SUPEROVULATION NEW MODELS INCLUDING FSH DOSE REDUCTION AND NEW PREPARATIONS

Abstract

It was estimated that every year around the world, approximately half a million bovine
embryos are produced (Cremonesi, 2020). The classic superovulation program involves
administering of a series of FSH injections to embryo donor cows starting on day 9-12 of the
oestrus cycle. In Europe, Pluset and Folltropin preparations are commercially used for this
purpose, both available on the market in Poland (Kulus, 2019). This is the mechanism
underlying superovulatory protocols that were developed in the 1980s, which were further
improved by refining hormonal preparations like human menopausal gonadotropin (HMG),
equine chorionic gonadotropin (eCG), or follicle-stimulating hormone (FSH) from porcine or
ovine pituitaries (Cremonesi 2020). Superovulation protocols vary widely based on the FSH
source, the diluent used, the number and timing of FSH injections and the timing and
utilisation of various prostaglandins, controlled internal progesterone releasing devices,
gonadotrophin-releasing hormone, and other means of controlling follicular development and
ovulation (Mikkola, 2019). These may include nutritional status, reproductive history, age,
season, breed, effects of repeated superovulations and ovarian status at the time of
treatment (Cremonesi 2020). An approach that has shown promise is to initiate FSH
treatments at the time of the emergence of the first follicular wave following GnRH-induced
ovulation. Using of aspiration of dominant follicle is possible to induce new follicular wave.
This simple biotechnical treatment has a final impact on the number of in vivo produced
embryos. Its seems, that of the interval from follicle aspiration to initiation of lengthened FSH
treatment (Cirit, 2019). However, it has been shown that it may be possible to ignore
follicular wave status, and by extending the treatment protocol induce smaller follicles to
grow and reach maturity and superovulate. Finally, the short halflife of pituitary FSH
necessitates twice daily treatments which are time-consuming, stressful and subject to error.
Recent treatment protocols have permitted superstimulation with a single or alternatively,
two FSH treatments, reducing the need for animal handling during FSH treatment (Mapletoft,
2013). A single dose protocol of FSH for superstimulation in cattle may improve compliance
and superovulatory response. A single subcutaneous (sc) administration of pFSH was
efficacious, but response depended on body condition and injection site; the adipose tissue
pad behind the shoulder was most efficacious. Inconsistent results in Holsteins were partially
overcome by sc administration of 75% of the total pFSH dose behind the shoulder on the first
day followed by 25% 48 h later (Bo, 2018). The split-single injection given ischiorectal fossa
(split-single IRF administration had a comparable superovulatory response to the traditional
twice-daily protocol. Moreover, the ovulation rate, ovarian follicle responses, and embryo
quality were affected by heat stress (Chumchai, 2021, Ratsiri, 2022). In the other study the
ovarian responses in the split-single IRF group were similar to those of the control group (p >
.05) but higher compared with the split-single IM group. Regardless of the route of
administration of FSH. The high THI affected ovulation rate as well as the numbers of
transferable embryos and degenerated embryos (Thanaporn, 2021). A recombinant longacting
ovine follicle stimulating hormone (roFSH) has been devised and its biological
effectiveness following a single dose has been assessed in several experiments under field
conditions, in pasture-based beef and dairy farming in New Zealand. Owing to the molecular
structure of this long-acting roFSH, which includes additional N-glycosylation sites, a single
dose combined with a simple CIDR-based superovulatory regime elicits successful ovarian
stimulation with averages of 11.8 corpora lutea and of 6.1 good quality embryos collected in
cattle. Solid performance of this novel FSH was demonstrated in several beef and dairy
breeds which included yearling heifers and mixed age cows, with embryo production results
in the same range as those observed nowadays with eight doses of commercial pituitary FSH
(pFSH). Viable embryos produced from these collections, when implanted either fresh or
frozen and thawed, gave pregnancy rates in recipients similar to those collected from cows
and heifers superstimulated with pFSH. Repeated superovulatory treatment of the same cows
was not associated with a decrease in ovarian response or embryo yield. The single
administration of this long-acting roFSH when combined with a modified simple
superovulatory regime has the advantage of reducing animal welfare concerns, lowering
labour resource requirements and giving similar results to other commercially prepared
pituitary FSH extracts (Sanderson, 2020, Gutierrez-Rreinoso, 2022). It is well known that 70%
of embryos are produced by 30% of donors. This very high variability was tried to be
reduced, with very good results by administrating platelet rich plasma (PRP) inside the ovary
before the superovulation protocol. This hemocomponent is rich in growth factors and
cytokines known for their regenerative properties in human and veterinary medicine
(Cremonesi, 2020, Cirit, 2020).