ASAS Centennial Paper: Contributions in the Journal of Animal Science to the development of protocols for breeding management of cattle through synchronization of estrus and ovulation

Abstract

American Society of Animal Science members, publishing in Journal of Animal Science (JAS), completed research that resulted in understanding the estrous cycle of cattle, which led to the ability to inseminate cattle on a given day with pregnancy rates similar to those achieved by 21-d breeding by a fertile and sound bull. Research published in JAS led to understanding estrus, ovulation, the estrous cycle, and postpartum interval for cattle (1930s through 1960s) and hormonal factors affecting corpus luteum lifespan of cattle (1950s through 1980s). Research during the 1940s to 1960s, using gonadotropins and progesterone to manage the estrous cycle of cattle, established the concepts for estrous synchronization and stimulated commercial research directed at developing cost-effective progestogen estrous synchronization products, leading to commercially available products from 1967 through today (Repromix, melengestrol acetate, Syncro-Mate-B, controlled internal drug release). Prostaglandin F(2alpha) products were approved for estrous synchronization (1970s, 1980s), and GnRH products were approved for use in cattle to treat ovarian follicular cysts (1970s, 1980s). Research published in JAS was essential for understanding the biology of and potential value of both PGF(2alpha) and GnRH and contributed both to new knowledge and scientific bases for future Food and Drug Administration Center for Veterinary Medicine approval of those products. Research during the1980s through 2000s led to understanding ovarian follicular waves and described the timing of follicular recruitment, selection, dominance, and atresia; this research was essential for the ability to effectively manage follicles to achieve success with timed AI. The knowledge gained through research published in JAS resulted in development of the numerous estrous synchronization and breeding management protocols that are cost-effective and meet the breeding management needs of most beef and dairy enterprises.

Relationships between follicle and corpus luteum diameter, blood flow, and progesterone production in beef cows and heifers: preliminary results

“…Likewise, in Bos taurus beef cows, a decrease in pregnancy rates was reported when using GnRH-induced ovulation of small ovulatory-sized follicles (Perry et al, 2005(Perry et al, , 2007; however, there was no effect on pregnancy rate when follicles within the same size range ovulated spontaneously (Perry et al, 2005). Optimal sizing of ovulating follicles is still a major concern in both the beef (Perry et al, 2005(Perry et al, , 2007Busch et al, 2008) and dairy industry (Wiltbank et al, 2011;Vasconcelos et al, 2013;Bisinotto et al, 2014), especially when modern production systems are dependent on estrous synchronization strategies (Baruselli et al, 2004;Lauderdale, 2008;Pohler et al, 2012) and because less than 50% of the cycling cows ovulate a follicle with an optimal size (Wiltbank and Pursley, 2014). Another singular finding in our study was that pregnant beef cows tended to have a greater follicle wall blood flow than non-pregnant cows in data normalized to maximum values.…”

“…Additionally, modern cattle systems try to overcome the low fertility rates that are commonly associated with high production levels (Lopez et al, 2004(Lopez et al, , 2005 by increasing herd size. Therefore, the use of hormonal estrous synchronization is a crucial tool for the reproductive management of the beef and dairy cattle industries (Baruselli et al, 2004;Lauderdale, 2008;Bisinotto et al, 2014). Concerns with how the synchronization protocols in cattle can interfere with follicle growth (Adams et al, 2008;Atkins et al, 2010a), ovulatory capacity Gimenes et al, 2008), and oocyte maturity (Pohler et al, 2012;Geary et al, 2013) during artificial insemination (AI) programs have produced a wide range of research data designed to study the fertility rates under controlled hormonal conditions (Wiltbank et al, 2011;Bó et al, 2012;Wiltbank and Pursley, 2014).…”

Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

“…A large proportion of cows on D 15 through 17 of their estrous cycles failed to ovulate in response to GnRH [10]. Injection of a single dose of PG induced CL regression and estrus in the majority of cows between D 6 and 16 of the estrous cycle [26].…”

Impacts of Reproductive Technologies on Beef Production in the United States

“…When queried as to their reluctance to utilize AI, over 53 % of operations cited labor concerns or complicated estrous synchronization protocols as primary reasons for not implementing this reproductive technology (NAHMS 2009a ). Research projects addressing these key areas of producer concern have been developed and improvements in the actual protocols and their subsequent ability to effectively synchronize estrous and ovulation have been made ( Lauderdale 2009 ).…”

“…When assessing all embryos (in vivo and in vitro, fresh and frozen), 841,540 were transferred in 2009, 990,993 in 2010, and 921,836 in 2011(IETS 2011. With the rapid pace of improved genetics garnered with the use of embryo transfer, effi ciency of beef production in herds incorporating the technology will rapidly improve as well.…”