Author:
Skidmore Julian A.,Billah M.,Allen W. R.
Abstract
The uteri of 36 adult dromedary camels were flushed non-surgically three times
each with 90–120 mL of embryo flushing medium 7 days after ovulation. A
total of 242 embryos were recovered, of which 139 were transferred
non-surgically to recipient camels that were either at different levels of
synchrony with respect to the Day 7 donor (+1 to –3 days;
n = 58), or were at Day 6 after ovulation, but
received one of the following treatments: (i) none
(controls, n = 15); (ii)
150 mg progesterone-in-oil injected intramuscularly once daily during Days
5–20 after ovulation inclusive (n = 16);
(iii) 500 mg flunixin meglumine given intravenously 15
min before transfer of the embryo (n = 6);
(iv) 20 μg of the gonadotrophin-releasing hormone
(GnRH) analogue buserelin given on Day 5 after ovulation
(n = 12); or (v) the embryo
was cooled to 4˚C and held at this temperature in an insulated container
for 24 h before being transferred (n = 32).
Jugular vein blood samples, taken daily from all the recipient camels during
Days 0–20 after ovulation, were assayed for progesterone concentration
and closely timed serial samples taken from the camels receiving flunixin
meglumine or GnRH were assayed for 13,14-dihydro-15-keto prostaglandin
F2α (PGFM) or oestradiol concentrations. The
pregnancy rate increased to a maximum of 67% when ovulation in the
recipient was negatively synchronized to have occurred 1 day behind that in
the donor, and it fell dramatically when the level of asynchrony between
recipient and donor increased to +1 (9%) or –3 (10%)
days. It was not improved by daily injections of progesterone (44%),
flunixin meglumine given before transfer (16%), or GnRH given on Day 5
(33%). Of the 32 embryos that were cooled to 4˚C before being
transferred to Day 6 recipients, 20 resulted in pregnancies (63%) to
give a success rate similar to that attained with the control fresh embryos
(67%). Serum progesterone concentrations in the recipients increased to
a mean ± SEM of 2.6 ± 0.8 ng mL–1 by
Day 8 after ovulation and, in those that were pregnant, levels remained
elevated at 3–5 ng mL–1 for the remainder of
the sampling period; in non-pregnant recipients the concentrations declined to
<1 ng mL–1 by Day 11. Plasma PGFM
concentrations in the flunixin meglumine-treated camels remained low
(40–90 pg mL–1) compared with those in the
untreated control camels, in which peak values of around 180 pg
mL–1 were reached within 10 min after transfer
after which a steady decline occurred until resting concentrations of
90–100 pg mL–1 were reached by 110 min after
transfer. Treatment with GnRH on Day 5 after ovulation produced a transitory
increase in serum oestradiol-17β concentrations for 24 h. However, from
Day 8, oestradiol concentrations in both the GnRH-treated and the untreated
camels increased steadily to reach 2.5–3.5 pg
mL–1 by Day 12.
Subject
Developmental Biology,Endocrinology,Genetics,Molecular Biology,Animal Science and Zoology,Reproductive Medicine,Biotechnology
Cited by
49 articles.
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