans were conducted twice weekly from Days 25 to 65 and continued weekly until parturition. A total of 24 ewes (92%) became pregnant. A nonpregnant ewe was recognized 100% of the time by both methods of ultrasonic screening. Correct identification of a gravid ewe as pregnant was 100% from Days 51 to 150 of gestation using transabdominal real-time ultrasonography. There was a significant association (P < 0.005) between the number of lambs born and the number of fetuses observed using transabdominal real-time ultrasonography after Day 25 of gestation. Accurate differentiation of fetal numbers by transabdominal scanning was 100.0% for ewes carrying one lamb and 97.3% for ewes carrying two lambs at Days 51 to 75 of gestation. Fetal attrition was documented in one ewe at Day 49 of gestation. Hydrops allantois was diagnosed in another ewe at 110 d of gestation. A total of 37 lambs were born to 23 ewes in the project flock. No congenital abnormalities were noted in any of the lambs. Transabdominal real-time ultrasonography is a safe, rapid, accurate and practical method for assessing pregnancy status, fetal number and fetal viability in sheep.     

Uterine secretion of prostaglandin F2 alpha in response to oxytocin in ewes: changes during the estrous cycle and early pregnancy.

Experiment 1 was conducted to determine when the ovine uterus develops the ability to secrete prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin and how development is affected by pregnancy. Pregnant and nonpregnant ewes received an injection of oxytocin (10 IU, i.v.) on Day 10, 13, or 16 postestrus. Jugular venous blood samples were collected for 2 h after injection for quantification of 13,14-dihydro-15-keto-PGF2 alpha (PGFM). In nonpregnant ewes, concentrations of PGFM increased following oxytocin on Day 16 but not on Day 10 or 13. Concentrations of PGFM did not increase following treatment on Day 10, 13, or 16 in pregnant ewes. Therefore, the ability of oxytocin to induce uterine secretion of PGF2 alpha develops after Day 13 in nonpregnant but not in pregnant ewes. Experiment 2 was conducted to precisely define when uterine secretory responsiveness to oxytocin develops. Pregnant and nonpregnant ewes received oxytocin on Day 12, 13, 14, or 15. In nonpregnant ewes, concentrations of PGFM increased following treatment on Days 14 and 15, but not earlier. Peripheral concentrations of progesterone showed that uterine secretory responsiveness to oxytocin developed prior to the onset of luteal regression. As in experiment 1, the increase in concentrations of PGFM following administration of oxytocin was much lower in pregnant than in nonpregnant ewes; however, some pregnant ewes did respond to oxytocin with an increase in PGFM. In experiment 3, pregnant ewes received an injection of oxytocin on Day 18, 24, or 30 postmating. Concentrations of PGFM increased following oxytocin on Days 18 and 24. The conceptus appears to delay and attenuate the development of uterine secretory responsiveness to oxytocin.     

Concentrations of prostaglandins E2, F2 alpha and 6-keto-prostaglandin F1 alpha in the utero-ovarian venous plasma of nonpregnant and early pregnant ewes

The effect of pregnancy on concentrations of prostaglandins E2, F2 alpha and 6-keto-prostaglandin F1 alpha (PGE2, PGF2 alpha and 6-keto-PGF1 alpha) in utero-ovarian venous plasma was examined in ewes on Days 10 through 14 after estrus, an interval which includes the critical period for maternal recognition of pregnancy. The utero-ovarian vein ipsilateral to a corpus luteum was catheterized on Day 9 or 10 in 6 pregnant and 8 nonpregnant ewes. Five blood samples were collected at 30-min intervals for 2 h beginning at 0500 and 1700 h daily. Sampling began at 0500 h on the day after catheterization. The mean and variance within each 2-h collection period were calculated for each ewe. The natural logarithm of the variance in each collection period (ln variance) was used as an estimate of the fluctuations in secretory activity by the endometrial-conceptus complex. Patterns of the mean concentrations of PGE2 were different between pregnant and nonpregnant ewes (P less than 0.01); PGE2 being higher in the pregnant ewes beginning on Day 13. There was a trend for the patterns of ln variance in PGE2 to differ (P less than 0.1) with pregnancy status over the entire period; ln variance was greater in pregnant ewes beginning on Day 13. The patterns of the mean concentrations and ln variances for PGF2 alpha and 6-keto-PGF1 alpha did not differ between pregnant and nonpregnant ewes. There were significant increases in both of these prostaglandins over time, independent of pregnancy status (P less than 0.01). The association of higher concentrations of PGE2 in utero-ovarian venous plasma with early pregnancy is consistent with the hypothesis that PGE2, originating from the uterus and/or conceptus, is one factor involved in maintenance of the corpus luteum of pregnancy.     

Effect of recombinant alpha interferons on fertility and interestrous interval in sheep

In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 to 14 of one of the following treatments: 1) ovine conceptus secretory proteins (oCSP) containing 25 mug of ovine trophoblast protein-1 (oTP-1) as determined by RIA; 2) 25 or 50 mug recombinant human interferon alpha1 (rhlFN); or 3) 1500 ug of serum proteins (oSP) from a Day-16 pregnant ewe (estrus = Day 0) per uterine horn. Ewes receiving oCSP had longer interestrous intervals (27 +/- 2 days; P<0.05) than ewes receiving oSP (17 +/- 2 days). Ewes receiving either dose of rhlFN had an interestrous interval of 16 +/- 2 days which did not differ (P>0.10) from that of oSP-treated ewes. In Experiment 2, 59 normally cycling ewes, mated on Day 0, received twice-daily intramuscular injections of either 2 mg recombinant bovine interferon alpha1 (rblFN) or placebo on Days 12 to 15 post estrus. On Day 16, pregnancy was confirmed by flushing a morphologically normal conceptus from the uterus. Pregnancy rates for rblFN-treated (80%) and placebo-treated (62%) ewes were not different (P>0.10). Uterine flushings and conceptus-conditioned medium were assayed for oTP-1. Total oTP-1 in conceptus-conditioned culture medium was higher (P<0.02) when conceptuses were from placebo-treated (104 +/- 14 mug/conceptus) than from rblFN-treated (56 +/- 12 mug/conceptus) ewes; while total oTP-1 in uterine flushings was similar (P>0.10) for placebo-treated (132 +/- 15 mug/conceptus) and rblFN-treated (147 +/- 17 mug/conceptus) ewes. The interval from mating to subsequent estrus following conceptus removal was 31 +/- 1 and 28 +/- 1 days for pregnant ewes treated with rblFN and placebo, respectively. Interestrous intervals for nonpregnant ewes were longer (P<0.02) for rblFN-treated (27 +/- 3 days) than for placebo-treated (18 +/- 2 days) ewes.     

Validation of a new pregnancy-associated glycoprotein radioimmunoassay method for the detection of early pregnancy in ewes

The aim of the current study was to describe the use of a pool of different antisera raised against pregnancy-associated glycoproteins (PAGs; purified from both ovine and caprine placentas) for early pregnancy diagnosis in ovine species. Sixty-three pluriparous Sarda ewes (Ovis aries) were synchronized. Blood samples were withdrawn on Days 18, 24, 26, 28, 30, and 50 after mating. These samples were assayed for progesterone (radioimmunoassay [RIA] including an extraction step) and for pregnancy-associated glycoproteins (RIA-706 and RIA-srPool). Progesterone concentrations were under 1.0 ng/mL in all nonpregnant Sarda ewes. In pregnant ewes, mean progesterone concentrations ranged from 2.4 ng/mL (Day 24, single pregnancies) to 4.4 ng/mL (Day 28, multiple pregnancies). During all periods of examination, PAGs remained lower than 0.8 ng/mL in nonpregnant ewes. On Day 18 of pregnancy, PAG concentrations could be detected in 26 of 43 (60.5%) and in 41 of 43 (95.3%) pregnant ewes using the RIA-706 and RIA-srPool methods, respectively. From Day 24 to Day 50, using both RIA methods, PAGs could be detected in all pregnant ewes. On Day 24, the best threshold for pregnancy diagnosis was obtained by use of RIA-srPool, maximal concentration in nonpregnant ewes being 0.3 ng/mL and minimal concentration in pregnant ewes being 4.8 ng/mL. In general, progesterone and PAG concentrations were higher in multiple pregnancies than in single pregnancies. However, because of large individual variations, single pregnancies could not be differentiated from multiple pregnancies.     

Endometrial glands are required for preimplantation conceptus elongation and survival

Endometrial glands secrete molecules hypothesized to support conceptus growth and development. In sheep, endometrial gland morphogenesis occurs postnatally and can be epigenetically ablated by neonatal progestin exposure. The resulting stable adult uterine gland knockout (UGKO) phenotype was used here to test the hypothesis that endometrial glands are required for successful pregnancy. Mature UGKO ewes were bred repeatedly to fertile rams, but no pregnancies were detected by ultrasound on Day 25. Day 7 blastocysts from normal superovulated ewes were then transferred synchronously into Day 7 control or UGKO ewes. Ultrasonography on Days 25-65 postmating indicated that pregnancy was established in control, but not in UGKO ewes. To examine early uterine-embryo interactions, four control and eight UGKO ewes were bred to fertile rams. On Day 14, their uteri were flushed. The uterus of each control ewe contained two filamentous conceptuses of normal length. Uteri from four UGKO ewes contained no conceptus. Uteri of three UGKO ewes contained a single severely growth-retarded tubular conceptus, whereas the remaining ewe contained a single filamentous conceptus. Histological analyses of these uteri revealed that endometrial gland density was directly related to conceptus survival and developmental state. Day 14 UGKO uteri that were devoid of endometrial glands did not support normal conceptus development and contained either no conceptuses or growth-retarded tubular conceptuses. The Day 14 UGKO uterus with moderate gland development contained a filamentous conceptus. Collectively, these results demonstrate that endometrial glands and, by inference, their secretions are required for periimplantation conceptus survival and development.     

Plasma urea nitrogen in relation to pregnancy rate in dairy sheep

The aim of this field study was to investigate the relationship of plasma urea nitrogen (PUN) with the pregnancy rate in lactating Awassi × Merino ewes. One hundred and eighty-five Awassi × Merino ewes were used in the present study. Ewes were fed a diet containing 17.4% crude protein and were milked twice a day by the milking machine. The ewes were synchronized for estrus by insertion of intravaginal sponges containing 30 mg flurogestone acetate for 14 days. At the time of sponge removal each ewe was administered eCG (600 IU). All ewes were inseminated twice with fresh semen into the external os of the cervix at 48 and 56 h after sponge removal. The day of insemination was considered as Day 0 for calculating the gestational period. Blood samples were collected from each ewe at Days 0, 18 for measurement of PUN concentrations and at Day 22 after AI for measurement of pregnancy-associated glycoprotein (PAG) by radioimmunoassay (RIA). Thirty-eight ewes (20.5%) were confirmed pregnant by PAG-RIA test at Day 22 and by ultrasonography at Day 80. The mean (±S.D.) concentration of PUN in all ewes at Day 0 was 12.7±4.6 mmol/L. There were non-significant differences in the level of PUN between pregnant and non-pregnant ewes at Days 0 (12.2±4.2 mmol/L vs. 12.8±4.7 mmol/L, respectively) and 18 (9.6±2.9 mmol/L vs. 10.4±4.0 mmol/L, respectively) after AI. Mean PUN concentrations decreased significantly from Day 0 to Day 18 after AI in both pregnant and non-pregnant ewes. By using logistic regression analysis, there was no effect of PUN concentrations on the probability of pregnancy occurrence in the studied ewes (odds ratio: 0.97; 95% confidence interval: 0.9-1.05; P=0.45). In conclusion, there was no evidence of a relationship between PUN concentration and pregnancy rate for lactating Awassi × Merino ewes in the present study because of low pregnancy rate observed.     

Ovine trophoblast protein-1 and bovine trophoblast protein-1 are present as specific components of uterine flushings of pregnant ewes and cows

A rabbit antiserum raised against ovine trophoblast protein-1 (oTP-1) was used to stain Western blots of the protein components from the uterine flushings of pregnant ewes (n = 61), non-bred cyclic ewes (n = 22), bred-but-nonpregnant ewes (n = 36), pregnant cows (n = 34), and bred-but-nonpregnant cows (n = 15). Nonpregnant animals were defined as ones from which no embryo was recovered. Uterine flushings of pregnant ewes contained oTP-1 between Days 14 and 24 of pregnancy, but not at Day 12. All of the cyclic ewes and 34 of 36 bred ewes, judged as nonpregnant, tested negatively for the presence of oTP-1. With one exception, oTP-1 was not detected in the nongravid uterine horns of pregnant ewes in which the conceptus had been confined to one uterine horn. Bovine trophoblast protein-1 (bTP-1), which cross-reacts immunologically with oTP-1, was also detectable specifically in the uterine flushings of pregnant cows when anti-oTP-1 antiserum was used. The urine (n = 14) and certival mucus (n = 20) samples of all the pregnant ewes tested were free of any detectable oTP-1. Thus, a useful pregnancy test for ewes based on oTP-1 release into these fluids seems unlikely. Results of this study show that oTP-1 and bTP-1 are pregnancy-specific proteins that are secreted into the uterine lumen where they possibly exert a local response.     

Relationship between ultrasonic characteristics of the corpus luteum, plasma progesterone concentration and early pregnancy diagnosis in Friesian mares

The purpose of the present study was to evaluate the change in cross-sectional area of the early corpus luteum (CL) and progesterone production in relation to subsequent pregnancy diagnosis. The cross-sectional area of the CL of 75 Friesian brood mares was measured by ultrasonography on Day 1 or 2 and Day 8 or 9 after ovulation. The change in cross-sectional area was expressed in a volume ratio. Plasma progesterone concentrations were measured on Days 8 to 9, and ultrasonography to determine pregnancy status was carried out on Day 17. The data obtained were analyzed by using a multiple logistic regression model. There were significant differences in the age, volume ratio and progesterone concentration between pregnant and nonpregnant mares. Pregnancy on Day 17 was related to the change in size of the CL up to Days 8 to 9 and progesterone concentration on Days 8 to 9. These differences between pregnant and nonpregnant mares might reflect the first luteal response to pregnancy.     

Receptors for prostaglandins F2 alpha and E2 in ovine corpora lutea during maternal recognition of pregnancy.

Plasma membrane receptors for prostaglandins (PG) F2 alpha and E2 were quantified in ovine corpora lutea obtained from nonpregnant and pregnant ewes on Days 10, 13, and 15 post-estrus, and from additional ewes on Days 25 and 40 of pregnancy. Regardless of reproductive status or day post-estrus, concentrations of luteal receptors for PGF2 alpha were 7- to 10-fold greater than those for PGE2. In pregnant ewes the concentration of receptors for PGF2 alpha was highest on Day 10 (35.4 +/- 2.8 fmol/mg) and lowest on Day 25 (22.3 +/- 2.5 fmol/mg). A difference in the concentration of luteal receptors for PGF2 alpha between pregnant and nonpregnant ewes was apparent only on Day 15 post-estrus, at which time the concentration of receptors for PGF2 alpha was higher in pregnant ewes than in nonpregnant ewes (27.1 +/- 2.7 vs. 17.7 +/- 2.7 fmol/mg). Concentrations of receptors for PGE2 in pregnant ewes were similar (p > 0.05; 2.8 +/- 0.3 to 3.7 +/- 0.2 fmol/mg) between Days 13 and 40 but were higher (p < 0.05) than in corpora lutea obtained from nonpregnant ewes on Days 10 (5.0 +/- 0.4 vs. 4.1 +/- 0.2 fmol/mg) and 15 (3.7 +/- 0.2 vs. 2.0 +/- 0.4 fmol/mg) post-estrus. Although concentrations of receptors for both PGF2 alpha and PGE2 were lowest in corpora lutea obtained from nonpregnant ewes on Day 15, this was not due to luteal regression since the weights and concentrations of progesterone in corpora lutea on Day 15 were not lower than those for corpora lutea obtained on Days 10 and 13.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of pituitary responsiveness to LHRH as a pregnancy test in ewes

Pregnant and nonpregnant ewes were injected with luteinizing hormone-releasing hormone (LHRH). Pituitary responsiveness, based on serum luteinizing hormone (LH), and follicle stimulating hormone (FSH) concentration, 2 hr after injection was then determined for each ewe, by radioimmunoassay (RIA) and correlated with the physiological reproductive state of each ewe. The serum LH release in pregnant ewes was significantly lower than that in nonpregnant ewes. Serum LH concentrations of pregnant ewes were further categorized according to whether the ewes were multiple (ML) or single lambing (SL). The responses by ML ewes were lower for LH than the SL responses. Follicle stimulating hormone responses were not different between pregnant or nonpregnant groups. Luteinizing hormone responses between pregnant ewes which were grouped according to 3 stages of pregnancy (1 to 5, 5 to 10 and 10 to 15 weeks pregnant) were not different from each other. Pregnancy diagnoses were made based on a fixed cut-off value, to which the LH response of each ewe to 5 mug LHRH was compared. Ewes whose response fell below this cut-off were diagnosed as pregnant. Accuracy of the diagnoses were determined by known lambing data. Diagnostic accuracy ranged from a low of 60% for nonpregnant, to a high of 95% for ML ewes. Accuracy for SL ewes (64%) was lower than for the overall pregnant group (79%), as well as that for ML ewes. Doses of LHRH, higher than 5 mug per ewe, generally produced LH release in pregnant ewes which was not significantly suppressed relative to responses of nonpregnant ewes. These results lead to the conclusion that gonadotropin response to exogenous LHRH injection is not an effective tool for pregnancy diagnosis.     

Myometrial activity and plasma progesterone and oxytocin concentrations in cycling and early-pregnant ewes

Myometrial activity and plasma progesterone (P) and oxytocin (OT) were measured in early pregnant (n = 5) and cycling (n = 5) ewes. Electromyography (EMG) leads and jugular and inferior vena cava (IVC) catheters were surgically placed in ewes about 1 wk before data collection. When ewes returned to estrus, they were bred to either an intact or vasectomized ram. Continuous EMG data were collected, and blood samples were collected twice daily from day of estrus (Day 0) until Day 18. Ewes bred with an intact ram were checked surgically for pregnancy on Day 20. Computerized, quantitative analysis of EMG events showed no difference in signal from the right to left uterine horns, and no differences between pregnant and cycling ewes (p less than 0.05) until Days 14-18 when nonpregnant ewes returned to estrus and had increased EMG activity. The mean number of EMG events 180-900 s in length decreased in pregnant ewes, but this difference was not significant (p less than 0.05). Jugular plasma progesterone (P) levels confirmed corpus luteum (CL) formation in all ewes, and no differences in P between pregnant and nonpregnant ewes were measured until Days 14-18, when cycling ewes underwent luteolysis and pregnant ewes maintained CL. IVC plasma oxytocin concentrations were increased in pregnant ewes compared to concentrations in nonpregnant ewes on Days 5-13 (p less than 0.05), and the difference was largest at Day 6 (means +/- SEM pg/ml: pregnant = 68.7 +/- 13.9, nonpregnant = 30.9 +/- 19.9).(ABSTRACT TRUNCATED AT 250 WORDS)     

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 (E1) measurement as a tool for pregnancy diagnosis was investigated. Concentrations of E1 were measured in feces from pregnant and nonpregnant sows by a direct ELISA without extraction. Highly significant differences in E1 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 E1 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 E1 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 E1/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 E1 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 E1 concentrations in both nonpregnant and pregnant sows offers a suitable basis for the development of a simple, sow-side pregnancy test.     

Effect of eCG on the pregnancy rate of ewes transcervically inseminated with frozen-thawed semen outside the breeding season

An experiment was conducted to determine whether factors affecting pregnancy rate out-of-season are associated more with transcervical artificial insemination (T-AI) procedures or with the reproductive state of the ewe. Twenty Finncross ewes were treated with progesterone sponges, and at sponge removal (0 h) 10 ewes were treated with eCG. Blood samples were collected for LH and progesterone analyses, and follicular development was monitored using ultrasonography. Ewes were inseminated from 48 to 52 h with 200 million motile frozen-thawed spermatozoa. The incidence of estrus, LH surges and ovulation was greater (P < 0.01) and intervals to these responses were shorter (P < 0.01) in the eCG-treated ewes. The number of follicles > 5 mm was higher (P < 0.05) in eCG-treated than control ewes. Progesterone concentrations increased and remained elevated through Day 19 in 7 eCG-treated and in 1 control ewe, and these ewes were pregnant based upon ultrasonographic examination. The results demonstrate that the T-AI technique using frozen-thawed semen produces a relatively high (70%) pregnancy rate out-of-season. The pregnancy rate was found to reflect primarily the reproductive condition of the ewe.     

Accuracy of ultrasonography and pregnancy-associated glycoprotein test for pregnancy diagnosis in buffaloes

The aims of the present study were to evaluate and compare the accuracy of transrectal ultrasonography and pregnancy-associated glycoprotein radioimmunoassay (PAG-RIA) test for diagnosis of pregnancy in buffaloes. Two hundred and seventy-five buffalo cows and heifers were examined once for pregnancy diagnosis by transrectal ultrasonography using a 5 MHz linear-array transducer between Days 19 and 55 after mating. After ultrasound scanning, a blood sample was withdrawn from jugular vein of each animal for measuring pregnancy-associated glycoprotein using a heterologous double-antibody RIA. Based on palpation of the uterus per rectum at Days 75-90, 87 animals were designated pregnant and 188 as non-pregnant. The sensitivity of transrectal ultrasonography at Days 19-24 was 44.4%, reaching 100% from Day 31 after mating. The specificity of transrectal ultrasonography ranged between 92.5 and 100% from Days 19 to 55 after mating. The sensitivity of PAG-RIA test was 11.1% at Days 19-24 and reached 100% from Day 31 after mating. The specificity of PAG-RIA test ranged from 90 to 100% from Days 19 to 55 after mating. There were no significant differences between the sensitivity and specificity of the two tests in all examined periods. In conclusion, transrectal ultrasonography and PAG-RIA test are highly accurate tests for detecting pregnant buffaloes from Day 31 after mating onwards.     

Early pregnancy diagnosis in sheep using near-infrared spectroscopy on blood plasma

The objective of this study was to evaluate the ability of near-infrared reflectance spectroscopy (NIRS) to discriminate between pregnant and nonpregnant ewes in early stages of pregnancy after artificial insemination (AI) from blood plasma. Samples were collected using jugular puncture at 18 and 25 days after AI from 188 Rasa Aragonesa and Ansotana ewes. Plasma samples were analyzed for pregnancy-associated glycoprotein (PAG) and progesterone (P4) using ELISA commercial kits. The spectra of plasma samples were recorded in the visible and near-infrared ranges. The performance of these tests were compared, using as criterion standard the pregnancy status determined using transabdominal ultrasonography at 45 days after AI. Pregnancy rate was 47.9% (90/188). At Day 18, sensitivity was similar in NIRS and P4 tests (98.9% vs. 100%; not significant) and greater than PAG (32.2%; both P < 0.001). Specificity was similar in NIRS and PAG tests (both 100%) and greater than that of P4 (84.7%; P < 0.001). At Day 25, sensitivity and specificity of NIRS and PAG were both 100%. It can be concluded that NIRS was an accurate method of diagnosis of pregnancy at Days 18 and 25 after AI in ewes.     

The effects of GnRH analogue (buserelin) or hCG (Chorulon) on Day 12 of pregnancy on ovarian function, plasma hormone concentrations, conceptus growth and placentation in ewes and ewe lambs

The objectives of this study were to determine the effect of GnRH analogue (buserelin) or human chorionic gonadotrophin (hCG, Chorulon) treatment on Day 12 of pregnancy on ovarian function, plasma hormone concentrations, conceptus growth and placentation in ewes and ewe lambs. After oestrus synchronization with progestagen sponges and eCG, all the animals were mated with fertile rams. Both ewes and ewe lambs (20 per treatment group) were given either normal saline or 4 microg GnRH or 200 IU hCG on Day 12 post-mating. Pre- and post-treatment plasma hormone concentrations were determined in seven pregnant animals per treatment group in samples collected 1h before and 0, 2, 4, 6, 8, 24, 48 and 72 h after treatment. Overall mean progesterone concentrations were higher (P<0.001) in ewes as compared with ewe lambs in saline-treated controls. GnRH or hCG treatment increased (P<0.001) mean plasma progesterone concentrations in both age groups, however, post-treatment concentrations were significantly (P<0.05) higher in ewes than in ewe lambs. Oestradiol concentrations were similar in the two control groups. In ewes, but not in ewe lambs, both GnRH and hCG treatments significantly (P<0.05) increased the mean oestradiol concentrations above pre-treatment levels. Moreover, post-treatment oestradiol concentrations in GnRH- and hCG-treated animals were significantly (P<0.05) higher than those in the saline-treated controls. LH release in response to GnRH treatment was greater (P<0.05) in ewes than in ewe lambs, whereas FSH release in ewes was less (P<0.05) than that of ewe lambs. The effects of GnRH or hCG on conceptus growth and placentation was determined at slaughter on Day 25. In ewes, GnRH treatment increased (P<0.05) luteal weight, amniotic sac width and length, and crown-rump length compared with controls, but had no effect on these parameters in ewe lambs. In ewes, hCG treatment also enhanced (P<0.05) luteal weight, amniotic sac width and length, crown-rump length, embryo weight and number of placentomes as compared with controls. In ewe lambs, there was no difference (P<0.05) between hCG and control groups in luteal weight, embryo weight and amniotic sac width but crown-rump length, amniotic sac length and the number of placentomes forming the placenta were greater (P<0.05). In conclusion, GnRH or hCG treatment on Day 12 of pregnancy can increase ovarian function, conceptus growth and placental attachment in ewes. However, these treatments were less effective in ewe lambs.     

Diagnosis of pregnancy in the ewe at mid-gestation

Detection of the pregnancy-specific antigen, chorionic somatomammotrophin in serum was applied to the diagnosis of pregnancy in a commercial-type flock of 286 sheep 70 days after joining with rams. At the time of testing the ewes were between Days 47 and 70 of pregnancy. Based upon lambing results, the positive diagnoses were 97% correct. However, the accuracy in diagnosing non-pregnancy, which rose from 85% when all the ewes (Day 47–70) were considered to 99% after Day 55, suggest that some pregnant ewes whose stage of pregnancy was earlier than Day 55 were not being detected and were wrongly designated non-pregnant. This pregnancy test can be successfully used from Day 55, although a correct prediction of pregnancy was made in 40 ewes between Days 47 and 54.     

Correlation between the release of ovine trophoblast protein-1 by the conceptus and the production of polypeptides by the maternal endometrium of ewes

We studied the biosynthesis of two proteins, p70 (Mr 70,000; pI 4.0) and p15 (Mr 15,000; pI 5.7), by endometrial tissues from ewes between Days 12 and 24 of pregnancy and between Days 12 and 16 of the oestrous cycle to determine whether production of the two was correlated with the period of biosynthesis of ovine trophoblast protein-1 (oTP-1) by the conceptus. We also compared the protein synthetic activities of endometrium from gravid and non-gravid horns of pregnant ewes at Days 14, 16 and 18 in which the conceptus had been confined to one uterine horn. Proteins p70 and p15 were produced maximally between Days 14 and 20 of pregnancy, but synthesis by endometrial cultures from cyclic ewes was low or absent. Furthermore, synthesis of Protein p70 in particular was much greater by the gravid than non-gravid horn of unilaterally pregnant ewes. We conclude that synthesis of Proteins p70 and p15 by the uterus of sheep coincides with the time of oTP-1 production by the conceptus.