259 PRODUCTION OF TROPICAL DAIRY CALVES BY EMBRYO TRANSFER USINGLOCAL LAISIND (BOS INDICUS) RECIPIENTS AND INTERCONTINENTAL FRESHIVF SHIPPED EMBRYOS

Increasing the diary population and milk production is a goal of many tropical developing countries. We report in this paper an attempt to develop a system of intercontinental shipping for transfer of fresh crossbred Bos taurus × Bos indicus IVF embryos into local Laisind (Bos indicus) recipients as a way to produce tropical dairy calves with highly improved milk productivity. The production of embryos was done at BOMED, Inc (Madison, WI, USA). Oocytes collected from ovaries of Holstein (Bos taurus) at slaughter and semen from milking Gir (Bos indicus) were used for IVP. Cleaved embryos were selected for air shipping in portable incubators at Day 4 (Group 1), Day 3 (Group 2) or Day 2 (Group 3) after IVF. The duration of shipping varied from 60 to 65 h. Embryo transfer was done in Vietnam. Laisind cows (Yellow cattle × Red Sindhi) with body weight more then 280 kg and normal reproductive activity were selected for treatment of estrous synchronization with double 11-day interval injection of PG2a (Intervet, Boxmeer, The Netherlands) and single injection of eCG (SABC Vietnam) two days before the second injection of PG2a. Timing of injections was calculated according to the IVF schedule. Embryos collected from portable incubators were transferred to a CO2 incubator for further culture at 39°C. Two experiments were carried out: (1) transfer of embryos without sexing;; (2) transfer of embryos after biopsy and sex determination by PCR. In experiment 2, compact morulae or morula-blastocysts were selected for sex determination. Four to five blastomeres were aspirated from each embryo using a cutting pipette and an aspiration pipette of 30-µm diameter. PCR was done as previously described (Uoc et al., 1999 J. Biology). After biopsy, embryos were kept in culture for one day to observe the development in vitro. Embryos developed to morula-blastocyst or hatching blastocyst at Day 7 or Day 8 after IVF were transferred nonsurgically to recipients with estrus detected in the period from 0 to 12 h before or after the starting IVF. Pregnancy was confirmed by rectal palpation 3 months after embryo transfer. The average rate of embryos developed into morula-blastocyst was more then 50% (Table 1) and there were no significant differences among different shipping groups. For experiment 2, more then 87 % of embryos biopsied developed in vitro to expanding and hatching embryos. The average rate of female embryos was 56.3%. The pregnancy rate at 3 months was more then 44% (n = 188). The first group of calves was born without unusual birthing problems. In conclusion, the system of embryo transfer using intercontinental shipping of fresh IVF embryos and local Bos indicus recipients can be applied for production of dairy calves. Supported by grant from the AIRE-Development agency. Table 1 Development in vitro of IVP embryos