as a strategy to improve the viability and sustainability of dairy cattle farms
The last two decades have seen a decline in fertility and an increase in milk production. This decline in fertility is associated with genetic progress, such as improvements in nutrition and management, which have led to a continued increase in milk production. This increase in milk production has also been linked to the incidence of twin calving, which is undesirable in dairy cattle, as it causes a decrease in livestock profitability and animal longevity, and increased use of antibiotics. One of the most effective strategies to improve dairy cattle fertility, especially during warm seasons, or to reduce twin calving, and therefore twin pregnancies, is embryo transfer. With embryo transfer, the negative effects of decreased fertility and increased pregnancy losses would be drastically reduced.
Embryo transfer would allow focusing nulliparous and primiparous cows on the production of female offspring of high genetic value for replacement, and multiparous cows on the production of milk. This would increase the farm’s average lactation number and the price of the calves sold. Despite all these benefits, this system is neither implemented in Spain nor in Europe. A change of farmers’ and the veterinarians’ mentality would be required in order to make routine use of this technique in females that have given birth more than twice on commercial dairy farms. This technique could only be implemented on well-managed farms, where other factors that may affect the process, such as nutrition or stress, are under control.
SCOPES OF APPLICATION
Dairy cows It cab be carried out with beef bovine embryos to increase the added value of the calf In cows with 3 or more parturitions, the most productive ones, it favours pregnancy rate
It reduces the number of twin pregnancies An experienced technician and a reference in vitro embryo laboratory are required Slaughterhouse female oocytes may be used for offspring that will not be destined for replacement
DESCRIPTION OF THE TECHNIQUE
The embryo transfer technique is performed on multiparous cows, especially those having calved twice or more, intended for dairy production. The aim is for the most productive but the least fertile cows to become pregnant and thus not be eliminated.
In addition, this technique of transferring a beef bovine embryo, such as the Angus breed, not only increases the added value of the calves, but also drastically reduces twin pregnancies. It should be noted that twin pregnancies are one of the most common causes of:
- Elimination of a producing cow
- Increase in open days
- Use of postpartum antibiotics
- Death upon calving of calves and mothers
STEPS TO BE TAKEN
Fresh embryo preparation
.1 Collect ovaries from the slaughterhouse (Angus or Holstein -–Friesian) and transport to the laboratory at 35-37ºC in saline liquid
.2 Aspiration of 2-8 mm follicles
.3 In vitro maturation (IVM) in a TCM-199 medium and 10% FBS (24h)
.4 Oocyte recovery and in vitro fertilization (IVF) (with Angus semen) in a TCM-199 medium and 10% FBS.
.5 In vitro culture (IVC) of embryos for 7 days
.6 Selection of excellent blastocytes
.7 They are placed on a straw and transferred fresh. The journey to the farm should be in a portable incubator at a controlled temperature of 38ºC
Preparation of receiving females
.1 Prior synchronization with the methods used by the farm. Preferably progesterone based
.2 Perform transrectal ultrasound to detect the follicles when in cow is in estrus. Apply an ovulation inducer (GnRH, Depherelin, hCG)
.3 Detect the presence of a corpus luteum by ultrasound at the time of transfer (7 days after being in estrus). Eliminate those that have suffered ovulatory failure or have a poor quality corpus luteum. Administer an ovulation inducer to favour corpus luteum maintenance (GnRH, Depherelin, hCG)
.4 Administer epidural
.5 Clean the vulva using water with iodine
.6 The embryo is transferred via deep ipsilateral unicornual transfer to the corpus luteum
.7 Diagnosis of pregnancy on day 21 after embryo transfer
.8 Confirmation of pregnancy 14 days later
Seasonal fertility study
Different letters indicate significant differences between groups P<0.05
Comparative study of GnRH vs hCG
Forty-nine cows (48.3%) of the 120 transferred cows became pregnant after embryo transfer: 16 in the GnRH group (26.7%) and 33 in the hCG group (55%). Taking GnRH-treated cows as a reference, the likelihood of cows treated with hCG becoming pregnant was 3.3 times higher.
Irina Garcia-Ispierto holds a PhD from the University of Barcelona (2008). She is currently a contracted professor at the Department of Animal Science at the University of Lleida and head of research of the Animal Reproduction Group at the Agrotecnio Research Centre. Her research focuses on the reproduction of dairy cattle. Her specialities are twin pregnancies, synchronization methods, reproductive ultrasound, and fertility problems. She has also studied infections such as Coxiella burnetti and parasites such as Neospora caninum.
She has published over 100 articles in indexed journals and has taken part in over 100 conferences, both national and international. She has participated in symposiums organized by companies such as ECUPHAR and Ceva and has written several articles in general interest magazines.
She is the principal investigator of numerous contracts with pharmaceutical companies and dairy cattle farms in the Segrià area, and the principal investigator of an SGR group of the Catalan Government, in addition to a Demonstration project of the Catalan Government. She is currently the editor of the journal Animals, animal reproduction section, and a reviewer for several journals such as Reproduction in Domestic Animals, Theriogenology, and Journal of Dairy Science.
Articles in scientific journals
López-Gatius, Fernando i Garcia-Ispierto, Irina. 2020. Tranfer of a single embryo versus drainage of subordinate follicles to prevent twin pregnàncies in dairy cows. Why not both? Journal of Reproduction and Development, Advanced Epub April 7, 2020.
López-Gatius, Fernando; Garcia-Isperto, Irina; Serrano-Pérez, Beatriz; Balogh, Orsolya G.; Gábor, György i Hunter, Ronald H. F. 2019. Luteal activity following follicular drainage of subordinate follicles for twin pregnancy prevention in bi-ovular dairy cows. Research in Veterinary Science, 124: 439-443.
Articles in professional journals
Garcia-Ispierto, Irina. 2020. Prevención de las gestaciones gemelares en vacuno lechero: un camino hacia la innovación. Albéitar, 234: 4-6.