Incidence Of Embryonic Death Research Articles

Viability of Gyr (Bos indicus) in vitro produced embryos after vitrification under field conditions

The aim of this study was to evaluate the pregnancy rate of in vitro produced embryos of Gyr cattle (Bos indicus) after cryopreservation by the vitrification method under field conditions. Blastocysts in different developmental stages were transferred to recipient cows either fresh (n = 140) or warmed after vitrification (n = 138). The pregnancy rates obtained for fresh embryos were 46.15% (initial blastocyst), 46.93% (blastocyst) and 50.0% (expanded blastocyst) at 35 days post-fertilization, and 43.58% (initial blastocyst), 46.93% (blastocyst) and 50.0% (expanded blastocyst) at 60 days. The pregnancy rates after embryo vitrification were 35.0% (initial blastocyst), 42.3% (blastocyst) and 43.47% (expanded blastocyst) at 35 days post-fertilization, and 32.5% (initial blastocyst), 38.46% (blastocyst) and 43.47% (expanded blastocyst) at 60 days. Embryo vitrification or blastocyst development stage did not affect pregnancy rates or the incidence of embryonic death. In conclusion, vitrification of Gyr (Bos indicus) embryos under field conditions is an efficient method that can be implemented to use surplus in vitro produced embryos without affecting pregnancy rates.

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

A total of 384 Thoroughbred mares were investigated to determine and evaluate the features of early embryonic death at nine equine farms on Jeju Island, South Korea, from 2001 to 2003. Overall, 771 matings for 384 mares resulted in 376 pregnancies 15 days after ovulation. Subsequently, 12.2% (46/376) of these early conceptuses were lost within 45 days after ovulation. Furthermore, about three quarters of the 46 embryonic deaths occurred between 16 and 25 days after ovulation. The incidence of embryonic death was highest in the barren (17.2%), more than 15 years old (15.4%), and more than 10 parities (18.2%) groups compared with the other groups (9.1-16.9%). Mares mated in March, April, and during the first estrus postpartum had higher embryonic death rates, (19.6%, 17.2%, and 24.6%, respectively). Mares with abnormal fluid and cysts in the uterus (18.0%) or multiple embryonic vesicles (23.1%) had higher embryonic death rates than those with normal uterine conditions (9.8%) or single embryonic vesicles (10.5%). The condition of mares, such as breeding condition and the environment of the embryo or fetus, are the major factors in relation to occurrence of early embryonic death.

Ultrasonography as Aid for Early Pregnancy Diagnosis in Zebu Cattle in a Natural Mating Programme

Galicia, L.L., Estrada, K.S, Galina, C.S, Pérez, G.E, Romero, J.J. and Molina, S.R. 2006. Ultrasonography as aid for early pregnancy diagnosis in Zebu cattle in a natural mating programme. J. Appl. Anim. Res, 29: 53–58. To utilise ultrasonography in Zebu cattle to test early pregnancy, multiparous Bos indicus cows (n=74) were allocated with 2 mature Brahman bulls, which were replaced with new ones every four weeks. Cows were bled for radioimmunoassay progesterone analysis at the time of ultrasound and four days prior or after this event. The efficiency of the ultrasound findings and progesterone levels were compared wit' Kappa index using the computer programme (WIN) EPISCOPE. Ultrasound precision for early pregnancy diagnosis was 96%. Moreover, animals not clearly defined as pregnant, following examination revealed that only 54% were actually pregnant. The efficiency to detect the lack of ovarian activity was only 25% as revealed by progesterone concentrations lower than 1ng/ml. In contrast, the association between a detectable CL by ultrasound and progesterone values higher than 1ng/ml was 90%. The incidence of embryonic death was 15.4%. Based on these results the efficacy for detecting early pregnancy by ultrasound and the presence of an active CL is satisfactory, whereas the precision to detect non-cycling animal is questionable and the incidence of embryonic death is high.

160 DETERMINATION OF THE INCIDENCE OF EMBRYONIC MORTALITY IN SYNCHRONIZED EWES DURING THE BREEDING SEASON

The aim of the present study was to evaluate the incidence of embryonic mortality in synchronized Konya Merino ewes (2–4 years of age) during the the breeding season. The flushing procedure started in 126 ewes, beginning 1 week before the breeding period until mating. The ewes were synchronized using progesterone : PMSG; a sponge containing 40 mg florogestone acetate was placed into vagina for 12 days. PMSG (500 IU) was given intramuscularly at the time of sponge removal and ewes were allowed to mate 48-60 hours (Day 0) after PMSG injection. The first pregnancy diagnosis was done transrectally 18 days after mating by using B-mode, linear array, 5 MHz real-time ultrasonography, and it was repeated again on Days 22, 26, 30, and 34. One hundred eleven ewes were pregnant on Day 18, and 191 embryos were detected in 111 pregnant ewes. There were 44 single, 54 twin, and 13 triple pregnancies. Embryonic death was determined in 39 out of 111 ewes (35.1%), and 45 embryos out of the total of 191 were lost (23.6%). Among the ewes which experienced embryonic death, 28 ewes maintained pregnancy while 11 ewes (9 single, 1 twin, and 1 triple pregnancy) did not. Among the embryos that were dead, 9 (20%), 20 (44.4%), and 16 (35.6%) were from single, twin, and triple pregnancies, respectively. Rates of embryonic death in the total number of embryos according to type pregnancy were 20% (9/45), 18.5% (20/108), and 41% (16/39). Incidence of embryonic deaths were 22.2% (10/45), 51.1% (23/45), 22.2% (10/45), and 4.5% (2/45) for Days 22, 26, 30, and 34, respectively. The majority of embryonic deaths were observed by Day 22 in single pregnancies and by Day 26 in multiple pregnancies. Incidence of termination of pregnancy in single pregnancies was significantly higher than for twin pregnancies (P < 0.01). The rate of embryonic mortality between single and twin pregnancies was not significant, whereas it was significant among single and triple and among twin and triple pregnancies (P < 0.05 and P < 0.01, respectively). In conclusion, incidence of embryonic death was similar between single and twin pregnancies but the majority of pregnancy losses were observed in single pregnancies. Although embryonic deaths are observed, maintenance of pregnancy conceals the problem of embryonic mortality in multiple pregnancies. Therefore, applications to improve the survival of embryos during the first month after mating could yield higher numbers of lambs.

Spontaneous embryonic death on Days 20 to 40 in heifers

Transrectal ultrasound examinations were used in nulliparous Holstein heifers to study the association between time of spontaneous embryonic death (cessation of heartbeat) and luteal regression, and to determine the fate of the conceptus after embryonic death. There was no significant difference between nonbred heifers (n = 135) and bred, nonpregnant heifers (embryonic heartbeat never detected, n = 40) for day of onset of luteal regression (means, 17.6 and 17.9, respectively) or for length of interovulatory interval (means, 20.6 and 20.9 days, respectively). Pregnancy was confirmed by detection of an embryonic heartbeat on Day 24 (ovulation = Day 0) or later, or on two consecutive days prior to Day 24; on average, an embryonic heartbeat was detected on Day 22.0 (n = 104). Pregnancy rate on Day 24 was higher (P<0.02) in heifers bred on Day −1 (116/149, 77.8%) than in heifers bred on Day −2 (51/79, 64.6%), and was higher (P<0.05) in heifers with an embryo transferred ipsilateral to the corpus luteum than in heifers with an embryo transferred contralateral to the corpus luteum (3/4 vs 0/5). Embryonic death (lack of embryonic heartbeat following confirmation of pregnancy) and presumptive embryonic death (embryonic heartbeat detected on one day only, prior to Day 24) were detected prior to Day 25 in one and two bred heifers, respectively, and in one and two heifers with an embryo transferred contralateral to the corpus luteum, respectively. In these six heifers, luteal regression preceded, and apparently caused, embryonic death. In seven of eight heifers in which embryonic death was detected between Days 25 and 40, the onset of luteal regression was detected at least 3 d (range, 3 to 42 d) after detection of embryonic death. The incidence of embryonic death on Days 29 to 32 was lower (P<0.02) in heifers bred on Day −1 than in heifers bred on Day −2 (0 of 96 vs 3 of 40, respectively). In heifers in which luteal regression preceded embryonic death, the conceptus was lost rapidly, with minimal evidence of degeneration. In heifers in which embryonic death preceded luteal regression, there was ultrasonic evidence of conceptus degeneration, but conceptus fluid and tissue appeared to be maintained. In all heifers with embryonic death, the conceptus and its breakdown products apparently were eliminated by expulsion through the cervix rather than by resorption.

Induction of malformations in the cynomolgus monkey with 13‐cis retinoic acid

The embryotoxic and teratogenic potential of 13-cis retinoic acid was assessed in the cynomolgus macaque (Macaca fascicularis). A total of 41 animals was orally administered 13-cis retinoic acid in four sequential experiments. In Exp. 1 three dose levels, 2, 10, and 25 mg/kg, were administered on gestational day (GD) 18-28; 5 mg/kg was administered as an equally divided dose twice daily in Exp. 2 and 3 on GD 21-24 and on GD 25-27, respectively; in Exp. 4 the drug was administered at 2.5 mg/kg once daily from GD 10 to 25 and twice daily (2 x 2.5 mg/kg) on GD 26 and 27. Maternal death and toxicity, manifested as reduction in maternal weight and food consumption, and diarrhea, was observed in Exp. 1 in all three dose groups. No significant maternal toxicity was observed in the treatment groups in Exp. 2, 3, and 4 or in the control group. The primary manifestation of developmental toxicity was embryolethality in Exp. 1 and 2. The incidence of embryonic deaths in Exp. 3 was comparable to the historical controls. No malformations in GD 100 fetuses were observed in Exp. 1, 2, and 3. In Exp. 4, five of seven fetuses (71%) had malformations of both external ears, four of seven fetuses (57%) exhibited hypo- or aplasia of the thymus, and two of seven (29%) had malformations (transposition of the great vessels, ventricular septal defect) of the heart. The teratogenic dose for the cynomolgus monkey in the present study was lower than that reported for all other experimental species. Although central nervous system and craniofacial defects were not observed, the incidence of ear and thymus defects was similar to that reported for the human. The cardiovascular defects resembled those reported clinically, but the incidence was lower in the cynomolgus monkey. The similarity in teratogenic sensitivity to humans supports the use of the monkey as a model for developmental toxicity studies of vitamin A-related compounds.

The influence of radiant heat load on reproduction in the Merino ewe. I. The effect of timing and duration of heating

Merino ewes were subjected to a source of radiant heat during early pregnancy in two experiments in which the incidence of embryonic death was examined as reflected by the proportion of ewes that failed to return to service but did not lamb. Ewes were artificially inseminated (day 0) and exposed to hot-room conditions during days 1–3, 4–6 or 7–9 or not at all (control) (experiment I), and during days 1–3, 1–6 or 1–9 or not at all (control) (experiment 2). Conditions in the hot room and control room were respectively 40–43°C and 1.36–3.06 kPa vapour pressure, and 22–26°C and 1.12–1.96 kPa. Ewes exposed to hot-room conditions had significantly higher rectal temperatures and respiration rates during treatment than did control ewes (40.2° v. 39.3° and 186 v. 61 respirations/min, P &lt; 0.001). The number of ewes which conceived and eventually lambed was reduced by exposure to high environmental temperatures shortly after insemination. The most critical period was during the first 3 days after insemination. If ewes were heated for periods longer than this, fertility was not reduced significantly further. This suggested that the timing of the heating was more critical than the duration of heating in early pregnancy. The reduction in the number of ewes lambing (experiment 1) or in the number of ewes pregnant at 30 days (experiment 2) was due almost entirely to either fertilization failure or early embryo death. Most infertile ewes showed oestrus within a normal cycle (16–19 days). Only in experiment 1, where heating lasted 3 days, did ewes return to oestrus after extended intervals from insemination. In experiment 2 the proportion of ewes which showed oestrus after an extended period from insemination was very small. It was concluded that death of developed embryos due to the effects of high environmental temperatures during early pregnancy was insufficient to explain the large reproductive wastage associated with ewes which apparently conceive but fail to lamb.

Bacteriological Studies of Uteri of Clinically Normal Cows of Low Fertility

Summary This study was undertaken to determine if the uteri of clinically normal repeat-breeder cows contained microorganisms at 16 days postbreeding, a stage immediately followed by a high incidence of embryonic death. Sixty-nine repeat-breeders were slaughtered, the uteri removed aseptically, and flushed with 15ml. of 0.1% tryptone broth. Various media were inoculated with the recovered fluid and incubated in air, in 15% CO 2 and reduced air, and in an anaerobic jar. Triturated endometrial tissue of 35 animals in the study was similarly cultured. Microorganisms were recovered from the uteri of eight (11.6%) of the 69 repeat-breeders. A yeast, Candida krusei , was isolated from four uteri, an Escherichia species from one, a Pseudomonas from one, Brucella abortus from one, and a paracolon from one. Embryos were recovered from 31 of 62 uteri from cows with anatomically normal reproductive tracts; three embryos were recovered from the eight infected uteri. Vaginal mucus samples were obtained from 35 of the animals at from 11 to 13 days postbreeding and at slaughter. One cow had a positive mucus agglutination test for Vibro fetus . Serum agglutination-lysis tests for leptospirosis were made on all animals. None was positive. Microbial infection apparently accounted for few of the embryonic deaths in these clinically normal repeat-breeders.