The development of a double antibody radioimmunoassay for a bovine pregnancy-specific protein (pregnancy-specific protein B; PSPB) is presented. By means of this assay, PSPB could be measured in serum of pregnant cows. Five dairy cows were bled throughout gestation to measure serum levels of PSPB. Serum concentrations (means +/- SE) exceeded 1 ng/ml by 30 days postbreeding and increased gradually through three months (9 +/- 0.6 ng/ml), six months (35 +/- 6 ng/ml), and nine months (150 +/- 75 ng/ml) of gestation. Maximum levels of PSPB (542 +/- 144 ng/ml) were reached two days before parturition and then steadily declined to less than 78 ng/ml by 21 days postpartum. In 21 cows bled daily from 15 through 30 days postbreeding, PSPB could be measured in a few cows before and in most cows by 24 days after breeding. In a commercial herd of 102 beef cows, the assay could detect pregnancy earlier and more accurately than the routine method of rectal palpation. This radioimmunoassay measures a unique antigen that, for the first time, provides a serological method for detecting pregnancy in cows.
Two pregnancy-specific proteins were detected by immunoelectrophoresis using antisera developed to homogenates of bovine extraembryonic membranes. Antisera also reacted to extracts of endometrium from pregnant cows and extraembryonic fluids. However, antisera did not react with a preparation presumed to be bovine placental lactogen, fetuin, extracts of various somatic tissues from pregnant cows or extracts of endometrium from nonpregnant cows. One of the proteins had an estimated molecular weight of 65,000-70,000, an isoelectric point of 4.6-4.8 and yielded a reaction of identity with bovine alpha 1-fetoprotein by immunodiffusion. The second protein yielded a reaction of identity with bovine alpha 1-fetoprotein by immunodiffusion. The second protein had no immunological cross-reactivity with the known proteins or organ extracts which were tested. The molecular weight and isoelectric point was 47,000-53,000 and 4.0-4.4, respectively. These data demonstrate the presence of at least 2 pregnancy-specific proteins in cattle.
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.
Ovine pregnancy-specific protein B (oPSPB) was isolated from sheep placentas. Antiserum to oPSPB was developed in rabbits. A quantitative RIA was developed and used to assay the serum concentrations of oPSPB during and after pregnancy in ewes bearing single or twin fetuses. Suffolk and Panama ewes, kept with rams equipped with a marking harness, were checked daily for breeding marks as an indication of estrus and bled daily between 10 and 30 d after marking. Ovine PSPB became detectable at 19.7 +/- .14 (mean +/- SE) d after breeding and increased steadily to d 30. Panama oPSPB concentration increased at a greater rate than that of Suffolks (breed x day interaction, P < .01). Ten ewes were bled twice weekly 3 wk before their expected date of lambing and weekly for 7 wk postpartum. Serum concentrations differed considerably between prepartum ewes, but concentrations remained stable within the period of 20 d prepartum. Following parturition, oPSPB concentrations dropped rapidly. In nine ewes, oPSPB was last detectable at 12.78 +/- 2.26 (mean +/- SE) d postpartum. In the 10th ewe, oPSPB was .65 ng/mL at the last sample on d 46 postpartum. To determine the effect of fetal number on oPSPB concentrations, ewes in which estrus was synchronized were bled at d 18, 25, 38, 60, 90, and 120 after breeding. Ewes were killed at d 60, 90, 120, and 148 and fetal number determined. There was a significant (P < .01) difference in the log of oPSPB concentrations according to number of fetuses, day postbreeding, and the day x fetal number interaction.(ABSTRACT TRUNCATED AT 250 WORDS)
Pregnancy-specific protein B (PSPB) and progesterone concentrations were determined by RIAs in venous plasma during early pregnancy after 177 artificial inseminations (AI) performed in 76 cows and 71 heifers. The females were bled at 24, 26, 30\p=n-\35 days and \m=~\70 days (for non-returns to oestrus) after AI. In non-pregnant females without extended CL maintenance (progesterone < 1\m=.\5 ng/ml on Day 24) and or showing a normal time of return to oestrus (Group 1, N = 63), PSPB concentrations were undetectable whatever the stage after AI except in 2 cows. In pregnant animals (N = 83; Group 2) progesterone concentrations were > 10 ng/ml from Day 24 to the time of rectal palpation and PSPB concentrations rose continuously from 0\m=.\42\m=+-\0\m=.\07 (s.e.m.) ng/ml (Day 24) to 4\m=.\06 \ m=+-\ 0\m=.\3 ng/ml (time of rectal palpation). No coefficient of correlation between PSPB and progesterone concentrations was significant whatever the day of gestation studied. In cows with extended luteal function and subsequently found to be non-pregnant (late embryonic mortality) PSPB was undetectable (N = 21; Group 3) or detectable (N = 10; Group 4) at Days 24, 26 and/or 30\p=n-\35of pregnancy. At 24 and 26 days after AI progesterone concentrations were intermediate between those of Groups 1 and 2. At Day 24 females of Group 4 had higher progesterone concentrations than those of Group 3 (P < 0\m=.\05), but no differences between these two groups existed at subsequent stages after AI. Animals of Group 4 had lower PSBP concentrations than those of Group 2 between Days 24 and 30\p=n-\35 (P < 0\m=.\025) but at the time of rectal palpation PSPB values fell to undetectable levels in all but 1 cow of Group 4. We conclude that (1) most pregnancy failures in cows are due to nonfertilization or early embryonic death and if AI is performed after 70 days post partum >95% of these females have no detectable PSPB concentrations; (2) peripheral progesterone concentrations are lower at Days 24\p=n-\26after AI in cows with late embryonic mortality than in pregnant cows; (3) only 30% of non-pregnant females with extended luteal function (late embryonic mortality) have detectable PSPB levels which are lower than in pregnant cows; and (4) in pregnant animals there is no correlation between PSPB and progesterone concentrations. This suggests that under physiological conditions PSPB has no major effect on progesterone production or vice versa.
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