Embryo production by Holstein heifers superovulated with a recombinant long-acting follicle-stimulating hormone analog

This study explored a novel recombinant hormone to produce embryos in Holstein heifers, using a single injection of a long-acting human follicle-stimulating hormone (rFSH) compared with the traditional method of multiple injections of pituitary-derived follicle-stimulating hormone (FSH). We compared both hormones multiple times to evaluate the number of embryos produced. Our results showed that a single injection of rFSH was as effective as multiple injections of FSH in terms of recovered ova/embryos. However, when the single injection of rFSH was used repeatedly in the second part of the study, it resulted in a smaller total number of ova/embryos and freezable embryos. In conclusion, although a single injection of rFSH can effectively stimulate the ovaries, its repeated use may reduce the number of embryos produced. This finding is crucial for advancing embryo production techniques in dairy cattle.