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  • Author: R. G. Sasser x
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R. P. Del Vecchio, W. D. Sutherland and R. G. Sasser

A study was conducted to determine the effects of pregnancy-specific protein B (PSPB) and prostaglandin F (PGF) on bovine luteal cell progesterone, prostaglandin E2 (PGE2) and oxytocin production in vitro. Corpora lutea were enucleated from multiparous cows with normal oestrous cycles during the mid-luteal (days 10–12; n = 5) or late-luteal (days 17–18; n = 5) stage. Mixed large and small cells (1.5 × 105 cells per well) were incubated in 500 μl modified Ham's F-12 medium. Cells were incubated for 18 h before treatments were added. Cells were treated with PSPB (0, 2.5, 5.0 μg) and PGF (0, 100, 200 ng) in a 3 × 3 factorial arrangement. After treatments were added, media samples were collected at 6 and 12 h. During the 18 h pretreatment incubation, progesterone, PGE2 and oxytocin production was similar between the prospective treatment groups. Progesterone production was greater (P < 0.001) by mid-stage than by late-stage cells. In addition, progesterone decreased (P < 0.001) as incubation time increased. Progesterone production was not affected by PGF, but PSPB increased (P < 0.02) progesterone at the 5.0 μg dose. Late-stage luteal cells produced more (P < 0.001) PGE2 than did mid-stage cells; PGE2 production decreased (P < 0.001) with increased incubation time. Luteal PGE2 production increased in response to PSPB treatment (P < 0.01) and PGF treatment (P < 0.001). Luteal oxytocin production was greater (P < 0.01) by mid-stage compared with late-stage cells. Oxytocin production decreased (P < 0.001) with incubation time in mid-stage cells, but in late-stage cells oxytocin production was similar over time. Neither PSPB nor PGF had an effect on oxytocin. These results indicate that PSPB does not affect luteal oxytocin, but does increase progesterone and PGE2 production. In addition, PGF increases luteal PGE2, but does not affect progesterone or oxytocin production. These data do not show an interaction between PSPB and PGF in regulating bovine luteal cell endocrine function.

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R. A. Gustafson, G. B. Anderson, R. H. BonDurant and G. R. Sasser

Six hybrid pregnancies were established: three in sheep–goat chimaeras, one in a sheep–(sheep–goat)hybrid chimaera and two in does. Pregnancies were monitored weekly by ultrasonography and peripheral concentrations of pregnancy specific protein B (PSPB) were measured. Placental development as detected by ultrasonography appeared to be slower in hybrid-in-goat pregnancies than in hybrid-in-chimaera pregnancies, although this difference was not reflected in PSPB concentrations. Time of fetal death could not be predicted from PSPB concentrations. Chimaeras appeared to carry hybrid pregnancies longer than ewes and does usually carry hybrid pregnancies, but none was carried to term.

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P. Humblot, G. De Montigny, N. Jeanguyot, F. Tetedoie, B. Payen, M. Thibier and R. G. Sasser

Summary. The 34 French Alpine dairy goats originated from a single flock and were artificially inseminated 44 h after synchronization of oestrus. They were bled daily at the jugular vein from 15 to 27 days after AI. An early pregnancy diagnosis by RIA of progesterone concentration was performed 21 days after AI. In pregnant goats (≥ 1·5 ng progesterone/ml) daily sampling was extended until 30 days after AI and, from those, 9 were bled every 2 weeks until the end of pregnancy and at 50 and 63 days post partum. Pregnancy-specific protein B (PSPB) was also assayed.

The kidding rate was 67·6% (23/34). PSPB concentrations (ng/ml) in pregnant goats were significantly different from those of non-pregnant goats at 24 days after AI (0·82 ± 0·18 vs 1·78 ± 0·19; mean ± s.e.m.) and rose to 40 ng/ml at the end of pregnancy. From Day 25 and throughout gestation, females with 2 fetuses had higher PSPB concentrations than did those with a single fetus (P < 0·05). In the 2 goats exhibiting late embryonic mortality according to progesterone concentrations, one had a PSPB profile very similar to those of pregnant goats until 30 days while the other did not show any elevation of PSPB concentration. It is concluded that PSPB profiles in goats are similar to those found in cows throughout pregnancy and that PSPB RIA may be useful for pregnancy diagnosis or diagnosis of late embryonic mortality.

Keywords: PSPB; progesterone; pregnancy; embryonic mortality; goat

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P. Humblot, S. Camous, J. Martal, J. Charlery, N. Jeanguyot, M. Thibier and R. G. Sasser

Summary. 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, 30–35 days and ∼ 70 days (for non-returns to oestrus) after AI. In non-pregnant females without extended CL maintenance (progesterone < 1·5 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 0·42 ± 0·07 (s.e.m.) ng/ml (Day 24) to 4·06 ± 0·3 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 30–35 of 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 < 0·05), 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 30–35 (P < 0·025) 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 24–26 after 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.

Keywords: PSPB; progesterone; pregnancy; embryonic death; cow