Insemination timing affects pregnancy rates in beef cows treated with CO-Synch protocol including an intravaginal progesterone insert

Using estrus detection patches to optimally time insemination improved pregnancy risk in suckled beef cows enrolled in a fixed-time artificial insemination program12

“…The recommended optimal insemination time of 66 h after CIDR removal is not ideal for up to 53.7% of the cows in the present study that had not displayed estrus by 60 h. The results of the current study indicate that primiparous cows display estrus earlier than multiparous cows. This observation corroborates results of an earlier study (Dobbins et al, 2009) in which younger cows were more fertile when inseminated at an earlier fixed time (≤56 h after removal of the CIDR insert) than multiparous cows. A possible bimodal distribution of estrus between primiparous and multiparous cows indicates that insemination at 2 distinct times determined by estrus detection would result in more cows being inseminated after estrus expression.…”

“…In AI systems that allow all cows to be inseminated at a predetermined time (fixed-time AI, TaI), the demand for time conformity of insemination may supersede optimal timing of semen placement relative to estrus or ovulation. Several different strategies have been employed to minimize the difference between actual and optimal timing by examining various single-insemination timings to produce the greatest probability of conception (Busch et al, 2008;Dobbins et al, 2009;Wilson et al, 2010). Allocating cows to optimal fixed times utilizing specific criteria, except for varying the time of AI for all cows (Dobbins et al, 2009), is largely unexplored.…”

“…Several different strategies have been employed to minimize the difference between actual and optimal timing by examining various single-insemination timings to produce the greatest probability of conception (Busch et al, 2008;Dobbins et al, 2009;Wilson et al, 2010). Allocating cows to optimal fixed times utilizing specific criteria, except for varying the time of AI for all cows (Dobbins et al, 2009), is largely unexplored. Although distribution of ovulation has not been quantified in TAI systems, hours to estrus following PGF 2α treatments concurrent with progesterone withdrawal has been investigated in the CO-Synch + CIDR program (Busch et al, 2008;Wilson et al, 2010).…”

Impact of Equine Chorionic Gonadotropin Associated with Temporary Weaning, Estradiol Benzoate, or Estradiol Cypionate on Timed Artificial Insemination in Primiparous Bos Indicus Cows

“…Over the last decade, PR in beef cows has varied greatly among studies related to TAI. PR may extend from 27.0% ), 42.4 (Hill et al 2014), 49.6% (Sá Filho et al 2009), 50.7% (Baruselli et al 2012) to 62.4% (Dobbins et al 2009). The results of the present study showed no differences between treatments applied in three groups of cows to TAI (table 1).…”

The effects of intramuscular or intravenous injections of gonadotropin releasing hormone at fixed-time artificial insemination on pregnancy rates of Bos indicus beef cows

“…It allows the selection of desired characteristics through the use of proven bulls. The development of estrous synchronization protocols allows insemination of the without the need of heat detection, contributing to the widespread use of AI in beef cattle operations (Dobbins et al 2009). The use of estrous synchronization protocols maximizes the use of time, labor and financial resources, and it increases the uniformity of the calf crop and shortens the breeding season (Dahlen et al 2003).…”