Crossbred calves resulting under tropical conditions after direct transfer of cryopreserved F1 embryos produced in chemically defined media

HERNANDEZ-FONSECA, H. J.; SIRISATHIEN, S; SOTO-BELLOSO, E.; VELARDE, J. C.; GONZALEZ, R.; BOSCH, P.; LOTT, J. D.; DONDIZ, A.; BRACKETT, B. G.

Foz do Iguacu, Brasil

Congreso; 28 Annual Congress of the International Embryo Transfer Society; 2002

International Embryo Transfer Society

This work was designed to explore feasibility for production of Brahman x Holstein cattle the tropics by combining embryo production in chemically defined conditions with cryopreservation for transport (from the U.S.A.) and direct embryo transfer (in Venezuela). Influences of recombinant Leukemia Inhibitory Factor (LIF, Sigma) in embryo culture, and conditions for frozen storage during transport were investigated. Holstein oocytes obtained at slaughter were matured, fertilized by Brahman sperm, and resulting embryos were cultured, all in chemically defined conditions (Dinkins et al. Theriogenology 2001;55:1639-1655). Embryo culture was with or without LIF (100 ng/ml) during 48 h immediately preceding blastocyst cryopreservation. Excellent or good blastocysts were individually loaded into straws, precooled to -7 degrees C with seeding by touching with liquid nitrogen (LN). After 10 min at -7 degrees, straws were cooled further to -30 degrees C ar a rate of 0.3 degrees/min and then plunged into LN. Embryos were sent to Venezuela either in LN vapor (dry shipper, -120 degrees C) or submerged into LN (LN tank, -196 degrees C). Embryo transfers were performed early or late in the day to avoid conditions of highest humidity and heat. Synchronized recipient heifers in good or excellent body condition received one embryo in the horn ipsilateral to the corpus luteum. Pregnancies were diagnosed by rectal palpation 55 to 65 days later. Proportional data were analyzed by Chi-square with Yates’ correction. The pregnancy rate was higher when embryos were transported in LN than when transported in LN vapor, 14.3% (14/98) vs 4.5% (3/67), P£0.01. Addition of LIF to cultures did not increase blastocyst production or pregnancy rates; for embryo transport in LN, the LIF treated and control groups resulted in pregnancy rates of 9.8% (5/51) and 19.2% (9/47), respectively. Of these 14 pregnancies: 3 were aborted between 3 and 5 months; 3 calves died at birth; and 8 healthy calves (avg. wt. of 37.1 Kg) resulted, 5 female and 3 male. We have shown that it is possible obtain healthy F1 calves from frozen-thawed embryos produced in chemically defined media after direct transfer under tropical conditions. Further efforts are needed to elevate pregnancy rates and to eliminate losses inherent in procedures employed. Authors gratefully acknowledge support of UGA ASRT-5; Brown Packing Co., Gaffney, SC; and Santa Elena Ranch, Madisonville, TX.