The applications of timed artificial insemination and timed embryo transfer in reproductive management of dairy cattle

Abstract

Fertility of dairy cattle is generally decreasing. Overall estrus detection efficiency in lactating dairy cattle is low, as expression of estrus is often compromised. Consequently, undetected estrus, low AI-submission rates, and long inter-breeding intervals are the main contributors to poor reproductive efficiency. Although failure to become pregnant is the most common reason for culling dairy cattle, pregnancy rates could be improved by increasing the AI-submission rate through increased estrus detection efficiency, timed insemination (Timed-AI), or timed embryo transfer (Timed-ET). In these protocols, ovarian follicular development and luteolysis are controlled, culminating in synchronous ovulation in most cows. There are several modifications to improve pregnancy rates in Timed-AI protocols, e.g. presynchronization with 2 doses of PGF2a 14 d apart, and starting the Ovsynch protocol 12 d after the 2nd PGF2a. Timed-AI programs ensure a timely first breeding; this should be followed with early pregnancy diagnosis to identify nonpregnant cows, and prompt re-insemination. However, in a recent field study involving 23 dairy herds, the mean interval between 1st and 2nd breeding was 42 d; only 28% of the cows were rebred within 24 d after 1st breeding. Fortunately, there are several resynchronization protocols to reduce inter-breeding intervals. Anestrus cows, or those with cystic ovarian follicles, have a good chance of conceiving when subjected to synchronization of ovulation and Timed-AI. Furthermore, Timed-ET is a practical and viable option for synchronizing and selecting recipient cattle for embryo transfers. In summary, systematic and judicious use of Timed-AI and Timed-ET protocols can greatly enhance reproductive performance, and improve herd productivity.

Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review

“…Hormonal treatments have been developed to synchronize the time of ovulation, allowing the use of fixed TAI that does not require detection of estrus. The TAI protocol is commonly referred to as ovsynch and this consists of hormonal treatments of gonadotropin-releasing hormone (GnRH) (day 0), prostaglandin F2α (day 7) and GnRH (day 9) and artificial insemination is being performed 16-20 h after second GnRH treatment [ 68 ]. The ovysynch protocol can successfully synchronize ovulation in buffaloes and can also increase conception rate when combined with TAI [ 69 ].…”

Protocolos para inseminación artificial y transferencia de embrión a tiempo fijo en bovinos de carne bajo condiciones de trópico seco

“…Se ha reportado 40% para PG, en transferencias realizadas con embriones de FIV en fresco; por otro lado Bo et al (2018) reportaron rangos de variación para PG de 40 a 49%, en receptoras sincronizadas con J Synch o CIDR, resultados de Baruselli et al (2010) indican variaciones para PG de 39 a 56%. Por otro lado, la TETF también se ha utilizado en vacas de razas lecheras, con los valores para PG de 38 a 43% (Ambrose et al, 2010).…”

“…Posteriormente, se desarrolla la metodología de PEIV, con producción masiva de embriones (Hasler et al, 1995), cuya eficiencia mejoró considerablemente con la aspiración folicular y fecundación in vitro (AF-FIV, Pieterse et al, 1988;Ward et al, 2000); hoy en día se lleva a cabo de manera comercial en varios países (Trejo et al, 2020;Watanabe et al, 2017). Además, la IA y la producción masiva de embriones, originó el desarrollo de programas de manejo intensivo de la reproducción (BR´s), lo que ha permitido la aplicación de IA y TE a tiempo predeterminado (IATF y TETF, Ambrose et al, 2010;Baruselli et al, 2013). Se documentan resultados de la aplicación de programas de IATF y TETF, bajo condiciones de trópico seco del noreste de México.…”

Evaluation of the relationship between serum paraoxonase-1 activity and superovulation response/embryo yield in Holstein cows

“…(P4: progesterone, GnRH: gonadotropin-releasing hormone, FSH: follicle-stimulating hormone, PGF2α: prostaglandin F2α, FTAI: fixed-time artificial insemination). ) [ 3 , 6 ]. First, the progesterone device (1.38 g, Eazi-Breed CIDR, Zoetis, Parsippany, NJ, USA) was placed intravaginally (day 0), and later gonadotropin-releasing hormone (10 µg, Buserelin Acetate, Receptal, MSD, Kenilworth, NJ, USA) was intramuscularly injected (day 6).…”