Effect of fetal mass, number and stage of gestation on pregnancy-specific protein B concentrations in the bovine

In this study we characterized the peripheral plasma pregnancy-specific protein-B (PSPB) profile throughout gestation and examined the effect of stage of gestation, fetal mass and number on this profile in Holstein cows after non surgical embryo transfer. Cows (n = 12) were divided into 2 groups: Group 1 = single embryo recipient cows (n = 5), Group 2 = twin-embryo recipient cows (n = 7). Blood was collected approximately every third day from Day 0 (Day 0 = first day of standing estrus), then daily for the last 10 d of gestation, and sampling was stopped 1 d post partum. Two twin-embryo recipient cows had abnormal pregnancies; therefore, their data were excluded from the group. The time trend concentrations of plasma PSPB were significantly affected by the stage of gestation (P < 0.001) and fetal number (P < 0.001). In both groups PSPB increased gradually, with the mean levels being significantly higher (P < 0.01) in the twin-bearing group from Day 50 onwards (0.7 +/- 0.2 vs 9.2 +/- 4.5 ng/ml, singleton and twin-bearing cows, respectively) except for Day 10 pre-partum. By mid-gestation (Day 140), mean PSPB levels increased in the singleton (P < 0.001) cows by thirty-fold (21.2 +/- 3.2 ng/ml) as opposed to a ten-fold (98.4 +/- 13.2 ng/ml) increase in the twin-bearing (P < 0.001) group. The mean PSPB concentrations between Days 30 to 20 prepartum dramatically increased by about 700 to 200% in singleton (128.8 +/- 46.3 to 745.6 +/- 66.7 ng/ml) and twin-bearing cows (375.6 +/- 130.4 to 861.5 +/- 127.9 ng/ml), respectively. The PSPB levels between Day 10 prepartum to parturition were significantly higher (P < 0.001) in the twin-bearing group than in the singleton group (745.6 +/- 66.7 to 1627.4 +/- 238.9 ng/ml vs 861.5 +/- 127.9 to 3103.0 +/- 643.0 ng/ml in singleton and twin-bearing groups, respectively). Calf birthweight was correlated (P < 0.01) to peripheral PSPB concentration in singleton cows; however, this relationship decreased with the subsequent increase in fetal number. Cows giving birth prematurely to stillborn calves or to a schistosomus reflexus calf exhibited abnormal PSPB profiles. These results indicate that peripheral PSPB levels are correlated to the stage of gestation and fetal number. In addition, the peripheral pattern of PSPB is a valuable guage for predicting fetoplacental viability.

Prostaglandin F2 alpha, progesterone and oxytocin production by cultured bovine luteal cells treated with prostaglandin E2 and pregnancy-specific protein B

The objectives of this experiment were to study the effects of pregnancy-specific protein B (PSPB) and prostaglandin E2 (PGE2) on bovine luteal cell progesterone (P4), prostaglandin F2 alpha (PGF2 alpha) and oxytocin production. Corpora lutea were collected during the mid- (days 10-12; n = 5) or late-luteal (days 17-18; n = 5) stages of the estrous cycle. Luteal cells were dispersed and accessory cells removed. Luteal cells (1.5 x 10(5)) were incubated in a 3 x 3 factorial arrangement and treated with PSPB (0, 2.5, or 5.0 micrograms) and PGE2 (0, 100, or 200 ng) in 500 microL of Ham's F-12 medium. All cells were incubated for 18 h before adding treatments. Samples were then collected at 6 h and 12 h. During the 18 h pretreatment period, P4, PGF2 alpha, and oxytocin production was similar between the prospective treatment groups. The PSPB failed to increase P4 production. The PGE2 x time interaction showed that P4 increased in response to PGE2 treatment at 6 h (P < 0.001) and 12 h (P < 0.03). Also, the stage x time interaction indicated that mid-stage cells produced more (P < .001) P4 than late-stage cells during the pretreatment period at 6 h and 12 h. The PSPB did not alter PGF2 alpha production by mid-stage cells, but increased (P < .05) PGF2 alpha by late-stage cells. Also, PGE2 stimulated (P < 0.001) PGF2 alpha secretion by both mid- and late-stage cells; luteal cells treated with 200 ng of PGE2 produced more (P < 0.001) PGF2 alpha than 100 ng of PGE2. Oxytocin secretion was not changed by treatment with PGE2 or PSPB. Oxytocin production was greater (P < 0.001) by mid-stage than late-stage cells during the pretreatment period at 6 h and 12 h. Oxytocin production was similar between the 6 h and 12 h culture times within stage of the cycle. These data indicate that PSPB does not change bovine luteal cell P4 or oxytocin production, but elevates PGF2 alpha in late-stage cells. The PGE2 increases both P4 and PGF2 alpha, but does not alter oxytocin production. Lastly, PSPB and PGE2 do not interact to promote P4 PGF2 alpha, or oxytocin production by cultured bovine luteal cells.

Effect of pregnancy-specific protein B on luteal cell progesterone, prostaglandin, and oxytocin production during two stages of the bovine estrous cycle

This experiment was designed to evaluate the effects of pregnancy-specific protein B (PSPB) on luteal cell progesterone (P4), PGF2 alpha, PGE2, and oxytocin secretion. Corpora lutea were collected during the mid (d 10 to 12; n = 5) or late luteal (d 17 to 18; n = 5) stage of the estrous cycle. Large and small cells (1.5 x 10(5)/well) were treated with PSPB (0, 2.5, or 5.0 micrograms) and LH (0, 50, or 100 ng) in a 3 x 3 factorial arrangement. Cells were incubated for 18 h before adding treatments; after treatments, medium was collected at 6 and 12 h. During the 18-h pretreatment period, P4, PGF2 alpha, PGE2, and oxytocin production was similar between the prospective treatment groups. The PSPB did not affect P4 production. Stage of the cycle (stage) x time interaction (P < .001) indicated that mid-stage luteal cells produced more P4 than late-stage cells; regardless of stage, P4 decreased with time. The time x LH interaction (P < .001) revealed that at 6 and 12 h the 50- and 100-ng doses of LH increased P4 to greater than the 0-ng dose. Production of PGF2 alpha by mid-stage cells was similar among the three PSPB treatments; however, PGF2 alpha production by late-stage cells increased (P < .01) in response to the 5.0-micrograms dose of PSPB. The LH did not affect PGF2 alpha production. Late-stage luteal cells produced more (P < .001) PGF2 alpha than mid-stage cells during the 18-h pretreatment period and at 6, but not 12, h.(ABSTRACT TRUNCATED AT 250 WORDS)

Pregnancy determination by use of pregnancy-specific protein B radioimmunoassay in llamas

Blood samples were obtained from each of 30 llamas: 22 females that had been exposed to a male and were assumed to be pregnant (gestational stage, 2 to 244 days), 1 female that had not been exposed to a male, 3 sexually intact males, 1 castrated male, and 3 females with congenital reproductive anomalies. Serum was tested for the presence of pregnancy-specific protein B, using a radioimmunoassay that accurately detected pregnancy in cattle, sheep, and other ruminants. Pregnancy-specific protein B was not detected in the serum of the 30 llamas. On the basis of our results, the radioimmunoassay for pregnancy-specific protein B cannot be used in llamas for detection of pregnancy.

Fertility of bull semen packaged in .25- and .5-milliliter french straws

The fertility of bull semen packaged in .25- and .5-mL french straws was compared. One ejaculate from each of five Holstein bulls was split, extended to 10 x 10(6) spermatozoa/inseminate dose in whole homogenized milk, packaged in .25- and .5-mL french straws, frozen in liquid nitrogen (LN) vapor, and stored in LN. Semen was thawed at 37 degrees C for 30 s. Synchronized heifers (n = 1,360) were inseminated (during a 12-mo period) with semen packaged in either a .25- or .5-mL french straw. Blood was collected on the day of insemination and the serum was assayed for progesterone. Heifers with blood progesterone levels of > 1 ng/mL were eliminated from the data. Blood was collected at 30 to 45 d after insemination and the serum was assayed for the presence of bovine pregnancy-specific protein B (bPSPB) by RIA to determine pregnancy. Conception was 63.6 and 62.0% (P = .55) for semen packaged in the .25- and .5-mL french straws, respectively. There was neither a bull x packaging unit interaction (P = .49) nor a day of insemination x packaging unit interaction (P = .87). Conception among bulls ranged from 57.1 to 68.0% (P = .19). No evidence was found that meteorological factors influenced conception. Under the conditions of this experiment, semen packaged in the .25- and .5-mL french straw had similar fertility.

Detection of fetal twins in sheep using a radioimmunoassay for pregnancy-specific protein B

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)

Embryonic loss from 30 to 60 days post breeding and the effect of palpation per rectum on pregnancy

This study was conducted over a 12-mo period to determine the rate of bovine embryo death between 30 and 60 d of gestation. In addition, palpation per rectum as a means of pregnancy detection was evaluated as a possible cause of embryo death. Estrus was synchronized in Holstein heifers (n = 1358), weighing > or = 385 kg, with a single intramuscular injection of 25 mg prostaglandin F(2alpha). Estrus was primarily detected by the absence of paint marks on the tailhead. The heifers were artificially inseminated with semen from 5 Holstein sires. Blood was collected between 30 and 45 d after breeding, and sera were evaluated for the presence of bovine pregnancy-specific protein B (bPSPB) by RIA to determine pregnancy. Palpation for fetal membrane slip was conducted by an experienced technician in approximately one-half of the inseminated heifers. To determine embryonic survival, a second blood sample was collected at approximately 60 d from 862 heifers that were determined to be pregnant at the first blood sampling. Embryonic loss averaged 5.3% during the interval between the initial detection of pregnancy at 30 to 45 d and the subsequent detection of pregnancy at 60 d of gestation. Embryo loss in heifers that were palpated was 6.5% compared with that of 4.3% in the control heifers (X(2): P = 0.145). These findings establish that there was substantial loss of embryos between 30 and 60 d post breeding but that embryo loss was not affected by palpation per rectum.

Effects of prostaglandin F2 alpha (PGF2 alpha) on secretion of pregnancy specific protein B (PSPB) and placentome weights in intact or ovariectomized 90 to 100 day pregnant ewes

Vehicle or 8 or 16 mg PGF2 alpha/58 kg/body weight (BW) was given intramuscularly to intact or ovariectomized 90 to 100 day pregnant ewes in two separate experiments. Treatment with 8 mg PGF2 alpha in intact 90 to 100 day pregnant ewes increased (P < or = 0.05) placentome weights, but not in ovariectomized 90 to 100 day pregnant ewes (P > or = 0.05). Concentrations of PSPB in uterine venous plasma of control 90 to 100 day intact pregnant ewes over the 72 hour sampling period averaged 52 +/- 5 ng/ml. Profiles of PSPB in uterine plasma in the 16 mg PGF2 alpha/58 kg/BW-treated ewes differed (P < or = 0.05) from control or 8 mg PGF2 alpha-treated 90 to 100 day intact pregnant ewes. Pregnancy specific protein B was increased (P < or = 0.05) at 64 hr in intact 90 to 100 day pregnant ewes by treatment with 8 mg PGF2 alpha/58 kg/BW. There was a quadratic increase (P < or = 0.09) in PSPB in uterine venous plasma of all three treatment groups of intact 90 to 100 day pregnant ewes. Concentrations of PSPB in uterine venous plasma of control 90 to 100 day ovariectomized pregnant ewes over the 72 hr treatment period averaged 90 +/- 5 ng/ml. Profiles of PSPB did not differ among the vehicle, 8 mg PGF2 alpha or 16 mg PGF2 alpha-treated ovariectomized 90 to 100 day pregnant ewes. There was a quadratic increase (P < or = 0.10) in PSPB in uterine venous plasma of ovariectomized 90 to 100 day pregnant ewes treated with 8 or 16 mg PGF2 alpha/58 kg/BW. It is suggested that PSPB may have a role in regulating placental steroidogenesis.

Methods for pregnancy determination and the effects of body condition on pregnancy status in Rocky mountain elk ( )

The objective of this study was to determine the effectiveness of transrectal ultrasonography and serum progesterone (P(4)), estrone sulfate (E(1)S) and pregnancy-specific protein B (PSPB), without prior knowledge of reproductive status, in detecting pregnancy in elk cows. In addition, body weight and body condition score (BCS) were determined to assess whether body condition affects pregnancy status in elk cows. Twenty-five elk cows were sampled during the early rut (Period 1) and after the rut (Period 2), an interval of 120 d. Age, weight, BCS and blood samples, for P(4), E(1)S and PSPB determinations, were taken at Periods 1 and 2. Ultrasonography was performed at Period 2. The younger elk cows weighed less (P<0.05) than older cows. However, pregnancy status was not affected (P> 0.10) by age or weight of the cow. Elk cows that calved had higher (P<0.02) BCS at Periods 1 and 2 than cows that remained open. Serum P(4) and E(1)S were higher (P<0.0001) in pregnant cows at Period 2 than in open cows. Progesterone was 85.8% accurate in detecting pregnant versus open cows at Period 1, while E(1)S and PSPB were not effective. Elk cows at Period 1 were <20 d pregnant with the exception of 1 cow at 46 d. Ultrasonography was 92% accurate, P(4) was 95% accurate, and E(1)S and PSPB were both 100% accurate in determining pregnant versus open cows at Period 2. Pregnant cows at Period 2 were all > 100 d pregnant. Ultrasonography, serum E(1)S and PSPB all may provide a reliable means for pregnancy diagnosis in elk cows at > 100 d of gestation, while serum P(4) may be effective when multiple samples are compared during or after the rut, or when used in combination with the other diagnostic methods described. Further research is needed to determine the optimum time period after breeding in elk cows for accurate pregnancy detection through hormonal analysis.

Diagnosis of pregnancy in moose using a bovine assay for pregnancy-specific protein B

Blood samples were collected from 26 moose (Alces alces ) and evaluated for the presence of an antigen that cross-reacted with antisera to bovine pregnancy-specific protein B (P-SPB). The objective of this study was to determine if the P-SPB radioimmunoassay (RIA) was a reliable indicator of pregnancy in these animals. In the first year of the study calf production the following summer was used as the index of previous pregnancy. In the second year all females were subjected to palpation per rectum after chemical immobilization. Seven of the 10 cows sampled in the first year were also sampled in the second year. All animals determined pregnant by rectal palpation were positive for P-SPB; however, P-SPB was not detected in males.

Pregnancy-specific protein B in serum of postpartum beef cows

To determine whether the uterus was the source of serum pregnancy-specific protein B (PSPB) after calving, five beef cows were hysterectomized at 21 d postpartum and five served as intact controls. A single blood sample was taken from all cows immediately after calving and then twice weekly until 21 d postpartum. Beginning on d 22, blood samples were taken from all cows at 3-h intervals for 4 d and then twice weekly until 53 d postpartum. When the half-life calculated for the interval from d 1 to 21 was used as a covariate, the adjusted d-22 to -53 half-lives were 8.4 d for control cows vs 7.3 d for hysterectomized cows (P = .044). Data show that PSPB has a long half-life in the circulation and that the uterus is a minimal, if any, source of postpartum circulating PSPB. In another experiment, PSPB was measured weekly after calving in serum of 58 Polled Hereford and Simmental cows. Cows were exposed to fertile bulls and allowed to mate at every estrus. Observations were made for estrus, and progesterone concentrations in serum were measured to estimate the time of ovulations. Levels of PSPB were highest at approximately the time of calving, then decreased rapidly. Concentrations of PSPB were < 1 ng/mL by 80 d in eight cows that had not conceived since calving. Two cows eventually had nondetectable PSPB levels, one by 86 d and the other by 96 d after calving.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration of GnRH at estrus influences pregnancy rates, serum concentrations of LH, FSH, estradiol-17 beta, pregnancy-specific protein B, and progesterone, proportion of luteal cell types, and in vitro production of progesterone in dairy cows

Four experiments were conducted to examine effects of GnRH administered at estrus on various reproductive characteristics in repeat-breeding dairy cows (eligible for third service). In Exp. 1, cows (n = 8 per group) received (i.m.) either saline or 50, 100, or 250 micrograms of GnRH at 12 h after onset of estrus. There was a positive linear (P < .05) effect of dose on concentrations of LH, but not of FSH, in serum at 2 h after the injection. Concentrations of progesterone (P4) were higher (P = .10) through 16 d after estrus in nonpregnant cows that returned to estrus 18 to 24 d after GnRH treatment than in nonpregnant cows given saline. Likewise, among cows with elevated concentrations of P4 through 30 d after estrus (diagnosed pregnant by increased concentrations of pregnancy-specific protein B; PSPB), P4 was higher (P = .10) in those given GnRH than in those given saline. In Exp. 2, concentrations of LH, FSH, and estradiol-17 beta (E2) were similar among 12 cows during the periestrual period before they received (i.m.) 100 micrograms of GnRH or saline at estrus. Concentrations of P4 after estrus were increased 2 d earlier (P < .05) in GnRH- than in saline-treated cows. Among cows with elevated concentrations of P4 and PSPB through 40 d after AI, P4 was higher (P < .05) in those given GnRH than in those given saline. In Exp. 1 and 2, a greater proportion (43 vs 14%; P = .07) of cows given GnRH was pregnant 42 to 56 d after estrus than of those given saline, but calving rate was similar (27 vs 14%). In Exp. 3, average number of LH pulses per 8 h was similar between saline- and GnRH-treated cows on d 1, 3, and 8, but overall concentrations of LH were reduced (P < .05) in GnRH-treated cows. Concentrations and number of pulses of FSH were increased (P < .05) on d 8 after treatment with GnRH. Concentrations of P4 were increased earlier (P < .05) after estrus in GnRH-treated (69 +/- 12 h) than in saline-treated cows (126 +/- 12 h), with higher (P < .05) concentrations of P4 on d 4 to 8. In Exp. 4, eight cows received either 100 micrograms of GnRH or saline at 12 h after onset of estrus (d 0) in a cross-over design.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of pregnancy-specific protein B on prostaglandin F2 alpha and prostaglandin E2 release by day 16-perifused bovine endometrial tissue

Five normal estrous cycling multiparous non-lactating Brahman cows were utilized to determine if pregnancy-specific protein B (PSPB) would alter prostaglandin F2 alpha (PGF) and prostaglandin E2 (PGE) synthesis/release by endometrial tissue. The uterine horn ipsilateral to the corpus luteum was excised on Day 16 of the estrous cycle. Endometrial tissue (200 mg wet wt) was cultured in Nutrient Mixture F-10 medium in a perifusion system. The tissue and medium were aerated with 95% O2: 5% CO2 and temperature was maintained at 39 degrees C. The medium flow rate was 100 microliters/min and fractions were collected at 20 min intervals. After a 120 min settling period, tissue culture continued with: 1) control (medium only); 2) 2 micrograms [Asu1,6]-oxytocin/ml medium for 1 h; 3) 4 or 8 micrograms PSPB/ml medium for 2 h; or 4) 4 or 8 micrograms PSPB/ml medium for 2 h plus 2 micrograms oxytocin/ml medium during the second h. Differences in PGF and PGE secretion rate were not found between 4 and 8 micrograms PSPB. Therefore, groups were combined and data were analyzed according to tissue not receiving PSPB (control); receiving PSPB and receiving PSPB plus oxytocin. A nonsignificant rise (p greater than 0.10) in PGF secretion was observed in response to PSPB and PSPB plus oxytocin above the control by the end of the perifusion period (263.7 +/- 41.7, 220.0 +/- 41.7 and 166.1 +/- 41.7 pg/(100 mg tissue/min), respectively). Treatment with PSPB alone elevated (p less than 0.05) PGE secretion rate above control by 100 and 160 min post-removal of PSPB treatment. Treatment with PSPB plus oxytocin elevated (p less than 0.05) PGE release above control by 20 min after starting oxytocin treatment and continued throughout the duration of the perifusion. Pregnancy-specific protein B plus oxytocin-induced PGE release was greater (p less than 0.05) than PSPB alone after initiating the oxytocin treatment until 20 min after removal of the treatments. However, no further differences between PSPB alone and PSPB plus oxytocin treatments were detected throughout the remainder of the perifusion period. It appears that PSPB tends to elevate PGF release and significantly elevates PGE release from Day 16 endometrial tissue.

Pregnancy-specific protein B and progesterone concentrations in French Alpine goats throughout gestation

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 (greater than 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 less than 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.

Postpartum reproduction in protein restricted beef cows: effect on the hypothalamic-pituitary-ovarian axis

The influence of dietary CP on circulating LH and anterior pituitary and hypothalamic function was examined. In Exp. 1, 28 cows were randomly assigned to four treatment groups: adequate CP (ADQ; .96 kg/d) or deficient CP (DEF; .32 kg/d) beginning at 90, 60 and 30 d before parturition and continued at a 33% increase in feed consumption after parturition. Cows were bled at 15-min intervals for 8 h on d 20, 40 and 60 after parturition. Pituitaries were collected on d 62 to analyze GnRH receptor numbers and gonadotropin content. Frequency of pulsatile LH release increased (P less than .05) from 20 to 60 d in ADQ cows. Basal and mean LH were not affected (P greater than .10) by CP restriction or by days after parturition. Crude protein did not affect pituitary GnRH receptors (P greater than .10), but it did affect pituitary LH content, FSH content and FSH concentration (P less than .05). In Exp. 2, 28 cows were assigned to treatment groups as in Exp. 1. All cows were challenged with GnRH (.22 micrograms/kg BW) at 20, 40 and 60 d after parturition and were bled every 30 min for 6 h. Responsiveness to GnRH increased with increased time after parturition (P less than .07). Deficient CP decreased GnRH-induced LH release (P less than .05). In Exp. 3, 12 cows were randomly assigned to ADQ or DEF CP beginning 120 d before parturition. All cows received 1 mg estradiol-17 beta (E2) on d 19, 39 and 59 after parturition and were bled every 30 min for 14 h beginning 14 h following E2. Response to E2 was unaffected by CP restriction (P greater than .10), whereas time to E2-induced LH peak decreased as time after parturition increased in ADQ cows (P less than .05). Results suggest that delayed return to estrus in CP-deficient postpartum beef cows might be due to reduced gonadotropin release from the anterior pituitary and decreased anterior pituitary responsiveness to GnRH.

Postpartum reproductive performance in crude protein-restricted beef cows: return to estrus and conception

A study was conducted to evaluate the effect of a deficiency in dietary crude protein intake on postpartum reproductive performance of first-calf beef cows. Forty primigravid Hereford heifers were randomly assigned to two groups that were fed isocaloric (100% NRC requirements) diets containing .96 (adequate) or .32 (deficient) kg crude protein per head daily. Animals were individually fed from 150 d prepartum to 40 d postpartum and then were group-fed until the end of the experiment at 110 d postpartum. Total nutrient intake was increased by 33% at time of parturition to meet lactation requirements. Animals were artificially inseminated between 45 and 110 d postpartum when they showed estrus. Eighty-nine percent of those fed adequate protein showed estrus, whereas only 63% of protein-restricted heifers exhibited estrus (P less than .05). First-service conception (P less than .05; 71 vs 25%) and overall pregnancy rates (P less than .05; 74 vs 32%) were lower in protein-restricted heifers. Compared with those fed adequately, protein-restricted heifers had a tendency for longer intervals to first estrus (P less than .08; 75 vs 86 d), to first service (P less than .09; 76 vs 87 d) and to conception (P less than .09; 81 vs 92 d). Regardless of diet, weight at first estrus, weight at first service and average daily gain to 40 d postpartum were negatively correlated (P less than .01) with length of intervals from parturition to first estrus and first service.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of protein turnover by recombinant human insulin-like growth factor-I in L6 myotube cultures

Muscle cell culture experiments were conducted to determine the relative regulatory effects of insulin-like growth factors (IGF) on protein turnover. The effects of recombinant (rc) human IGF-I, ovine somatomedin (oSm/oIGF-I), and insulin on rates of protein labeling and degradation in L6 myotube cultures were evaluated. Myotube cultures were treated with growth factors following a 4-h serum-free incubation period. Protein labeling was measured by determining the rate of [3H] leucine incorporation into cell protein. Protein degradation was measured by a pulse-chase procedure using [3H] leucine. The apparent half maximal stimulation of protein labeling (12%, 8%, 7%) occurred at approximately .1 nM rcIGF-I, 1 nM oSm/oIGF-I and 15 nM insulin, respectively. The apparent half maximal inhibition of proteolysis (18%, 15% and 11%) occurred at .4 nM rcIGF-I, .6 nM oSm/oIGF-I and 4 nM insulin, respectively. The magnitude of the response for protein labeling and degradation was greatest for rcIGF-I. The results provide additional evidence that IGFs play a primary role in regulating protein turnover in muscle.

Pregnancy-specific protein B, progesterone concentrations and embryonic mortality during early pregnancy in dairy cows

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 approximately 70 days (for non-returns to oestrus) after AI. In non-pregnant females without extended CL maintenance (progesterone less than 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 greater than 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 less than 0.05), but no differences between these two groups existed at subsequent stages after AI.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of pregnancy in sheep by radioimmunoassay of sera for pregnancy-specific protein B

A radioimmunoassay (RIA) for bovine pregnancy-specific protein B (bPSPB) has been shown to be a reliable test for pregnancy in cows. Pregnant ewes have a blood antigen that cross-reacts in this RIA. Two studies were conducted to determine the accuracy of detection of pregnancy in sheep using the bPSPB RIA. In Study 1, 33 ewe lambs were bred over a 70-d period in late fall. At 26, 56, and 83 d after the end of the breeding period, blood samples were collected for assay in the bPSPB RIA, and the Pregmatic 3 ultrasonic device was used to detect pregnancy. Pregmatic 3 detected pregnancy in 14, 27 and 28 ewes and nonpregnancy in 19, 6 and 3 ewes at Days 26, 56 and 83 past the breeding period, respectively. The bPSPB assay detected pregnancy in 32, 31 and 30 ewes and nonpregnancy in 1, 2 and 2 ewes at Days 26, 56 and 83 past breeding, respectively, Thirty ewes lambed and three did not. In Study 2, 180 multiparous ewes were bred over a 60-d period in summer. At 35 d after the end of the breeding period, blood samples were collected for assay in the RIA, and a real-time ultrasonic scan was done to detect pregnancy. Real-time ultrasonic testing detected pregnancy in 163 ewes and nonpregnancy in 17 ewes; whereas, the RIA detected pregnancy in 161 ewes and nonpregnancy in 19 ewes. One hundred fifty-nine ewes lambed and 21 did not. The bPSPB RIA detected pregnancy earlier and more accurately than the Pregmatic 3 ultrasonic device and was equally as accurate as the real-time scanning instrument. These studies demonstrate an accurate serological test for a pregnancy-specific antigen in sheep.

Detection of pregnancy by radioimmunoassay of a novel pregnancy-specific protein in serum of cows and a profile of serum concentrations during gestation

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.

Partial purification and characterization of somatomedin from sheep serum

A rapid, high yield preparative technique for the isolation of sheep somatomedin is reported. Purification of biologically active somatomedin from the 60% ammonium sulfate precipitate of sheep serum was accomplished using three gentle fractionation steps. Biological activity during purification was monitored using the rat adipocyte nonsuppressible insulin-like activity (NSILA) assay. A stepwise pH elution (pH 2.85, 3.5, 4.5, and 6.0) from SP-Sephadex resulted in the elimination of more than 99% of the serum proteins and a 500-fold enhancement of biological activity. The active fraction eluted at pH 6.0 and was further fractionated on Sephadex G-50 (fine) chromatography at pH 2.85. This resulted in about a 10,000-fold enhancement of activity over serum activity. The most active fractions from Sephadex chromatography were further separated on reverse phase HPLC in 0.1% trifluoroacetic acid using a linear gradient of 24-60% acetonitrile. The biological activity of the final preparation was enhanced 61,000- to 182,000-fold over that of serum (mean, 93,000-fold) when assayed in the NSILA assay. Protein yield was estimated to be 467 micrograms/liter serum. In addition to the NSILA activity, the final preparation demonstrated dose-dependent sulfation factor activity in the embryonic chick pelvic leaflet bioassay. Sheep somatomedin was active at physiological levels in both bioassays. Analysis of the somatomedin preparation by sodium dodecyl sulfate-electrophoresis at pH 8.8 showed that it was homogeneous by this criterion. The activity eluted from Sephadex G-50 was estimated to have a molecular size of 6900. Two Coomassie blue-stained bands were present in the final sheep somatomedin preparation after polyacrylamide gel electrophoresis at pH 3.2. Our purification process is a rapid, high yield technique which yields a polypeptide fraction enriched in NSILA and somatomedin-like activity. The molecular size and biological activity in the NSILA and sulfation factor assays suggest that our sheep NSILA is analogous to somatomedins purified from other species of animals.

Detection and partial characterization of two bovine pregnancy-specific proteins

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.

Estrogen in plasma of parturient paretic and normal cows

The endocrine factors associated with parturient paresis have not been defined totally. Estrogens stimulate uptake of calcium by bone. Since secretion of estrogen increases dramatically as parturition approaches, estrogen may be involved in homeostatic mechanisms regulating calcium metabolism. Plasma was collected for 30 days (-30) prepartum to 5 days (+5) postpartum from six Holstein and nine Jersey cows approaching three or more lactations. Of all cows, six Jerseys contracted parturient paresis. Estradiol and estrone were analyzed by radioimmunoassay, total calcium and total magnesium by atomic absorption spectrophotometry, and total phosphorus by colorimetry. Data were grouped into periods respresenting days -30 to -21, -20 to -11, -10 to -6, -5 to -4, -3 to -2, -1, 0 (parturition), +1, +2 to +3, and +4 to +5. Calcium in plasma was lower in parturient paresis cows on days +1 and +2 to +3, and magnesium was higher during the same periods but lower on days -4 to -5. Total phosphorus, estrone, and estradiol of normal cows and those with parturient paresis were not different. During the entire sampling period, phosphorus and estradiol were similar in both groups while magnesium was higher and calcium lower in cows with parturient paresis. Estrone was lower in cows with parturient paresis. Lower estrone in cows with parturient paresis may be predisposing for parturient paresis.

Failure of LH and/or prolactin to prevent PGF 2alpha-induced luteolysis of ovine corpora lutea

Infusions of phosphate buffered saline, LH (4 microgram/min or 14 microgram/min), prolactin (42 microgram/min) or LH (4 microgram/min) plus prolactin (42 microgram/min) for 12 hr did not prevent luteolysis following intramuscular injections of prostaglandin F2alpha-tham salt two and six hr after beginning the infusion. Likewise, these treatments did not delay luteolysis since a similar rate of decline in peripheral plasma progesterone occurred in all groups. It was concluded that elevation of serum concentrations of LH and prolactin to high levels had no effect on PGF2alpha-induced luteolysis on day 8 following induced ovulation.