# In vitro maturation of Nelore breed (Bos taurus indicus) oocytes using either purified porcine FSH or recombinant human FSH: results from a large-scale in vitro embryo production routine

## TL;DR

This study compares two types of FSH to mature cattle eggs in a lab setting, finding that a human-made version works as well as a porcine one.

## Contribution

Demonstrates that recombinant human FSH can replace porcine FSH in large-scale bovine in vitro embryo production.

## Key findings

- Blastocyst rates were higher with FSH treatment compared to no FSH.
- Recombinant human FSH produced blastocysts with more trophoblast cells than porcine FSH.
- Both FSH types improved cleavage and blastocyst rates but did not significantly affect pregnancy rates in a commercial setting.

## Abstract

This study evaluated whether porcine FSH (pFSH) could be replaced by follitropin-alpha, a recombinant human FSH (rhFSH), during in vitro maturation (IVM) of cumulus-oocyte complexes (COC) recovered from Nelore (Bos taurus indicus) cattle in a large-scale in vitro embryo production (IVP) program.

We performed three experiments, all using grade I COC (n = 10,208) submitted to IVM in TCM199 without FSH (-FSH, negative control) or supplemented with either 0.5 μg/mL pFSH (Folltropin-V) or 0.1 IU rhFSH (Gonal-F). The remaining procedures, media, and culture conditions for in vitro embryo production (IVP) were similar. In Exp. 1, COC (n = 2,791) were IVM in the absence of FSH (-FSH) or with pFSH or rhFSH, and underwent IVP. Blastocysts were assessed for hatching as fresh or after vitrification and warming. In Exp. 2, COC (n = 720) were IVM in groups -FSH, pFSH, or rhFSH, and the expanded blastocysts produced were stained with Hoechst 33342 and propidium iodide for total, trophoblast and ICM cell count. In Exp. 3, we used the same experimental design as in Exp. 1 but in a commercial IVP routine, which included the use of COC (n = 6,697) recovered both by OPU and from slaughterhouse, Y-sorted semen, and the transfer of part of the blastocysts produced.

In Exp. 1, blastocyst rates were greater (p < 0.05) in groups treated with than without FSH (39.3% and 40.6% vs 34.8% for pFSH, rhFSH and -FSH, respectively; p = 0.0244). However, there was no effect of treatment on hatching rates of fresh (74.5%, 79.0% and 70.1% for -FSH, pFSH, and rhFSH, respectively; p = 0.2621) or vitrified blastocysts (75.0%, 69.6% and 73.2% for -FSH, pFSH, and rhFSH, respectively; p = 0.7623). In Exp. 2, blastocysts from the rhFSH group presented more cells in the trophoblast (110.3±5.6 vs 80.0±5.7 and 878.4±5.1 for rhFSH, -FSH, and pFSH, respectively; P=0.0002), but not in the ICM (p = 0.3231), when compared with pFSH and -FSH groups. In Exp. 3, both pFSH and rhFSH increased cleavage (76.0% and 75.1% vs 71.6%, p = 0.0035) and blastocyst rates (38.1% and 39.5% vs 34.3%, p = 0.0102), but not pregnancy rate (43.8% and 33.3% vs 56.0%, p = 0.1080), compared with -FSH.

In summary, follitropin-alpha is an alternative to pFSH as a medium supplement for IVM of bovine COC.