In Vitro Fertilization and Embryo Development in Vitro and in Vivo in the Tiger (Panthera Tigris)1

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Abstract
A study was conducted to evaluate the adaptability to the tiger of an in vitro fertilization/embryo culture system previously developed in the domestic cat. In Trial 1 (July 1989), 10 female tigers were treated with either 2 500 (n = 5) or 5 000 (n = 5) IU eCG i.m. and with 2 000 IU hCG i.m. 84 h later. In Trial II (January 1990), 6 females (5 of which were treated in Trial I) were given 2 500 IU eCG i.m. and 2 000 IU hCG i.m. 84 h later. Twenty-four to twenty-six hours after hCG treatment, all tigers were subjected to laparoscopy, and oocytes were aspirated transabdominally. On the basis of follicular development (follicles .gtoreq. 2 mm in diameter), all females responded to exogenous gonadotropins (range, 6-52 follicles/female). Follicle number and oocyte recovery rate were unaffected (p > 0.05) by eCG dose or time of year. A total of 456 oocytes were collected from 468 follicles (97.4% recovery; mean, 28.5 .+-. 3.4 oocytes/female). Of these, 378 (82.9%) qualified as mature, 48 (10.5%) as immature, and 30 (6.6%) as degenerate. During Trial I, 8 electroejaculates were collected from 7 male tigers, and in Trial II, 3 semen samples were collected from 3 males. Motile sperm were recovered on each occasion; the overall mean (.+-. SEM) ejaculate volume was 7.5 .+-. 0.7 ml, the number of motile sperm/ejaculate was 105.9 .+-. 20.6 .times. 106, and the percentage of structurally normal sperm/ejaculate was 81.4 .+-. 2.0%. After swim-up processing, 0.05 .times. 106 motile sperm were co-cultured with 10 or fewer tiger oocytes in a humidified atmosphere (38.degree.C) of 5% CO2 in air. Of the 358 mature oocytes inesminated, 227 (63.4%) were fertilized. Oocytes from 2 females became contaminated in culture and, therefore, were excluded from embryo cleavage calculations. Of the remaining 195 fertilized oocytes, 187 (95.5%) cleaved to the two-cell stage. No parthenogenetic cleavage was observed in noninseminated control oocytes (n = 20). Eighty-six good-to-excellent-quality two- to four-cell embryos were transferred surgically into the oviducts of 4 of the orginal oocyte donors in trial I and 2 females in Trial II. A pregnancy occurred in 1 female in Trial II, and 3 live-born cubs were delivered by Cesarian section 107 days after embryo transfer. Of the 56 cleaved embryos cultured in vitro in Ham''s F10 for 72 h, 14 (25.0%) were at the sixteen-cell stage, and 15 (26.8%) were morulae. Of the 46 embryos cultured for 96 h, 20 (43.5%) advanced to morulae, and 14 (30.5%) to early blastocysts. The data demonstrate the ability of tiger sperm to fertilize follicular oocytes in vitro. The resulting embryos are capable of advancing to morulae and blastocysts in culture and to live-born offspring embryo transfer.