Artificial insemination system without estrous observation in suckled beef cows

Abstract

The aim was to develop a timed artificial insemination (TAI) system in suckled beef cows. Cows (n=227), 60-80 days postpartum, received estradiol benzoate (5mg) and a vaginal device containing 250µg of medroxyprogesterone acetate (MPA; day 0). On day six, cloprostenol (125µg) and eCG (400IU) were administrated and calves were weaned for 88h. The devices were removed on day seven (BioRep group) or on day eight (TAI group). All cows of TAI group and cows of BioRep group that did not exhibit standing estrus received GnRH (100µg) on day 9. In experiment I, the follicular growth was monitored daily by transrectal ultrasound exams, from day 6 to day 9. The average size of the dominant follicle on day nine was 11.1±0.99mm (BioRep, n=7) and 11.5±0.65mm (TAI, n=7) and all animals ovulated. In experiment II, the BioRep group cows (n=106) were observed for estrous behavior after withdrawal of the device, twice a day for 48h, and inseminated 12h after detection. In the TAI group (n=107), the devices were withdrawn on day eight and after 24h these cows and those from the BioRep group, which were not stand in estrus, received 100µg of GnRH and TAI 16h later. The pregnancy rates were 57.6% (BioRep) and 52.3% (TAI). In conclusion, an increase on MPA exposure time did not affect the follicular dynamics and pregnancy rates and allow TAI without estrous observation. Furthermore, the treatment for eight days provides an efficient TAI system in suckled beef cows.

Accessibility to Reproductive Technologies by Low-Income Beef Farmers in South Africa

“…The current study observed an overall conception rate of 55%. This result falls within the suggested conception rate of between 25 and 67% as reported by Baruselli et al (34), conception rates of between 50 and 90% suggested by Borges et al (35) and conception rates of between 40 and 60% suggested by Woldu et al (36). The results show an improvement when compared with previous documented indigenous low-income beef cattle conception rates such as 27.06% in Ethiopia (37), 41% in South Africa ( 27), 47.5% in Ethiopia (38), 48.3% in Ethiopia (36), and 47% in South Africa (25).…”

Medroxyprogesterone-encapsulated poly(3-hydroxybutirate-co-3-hydroxyvalerate) nanoparticles using supercritical fluid extraction of emulsions

“…Estrus synchronization in cattleby steroid hormones is of great relevance in the production of suckled beef cows as it provides for an opportunity for the herd to return to cyclicity and to begin a new gestation in a reduced period of time [1]. The Artificial Insemination (AI) is one of the most widespread biotechnology used with instrument effective and economic in the reproduction of bovine [2].There are several protocols in the cattle industry that useprogestogensfor estrous synchronization prior to AI ofcows at a fixed time [3].Widespread acceptance of AI in beef cattle partly depends on the success of programs that facilitate insemination at a predetermined time [3].The success of a fixed-time artificial insemination (FTAI)program is dependent on a high ovulation rate duringa short interval [4].Synchronization of ovulation and timed artificial insemination are able to precisely control the time of ovulation and thus avoid the need for estrus detection [5].Medroxyprogesterone acetate (MPA, Figure 1a) is a hormoneof particular importance in estrus induction protocols post partum in the context of FTAI [6].However, MPA ispoorly soluble in aqueous solution and has lowbioavailability [7].…”

Uso De Antioxidantes Para Melhorar a Eficiência Reprodutiva De Rebanho Bovino Submetido a Protocolo De Sincronização Com Progesterona (P4)

“…Porém, o grau de fertilidade animal, com a utilização de implantes com progesterona exógena, é reduzido, como foi descrito por AINSWORTH & SHRESTHA (1983). Trabalhos recentes de sincronização de estro apresentaram taxas de prenhez entre 37,68% e 57,6% (CÂMARA et al, 2006;BORGES et al, 2009).…”

“…Por esse motivo, o uso da hormonioterapia com a intenção de sincronizar o estro e a inseminação artificial em tempo fixo (IATF) têm sido de grande interesse (BARROS et al, 1995). A progesterona (P4) exógena, o estrogênio (E2), o gonadotrofina coriônica equina (eCG) e GnRH têm sido amplamente utilizados em protocolos de sincronização do estro e da ovulação, inclusive em animais em anestro (ROCHE et al, 1992;JOLLY et al, 1995;MORAES & JAUME, 1997;CÂMARA et al, 2006;BORGES et al, 2009). A utilização desses hormônios visa mimetizar o ciclo estral, bem como estimular o eixo hipotálamo-hipofisário-gonadal da fêmea e as células dessas estruturas (GONZALEZ-PADILHA et al, 1975;TROXEL et al, 1993;KESLER & FAVERO, 1996;WILTBANK et al, 1996;BAYARD et al, 2002).…”