engleski

The use of embryo transfer and reproductive technologies in the cattle breeding of Ccroatia : a retrospective study

The application of assisted reproductive technology (ART) in stockbreeding has tremendously changed the genetic improvement rates in breeding programs and strategies. Multiple ovulation and embryo transfer (MOET) has been well established for many years and still accounts for the majority of the embryos produced worldwide. However, no progress has been made in the last 20 years to increase the number of transferable embryos and to reduce the side effects on the reproductive performance of the donors. Ultrasound-guided ovum pick-up (OPU) followed by in vitro embryo production (IVP) offers an alternative to produce offspring from genetically superior dams, pregnant cows and heifers, post-partum cows and even from prepubertal heifers and cows with reproductive disorders. Over the last decades basic and applied research projects have been conducted in the Croatia with the aim of application and commercialization of ART in our cattle breeding schemes. The Laboratory for Assisted Reproduction at the Faculty of Veterinary Medicine, University in Zagreb, along with the Center for reproduction and animal breeding of Croatia, represent the nucleus unit for application of these modern embryo technologies in our stock breeding schemes. During a 10 years period (2002 to 2012) the embryo transfer team of the Center for reproduction and animal breeding of Croatia transferred 368 cattle embryos and produced 166 calves (75 bulls, 89 heifers and 2 recipients had abortion). The same team has also flushed Holstein-Friesian (n=45) and Simmental (n=87) superovulated donors. On average the ovulation rate (the number of corpora lutea), oocyte rate and embryo rate were: 409 CL, (X=9.8), 225 oocytes (X=5.0) and 98 transferrable embryos (X=2.2) in Holstein-Friesian donors and 1310 CL, (X=15.1), 1271 oocytes (X=14.6) and 794 transferrable embryos (X=9.2) in Simmental donors. The number of ovulated follicles after superovulation, the numer of produced oocytes and transferrable embryos was significantly higher for Simmental comparing to Holstein-Friesian donor cows. In vitro embryo production (IVP) is a newer and more flexible approach to produce cattle embryos, although it is technically more demanding and requires specific and costly laboratory equipment. A present standard protocol for IVP of bovine embryos in the Laboratory for Assisted Reproduction at the Faculty of Veterinary Medicine, University in Zagreb is based on the use of BoviPure® for sperm preparation for in vitro fertilization (IVF) and synthetic oviductal fluid with amino acids and bovine serum albumin (SOFaaBSA) for in vitro culture (IVC). During the 10 years period more than 230 OPU sessions were carried out in 63 stimulated and/or cyclic heifers and cows, resulted with 578 transferable embryos. The animals submitted to ART are under strict sanitary control what ensure the minimum risk for transmition of pathogenic agents. Considering all this facts, not only that we facilitate genetic improvement in the cattle industry by obtaining a large number of calves from cattle of high genetic quality, but we also have the opportunity to control health of the animals and indirectly of humans by producing the final product free from infectious diseases.

embryo transfer ; cattle ; in vitro ; ovum pick-up.

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