Biomedical subjects

R J Mapletoft

Publications and source records attributed to R J Mapletoft.

At least 55 records · Page 3Linked to original sources

PubMed1995

Media alternatives for the collection, culture and freezing of mouse and cattle embryos.

The replacement of biological products in media for the collection, culture and freezing of mammalian embryos was studied. To test the hypothesis that chemically defined surfactants can replace bovine serum albumin (BSA) or serum in embryo media, morula-stage mouse and cattle embryos were collected, cultured, and/or frozen in the surfactant compound, VF5. Collection efficiency of mouse and cattle embryos did not differ whether the medium contained serum or surfactant. In addition, morula-stage mouse and cattle embryos developed and hatched at similar rates in culture media containing either BSA or surfactant. Although the freeze/thaw survival and development in culture of bovine embryos was not significantly different in any of the media, there was a significantly lower hatching rate of mouse embryos frozen with serum or surfactant than with cryoprotectant alone or with cryoprotectant plus albumin-free serum. However, the absence of serum or surfactant in embryo freezing media resulted in embryo loss, presumably due to stickiness. The data suggest that serum can be replaced by a chemically defined surfactant in mouse and cattle embryo transfer systems for the collection, culturing and freezing of embryos. It is likely that the beneficial effects of serum are due to its surfactant properties.

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PubMed1994

Superovulatory response to a single subcutaneous injection of Folltropin-V in beef cattle.

A series of 4 experiments were designed to evaluate the feasibility of superstimulation in beef cattle with a single sc injection of the porcine pituitary extract, Folltropin-V. In the preliminary study (Experiment 1), superovulatory response of cows (n=7) treated with a single sc injection of 400 mg NIH-FSH-P1 Folltropin-V was not different than that of cows (n=8) superstimulated with twice daily im injections over 4 d, or a single sc injection plus an injection of eCG (n=12). Experiments 2 and 3 were designed to determine the optimal site of a single sc injection. In Experiment 2, cows (n=25) with body condition scores (BCS) of 1 to 2 were used. The mean number of CL counted and ova/embryos collected was lower (P<0.05) in cows treated with the single sc injection in the neck region than in cows treated with a single sc injection behind the shoulder, or with the twice daily im injection treatment. In Experiment 3, cows (n=49) with BCS of 3 to 5 were used. There were no differences in the number of CL, total ova/embrvos collected, fertilized ova and transferable embryos whether treatments were given in the neck region or behind the shoulder, or whether the cows were implanted or not implanted with Syncro-Mate-B. Experiment 4 was designed to determine the optimal superstimulatory dosage of Folltropin-V administered by a single sc injection. Superovulatory response of cows treated with the higher doses (400 mg, 600 mg or 800 mg NIH-FSH-P1) was higher (P<0.05) than those treated with 200 mg NIH-FSH-P1. The number of unovulated (>or=10 mm) follicles at the time of ova/embryo collection was higher (P<0.05) in the 600 and 800 mg groups, and progesterone concentration at estrus was higher (P<0.05) in cows treated with 800 mg than with 400 or 200 mg. It was concluded that a single, bolus sc injection of 400 mg NIH-FSH-P1 of Folltropin-V is as efficacious as the 4-d, twice daily im treatment protocol for inducing superovulation in beef cows. The amount of subcutaneous fat and site of injection appeared to affect the efficacy of a single sc injection; a single bolus sc injection of Folltropin-V behind the shoulder resulted in the most predictable superovulatory response.

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PubMed1994

The relationship between scrotal circumference and quantitative testicular traits in yearling beef bulls.

A study was designed to investigate relationships between testicle size and histological, sperm production and endocrinological traits in yearling beef bulls at the end of performance test. Twenty-five beef bulls, (Hereford, n=16; Angus, n=4; and Charolais, n=5), with scrotal circumference (SC) measurements ranging from 28.5 to 36.0 cm, were used. Just prior to slaughter at 15 mo of age, SC measurements were taken, semen was collected, and a GnRH response test was conducted. Testicles were processed for daily sperm production (DSP), epididymal sperm reserves (ESR), seminiferous epithelial area (SEA), and degree of germinal epithelial loss (DGEL). There were significant positive correlations between SC and testicular weight (P<0.05), DSP/g (P<0.02), and DSP/bull (P<0.01) and ESR (P<0.01); however, the correlation between SC and SEA was not significant (P=0.4). Scrotal circumference was negatively correlated with DGEL (P<0.05). Degree of germinal epithelial loss was also negatively correlated with DSP/g, DSP/bull and ESR (P<0.01). Morphological characteristics of spermatozoa were diversely related to sperm production traits, and the percentage of normal spermatozoa was positively related to SC (P<0.02) and negatively related to DGEL (P<0.001). Gonadotropin releasing hormone stimulation did not reveal evidence of gonadotropin deficiency in any of the bulls. However, peak testosterone levels were lower in bulls with SC below 31 cm (P<0.05) than those with SC measurements above 31 cm.

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PubMed1994

In vitro fertilization and development of llama (Lama glama ) oocytes using epididymal spermatozoa and oviductal cell co-culture.

A study was designed to determine the feasibility of developing in vitro maturation, fertilization and culture systems utilizing follicular oocytes and epididymal spermatozoa collected from llamas at slaughter. From a total of 1324 cumulus oocyte complexes (COCs) recovered, 972 were cultured in 50-ul drops of TCM-199 medium with 10% heat inactivated steer serum (DBS) and hormones for 30 h. After maturation, the oocytes were randomly allocated into 4 groups in a 2x2 factorial design: cumulus-enclosed oocytes, 2 ug/ml heparin (Group 1); cumulus-enclosed oocytes, 5 ug/ml heparin (Group 2); denuded oocytes, 2 ug/ml heparin (Group 3); and denuded oocytes, 5 ug/ml heparin (Group 4). Denuded oocytes were obtained for groups 3 and 4 by vortexing. Epididymides were also collected at slaugther and fresh spermatozoa (for each replicate) were obtained by mincing the cauda epididymis with a scalpel blade. A total of 721 oocytes were inseminated with 2-3 x 10(6) epididymal spermatozoa/ml in a 50-ul drop of FERT-TALP medium. After 18 h of in vitro insemination, 234 oocytes were placed in a llama oviductal epithelial cell (LLOEC) co-culture in TCM-199 for 9 d. All cultures were done at 38.5 degrees C under 5% CO(2) in air with high humidity. The rate of fertilization, initial cleavage and development in co-culture were evaluated and compared. Of 192 oocytes examined for signs of fertilization, 56 (29.2%) were penetrated by spermatozoa with 57.1% (32 56 ) of the penetrated oocytes having a male and female pronucleus. There were no differences among treatment groups in total fertilization. However, the frequency of oocytes fertilized normally tended to be higher in the denuded oocytes 67.7% (21 31 ) than the oocytes inseminated with cumulus cells 44.0% (11 25 ) independent of heparin concentration (P<0.06). The total embryo development rate to the 2 cells to blastocyst stage was 32.1% (75 234 ). There was no difference in development rate between groups. From the 234 oocytes co-cultured in LLOEC for 9 d, 15.8% developed into 2 to 16 cells, 5.6% into morulae, 6.0% into early/expanded blastocysts and 4.7% into hatching/hatched blastocysts. The results indicate that an in vitro fertilization system is possible in the llama utilizing slaughterhouse material and that llama oocytes can be fertilized in the presence of heparin and epididymal spermatozoa.

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PubMed1994

Superovulatory response of ovarian follicles of Wave 1 versus Wave 2 in heifers.

Experiments were designed to test the hypotheses that ovarian follicular response to superstimulatory treatment initiated during Wave 1 is equivalent to that of Wave 2, and recovery rate and quality of ova embryos derived from follicles of Wave 1 are equivalent to those derived from follicles of Wave 2. In a preliminary experiment (Experiment 1), heifers were given Folltropin-V (20 mg NIH-FSH-P1, im, bid for 5 d) beginning the day after emergence of the first (n=10) or second (n=10) follicular wave of the estrous cycle, equivalent to approximately Day 1 and Day 10, respectively (Day 0=ovulation). Luteolysis was induced with cloprostenol (500 mug im, bid) on the fourth day of treatment. Fewer (P<0.05) ovulations per heifer were induced in the Wave 1 group than in the Wave 2 group (4.6+/-1.0 vs 9.1+/-1.3). However, the interval from wave emergence to initiation of treatment was found, in retrospect, to have been longer (P<0.05) in the Wave 1 group, i.e., treatment was initiated relatively later with respect to wave emergence. Experiment 2 was designed to correct this disparity and to initiate the same treatment protocol on the day of wave emergence rather than the day after (n=21 per Wave group). There was no difference between Wave 1 and Wave 2 groups in the interval from wave emergence to initiation of treatment (0.4+/-0.1 d), the number of ovulations detected by ultrasonography (6.6+/-1.0 vs 8.2+/-1.7), the number of CL detected at slaughter (6.5+/-0.9 vs 8.1+/-1.8), the total number of ova embryos recovered (5.2+/-0.7 vs 5.1+/-0.8), or the number of fertilized embryos collected (2.8+/-0.6 vs 3.0+/-0.6). In addition, there was no difference between groups in the proportion of heifers that ovulated in either experiment; collectively, luteolysis and ovulation was induced in 58 of 60 heifers. The results supported the general hypothesis that follicles and oocytes of the first and second follicular waves are equivalent in the response to superstimulatory treatment. Regardless of which follicular wave, initiation of treatment near the time of wave emergence appears critical for maximal superovulatory response. Because of the consistency in the time of emergence of Wave 1 (day of ovulation) and equivalence in superovulatory response, use of Wave 1 rather than subsequent follicular waves may be more convenient and time-sparing in superovulation programs; the day of estrus (day before ovulation) may be used as a consistent point of reference for the start of treatment.

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PubMed1994

Role of luteal regression in embryo death in cattle.

Inseminated crossbred beef cows and heifers were used in 2 experiments to investigate embryo survival after prostaglandin-induced or spontaneous luteal regression. In Experiment 1, luteal regression was induced by an intramuscular (im) injection of cloprostenol (500 mug) on Day 15 (day of ovulation = Day 0). Progestagen was replaced 24 or 36 h later either by one-and-a-half Syncro-Mate-B (SMB) ear implants (9 mg of norgestomet) and norgestomet solution (2.25 mg, im) containing no estradiol in 1 replicate or by 2 SMB implants (12 mg of norgestomet) and progesterone (100 mg, im) in the second replicate. Combined for both replicates, the Day-24 pregnancy rate in an untreated control group (Group 1, 16/19; 84%) was higher (P < 0.01) than in the 24-h group (Group 2, 9/20; 45%), which also was higher (P < 0.02) than in the 36-h group (Group 3, 3/23; 13%). In Experiment 2, 15 or 16 d after breeding, cattle with a corpus luteum at least 16 x 16 mm were given either 2 SMB implants or no treatment. At 24 to 26 d after breeding, pregnancy rates (48/65, 74% versus 49/68, 72%) were not significantly different, and all but 1 of the pregnant progestagen-supplemented cattle had a functional corpus luteum.

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PubMed1994

Ovarian follicular development and endocrine responses in follicular-fluid-treated and hemi-ovariectomized heifers.

The effects of charcoal-extracted bovine follicular fluid (BFF) on endocrine profiles and follicular development in intact and hemiovariectomized postpubertal heifers were examined. Oestrus-synchronized heifers received Norgestomet implants on day 1 and 7 of treatment and were then injected s.c. with 11 ml saline (control) or 11 ml BFF twice a day for 12 days. The ovary bearing the largest follicle (OV1) was removed on day 7 and the remaining ovary (OV2) was collected on day 13. Follicles were observed by daily ultrasonography and were classified according to diameter (size 1: 2-3 mm; size 2: 4-6 mm; size 3: 7-10 mm; size 4: > 10 mm). After ovariectomy they were classified by diameter and histologically as normal or atretic. Intact control heifers had increased numbers of size 4 follicles on OV1 on days 6 and 7; no increase was observed in BFF-treated heifers (P < 0.03). In BFF-treated heifers, the mean basal LH concentration was higher (P < 0.05) and that of FSH was lower (P < 0.04) than in controls. FSH concentrations in BFF-treated heifers decreased from 0.60 +/- 0.08 ng ml-1 (day 1) to 0.22 +/- 0.05 ng ml-1 (day 7; P < 0.04). The concentration of oestradiol increased in control heifers, but not in BFF-treated heifers (P < 0.001). After hemicastration, OV2 underwent compensatory hypertrophy in control heifers, with an increase in the number of size 2, 3 and 4 follicles (P < 0.05), whereas BFF-treated heifers did not. Thus, total follicular volume was much lower in BFF-treated than in control heifers on day 13 (92.2 +/- 15.4 versus 1393.8 +/- 276.6 mm3; P < 0.0002). A transient increase in FSH (P < 0.006) and oestradiol (P < 0.01) concentrations occurred after hemiovariectomy in control but not in BFF-treated animals. In control heifers, an analysis of temporal relationships showed negative correlations between the volume of size 3 and size 4 follicles, and between FSH concentrations and the volume of size 3 and 4 follicles. A positive correlation was found between the mean diameter of the largest follicle and the concentration of oestradiol, whereas negative relationships were found between the concentrations of FSH and oestradiol, and between FSH and the mean diameter of the largest follicle. Analysis of the histological data showed that the number and volume of follicles > 8.57 mm was lower in the BFF-treated OV1 ovary, whereas no differences were found for follicles < or = 8.57 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Induction of parturition in cattle: effect of triamcinolone pretreatment on the incidence of retained placenta.

Two experiments were designed to determine whether pretreatment with triamcinolone acetonide (TRI)prior to induction of parturition with dexamethasone(DEX) and cloprostenol (CLO) would reduce the incidence of retained placenta. Experiment 1 was conducted to determine the optimum dosage of TRI and to approximate the optimum interval from TRI to induction with DEX+CLO. All cows received TRI on day 270 of gestation. Cows in group I received 1 mg/30 kg of body weight (BW) of TRI and were induced to calve with DEX+CLO on day 276. Cows in groups II and III received 1 mg/45 kg BW and were induced on days 276 or 277, respectively. Cows in groups IV and V received 1 mg/60 kg BW and were induced on days 277 or 278, respectively. Group VI cows served as untreated controls. There was no difference in the incidence of retained placenta among the treated and control groups. Experiment 2 was conducted to more precisely determine the optimum interval from pretreatment to induction treatment with the chosen dose of TRI. All cows in groups I, II, and III were pretreated with 1 mg/60 kg BW of TRI on day 270 of gestation and received DEX+CLO on days 275, 276 or 277,respectively. Group IV cows served as untreated controls. The incidence of retained placenta was higher (p < 0.05) in groups I and II than in the control group, with group III intermediate and not different from the others. Cows that retained their placentas had higher (p < 0.05) body temperatures from day 2 to day 7 after calving and tended to have a lower pregnancy rate in the subsequent breeding season than cows that did not retain their placentas.Results indicate that pretreatment with TRI seven days prior to induction of parturition with DEX+CLO resulted in a reduced incidence of retained placenta,apparently by advancing placental maturation.

Animals↗

PubMed1994

Superovulation in the cow with pregnant mare serum gonadotrophin: effects of dose and antipregnant mare serum gonadotrophin serum.

The effects of pregnant mare serum gonadotrophin (PMSG) dose and PMSG antiserum on superovulation in crossbred beef cows were studied. In experiment I, three groups were treated with 1200, 2400 or 3600 IU of PMSG and 48 h later with prostaglandin (PGF). The mean numbers of corpora lutea (CL), unovulated follicles, and total ova/embryos collected increased as the PMSG dose increased. The percent of fertilized ova and transferable embryos was lowest in the highest dose group (p < 0.05). In experiment II, all cows received 2500 IU of PMSG; groups 1 and 2 were treated with sheep anti-PMSG serum at 48 h or 60 h after PGF; group 3 cows were PMSG-only controls. The number of CL was lowest and the number of unovulated follicles highest in the PMSG-only group (p < 0.05). The number of CL was higher in group 2 (anti-PMSG at 60 h) than in the control group, with the anti-PMSG at 48 h not different from the other groups. Numbers of total ova/embryos, fertilized ova, and transferable embryos were higher (p < 0.05) in both antiserum-treated groups relative to the PMSG-only group. We conclude that superovulation of beef cows with PMSG and treatment with PMSG antiserum will induce a higher superovulatory response and will result in higher CL numbers and fewer unovulated follicles. Further, the variability in the superovulatory response to PMSG treatment was still evident when PMSG antiserum was administered.

Animals↗

PubMed1993

The use of sodium hyaluronate in freezing media for bovine and murine embryos.

Four experiments were designed to determine whether sodium hyaluronate (SH) may be used to replace newborn calf serum (NCS) in murine and bovine embryo freezing media. A total of 780 mouse and 178 cattle embryos were frozen. Freezing media were prepared in Dulbecco's phosphate-buffered saline supplemented with 20% NCS and 10% glycerol (v/v) (medium A). In experiments I and II, NCS was replaced by 0.1% SH (w/v) in medium B and by 0.1% polyvinyl alcohol (PVA) (w/v) in medium C. In experiments III and IV, NCS was replaced in mouse embryo freezing medium by three different molecular weights of SH as follows: 0.1 or 0.2% (SH-1; < 3 x 10(5) Da) in medium B, by 0.1 or 0.05% (SH-2; 5-7.5 x 10(5) Da) in medium C, and by 0.1 or 0.025% (SH-3; > 1.2 x 10(6) Da) in medium D. Embryos were frozen and thawed using standard procedures. Glycerol was diluted from embryos after thawing in a single step with 1.0 M sucrose. After 48 h in culture (Ham's F-10 medium for cattle embryos and BWW medium for mouse embryos), embryos were evaluated for development to expanded or hatched blastocysts. Survival rates were compared by chi 2 analysis. In experiment I, there were no significant differences in mouse embryo survival or development between NCS, SH, and PVA groups (84.1, 79.2, and 83.3%, respectively). In experiment II, there were no significant differences in bovine embryo survival between NCS and SH groups (67.2 and 67.7%), but both had significantly higher survival than the PVA group (37.9%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Ovarian superstimulatory response relative to follicular wave emergence in heifers.

Two experiments were designed to evaluate the responsiveness of beef heifers to superstimulatory treatments administered during the first follicular wave. Heifers were examined daily (Experiment 1) or twice daily (Experiment 2) by ultrasonography to determine the status of follicular wave development and the day of initiation of superstimulatory treatment. Heifers in both experiments were superstimulated with a total dose of 10 ml Folltropin (equivalent to 200 mg of NIH-FSH-P1), divided into 10 equal intramuscular injections over 5 days. On the last day of treatment, heifers received 500 mug of cloprostenol after each injection of Folltropin to induce luteolysis. In the respective groups, superstimulatory treatments were initiated on Day -1, Day 0 (day of ovulation) or Day +1 for Experiment 1, and on Day -1, Day 0, Day +1 or Day +2 for Experiment 2. In Experiment 1, the number of ovulations in each ovary was assessed by ultrasonography and by counting the number of corpora lutea (CL) in each ovary at slaughter. The correlation between both techniques for assessing ovulatory response was high (r= 0.98; P< 0.0001), and there was no significant difference in the mean number of ovulations detected by ultrasound (5.7+/-1.1) versus the mean number of CL counted at slaughter (6.2+/-1.2). In Experiment 1, the mean (+/- SEM) number of CL counted at slaughter in heifers treated on Day -1 (9.4+/-3.8) and Day 0 (7.3+/-1.6) was higher (P< 0.05) than that of heifers treated on Day +1 (0.7+/-0.3). The mean number of follicles >/=7 mm in diameter on the last day of treatment was also higher (P<0.05) in the Day -1 group compared with the Day +1 group; the Day 0 group was intermediate. In Experiment 2, the mean number of ovulations was higher (P< 0.05) in the Day 0 group (18.4+/-3.4) than the Day -1 (9.5+/-2.3), Day +1 (6.7+/-2.2) or Day +2 (6.5+/-2.3) groups. Heifers in the Day -1, and Day 0 groups had more (P< 0.05) follicles >/=7 mm at the end of treatment compared with heifers in the Day +1 or the Day +2 group. The stated hypothesis was supported: exogenous FSH treatment initiated at the time of wave emergence, near the expected time of the endogenous wave-eliciting FSH surge, has a positive effect on the superstimulatory response. A higher superstimulatory response was elicited when treatments were initiated on the day of, or the day before, wave emergence compared with that of later treatments.

Journal Article↗

PubMed1993

Effect of estradiol valerate on ovarian follicles, emergence of follicular waves and circulating gonadotropins in heifers.

An experiment was designed to examine the effect of estradiol valerate (EV) on the growth and regression of follicles of a wave and on the emergence of the next follicular wave. Twenty-six beef heifers were xamined daily by ultrasonography and randomly allocated to 1 of 4 treatment groups at the time of ovulation (Day 0): unterated control heifers and those that received 5 mg EV intramuscularly on Day 1, Day 3 or Day 6. Maximum diameter of the dominant follicle was greater (P<0.05) in control heifers than in heifers treated on Day 1 or Day 3. Mean day of onset of regression of the dominant follicle was later (P<0.05) in control heifers than in heifers treated on Day 1 but was not different from heifers treated on Day 3. In heifers treated on Day 6, cessation of growth, maximum diameter and onset of regression were not different from that of control heifers. The emergence of the next follicular wave was earlier (P<0.05) in heifers treated on Day 1 than in control heifers, whereas wave emergence was delayed (P<0.05) in heifers treated on Day 3 or Day 6. The mean day of maximum concentration of FSH prior to the emergence of the next wave was earlier in heifers treated with EV on Day 1 and later in heifers treated on Day 3 or Day 6 compared with that of the controls (P<0.05). Treatment on Day 1 or Day 3 resulted in a significant LH surge in 8 13 heifers, whereas no LH surges were detected in control heifers or in heifers treated on Day 6. The hypothesis that EV suppresses the growth of the dominant follicle, was supported. Estradiol valerate treatment resulted in early emergence of the next follicular wave in heifers treated on Day 1, but treatment on Day 3 or Day 6 resulted in delayed emergence of the next follicular wave.

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PubMed1992

Reduced incidence of retained placenta with induction of parturition in the cow.

Two experiments were designed to determine whether pretreatment with Opticortenol (OPT), a long-acting corticosteroid, prior to induction of parturition with 25 mg of dexamethasone (DEX) alone or in combination with 500 mug cloprostenol (CLO) would result in a reduced incidence of retained placenta. In Experiment 1, 70% of the cows pretreated with 25 mg OPT on Day 270 of gestation calved before or within 24 hours of the scheduled induction treatment on Day 277. Cows induced to calve with DEX plus CLO without OPT pretreatment had an increased rate of placental retention (P<0.05), whereas, cows that received OPT were not different from the controls. In Experiment 2, cows received either 1 mg/25 kg OPT (high dosage) or 1 mg/50 kg OPT (low dosage) on Day 270 of gestation and were induced with DEX plus CLO on either Day 274 (4 days) or Day 276 (6 days). Cows claved 29.0 to 31.8 hours after induction treatment with 95% beginning to calve between 0700 and 1900 hours. The interval from calving to placental release and the incidence of retained placenta was not different between the high dosage 6-day group (29.4+/-8.2 hours, 29%) and the non-induced control cows (16.1+/-10.7 hours, 5%). When three cows in the high dosage 6-day group that retained their placentas for 30 to 36 hours were considered as not retained, the incidence of placental retention for that group was reduced still further to 17%. First service conception rates and pregnancy rates were lower in cows with retained placentas. Differences were significant (P<0.01) in Experiment 1 but not in Experiment 2. It was concluded that pretreatment with 1 mg/25 kg OPT 6 days prior to induction of parturition with DEX plus CLO in combination results in a predictable calving time, high calf viability, and a low incidence of placental retention.

Journal Article↗

PubMed1991

The effect of estradiol valerate on follicular dynamics and superovulatory response in cows with Syncro-Mate-B implants.

Two experiments were designed to evaluate the effect of estradiol valerate on follicular dynamics and superovulatory response in cows with Syncro-Mate-B (SMB)implants. In Experiment 1, 5 mg estradiol valerate (E(2)), injected at the same time as superstimulation treatments were initiated, resulted in fewer corpora lutea (CL), ova/embryos collected and fertilized ova (P<0.05) than if E(2) was administered with the SMB implant 7 days earlier. In Experiment 2, 31 beef cows and 26 Holstein cows were placed in one of four treatment groups. Group I (control) cows were superstimulated on Day 9 (estrus=Day 0). On Day 2, cows in Groups II, III, and IV received SMB and cows in Group III received E(2). On Day 9, cows in Group IV received E(2), and all cows were superstimulated with Folltropin. The number of CL did not differ (P>0.19) among groups. However, there were more follicles < 10 mm and fewer fertilized ova and transferable embryos (P<0.02) in Group IV cows. Ovarian ultrasonography revealed that the diameter of the largest follicle in Group III cows declined from Day 2 to Day 7 and subsequently increased until Day 13. In contrast, Groups I, II and IV were characterized by apparently linear growth between Days 2 and 13. Differences (P<0.05) were detected between Days 5 and 9. Mean diameter of the largest follicle was smaller for cows in Group III than for the remaining groups on Day 9. It was concluded that SMB did not adversely affect superovulatory response and that E(2) administration resulted in atresia of the antral follicles in the cows with SMB implants.

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PubMed1991

Embryonic loss in superovulated cattle caused by the 1;29 Robertsonian translocation.

The effect of the 1;29 Robertsonian translocation on fertility was studied using embryos resulting from matings of nine carrier cows and two carrier bulls. Embryos were collected from the following three mating groups utilizing superovulation: normal bull cross normal cow, normal bull cross translocation carrier cow, and translocation carrier bull cross normal cow. The proportion of ova which were fertilized did not vary among the groups, indicating that fertilization rates were not affected by the translocation. The translocation cows did yield fewer embryos on average than did cows with normal karyotypes, which may suggest ovulation rates are reduced (at least after superovulation attempts) in cattle carrying the 1;29 translocation. Twenty of 39 embryos successfully karyotyped had abnormal chromosome complements. All four of the theoretically predicted karyotypes and two additional abnormal combinations were found. Eight of 39 (20.5%) embryos karyotyped had unbalanced karyotypes which would have resulted in embryonic loss. The proportion of embryos with unbalanced karyotypes, was slightly higher when the cow (36%) carried the translocation than when the bull (19%) did. Results of this study indicate that fertility is impaired due to the presence of this translocation. The major loss in reproductive potential appears to be due to embryonic loss rather than fertilization failure.

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PubMed1990

Superovulation of beef heifers with Folltropin: A new FSH preparation containing reduced LH activity.

The optimum superovulatory dose of Folltropin was determined and compared with a standard 28 mg dose of FSH-P in beef heifers. In Experiment 1, mean numbers of corpora lutea (CL) did not differ among the groups treated with 10, 20, 30 or 40 mg Folltropin or FSH-P, and the mean CL number was reduced (P<0.05) only in the 5 mg Folltropin group. Mean numbers of ova/embryos recovered, fertilized and transferable were greater (P<0.05) for the 10, 20 and 30 mg Folltropin groups than for the 5 mg group. The 40 mg Folltropin group and the FSH-P group were intermediate. The percentage of fertilized and transferable embryos did not differ over the dosages used in this experiment. In Experiment 2, mean numbers of CL were greater for the 9, 18 and 36 mg Folltropin groups than for the 4.5 mg group, with the 9 mg group being lower than the 36 mg group (P<0.05). The 18 mg group was intermediate and did not differ. Mean numbers of ova/embryos recovered and fertilized ova were greater for the 9, 18 and 36 mg groups (P<0.05) than for the 4.5 mg group. The percent of fertilized and mean number and percentage of transferable embryos did not differ among treatments. We conclude that Folltropin may be a satisfactory superovulatory replacement for FSH-P and that a dose of 18 to 20 mg Folltropin may be within the optimum superovulatory dosage range for beef heifers. Dosages of Folltropin of more than twice the optimum did not result in deterioration of ova/embryo quality.

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PubMed1989

Immunization of cattle against modified peptides of gonadotropin releasing hormone conjugated to carriers: Effectiveness of Freund's and alternative adjuvants.

Two gonadotropin-releasing hormone (GnRH) peptides with a cystein substitution of the first (C1-GnRH) or tenth (C10-GnRH) amino acid were conjugated to ovalbumin and equine serum albumin, respectively, via the sulfhydryl group of the introduced cysteine. Animals were immunized three times at 3-wk intervals with both conjugates in either saline (n = 5), Freund's complete adjuvant (FCA; n = 5), Havlogen (n = 6), Ribi adjuvant system (RAS; n = 5), dimethyl dioctadecyl ammonium bromide (DDA; n = 4), Alhydrogel (n = 5) or Regressin (n = 5). Animals immunized with conjugates in saline or RAS did not produce anti-GnRH titers. The highest anti-GnRH titers were produced by animals treated with FCA. The Alhydrogel and DDA treatments stimulated the production of GnRH antibodies in all animals treated, but titers were lower than in animals immunized with FCA. When vaccines were formulated with Havlogen or Regressin, anti-GnRH titers were low or absent. Serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels were depressed in FCA and in Alhydrogel treated animals. The antisera raised were predominantly directed against either the carboxy- or the amino-terminal end of the GnRH peptide, or directed equally against both, depending on the individual animal. Results suggest that no epitope of GnRH dominates the immune response in cattle and show that the best alternative to FCA is Alhydrogel.

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PubMed1989

Immunization of sheep against modified peptides of gonadotropin releasing hormone conjugated to carriers.

The efficacy of antigens based on modified GnRH peptides in stimulating the production of antibodies against GnRH in sheep was tested. In the first study cysteine-containing GnRH peptides were conjugated to keyhold limpet haemocyanin (KLH) in 3 different orientations. The 3 conjugates were prepared in an emulsion of Freund's complete adjuvant (FCA) and were injected into 3 groups of 6 castrated male lambs. The 3 vaccines efficiently induced anti-GnRH titers in all the animals treated. The specificity of the GnRH antisera raised varied depending on the orientation of the GnRH molecule in the antigen and on the individual animal. In a second trial designed to evaluate carrier molecules, a cysteine-containing GnRH peptide was conjugated to either KLH, equine serum albumin, ovalbumin or tetanus toxoid. The conjugates were prepared with FCA and injected into intact male lambs. All 4 vaccines stimulated the production of antibodies against GnRH in all the animals treated. The conjugates prepared with equine serum albumin or ovalbumin were the most effective in raising high anti-GnRH titers. In 18 of 20 lambs treated, anti-GnRH titers resulted in a marked atrophy of the testes. We conclude that: 1) the different epitopes of the GnRH molecule are equally immunogenic in sheep; 2) the GnRH antibody response is affected by the carrier used; and, 3) anti-GnRH vaccines based on cysteine-substituted GnRH analogues show potential for use in immunocastration of livestock.

Animals↗