Progress 09/15/01 to 09/30/04
Outputs
Success of embryo transfer in cattle can be limited by low pregnancy rates, especially for in vitro produced (IVP) embryos and by problems of oestrous detection. One approach to improve embryo survival is to treat the recipient hormonally. Administration of recombinant bovine somatotropin (bST) to lactating dairy cows increased pregnancy rates following transfer of frozen/thawed embryos produced by superovulation. It is unclear whether the beneficial effect of bST on fertility observed in lactating cows are also observed in nonlactating cows since the latter have higher plasma concentrations of IGF-1. Objectives of the present experiments were to determine whether 1) administration of bST to nonlactating recipients would improve the post-transfer survival of IVP embryos and 2) pregnancy rates achieved following TET with IVP embryos or embryos produced by superovulation are similar to pregnancy rates following timed artificial insemination (TAI). In the first
experiment, embryos were produced in vitro. Seven days after fertilization, grade 1 and 2 blastocysts (n=33 and 7, respectively) and grade 1 morula (n=5) were harvested for transfer. Nonlactating females (Angus n=11 and Holstein n=36, a mix of heifers and cows) were synchronized for TET with two presynchronization injections of prostaglandin followed 12 days later by the OvSynch protocol. On day 0, the day of synchronized ovulation, recipients were randomly assigned to receive 500 mg bST, s.c., (Monsanto, Chesterfield, MO) or to be used as untreated controls. On day 7 after synchronized ovulation, a single, fresh IVP embryo was transferred to the horn ipsilateral to the ovary with a corpus luteum. Results indicated that pregnancy rate was not significantly affected by bST and was similar between groups. While there was a numerically higher pregnancy rate in Angus, there was no significant effect of breed of recipient. In the second experiment, nonlactating Holstein cows and heifers
were assigned to one of three groups: TAI, TET with a fresh IVP embryo or TET with a frozen/thawed superovulated embryo. The experiment was conducted on three separate occasions. The embryo culture medium contained 100 ng/ml human recombinant IGF-1. The proportion and percentage of cows pregnant were 11/27 cows (40.7%) for TAI, 6/14 cows (42.9%) for TET/superovulated embryo, and 6/15 cows (40%) for TET/IVP embryo. There was no significant effect of treatment on pregnancy rate as determined by logistic regression. Results indicate that administration of bST to nonlactating recipients does not increase embryo survival following TET with IVP embryos. This finding is in contrast to a previous study with lactating cows. Thus, bST administration may improve embryonic survival in lactating cows by increasing plasma concentration of IGF-1 but be without beneficial effect in nonlactating cows because circulating concentrations of IGF-1 are already adequate.
Impacts
Results indicate that bST does not affect pregnancy rates in non-lactating recipients following TET with IVP embryos.
Publications
- Hernandez-Ceron, J., Chase, C.C. Jr, and Hansen, P.J. (2004) Differences in heat tolerance between preimplantation embryos from Brahman, Romosinuano, and Angus Breeds. J. Dairy Sci., 87, 53-58.
- Jousan, F.D., and Hansen, P.J. (2004) Insulin-like growth factor-I as a survival factor for the bovine preimplantation embryo exposed to heat shock. Biol. Reprod. 71, 1665-1650.
- Block, J., Rivera, R.M., Drost, M., Jousan, F.D., Looney, C.R., Silvestre, F., Paula-Lopes, F.F., Ocon, O.M., Rosson, H., Bilby, T.R., Monson, R.L., Rutledge, J.J., and Hansen, P.J. (2004) Effect of bovine somatotropin and breed on pregnancy rates following timed embryo transfer in non-lactating cows. Vet. Rec., in press.
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Progress 10/01/02 to 10/01/03
Outputs
Experiments were conducted to test the effects of bovine somatotropin (bST), breed and plasma progesterone concentrations on the survival of in-vitro produced embryos following transfer to non-lactating recipients. For experiment 1, 36 Braford cows were given an injection of prostaglandin F2 alpha (PGF), followed 12 days later by the OvSynch protocol. On day 0 (anticipated ovulation), recipients were treated with bST or not. Embryos were transferred to all recipients having a palpable corpus luteum on day 7. Pregnancy was diagnosed at day 30 and 90. In experiment 2, 66 recipients of three breed types (Angus, Holstein, and Brahman & Brahman crossbreds) were given two PGF injections 14 days apart followed 12 days later by the OvSynch protocol. Plasma progesterone concentrations on days 0 and 7 were used to determine synchrony of estrous cycles. Pregnancy was diagnosed between days 42 and 49. All other procedures were as for experiment 1. There was no effect of bST on
any trait measured including pregnancy rate. In Experiment 2, concentrations of plasma progesterone on day 7 and the proportion of cows synchronized were not affected by breed but pregnancy rate was lower for Brahman/Brahman crossbreds than for the other two breeds (p<0.05). For both experiments, there was a non-significant trend for recipients with < 2.5 ng/ml plasma progesterone on day 7 to have lower pregnancy rates than those with plasma progesterone > 2.5 ng/ml.
Impacts
Results indicate that breed of recipient but not bST affects pregnancy rates in non-lactating recipients following TET with IVP embryos.
Publications
- Paula-Lopes, F.F., Chase, C.C., Jr., Al-Katanani, Y.M., Krininger, C.E. III, Rivera, R.M., Tekin, S., Majewski, A.C., Ocon, O.M., Olson, T.A., and Hansen, P.J. (2003) Genetic divergence in cellular resistance to heat shock in cattle: Differences between breeds developed in temperate versus hot climates in responses of preimplantation embryos, reproductive tract tissues and lymphocytes to increased culture temperatures. Reproduction 125, 285-294.
- Krininger III, C.E., Block, J., Al-Katanani, Y.M., Rivera, R.M., Chase, C.C., Jr., and Hansen, P.J. (2003) Differences between Brahman and Holstein cows in response to estrous synchronization, superovulation and resistance of embryos to heat shock. Anim. Reprod. Sci., 78, 13-24.
- Block, J., Drost, M., Monson, R.L., Rutledge, J.J., Rivera, R.M., Paula-Lopes, F.F., Ocon, O.M., Krininger, C.E. III, Liu, J., and Hansen, P.J. (2003) Use of insulin-like growth factor-1 during embryo culture and treatment of recipients with GnRH to increase pregnancy rates following the transfer of in vitro produced embryos to heat-stressed, lactating cows. J. Anim. Sci. 81: 1590-1602.
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Progress 10/01/01 to 10/01/02
Outputs
Studies have reported the positive effect of insulin-like growth factor-1 (IGF-1) on embryonic development in vitro. In addition, there are reports that administration of GnRH on d 11 improves pregnancy rates following artificial insemination. Objectives of this study were to determine if pregnancy rate following timed embryo transfer would be improved by 1) culturing embryos in the presence of IGF-1 and 2) treating recipients with GnRH on d 11 after putative estrus. The experiment was conducted between June and September, 2001. Embryos were produced from Holstein oocytes collected from ovaries from a Wisconsin abbatoir. Oocytes were shipped overnight to Gainesville where fertilization took place. Following fertilization, oocytes were cultured in the presence or absence of 100 ng/ml IGF-1. A total of 210 primiparous and multiparous lactating Holstein cows were synchronized using the OvSynch protocol and used as recipients in 13 replicates (6 to 24
recipients/replicate). Fair to excellent quality blastocysts and morulae were collected at d 8 after fertilization and randomly transferred to day 7 (d 0 = the day following the 2nd GnRH injection) recipients. For the first 3 replicates (n = 46), recipients received no additional treatment. For the remaining 10 replicates (n = 164), recipients randomly received either GnRH (Cystorelin7, 100 microgram) or placebo on d 11. Pregnancy was diagnosed 45 d after embryo transfer. Recipients which received IGF-1 treated embryos had higher pregnancy rates than controls (p<0.05, 29/124 = 23.4% vs. 10/86 = 11.6%). Among cows receiving GnRH or placebo at d 11, pregnancy rate was higher (p<0.05) for those receiving GnRH (22/93 = 23.7%) than for those receiving placebo (8/71 = 11.3%). Results indicate that addition of IGF-1 to embryo culture and administration of GnRH on day 11 can improve pregnancy rates to timed embryo transfer in lactating dairy cows.
Impacts
Data demonstrate that acceptable pregnancy rates can be achieved in heat stressed cows using embryo transfer. Moreover, use of IGF-1 in culture medium can enhance subsequent pregnancy rate after embryo transfer.
Publications
- Al-Katanani, Y.M., Paula-Lopes, F.F., and Hansen, P.J. (2002) Effect of season and exposure to heat stress on oocyte competence in Holstein cows. J. Dairy Sci. 85, 390-396.
- Al-Katanani, Y.M., Rivera, R.M., and Hansen, P.J. (2002) Seasonal variation in development of in vitro produced bovine embryos. Vet. Rec., 150, 486-487.
- Al-Katanani, Y.M., and Hansen, P.J. (2002) Induced thermotolerance in bovine two-cell embryos and the role of heat shock protein 70 in embryonic development. Mol. Reprod. Dev. 64, 174-180.
- Al-Katanani, Y.M., Drost, M., Monson, R.L., Rutledge, J.J., Krininger III, C.E., Block, J., Thatcher, W.W., and Hansen, P.J. (2002) Pregnancy rates following timed embryo transfer with fresh or vitrified in vitro produced embryos in lactating dairy cows under heat stress conditions. Theriogenology 58, 171-182.
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