Assisted Reproductive Technologies (ART) in Dairy Cattle: Evidence-Based Guidance for Veterinary Practice

Assisted reproductive technologies have shifted from specialised breeding units into routine dairy herd management, driven by improvements in oocyte handling, in vitro embryo production (IVP), cryopreservation and reproductive monitoring. Recent peer-reviewed evidence shows that ART is now a practical tool for stabilising fertility in modern high-yield cows, improving genetic progress and supporting integrated dairy–beef strategies. 

Over the last decade, the adoption of embryo transfer (ET) has increased sharply. In the United States, embryo-derived births expanded to approximately 11% of national dairy calvings by 2021, compelling changes in fertility evaluation methods to reflect this rapid structural shift in breeding practices¹. Globally, this rise parallels improvements in embryo culture systems and oocyte competence, enabling more reliable outcomes and broader application of ART. 

Pregnancy Outcomes in Modern ART Programmes 

Comparative field trials now give a clearer picture of how ART performs relative to conventional AI. In lactating dairy cows, timed embryo transfer with fresh IVP embryos achieves pregnancy-per-service rates comparable to timed AI^2,3. This is a significant advancement because ET was traditionally reserved for problem cows; today, evidence shows it can be strategically used in high-producing animals where AI fertility is compromised. The same trials consistently demonstrate that frozen IVP embryos remain less robust, resulting in lower pregnancy success and higher early embryonic losses², reaffirming well-documented vulnerabilities associated with cryoinjury^2,4. 

Pregnancy loss is an area of continued concern. Multiple studies confirm that early embryonic loss between days 32 and 60 is higher following ET than AI. This is especially evident with frozen IVP embryos, which appear more sensitive to uterine and metabolic challenges. Fresh embryos, by contrast, show superior survival through the luteal phase and more stable progression to late gestation². 

Why Fresh Embryos Perform Better 

Fresh IVP embryos benefit from avoiding the osmotic and thermal stress associated with cryopreservation. They also provide better synchrony between embryo developmental stage and uterine environment, which is one of the strongest determinants of successful implantation⁴. Notably, transferring a single fresh IVP embryo has been shown to prevent twin pregnancies without compromising overall fertility, an important consideration for high-yield herds where twin gestations carry substantial metabolic and health risks. 

Recipient Preparation and Synchronisation: Where Outcomes Are Won or Lost 

Across all studies, the factor most consistently associated with ART success is the preparation of the recipient cow. Strict synchronisation protocols improve the alignment between embryo stage and the uterine environment, and cows with optimal body condition; no postpartum uterine disease and regular cyclicity achieve higher conception and lower early loss^2,3. This means that even the best embryos cannot compensate for poor recipient readiness. 

Modern reproductive monitoring systems are also becoming increasingly valuable. Automated activity and behavioural sensors, coupled with machine-learning prediction models, can help identify cows approaching ideal fertility windows, allowing more precise timing of AI or ET⁵. These technologies enhance decision-making and reduce mistimed inseminations, which remain a common cause of suboptimal ART outcomes. 

Vet Pearl 

Fresh IVP embryos can outperform AI in cows experiencing high metabolic load or short calving-to-breeding intervals, offering a practical solution where conventional methods struggle⁶. 

Genetic and Economic Advantages 

ART is no longer viewed solely as a fertility-fixing tool. Current evidence highlights its value in accelerating genetic gain, particularly when elite donor cows are combined with IVP and high-quality recipient management⁴. Furthermore, ET supports dairy–beef integration by allowing targeted use of beef sires on lower-value cows while preserving the best genetics for herd replacement³. Fresh IVP ET also offers a controlled method to reduce dairy twin pregnancies⁷, improving welfare and reducing downstream clinical interventions. 

Conclusion 

Modern ART is a powerful reproductive tool that complements, rather than replaces, AI in well-managed dairy herds. Studies support the routine use of fresh IVP embryos, careful recipient selection, strict synchronisation and the integration of digital monitoring technologies. For veterinarians, the value of ART lies not only in improving conception outcomes but also in providing a strategic framework for managing fertility in high-producing cows, enhancing genetic progress and strengthening overall herd efficiency. 

References  

1. Miles AM, Hutchison JL, VanRaden PM. Improving national fertility evaluations by accounting for the rapid rise of embryo transfer in US dairy cattle. Journal of Dairy Science. 2023 Jul 1;106(7):4836-46. 

2. Crowe AD, Sánchez JM, Moore SG, McDonald M, Rodrigues R, Morales MF, de Freitas LO, Randi F, Furlong J, Browne JA, Rabaglino MB. Fertility in seasonal-calving pasture-based lactating dairy cows following timed artificial insemination or timed embryo transfer with fresh or frozen in vitro–produced embryos. Journal of Dairy Science. 2024 Mar 1;107(3):1788-804.  

3. Lonergan P, Crowe A, Thompson L, Murphy E, Butler S. Enhancing integration of the dairy and beef sectors through application of assisted reproductive technologies: pregnancy outcomes following timed AI and timed ET in lactating dairy cows. Animal Reproduction. 2025 Sep 15;22(3):e20250055. 

4. Mikkola M, Desmet KL, Kommisrud E, Riegler MA. Recent advancements to increase success in assisted reproductive technologies in cattle. Animal reproduction. 2024 Aug 12;21(3):e20240031. 

5. Marques TC, Marques LR, Fernandes PB, de Lima FS, do Prado Paim T, Leão KM. Machine learning to predict pregnancy in dairy cows: an approach integrating automated activity monitoring and on-farm data. Animals. 2024 May 25;14(11):1567. 

6. Lonergan P, Crowe A, Thompson L, Murphy E, Butler S. Enhancing integration of the dairy and beef sectors through application of assisted reproductive technologies: pregnancy outcomes following timed AI and timed ET in lactating dairy cows. Animal Reproduction. 2025 Sep 15;22(3):e20250055. 

7. Garcia-Ispierto I, López-Gatius F. Benefits and risks of preventing twin pregnancies. Animals. 2021 Jan 11;11(1):148.