Jr. Gibbons et al., EFFECTS OF ONCE-WEEKLY VERSUS TWICE-WEEKLY TRANSVAGINAL FOLLICULAR ASPIRATION ON BOVINE OOCYTE RECOVERY AND EMBRYO DEVELOPMENT, Theriogenology, 42(3), 1994, pp. 405-419
Ultrasound-guided transvaginal follicular aspiration combined with in
vitro maturation/in vitro fertilization (IVM/IVF) and culture was used
to obtain bovine preimplantation stage embryos. Evaluated were the ef
fects of aspiration frequency on oocyte recovery and embryo developmen
t following IVM/IVF. In Experiment 1, transvaginal follicular aspirati
on was performed once (n=5) or twice (n=5) weekly in multiparous Angus
cows with the aid of a transvaginal sector transducer (5-MHz). In Exp
eriment 2, aspiration was performed on Angus cows once weekly (n=6), t
wice weekly (n=4), or twice weekly after treatment with FSK (15 mg; n=
4) Follicles (>2 mm) were punctured using a 55-cm needle (17-g), and o
ocytes were aspirated through the needle and silastic tubing (2 m) by
vacuum suction (75 mmHg). The oocytes were examined for morphology and
were in vitro matured and fertilized. Following IVF, all ova were co-
cultured in vitro for 7 d on Buffalo Rat liver cells. Oocyte recovery
rates per aspiration session in Experiment 1 were not different betwee
n groups aspirated once or twice weekly (6.8+/-2.0 vs 6.3+/-1.1 oocyte
s/session; ($) over bar X+/-SEM) or in Experiment 2 between groups asp
irated once, twice, or twice plus FSH treatment (7.7+/-1.8 vs 9.5+/-1.
1 vs 6.2+/-1.1; P>0.10). In vitro development to the blastocyst stage
was not different between the once, twice or twice-weekly aspiration p
lus FSH treatments or control oocytes obtained from cows at slaughter
(23.1 vs 26.1 vs 18.0 vs 27.9%; P>0.10) Oocytes from the twice-weekly
and twice-weekly plus FSH aspiration groups generated a higher percent
age of Grade-1 quality embryos than the once-weekly group (P<0.05) In
commercial bovine oocyte aspiration, more transferable embryos can be
generated from twice-weekly aspirations than from once-weekly aspirati
on.