Objectives were to evaluate the effects of administering either one or two low doses of slow-release recombinant bovine somatotropin (bST) on hormone concentrations, conceptus development, and fertility in dairy cows. Cows from two farms were detected in estrus on or after 50 days postpartum (n = 1483), inseminated, and enrolled in the study (Day 0). Within farm, cows were blocked by parity and assigned randomly to receive a single placebo injection at insemination (control), a single injection with 325 mg of bST at insemination (S-bST), or two injections with 325 mg of bST administered on Days 0 and 14 (T-bST). From a subset of cows, blood was collected twice weekly from Day 0 to 42 for determination of hormone concentrations and on Day 19 for isolation of leucocytes and analysis of transcript abundance of selected interferon-stimulated genes. Pregnancy was diagnosed on Days 31 and 66, and ultrasonographic morphometry of the conceptus was performed on Days 34 and 48 in a subset of cows. Cows that received T-bST had increased plasma concentrations of GH and IGF1 for 4 wk, increased mRNA expression of ISG15 and RTP4 in leukocytes, earlier rise in the pregnancy-specific protein B in plasma of pregnant cows, increased conceptus size, and enhanced fertility. Cows that received S-bST had increased concentrations of GH and IGF1 for only 2 wk and it was insufficient to alter conceptus development and fertility. In conclusion, supplementation with low doses of bST during the pre- and peri-implantation periods enhanced conceptus development, reduced embryonic losses, and improved fertility in dairy cows.

The objective of the present study was to compare two commercially available blood-based pregnancy tests, namely BioPRYN, an ELISA for pregnancy-specific protein B (PSPB), and an ELISA for pregnancy-associated glycoprotein (PAG), for early pregnancy diagnosis in dairy cattle using transrectal ultrasonography as a gold standard. Transrectal ultrasonography was conducted 26-58 days after artificial insemination (AI) in 197 cattle from 19 farms. Concurrently, a blood sample was collected for determination of serum PSPB and PAG. Transrectal palpation was performed approximately 120 days after AI to verify that pregnancy was maintained. For PSPB and PAG, there were no significant differences (P>0.05) in sensitivity (98.0 and 97.8%), specificity (97.1 and 91.2%), positive predictive values (99.3 and 97.8%), negative predictive values (91.9 and 91.2%) and accuracy (97.8 and 96.4%). In conclusion, the two blood pregnancy assays were equally efficacious and were highly accurate (based on transrectal ultrasonography as the gold standard).

Environmental factors, such as photoperiod and heat stress, can be manipulated during the dry period to influence health, productivity, and reproductive performance of dairy cows in their subsequent lactation. The impacts of photoperiod and heat stress on subsequent lactation are related to alterations in prolactin (PRL) signaling and may affect the expression of pregnancy-specific protein B (PSPB). Additionally, exposure of cows to heat stress during the dry period decreases gestation length; however, the mechanism involved in this process is unknown. The objective of these experiments was to evaluate the influence of environmental factors (i.e., heat stress and photoperiod) during late gestation (i.e., dry period) on PSPB concentrations in plasma of dairy cows. In Exp. 1, cows were dried off in the summer months approximately 46 d before expected calving and assigned randomly to heat stress (HT; n=30) or cooling (CL; n=30) treatment. Cooling cows were housed with sprinklers, fans, and shade, whereas HT cows were provided only shade. In Exp. 2, cows were dried off at approximately 60 d before expected calving in summer/fall months and randomly assigned to 3 treatments: long day photoperiod (LDPP: 16L:8D; n=15), short day photoperiod (SDPP: 8L:16D; n=14) and SDPP+PRL implant (12 mg/d of PRL at 28 d or 16 mg/d of PRL at 39 d; n=11). In both experiments, plasma samples were collected at dry off and at -32, -18, -7, -3 and 0 d relative to calving. In Exp. 1, greater concentrations of PSPB were detected in plasma of CL versus HT cows (388.3±24.7 vs. 287.4±23.8 ng/mL; P<0.01). Concentrations of PSPB did not differ between -46 to -18 d before calving (66.0 ng/mL). However, PSPB concentrations were greater (P<0.01) for CL cows at d -7 (534.7>357.2 ng/mL), -3 (807.2>572.2 ng/mL) and 0 (800.8>563.5 ng/mL) relative to calving. Additionally, HT cows in Exp. 1 had increased PRL plasma concentrations compared with CL cows (21.01±1.6 vs. 13.78±1.6 ng/mL). In Exp. 2, no differences were detected in plasma concentrations of PSPB (ng/mL) among LDPP, SDPP, or SDPP+PRL groups on d -60 (41.5), -32 (51.7), -18 (58.5), -7 (532.9), -3 (838.2), and 0 (729.4) relative to parturition. Photoperiodic PRL concentrations were 10.81, 7.84, and 4.22 ng/mL for LDPP, SDPP+ PRL, and SDPP, respectively. Results indicate that HT alters PSPB concentrations in late pregnancy, suggesting that placental activity is altered in cows exposed to excessive elevated temperatures around the time of calving. However, the mechanism involved likely is not associated with changes in PRL secretion.

This study was undertaken to detect pregnancy in Iraqi riverine buffalo (Bubalus bubalis) using three different methods (rectal palpation, plasma progesterone concentration and detection of the presence of pregnancy-specific protein B (PSPB) with the BioPRYN(®) enzyme-linked immunosorbent assay (ELISA) test. The aim of the study was to identify the most sensitive, early and accurate method for detecting pregnancy. Twenty-two female riverine buffalo that were 6.0 ± 0.93 years old were used. Four blood samples per buffalo were taken via jugular venipuncture at days 22-24, 32-34, 42-44 and 58-61 post-mating (PM) to measure the progesterone concentration (ng/ml) and to detect the presence of plasma PSPB. The rectal palpation method was employed to evaluate all buffalo on days 42-44 and 58-61 PM. The BioPRYN(®) test differed (p<0.01) from the other tests with earlier accuracy for detecting pregnant and non-pregnant buffalo. Eighty-eight percent of pregnant and 76.9% of non-pregnant buffalo were distinguished early (days 22-24 PM) using BioPRYN(®) and plasma PSPB-ELISA level (2.09 ± 0.12 ng/ml) in relation to 66.7% and 53.9% detected using the progesterone assay at similar days (4.30 ± 0.40 ng/ml). In conclusion, these results described, for the first time, the early and accurate pregnancy detection of water riverine buffalo using BioPRYN(®) technology and provided the plasma levels of PSPB using an ELISA test. These findings will improve the reproductive and productive efficiency of Iraqi riverine buffalo by adapting the recent management and reproductive strategies in Iraq and in the world.

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