Technologies for fixed-time artificial insemination and their influence on reproductive performance of <I>Bos indicus</I> cattle

Synchronization of ovulation and fixed-time artificial insemination in beef cattle

“…Cows with larger ovulatory follicles had a greater ovulation rate and resulted in a greater number of pregnancies per AI (P/AI) in beef cattle (Bó et al, 2007;Perry et al, 2007;Sá Filho et al, 2010c). Furthermore, considering only those cows that ovulated following FTAI, the P/AI increased as the ovarian follicle size increased (Sá Filho et al, 2010c).…”

“…Therefore, in addition to the increased ovulation rate, ovulation of larger follicles could be responsible for other events, such as the improvement of endogenous E2 production, oocyte competence, CL diameter and concentration of progesterone in the subsequent oestrous cycle, which may benefit the fertility of beef cows following FTAI. Analysis from on-farm FTAI has shown that animals treated with progestin devices must have a BCS higher than 2.5 (scale 1 to 5) and ideally >3 to achieve pregnancy rates of 50% or higher (Bó et al, 2007). Conversely, the addition of eCG allowed for pregnancy rates close to 50% in cows with a BCS of ⩽2.5 (Bó et al, 2007).…”

“…Anoestrous is a common condition in extensively managed suckled beef herds (Bó et al, 2007;Baruselli et al, 2004) and the use of Ovsynch in beef herds has resulted in pregnancy rates as low as 15%, compared with 53% in cows treated with a progestin device and oestradiol . Other trials have confirmed that Ovsynch protocol yields low conception rate in beef herds showing high percentage of anoestrous animals (Barros et al, 2000;Diskin et al, 2002).…”

“…Analysis from on-farm FTAI has shown that animals treated with progestin devices must have a BCS higher than 2.5 (scale 1 to 5) and ideally >3 to achieve pregnancy rates of 50% or higher (Bó et al, 2007). Conversely, the addition of eCG allowed for pregnancy rates close to 50% in cows with a BCS of ⩽2.5 (Bó et al, 2007). It is very important to note that these results have been achieved only when cows were gaining body condition during the breeding season.…”

Effects of Equine Chorionic Gonadotropin on Follicular, Luteal and Conceptus Development of Non-LactatingBos IndicusBeef Cows Subjected to a Progesterone Plus Estradiol-Based Timed Artificial Insemination Protocol

“…This result could be explained by the use of non-lactating cows presenting a high BCS. Previous studies did not found effect of the eCG treatment in cows with high BCS (Bó et al, 2006), although the inclusion of eCG treatment in TAI synchronisation protocols was shown to be advantageous only in cows with a low BCS at the beginning of the protocol (Souza et al, 2009).…”