Associations between the manipulation of patterns of follicular development and fertility in cattle

Kl, Macmillan; Segwagwe, B.V.E.; Pino, C. S.

doi:10.1016/s0378-4320(03)00098-8

Cited by 71 publications

(45 citation statements)

References 84 publications

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“…The mechanisms for these effects was shown to be associated with the luteinization of ovarian follicles so that they could no longer produce estradiol with the consequential effect of preventing complete luteolysis by the injected PGF [7][8][9]. These effects were incorporated into the design of two field trials which showed that injecting 10 μg of the GnRH analogue buserelin from 8 to 10 days after insemination could significantly improve conception rates [10]; subsequent studies could not confirm this benefit [11].…”

Section: Gonadotropin Releasing Hormonementioning

confidence: 99%

Recent Advances in the Synchronization of Estrus and Ovulation in Dairy Cows

Macmillan

2010

J. Reprod. Dev.

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Abstract. Synchronization programs have become standard components in the current breeding management of cows in the dairy herds of most dairy industries. Many are based on protocols that allow timed inseminations (TAI) so as to circumvent the practical difficulties associated with estrus detection. These difficulties are exacerbated in modern herds of high producing cows either because of increasing herd size in which individual animal monitoring is difficult and often subjective, or because small intensively managed herds are milked in robotic systems that minimize animal: staff interactions. Additional reasons arise from high producing cows having less obvious symptoms of estrus, partly because of housing systems combined with intensive feeding and milking, partly because of higher metabolic clearance rates of reproductive hormones like estradiol and partly because of the increasing prevalence of prolonged post-partum anestrus and reproductive tract pathology. The most recently developed programs include protocols for resynchronization following first or subsequent inseminations. These re-synchronization protocols may involve selected forms of hormonal intervention during the diestrous and pro-estrous periods following TAI, or following pregnancy diagnosis by ultrasound from 28 days after TAI. The latter form of re-synchronization has become increasingly important with the recognition that late embryonic/early foetal death has become a major factor compromising the reproductive performance of high producing Holstein cows in many dairy industries. Although cows detected in estrus without any hormonal treatment before insemination have higher conception rates than those inseminated following synchronization and TAI, the low detection rates combined with embryonic death means that intervals from calving to conception (days open) are usually less when synchronization programs have been successfully implemented. One of the significant factors affecting a program's success is the compliance rate that may sometimes be less than 70%. Almost all programs involve strategically timed injections of prostaglandin F2α (PGF) and gonadotropin releasing hormone (GnRH). Injections of an estradiol ester and progesterone supplementation per vaginum may be included in some programs. The basic program is the "Ovsynch" regimen. Numerous variations have been tested and developed. Many involve increasingly complex protocols that increase the risk of non-compliance, none has consistently achieved conception rates that exceed 40% and few have reduced the incidence of embryonic death. These synchronization programs are the best that are currently available. They have not been able to overcome the consequences of lowered fertility associated with high levels of milk yield, forms of nutrition and environmental factors like heat stress that have profound effects on the physiology and metabolism of the high producing dairy cow.

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Section: Gonadotropin Releasing Hormonementioning

confidence: 99%

Recent Advances in the Synchronization of Estrus and Ovulation in Dairy Cows

Macmillan

2010

J. Reprod. Dev.

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“…The best time for initiation of the Ovsynch program is reportedly between days 5 and 12 of the estrous cycle (Vasconcelos et al 1999;Moreira et al 2000b). Asynchronous response (Vasconceles et al 1999), failure of complete luteal regression followed by PGF 2a (Burke et al 1996), and short estrous cycles (Macmillan et al 2003) may be the other reasons for low conception rate in cows subjected to Ovsynch. In previous work (Colazo et al 2009), we reported that 11% of cows ovulated before TAI, 15% did not respond to treatment with PGF and another 9% did not ovulate after the second treatment with GnRH, indicating that synchronization rate [defined as cows that had a regressed corpus luteum (CL) and ovulated within 24 h after TAI] was only 68% after Ovsynch.…”

Section: Discussionmentioning

confidence: 99%

“…Although some authors (Pursley et al 1997a, b;Ambrose et al 2003) have reported that P/AI to TAI after Ovsynch were comparable to that following insemination at detected estrus (IDE), others have reported lower P/AI (Tenhagen et al 2004a) and higher embryonic mortality rates (Macmillan et al 2003) following TAI compared with IDE. Factors such as the stage of lactation (Tenhagen et al 2003), season and high ambient temperature (De La Sota et al 1998;Al-Katanani et al 1999), body condition (Moreira et al 2000a), parity (Tenhagen et al 2004b;Balendran et al 2008), cyclicity status (Colazo et al 2013a) and stage of the estrous cycle during initiation of Ovsynch program (Vasconcelos et al 1999;Moreira et al 2000b) are also known to influence P/AI and pregnancy loss in dairy cattle.…”

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confidence: 99%

Pregnancy per artificial insemination and pregnancy loss in lactating dairy cows of a single herd following timed artificial insemination or insemination at detected estrus

et al. 2015

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Thangavelu, G., Gobikrushanth, M., Colazo, M. G. and Ambrose, D. J. 2015. Pregnancy per artificial insemination and pregnancy loss in lactating dairy cows of a single herd following timed artificial insemination or insemination at detected estrus. Can. J. Anim. Sci. 95: 383Á388. The objective of this retrospective study was to determine the factors affecting pregnancy per artificial insemination (P/AI) and pregnancy loss in lactating dairy cattle. Breeding records (n 01466) for 5 consecutive years were evaluated from one dairy herd. The effects of type of breeding [timed artificial insemination (TAI; n 01246) vs. insemination at detected estrus (IDE; n0220)], parity (primiparous vs. multiparous), body condition score (BCS; low 52.5 vs. high 2.5), year, season (summer vs. other seasons) and fertility group (high fertile B3 vs. low fertile ]3 inseminations), on P/AI and pregnancy loss (i.e., late embryonic/early fetal loss, abortion and stillbirth) were determined using the GLIMMIX procedures of SAS software. Pregnancy per AI was influenced by type of breeding and season. Pregnancy per AI was lower (PB0.05) in cows that were TAI (28.7%) than IDE (37.1%) and during summer (30.3%) than other seasons of the year (35.5%). Pregnancy loss was higher (PB0.05) in low BCS (9.1%) than in high BCS (1.9%) cows. However, parity, year, and fertility group affected neither P/AI nor pregnancy loss.Key words: Dairy cow, timed artificial insemination, insemination at detected estrus, pregnancy per AI, pregnancy loss Thangavelu, G., Gobikrushanth, M., Colazo, M. G. et Ambrose, D. J. 2015. Gestation par inse´mination artificielle et perte de gestation chez les vaches laitie`res en lactation au sein d'un seul troupeau suivant l'inse´mination artificielle pre´vue ou l'inse´mination lors de de´tection du cycle oestral. Can. J. Anim. Sci. 95: 383Á388. L'objectif de cette e´tude re´trospective e´tait de de´terminer les facteurs ayant un effet sur la gestation par inse´mination artificielle (P/AI Á « pregnancy per artificial insemination ») et la perte de gestation chez les vaches laitie`res en lactation. Les registres d'e´levage (n 01466) de 5 anne´es conse´cutives ont e´te´e´value´s pour un troupeau laitier. Les effets du type de reproduction [inse´mination artificielle pre´vue (TAI Á « timed artificial insemination » ; n 01246) c. inse´mination lors de de´tection du cycle aestral (IDE Á « insemination at detected estrus » ; n 0220)], la parite´(primipare c. multipare), cote de condition de chair (BCS Á « body condition score » ; faible 52,5 c. e´leve´e 2,5), l'anne´e, la saison (e´te´c. autres saisons) et groupe de fertilite´(hautement fertile B3 c. faiblement fertile ]3 inse´minations), sur la P/AI et la perte de gestation (c.-a`-d., perte au stade embryonnaire tardif/stade fe´tus pre´coce, avortement et mort-ne´) ont e´te´de´termine´s au moyen des proce´dures GLIMMIX de SAS. La gestation par AI e´tait influence´e par le type de reproduction et la saison. Les gestations par AI e´taient plus faibles (PB0,05) chez les vaches TAI (28,7 %)...

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“…In a study conducted by Ahmadzadeh, et al [11] a reduced dose of GnRH (gonadorelin) did not affect ovulation time relative to the second GnRH injection and did not compromise the incidence of ovulation and luteal development used in Ovsynch protocol. Buserelin is a more potent GnRH agonist than both gonadorelin and fertilerin in the bovine for FSH and LH release [12,13]. Therefore, it is generally used at 8-10 µg doses for synchronizing ovulation in the dairy cows [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Untitled

2016

Animal Review

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Associations between the manipulation of patterns of follicular development and fertility in cattle

Cited by 71 publications

References 84 publications

Recent Advances in the Synchronization of Estrus and Ovulation in Dairy Cows

Recent Advances in the Synchronization of Estrus and Ovulation in Dairy Cows

Pregnancy per artificial insemination and pregnancy loss in lactating dairy cows of a single herd following timed artificial insemination or insemination at detected estrus

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