Fertility in Angus cross beef cows following 5-day CO-Synch + CIDR or 7-day CO-Synch + CIDR estrus synchronization and timed artificial insemination

Whittier, W. Dee; Currin, John F.; Schramm, H.; Holland, Sarah; Kasimanickam, R.

doi:10.1016/j.theriogenology.2013.07.019

Cited by 41 publications

(14 citation statements)

References 17 publications

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“…In this study, AI‐PR was higher in heifers that expressed oestrus compared to those that did not comparable to other studies (Bucher et al., ; Kasimanickam, Whittier, Hall, & Kastelic, ; Mallory et al., ; Whittier, Currin, Schramm, Holland, & Kasimanickam, ). The expression of oestrus in cattle follows a rise in serum concentrations of oestradiol.…”

Section: Discussionsupporting

confidence: 83%

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

Kasimanickam

Hall

Whittier

2016

Reprod Domestic Animals

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This study compared artificial insemination pregnancy rate (AI-PR) between 14-day CIDR-GnRH-PGF2α-GnRH and CIDR-PGF2α-GnRH synchronization protocol with two fixed AI times (56 or 72 hr after PGF2α). On day 0, heifers (n = 1311) from nine locations assigned body condition score (BCS: 1, emaciated; 9, obese), reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic) and temperament score (0, calm; and 1, excited) and fitted with a controlled internal drug release (CIDR, 1.38 g of progesterone) insert for 14 days. Within herd, heifers were randomly assigned either to no-GnRH group (n = 635) or to GnRH group (n = 676), and heifers in GnRH group received 100 μg of GnRH (gonadorelin hydrochloride, IM) on day 23. All heifers received 25 mg of PGF2α (dinoprost, IM) on day 30 and oestrous detection aids at the same time. Heifers were observed for oestrus thrice daily until AI. Within GnRH groups, heifers were randomly assigned to either AI-56 or AI-72 groups. Heifers in AI-56 group (n = 667) were inseminated at 56 hr (day 32 PM), and heifers in AI-72 group (n = 644) were inseminated at 72 hr (day 33 AM) after PGF2α administration. All heifers were given 100 μg of GnRH concurrently at the time AI. Controlling for BCS (p < .05), RTS (p < .05), oestrous expression (p < .001), temperament (p < .001) and GnRH treatment by time of insemination (p < .001), the AI-PR differed between GnRH treatment [GnRH (Yes - 60.9% (412/676) vs. No - 55.1% (350/635); p < .05)] and insemination time [AI-56 - 54.6% (364/667) vs. AI-72 - 61.8% (398/644); (p < .01)] groups. The GnRH treatment by AI time interaction influenced AI-PR (GnRH56 - 61.0% (208/341); GnRH72 - 60.9% (204/335); No-GnRH56 - 47.9% (156/326); No-GnRH72 - 62.8% (194/309); p < .001). In conclusion, 14-day CIDR synchronization protocol for FTAI required inclusion of GnRH on day 23 if inseminations were to be performed at 56 hr after PGF2α in order to achieve greater AI-PR.

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Section: Discussionsupporting

confidence: 83%

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

Kasimanickam

Hall

Whittier

2016

Reprod Domestic Animals

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“…In that study, P/AI was 11% higher with the 5-day protocol. Similar results were recently reported by Whittier et al (2013) that found a significantly higher P/AI in cows treated with the 5-day CO-Synch than in those treated with the 7-day CO-Synch. It has been proposed that the higher pregnancy rates in the 5-day protocol is related to higher preovulatory oestradiol and luteal phase progesterone concentrations, especially in those cows not ovulating after the first GnRH (Bridges et al, 2014).…”

Section: The 5-day Co-synch Protocol In Beef Cattlesupporting

confidence: 91%

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

Bó

Baruselli²

2014

Animal

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The main objective of the implementation of artificial insemination (AI) in cattle is to produce a sustained genetic progress in the herd. Although AI is an old reproductive biotechnology, its widespread implementation is very recent and is mainly because of the use of protocols that allows AI without oestrus detection, commonly called fixed-time artificial insemination (FTAI). The development of FTAI protocols also allowed the application of AI in larger, extensively managed herds and especially in suckled cows instead of restricting the breeding programmes to the heifers. Fixed-time AI treatments are widely used in South America, with about 3 000 000 cows inseminated in the last season in Argentina and about 8 000 000 in Brazil. The objective of this review is to present and describe the various treatments available and some of the factors that may affect pregnancy rates in beef cattle.

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“…In the present study, there was no difference in circulating concentrations of estradiol at time of AI between heifers that did or did not exhibit estrus. In a previous examination of the 5-d CO-Synch + CIDR synchronization protocol, it was reported that the majority of animals expressed estrus at or before AI (Whittier et al, 2013). The transient rise in estradiol at the initiation of estrus triggers the preovulatory surge of LH (Chenault et al, 1975;Lemon et al, 1975).…”

Section: Discussionmentioning

confidence: 99%

Influence of estrus at fixed-time artificial insemination on early embryonic development in beef cattle

Larimore

Amundson

Bird

et al. 2015

Journal of Animal Science

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It has been repeatedly demonstrated that estrous expression before fixed-time AI (TAI) results in increased pregnancy success. Therefore, the objective of this experiment was to determine if preblastocyst embryonic developmental characteristics differed from heifers that did or did not exhibit estrus before TAI. Beef heifers (n = 113) were synchronized using the 5-d CO-Synch + controlled internal drug release device with TAI on d 0. Before TAI, estrous expression was assessed twice daily. On d 6, single embryos were collected and visually evaluated to determine quality (International Embryo Transfer Society standards; 1-4, in which 1 = excellent/good and 4 = degenerate) and stage (1-9, in which 1 = unfertilized and 9 = expanded hatched blastocyst). Embryos were stained and evaluated to determine number of dead blastomeres, number of total blastomeres, and number of accessory sperm. Estrous expression before TAI did not affect the percent of embryos recovered (P = 0.59), number of dead cells (P = 0.99), or number of total cells (P = 0.25). However, heifers that exhibited estrus had increased mean (P = 0.03) and median accessory sperm numbers and (P = 0.01) percent live cells when compared with nonestrus heifers. Heifers that exhibited estrus also produced embryos that had a more advanced stage (P = 0.03) and improved quality (P = 0.04) when compared with those heifers not exhibiting estrus. When all heifers were evaluated, there was no correlation between circulating concentration of estradiol at TAI and embryo quality or embryo stage. There was a significant correlation between accessory sperm numbers and embryo quality (P = 0.01) and embryo stage (P < 0.01), such that as accessory sperm numbers increased, embryo quality and stage increased. In conclusion, exhibiting estrus before TAI resulted in improved embryo quality and advanced embryo stage on d 6 and increased the number of accessory sperm associated with the embryo.

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Fertility in Angus cross beef cows following 5-day CO-Synch + CIDR or 7-day CO-Synch + CIDR estrus synchronization and timed artificial insemination

Cited by 41 publications

References 17 publications

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

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

Influence of estrus at fixed-time artificial insemination on early embryonic development in beef cattle

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