206 POSTNATAL MANAGEMENT OF CHRYPTORCHID BANTENG CALVES CLONED BY NUCLEAR TRANSFER UTILIZING FROZEN FIBROBLAST CULTURES AND ENUCLEATED COW OVA

Abstract

A multi-institutional collaboration was developed to evaluate the potential for conservation management of genetic variation in captive banteng calves via nuclear transfer cloning of a deceased genetically valuable individual. Fibroblast cultures frozen in 1978 were fused with enucleated cow ova and resulting embryos were transferred to domestic beef cattle for gestation. Two banteng (Bos javanicus) calves produced by heterologous nuclear transfer were delivered by standing Cesarean section on April 1 and 3, 2003. Birth weights for the two calves were 23.13 and 38.64 kg, respectively. The larger calf failed to gain strength and died on April 8. The surviving calf was transferred from Sioux Center, IA, to the San Diego Wild Animal Park in Escondido, CA on April 18, 2003. The calf was offered a goat’s milk-based formula containing 21.9 kJ metabolizable energy (ME) and 22% total solids. The total solids fraction consisted of 26.3% crude protein, 29.8% crude fat, 33.5% total carbohydrate. Intake and growth rate for this calf was compared to other hand-reared bovid calves produced by normal mating. Average daily gain from birth to 16 weeks of age was 767 g day⁻¹. A routine neonatal physical examination revealed that the surviving calf was bilaterally cryptorchid. The large calf that did not survive was noted to have one abdominally retained testicle, whereas the other testicle was scrotal. Ultrasound examination of the healthy banteng calf confirmed abdominal localization of the retained testicles. Both testes were located in the abdominal cavity about 4–6 cm from the caudal pole of the kidneys. Therapeutic intervention was considered because of the genetic value of the calf and because the cell donor exhibited normal scrotal testicles. In July, 2003, orchipexy was conducted on this calf. The left testis was exteriorized through a small abdominal flank incision. After freeing it from tissue holding it in place, it was relocated through a subcutaneous tunnel to a pouch created just in front of the scrotum. The attachments to the testis were not long enough to allow the testis to be placed fully in the scrotum. At a follow-up examination conducted four weeks after the surgery, the left testicle was palpable in the subcutaneous pouch just cranial to the scrotum. Under ultrasound examination, the left testicle was easily identified less than 1 cm deep with echogenic texture of a testis. Color flow Doppler ultrasound analysis demonstrated pulsatile flow in the center of the testis synchronous with the heart beat. These findings indicate testicular viability and blood supply.