Biomedical subjects

R P Elsden

Publications and source records attributed to R P Elsden.

At least 19 recordsLinked to original sources

PubMed1989

Effects of GnRH on superovulated cattle.

Gonadotropin releasing hormone (GnRH) was given to 109 cows and heifers during the course of 224 superovulations. Follicle stimulating hormone (FSH) was administered twice daily (5 or 6 mg) for 3.5 to 4 days beginning on any of Days 9 to 14 of the estrous cycle; prostaglandin (45 mg PGF(2)alpha or 750 ug cloprostenol) was given in a split dose on the fourth day. Donor cows and heifers were placed into four groups according to previous superovulation treatments, which consisted of one to three treatments or of no previous treatment. Every other cow or heifer within each of the four subgroups was treated with GnRH (200 mug i.m.) at standing estrus. Only donors that exhibited estrus within 32 to 72 h after the first prostaglandin treatment were used in the study. Animals were inseminated artificially 12 and 24 h after standing estrus was first observed. No differences were noted in the number of ovulations, total ova or transferable embryos recovered from the GnRH or control groups; however, two interactions were detected. Cows given GnRH had fewer palpable corpora lutea than control cows (P < 0.05), but this difference was not seen in heifers. The second interaction was that GnRH seemed to depress ovulation rate in donors not previously superovulated, but this effect was not observed with subsequent superovulations. Cows yielded more total ova than heifers (P < 0.01). There was no difference in return to estrus between GnRH and control groups after a second prostaglandin treatment at the time of embryo recovery. Most donors within each group resumed cycling between 5 and 12 d after embryo recovery.

Journal Article↗

PubMed1987

Use of sucrose during removal of cryoprotectants after thawing eight-cell mouse embryos.

Eight-cell mouse embryos were frozen in 0.5-ml plastic straws in modified Dulbecco's phosphate buffered saline (PBS) plus 5% steer serum plus either 1.32 M dimethyl sulfoxide (DMSO) or 1.32 M glycerol. Upon thawing, embryos were diluted 1:4 with 0.0, 0.2, 0.6, or 1.0 M sucrose solutions within the straws. Thawing was either in air at ambient temperature or in 8 degrees C or 38 degrees C water. After 48 h of culture, more embryos frozen in DMSO and thawed in 8 degrees C and 37 degrees C water developed to blastocysts (87 and 93%, respectively) than embryos thawed in air (75%; P<0.05). No significant differences in development were noted among the three thawing regimens when embryos were frozen with glycerol. There was no significant effect of concentration of sucrose during dilution on development of embryos postthaw. With glycerol as the cryoprotectant, damage to zonae pellucidae increased as thawing rates increased, whereas the opposite was observed with DMSO as the cryoprotectant (P<0.05).

Journal Article↗

PubMed1987

Transfer of bovine demi-embryos with and without the zona pellucida.

Bisected bovine embryos with or without the zona pellucida were transferred to recipients nonsurgically in five field trials. Embryos were collected from superovulated donors 6.5 to 7.5 d after estrus; only embryos of good and excellent quality were bisected. Demi-embryos were transferred either within a zona pellucida, without a zona pellucida, without a zona pellucida, or in the third and fourth trials, without a zona but embedded in 7% gelatin. Pregnancies were diagnosed at 44 to 68 d of gestation. In a preliminary trial, 9/29 zona pellucida-intact demi-embryos developed into fetuses compared with 1/10 zona pellucida-free demi-embryos (P greater than .1). The proportion of zona-free demi-embryos developing to fetuses was not significantly different from the zona-intact group in the second trial either, 24/49 and 5/19, respectively. In trial 3, the proportion of zona pellucida-free demi-embryos developing was 8/25; of zona-enclosed embryos, 29/88; and of zona-free demi-embryos embedded in gelatin, 8/22 (P greater than .1). Similarly, in the fourth trial the rate of development of zona-free demi-embryos to fetuses was 5/12, that of zona-enclosed embryos was 32/81, and that of zona-free demi-embryos embedded in gelatin was 3/12 (P greater than .1). In trial 5, survival of zona-enclosed demi-embryos to fetuses was 40/105, and of zona-free demi-embryos, 46/109 (P greater than .1). Except for trial 2, half of the demi-embryos were twinned, one to each uterine horn; twinning did not significantly affect the proportion developing to fetuses for any of the demi-embryo groups. It is concluded that placing post-compaction demi-embryos into the zona pellucida for transfer does not improve pregnancy rates significantly.

Animals↗

PubMed1985

A new procedure for the cryopreservation of equine embryos.

Early equine blastocysts and blastocysts were collected nonsurgically at six days post-ovulation. Thirty-two embryos were randomly assigned to a 2x2 factorial design. Factors were: 1) 0.5-ml straws or 1-ml glass ampules; and 2) plunging into liquid nitrogen (IN(2)) at -33 C or -38 C. Cryoprotectant, 10% glycerol in PBS plus 5% fetal calf serum (FCS) was added in two steps, 5% then 10%. Embryos were cooled at 4 C/min to -6 C and then seeded, 0.3 C/min to -30 or -35 C and 0.1 C/min to -33 or -38 C. Samples were thawed in 37 C water and glycerol removed in six steps, 10 min per step. Embryo quality and stage of development were evaluated prior to freezing, immediately post-thaw and after 24 h culture in Ham's F10 with 5% FCS. The mean post-thaw quality of embryos plunged at -33 C was superior (P<0.05) to that of embryos plunged at -38 C (2.0 vs 2.9). Embryos frozen in ampules and plunged at -38 C were of poorer quality (P<0.05) than those frozen in ampules and plunged at -33 C or frozen in straws and plunged at -33 C. After 24 h of culture, more embryos developed if frozen in straws compared to ampules, and plunging at -33 C resulted in higher quality embryos than plunging at -38 C. In Experiment 2, 23 embryos were packaged in straws and plunged at -33 C as described in Experiment 1. Six of the 23 surgically transferred frozen embryos were degenerate at thawing and the remaining 17 surgically transferred were via flank incision. Pregnancy rate at 50 days post-ovulation was 53% (nine of 17). Early blastocysts resulted in a higher (P<0.05) pregnancy rate (8 10 , 80%) than expanded blastocysts (1 7 , 14%).

Journal Article↗

PubMed1985

Effect of slow cooling end point temperature on survival of frozen bovine embryos.

One hundred sixty-two embryos were collected from superovulated crossbred beef cattle 7 to 8 d after the onset of estrus. Embryos were frozen in modified Dulbecco's phosphate-buffered saline supplemented with 20% heat-inactivated fetal calf serum (PBS + FCS) and dimethylsulfoxide (DMSO), which was added in three steps to a final concentration of 1.5 M. Embryos were placed in .25 ml of 1.5 M DMSO in PBS + FCS in 1-ml glass ampules and cooled at 1.0 C/min from ambient temperature to -7 C, seeded and then cooled at .3 C/min to -19, -26, -33, -38, -43, -50 or -57 C before immersion (plunging) in liquid nitrogen. Ampules were thawed in 25 C water, and DMSO was removed in six steps at .25 M increments. 10 min/step. After removal of DMSO, embryos were cultured 24 h in PBS + FCS and then fixed and stained. Just after thawing, embryos for which slow cooling was terminated at -50 C were of lower (P less than .05) morphological quality than other groups. After removal of cryoprotectant, embryos from both the -19 and -50 C treatments had deteriorated more (P less than .05) than had embryos from other treatments. After 24-h culture, embryos slow-cooled to -19, -26 and -50 C had a lower rate of survival (P less than .05) than did embryos from -33, -38, -43 and -57 C temperatures. Embryos slow-cooled to -33, -38 and -43 C showed a higher percentage of healthy nuclei than did embryos slow-cooled to -19, -26 and -50 C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Bovine embryo transfer pregnancies. I. Abortion rates and characteristics of calves.

Data were obtained from 1,908 pregnancies resulting from bovine embryo transfer procedures. Responses examined included sex ratio, fetal, neonatal and preweaning death losses, birth weight and calving assistance. The sex ratio for 1,751 embryo transfer calves examined was 51.11% males. Cows older than 10 yr that had become repeat breeders produced more (P less than .05) male calves than other donors. Breed of embryo, age and quality of embryos at the time of transfer, embryo storage time from collection to transfer, asynchrony of recipient with donor estrus and number of palpable corpora lutea in superovulated donors were not related to sex ratio (P greater than .05). The abortion rate between 2 and 3 mo of gestation in embryo transfer recipients was 3.15%, and between 3 to 7 mo, 2.14%. Neonatal and preweaning losses for 1,682 calves with complete information were 1) congenital defects, .54%; 2) death due to premature birth (7 to 8 mo of gestation), .18%; 3) dystocia-related deaths, 2.38%; 4) deaths of unknown causes at birth, 2.14%; 5) deaths of unknown causes from 24 h after birth to weaning, 1.43%; 6) deaths due to calfhood diseases, 1.25% and 7) deaths due to environmental factors, 1.13%. Total losses of 2-mo pregnancies due to abortion or death of calves or recipients were 14%. Birth weight of embryo transfer calves changed .29 kg/d of deviation from average gestation length (P less than .005) for pregnancies within breeds. Birth weight was also affected (P less than .005) by donor breed and recipient breed and age. Male calves averaged 2.19 kg heavier (P less than .005) than females. Calving assistance was affected by donor breed; Angus calves required the least assistance (P less than .005). Hereford, Holstein and Limousin calves were similar and intermediate; Simmental calves needed the most calving assistance. Recipient breed and age influenced calving ease, with younger recipients of Angus and Hereford descent requiring more assistance (average calving score, 2.1) than both cow (1.3) and heifer (1.5) recipients of the larger Continental European breeds. Characteristics of 305 non-embryo transfer calves were not significantly different from 185 embryo transfer calves from the same farms. We conclude that embryo transfer calves did not differ from the non-embryo transfer population in any of the characteristics studied.

Abortion, Veterinary↗

PubMed1985

Bovine embryo transfer pregnancies. II. Lengths of gestation.

Lengths of gestation were determined from 1,484 pregnancies resulting from embryo transfer procedures. Least-square means of lengths of gestation by breed of embryos (P less than .005) were: Holstein, 278.7; Angus, 281.0; Hereford, 285.7; Simmental, 287.6 and Limousin, 289.7 d. Recipient breed had a small effect on length of gestation (P less than .005). The length of gestation for recipients less than 4 yr old was 2.7 d shorter (P less than .005) than for older recipients. As asynchrony of recipient and donor estrus changed by 1 d, length of gestation changed linearly by .78 d (P less than .005). Male calves were carried 1.4 d longer than females (P less than .005). Embryo age at time of transfer, embryo quality, length of embryo storage between collection and transfer, and donor age did not affect length of gestation significantly. Lengths of gestation of 185 embryo transfer pregnancies were 1.5 d longer (P greater than .1) than those of 305 matched control pregnancies from the same farms. We conclude that length of gestation of embryo transfer calves and length of gestation of non-embryo transfer calves are influenced by similar factors.

Animals↗

PubMed1985

Infection of early bovine embryos with bovine herpesvirus-1.

Recently hatched bovine embryos were exposed in vitro to 1 of 4 strains of bovine herpesvirus-1 to determine whether the viruses would replicate in these embryos and, if so, what pathologic consequences would ensue. Exposure to each of the viruses resulted in embryonic infection and death, and replication of the agents was demonstrated by electron microscopy and titration of progeny virus. There were no dramatic differences between virus strains in pathogenicity or in the ultrastructural pathologic findings of infection.

Animals↗

PubMed1985

Bluetongue virus and embryo transfer in cattle.

Embryos recovered nonsurgically from donor cattle infected with bluetongue virus (BTV) were transferred to seronegative, uninfected recipients. High titers of BTV were found in donor blood at the time of embryo recovery and BTV could be isolated from the recovery medium obtained from many of the donors. Bluetongue virus was not isolated from the blood of any of the 39 recipients that received embryos from infected donors, and none of these recipients seroconverted within 60 days of transfer. There was no evidence that BTV was transmitted to the early embryo in viremic donors. These results indicate that, under standard conditions of embryo transfer, transmission of BTV from infected donors to recipients is unlikely to occur.

Animals↗

PubMed1984

Pregnancy rates with bisected bovine embryos.

A method for producing identical twin calves is described in which 5.5 to 7.5 day bovine embryos were bisected using a fine microsurgical blade. The resulting demi-embryos were transferred surgically or nonsurgically to the uterine horn ipsilateral to the corpus luteum of synchronous recipients (+/- 2 days), one demi-embryo per recipient. The mean pregnancy rate per demi-embryo was 48% (157/330), and per whole embryo split, it was 95% (157/165). Pregnancy rate was dependent on the stage of embryonic development. The pregnancy rate from bisected early morulae, 16% (7/44), was lower than that from bisected early blastocysts, 60% (58/96) P<0.01. The rate of identical twin production per embryo split reflected these pregnancy rates. Bisected blastocysts resulted in more identical twin sets, 39% (24/62), than early morulae, 9% (2/22) P<0.01. When used with normal embryo transfer procedures, this technique provides a method for routine production of identical twin calves. Furthermore, more calves are produced per two demi-embryos than per whole embryo.

Journal Article↗

PubMed1983

Embryo transfer from cattle infected with bluetongue virus.

Embryos recovered nonsurgically from donor cattle during the peak of bluetongue viremia were surgically transferred to seronegative recipients 7 to 8 or 10 to 11 days after the onset of donor estrus. Virus was isolated from the uterine flushing medium recovered from 11 of the 20 donors. Bluetongue virus was not isolated from the blood of any of 39 recipients, nor did any recipient seroconvert to the virus following transfer. The number of recipients that became pregnant after transfer of embryos from infected donors (21 of 39) was not significantly different from contemporary controls. Virus antigen was not detected by immunofluorescence in any of 63 embryos and oocytes recovered from viremic donors. These results indicate that under standard embryo transfer conditions, transmission of bluetongue virus from infected donors to uninfected recipients is unlikely to occur.

Animals↗

PubMed1981

Collection and transfer of equine embryos.

Embryos were recovered in 39 of 47 attempts (83%) during 1979 and in 75 of 104 attempts (72%) during 1980. The mean diameters of day 8 and 9 blastocysts were 1.00 and 2.13 mm, respectively. The injection of prostaglandin F2 alpha or prostalene on day 8 or 9 after ovulation resulted in a mean interval between embryo recovery attempts of 17.7 +/- 0.3 days. Number of embryos recovered within mares did not vary significantly with repeated attempts. Following surgical transfer, 8 of 15 recipients (53%) were pregnant at 50 days after ovulation, whereas only 4 of 15 recipients (27%) were pregnant at 50 days following nonsurgical embryo transfer.

Animals↗

PubMed1981

Development and viability of frozen-thawed cattle embryos.

Embryos recovered 7 to 8 days after estrus were frozen from -7 to -30 degrees C at 0.3 degrees C/min, from -30 to -33 degrees C at 0.1 degrees C/min, and then plunged into liquid nitrogen. They were thawed in a 25 degrees C waterbath. In a preliminary study, 15 of 18 embryos continued to develop during the 24-hour culture post-thaw in either Ham's F-10 or modified Dulbecco's phosphate buffered saline (PBS). In the main study, 5 of 20 embryos developed to 60-day pregnancies when embryos were transferred within 5 hours after thawing. The incidence of extended estrous cycles (pregnancy or presumed embryonic mortality) was 10 of 14, when the zona pellucida was intact after thawing, and 0 of 6, when it was ruptured or absent (P<.05). Embryos cultured in PBS tended to develop more readily than those in Ham's F-10 (15 of 20 vs 9 of 20, respectively, P reverse similar.1). Quality of the embryos, at recovery from the donor and after thawing, affected development in culture (19 of 27 embryos excellent at recovery developed vs 5 of 13 poor to very good, P reverse similar.1; 23 of 33 embryos good to excellent after thawing developed vs 1 of 7 poor, P<.05). The proportion of pyknotic nuclei in embryos which were cultured ranged from 18 to 100%. The pregnancy rate from embryos which were cultured was low (2 of 20). Thirty percent of frozen and thawed embryos had damaged zonae pellucidae. The study showed that: the pregnancy rate from frozen embryos was approximately half that achieved with unfrozen embryos; culturing embryos for 24 hours before transfer was not beneficial; the PBS culture system appears to be the system of choice for assessing embryo viability in vitro .

Journal Article↗

PubMed1981