Number of oocytes retrieved per donor during OPU and its relationship with in vitro embryo production and field fertility following embryo transfer

The association of OPU-IVEP is an important instrument to drive genetic progress. In vitro embryo production (IVEP) has remarkably expanded in the last decade compared to in vivo embryo production. Because of the high repeatability of oocyte retrieval within oocyte-donors, studies exploring the relationship between the number of oocytes recovered per OPU section with IVEP efficiency, as well as with field fertility (pregnancy results following embryo transfer; P/ET) are extremely important to guide cow-donor selection and optimize field reproduction efficiency and the herd’s genetic gain. Based on this rationale, our group conducted a retrospective analysis of a large database comprising IVEP records from several cattle breeds, including Bos indicus and Bos taurus for either beef or dairy purposes. A total of 205,140 oocytes recovered from 7,906 OPU procedures of 6,902 donors (5,227 beef and 1,675 dairy) of Brazilian farms were analyzed. Beef breeds analyzed were Nelore (Bos indicus) and Senepol (Bos taurus) and dairy breeds Were Gyr (Bos indicus) and Holstein (Bos taurus). According to our analysis, the IVEP in beef cattle had a great improvement throughout the last years, with a remarkable increase in numbers of pregnancies per OPU compared to late 90’s (averaging only 1 pregnancy per OPU in 1998 vs 2,4 in 2014). As for the distribution of oocytes retrieved, both Bos indicus beef (Nelore = 27.2) and dairy (Gyr = 23.8) breeds seem to yield greater average numbers of oocytes per OPU compared to Bos taurus (Senepol = 21.8; Holstein = 19.3).

Number of oocytes retrieved per donor during OPU and its relationship with in vitro embryo production and field fertility following embryo transfer

The association of OPU-IVEP is an important instrument to drive genetic progress. In vitro embryo production (IVEP) has remarkably expanded in the last decade compared to in vivo embryo production. Because of the high repeatability of oocyte retrieval within oocyte-donors, studies exploring the relationship between the number of oocytes recovered per OPU section with IVEP efficiency, as well as with field fertility (pregnancy results following embryo transfer; P/ET) are extremely important to guide cow-donor selection and optimize field reproduction efficiency and the herds genetic gain. Based on this rationale, our group conducted a retrospective analysis of a large database comprising IVEP records from several cattle breeds, including Bos indicus and Bos taurus for either beef or dairy purposes. A total of 205,140 oocytes recovered from 7,906 OPU procedures of 6,902 donors (5,227 beef and 1,675 dairy) of Brazilian farms were analyzed. Beef breeds analyzed were Nelore (Bos indicus) and Senepol (Bos taurus) and dairy breeds Were Gyr (Bos indicus) and Holstein (Bos taurus). According to our analysis, the IVEP in beef cattle had a great improvement throughout the last years, with a remarkable increase in numbers of pregnancies per OPU compared to late 90s (averaging only 1 pregnancy per OPU in 1998 vs 2,4 in 2014). As for the distribution of oocytes retrieved, both Bos indicus beef (Nelore = 27.2) and dairy (Gyr = 23.8) breeds seem to yield greater average numbers of oocytes per OPU compared to Bos taurus (Senepol = 21.8; Holstein = 19.3).(AU)

Uso de LH ou eCG no último dia do protocolo superovulatório em bovinos / Use of LH or eCG in the last day of superovulatolatory protocol in cattle

In the last decades several hormonal treatments to induce multiple ovulation and embryo transfer (MOET) have been developed. Tight control of the time of ovulation allowed the use of fixed-time artificial insemination (FTAI) in bovine embryos donors, facilitating animal management. Although, protocols that allow FTAI have evolved and yield as much embryo as conventional protocols that requires estrus detection, substantial increase in viable embryo production has not been observed in superestimulated bovine cattle. The present review put emphasis on superestimulatory protocols in wich the last two doses of pFSH are replaced by eCG or LH. Recent results indicate that an extra LH stimulus (using eCG or LH), on the last day of P-36 superestimulatory treatment, seems to improve transferable embryo yield in both Bos taurus and Bos indicus cattle.

Na última década, inúmeros tratamentos para induzir ovulação múltipla e transferência de embriões foram desenvolvidos. A sincronização precisa da ovulação permitiu a utilização da inseminação artificial em tempo fixo (IATF) em doadoras de embriões, facilitando o manejo destes animais. Embora os protocolos que permitem a IATF tenham evoluído e produzam tantos embriões viáveis quanto os protocolos convencionais que necessitam da observação do estro, não se observou aumento significativo na produção de embriões oriundos de fêmeas bovinas superestimuladas. Nesta mini-revisão será dada ênfase aos protocolos superestimulatórios nos quais as últimas duas doses de pFSH são substituídas por eCG or LH.Estudos recentes indicam que um estímulo extra de LH (por meio da aplicação de eCG ou LH), no último dia do tratamento superestimulatório, parece aumentar o número de embriões viáveis de raças zebuínas e taurinas.

Uso de LH ou eCG no último dia do protocolo superovulatório em bovinos / Use of LH or eCG in the last day of superovulatolatory protocol in cattle

In the last decades several hormonal treatments to induce multiple ovulation and embryo transfer (MOET) have been developed. Tight control of the time of ovulation allowed the use of fixed-time artificial insemination (FTAI) in bovine embryos donors, facilitating animal management. Although, protocols that allow FTAI have evolved and yield as much embryo as conventional protocols that requires estrus detection, substantial increase in viable embryo production has not been observed in superestimulated bovine cattle. The present review put emphasis on superestimulatory protocols in wich the last two doses of pFSH are replaced by eCG or LH. Recent results indicate that an extra LH stimulus (using eCG or LH), on the last day of P-36 superestimulatory treatment, seems to improve transferable embryo yield in both Bos taurus and Bos indicus cattle.(AU)

Na última década, inúmeros tratamentos para induzir ovulação múltipla e transferência de embriões foram desenvolvidos. A sincronização precisa da ovulação permitiu a utilização da inseminação artificial em tempo fixo (IATF) em doadoras de embriões, facilitando o manejo destes animais. Embora os protocolos que permitem a IATF tenham evoluído e produzam tantos embriões viáveis quanto os protocolos convencionais que necessitam da observação do estro, não se observou aumento significativo na produção de embriões oriundos de fêmeas bovinas superestimuladas. Nesta mini-revisão será dada ênfase aos protocolos superestimulatórios nos quais as últimas duas doses de pFSH são substituídas por eCG or LH.Estudos recentes indicam que um estímulo extra de LH (por meio da aplicação de eCG ou LH), no último dia do tratamento superestimulatório, parece aumentar o número de embriões viáveis de raças zebuínas e taurinas.(AU)

Expressão gênica do receptor do hormônio luteinizante (LHR), em células da teca e da granulosa de folículos antrais bovinos

Em células da teca e da granulosa, de folículos bovinos, foram detectados quatro transcritos alternativos do receptor do hormônio luteinizante (LHR). Apenas dois deles são traduzidos em proteínas funcionais com afinidades distintas em relação aos ligantes. Em humanos e símios, a isoforma completa ("full-length") tem afinidade pelo LH e hCG, enquanto que a isoforma que apresenta deleção do exon 10 tem afinidade somente pelo hCG. Além disso, isoformas com deleção do exon 3 foram observadas em ratos, embora nenhum outro estudo tenha investigado essa região do gene bovino. Objetivouse com este trabalho caracterizar o padrão da expressão do gene do LHR nas células da teca e da granulosa de folículos antrais bovinos. Ovários foram coletados em matadouro, os folículos (5-14 mm) foram dissecados e as células da teca e da granulosa separadas para extração de RNA total com Trizol. As concentrações de esteróides no fluido folicular foram determinadas por radioimunoensaio (RIE). A expressão gênica do LHR foi mensurada por RTPCR semiquantitativo com oligonucleotídeos iniciadores ("primers") específicos para amplificar o fragmento entre o final da região extracelular e o final da intracelular (LHRBC; "primers" posicionados nos exons 9 e 11). A ocorrência de transcritos alternativos oriundos do início da região extracelular (LHRA; "primers" posicionados nos exons 2 e 9) foi investigada mediante amplificação por RT-PCR. Como controle interno no PCR, utilizou-se a expressão da GAPDH. Paralelamente, células da granulosa cultivadas in vitro foram tratadas com 1 ou 10 ng de FSH no meio de cultura. Mediante RT-PCR, foi investigada a expressão das isoformas do LHRBC nas células da granulosa cultivadas e tratadas com FSH...

Growth of dominant follicle in the absence of circulating FSH and the events following the LH surge that culminate in ovulation, are dependent on the interaction between LH and its receptor (LHR). Four LHR alternative transcripts were described in theca and granulosa cells from bovine follicles. Only two of them can be translated to functional proteins (receptors coupled with G protein) with different affinities to their ligands. In humans and marmosets, the full-length isoform has affinity to both LH and hCG molecules, whereas the isoform with deletion of only exon 10 has affinity to hCG exclusively. Additionally, isoforms with deletion of exon 3 were observed in rats, although no previous report have investigated this region of the bovine gene. The objective of this study was to characterize the pattern of gene expression of the LHR in theca and granulosa cells from bovine antral follicles. Additionally, LHR expression was determined in cultured granulosa cells under FSH treatment. From ovaries collected in abattoir, antral follicles were dissected (5 to 14mm of diameter), and samples of theca and granulosa cells were obtained to total RNA extraction (Trizol protocol). Steroids concentrations in the follicular fluid were determined by RIA. Gene expression of LHR was measured by semiquantitative RT-PCR with specific primers to amplify part of extracellular region (LHRA; primers annealing on exons 2 and 9) and the fragment from the end of extracellular region, including the transmembrane domain and finishing near the end of intracellular region (LHRBC; primers annealing on exons 9 and 11). As internal control of the PCR, it was used GAPDH expression. Cultured granulosa cells were treated with 0, 1 or 10 ng of FSH (3 replicates each dose). As in vivo and positive control, theca cell sample was utilized to comparison...

Superovulação associada à inseminação artificial com tempo predeterminado, em vacas da raça Nelore

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