Five treatments were developed to compare
a new synchronized ovulation protocol,
which programs follicular development with
the regression of the corpus luteum, and
traditional prostaglandin protocols that only
control the regression of the corpus luteum.
The synchronized ovulation treatment, which
requires no heat detection before a fixed-time
insemination, tended to decrease pregnancy
rates compared to a similar synchronized
ovulation treatment in which inseminations
occurred at a detected estrus (30 vs 50%).
The traditional two-injection prostaglandin
protocol that synchronized estrus by regression
of the corpus luteum had a greater
pregnancy rate (57%) than similar two-injection
prostaglandin protocols in which
gonadotropin-releasing hormone (GnRH or
Cystorelin®) was used to induce ovulation of
the follicle before one fixed-time insemination
(21%) or one fixed-time insemination
was given in the absence of estrus (18%).
The synchronized ovulation protocol improved
pregnancy rates compared to prostaglandin
protocols with fixed-time inseminations,
but in either protocol, in which ovulation
or estrus was synchronized, pregnancy
rates were always greater when
inseminations were performed after detected
estrus