P.T. Cupps

Survival of bovine embryos stored at 4°C

Abstract These experiments were designed to test the efficacy of storing bovine embryos at 4°C. Of particular interest were the age of embryo at which maximum post-storage survival could be achieved and longevity at 4°C. A greater proportion of day 8 blastocysts developed in vitro at 37°C following refrigeration for 48 hr than did embryos collected 2, 4 or 6 days after estrus (P In vitro survival of nonstored embryos and embryos stored 1 day did not differ. Survival decreased after storage for 2 days (P In vitro survival was approximately 50% for blastocysts stored for 3 and 5 days, but few pregnancies resulted from transfer of embryos stored for these periods. In another experiment survival after transfer of blastocysts stored at 4°C for up to 2 days was similar to that of nonstored blastocysts.

Length of gestation in ewes carrying lambs of two different breeds

Length of gestation was studied in pregnancies established by intrabreed, interbreed, and mixed-breed embryo transfers of Finnish Landrace (Finn; mean gestation: 144.9 days) and Targhee (mean gestation: 150.4 days) embryos to Finn cross and Targhee recipients. At least one lamb of each breed comprised mixed-breed pregnancies. There was a significant effect of the breed of lamb (Finn, Targhee, or Finn and Targhee) on the length of gestation (P<.01), but not of breed of recipient. Mixed-breed pregnancies had a mean gestation period intermediate between those for pregnancies which contained only one breed of lamb. The mean gestation period for mixed-breed pregnancies was 2.10+/-.70 (x+/-S.E.) days longer than for pregnancies with only Finn lambs (P<.01) and 2.99+/-.73 days shorter than for pregnancies with only Targhee lambs (P<.001). The delay in parturition in mixed-breed pregnancies beyond the normal gestation period for Finn lambs occurred even in litters with a majority of Finn lambs. These results demonstrate an interaction between fetuses in the processes leading to parturition. Possible mechanisms by which the Targhee lamb delayed parturition in mixed-breed pregnancies are discussed.

Preliminary studies on bovine embryo survival following short-term storage at 4°C

Abstract A total of 113 non-surgically collected bovine embryos, 5–8 days of age, were stored for 48 hours at 4°C in a modified phosphate-buffered saline solution (PBS). Following storage, embryos were cultured for 8–12 hours at 37°C, and those which were morphologically normal were transferred to synchronized recipients by several methods designed to achieve twin pregnancies. Embryos which were collected and transferred on the same day served as controls. Of 113 embryos stored, 47 (42%) appeared to be transferable after the brief culture period. There was a marked breed effect on viability after refrigeration, with Hereford embryos surviving significantly better than Angus embryos (71% vs. 12%, respectively, p

Freemartins in beef cattle twins induced by embryo transfer

Abstract The incidence of freemartinism in heterosexual twins (male-female) resulting from embryo transfer was studied by determining sex chromosome chimerism in lymphocytes and masculinization of female reproductive tracts at slaughter. In one group of calves, ten of 11 heifers born co-twin to full sib, paternal half sib, or unrelated bull calves exhibited sex chromosome chimerism, a proportion in close agreement with that observed in naturally occurring twins. The ten calves with sex chromosome chimerism also had masculinized tracts whereas the other had an apparently normal female tract. Bull calves had a percentage of XY cells similar to their female co-twins, except for the twin set from which the “normal” female was obtained. The bull calf from this set had 5.6% XX cells although no XY cells were observed in the heifer in 66 metaphase spreads. No association was observed between the degree of sex chromosome chimerism and abnormalities of the female tract. Reproductive tracts from all female-female twin sets were normal. In another group of calves, all 20 heifers from heterosexual twin sets had masculinized reproductive tracts. It is concluded that the induction of twins by embryo transfer results in normal expression of freemartinism even though calves may be unrelated and are known to develop in separate uterine horns.

Transfer of cultured bovine embryos

A total of 126 bovine embryos were surgically collected from 16 superovulated donor heifers 5 days after estrus and randomly selected for either immediate transfer to synchronized recipients or invitro culture at 37°C for 24 hours and subsequent transfer. Twenty-four of 56 (42.8%) embryos maintained for 24 hours in Hams F10 medium supplemented with 10% heat treated fetal calf serum (HTFCS) and transferred to 32 recipients produced live calves. Survival of 70 noncultured embryos transferred to 35 recipients was 55.7% (39 calves). The percentages of recipients that were diagnosed pregnant at 42 days with cultured and control embryos were 59.4% (1932) and 74.3% (2635), respectively. No statistical difference was observed between the invitro cultured and control embryos for viability following transfer to recipient females. In a second study, Day 7 embryos maintained in Hams F10 medium supplemented with 10% HTFC serum for various culture periods were tested for viability following nonsurgical transfer to recipient females. A total of 15, 13 and 04 embryos cultured for 24, 48 and 72 hours, respectively, resulted in pregnant recipients following transfer.

Synchronization of estrus in cattle for embryo transfer

Abstract Two groups of donors (31 animals) receiving 2,000 to 3,000 IU of PMSG followed by 30 to 33 mg of prostaglandin F2α-THAM salt 48 hours later showed an average interval to estrus of 44 ± 2.7 and 51 ± 5.7 hours after prostaglandin treatment. Three groups of donors (32 animals) receiving the above treatment plus 500 μg estradiol 32 to 38 hours after prostaglandin showed an average interval to estrus of 50 ± 1.0, 36 ± 1.6 and 48 ± 5.2 hours after prostaglandin. One group of recipients (16 animals) receiving prostaglandin during the mid luteal phase of the cycle showed an average interval of 78 ± 9.2 hours to onset of estrus while a comparable group treated with estradiol 32 hours after prostaglandin had an average interval of 52 ± 5.0 hours to estrus. One group of recipients (15 animals) treated with prostaglandin during the late diestrous or early proestrus phase of the cycle had an average interval to estrus of 41 ± 3.7 hours and two groups of recipients (27 animals) treated at the same stages of the cycle and receiving estradiol had an average interval to estrus of 47 ± 2.0 and 48 ± 5.2 hours, respectively.