Resumo
Background: Programs of resynchronization of ovulation have the objective of allowing reinsemination of females that did not get pregnant after fixed time artificial insemination (TAI), in the lowest time interval possible. These protocols are usually composed of administration of estradiol benzoate (EB) concomitant to the insert of progesterone-based (P4) intravaginal implants 22 to 24 days after the first TAI. However, little information is available on the impact of hormonal manipulation in a pre-established pregnancy. The objective of this study was to evaluate if resynchronization of ovulation, started 24 days after the first TAI, would interfere in the function of the corpus luteum (CL), production of P4, and pre-established pregnancy.Materials, Methods & Results: For this study, 526 Brangus heifers with ages between 24 and 26 months, were subjected to TAI program in the beginning of the breeding season. Synchronization protocol for the first TAI started with insertion of an intravaginal implant containing 750 mg of P4 and administration of 2 mg of estradiol benzoate (EB) intramuscular (im) on day -9 (D-9). After seven days (D-2), P4 implants were removed, and 150 µg of D-cloprostenol (PGF), i.m., and 1 mg of estradiol cypionate (EC), i.m., were administered. The TAI was performed between 48 and 54 h after removal of the P4 implant (D0). Twenty-four days after the first TAI (D24), heifers were randomly divided into the following experimental groups: Control (n = 167, no treatment), EB (n = 208, 1 mg of EB, i.m.), and hCG (n = 151, 1000 IU of hCG, i.m.). Heifers of EB and hCG groups received a new intravaginal device containing 750 mg of P4 on D24. On day 31 (D31), P4 implants were removed and pregnancy diagnosis were performed by ultrasound. Pregnancy rates from the first TAI on D31 were 58.7% (98/167), 53.4% (111/208) and 52.9% (80/151) respectively for groups Control, EB and hCG.[...](AU)
Assuntos
Animais , Feminino , Gravidez , Bovinos , Sincronização do Estro/métodos , Benzoatos/uso terapêutico , Estradiol/uso terapêutico , Gonadotropina Coriônica/uso terapêutico , Inseminação Artificial/veterináriaResumo
Background: Programs of resynchronization of ovulation have the objective of allowing reinsemination of females that did not get pregnant after fixed time artificial insemination (TAI), in the lowest time interval possible. These protocols are usually composed of administration of estradiol benzoate (EB) concomitant to the insert of progesterone-based (P4) intravaginal implants 22 to 24 days after the first TAI. However, little information is available on the impact of hormonal manipulation in a pre-established pregnancy. The objective of this study was to evaluate if resynchronization of ovulation, started 24 days after the first TAI, would interfere in the function of the corpus luteum (CL), production of P4, and pre-established pregnancy.Materials, Methods & Results: For this study, 526 Brangus heifers with ages between 24 and 26 months, were subjected to TAI program in the beginning of the breeding season. Synchronization protocol for the first TAI started with insertion of an intravaginal implant containing 750 mg of P4 and administration of 2 mg of estradiol benzoate (EB) intramuscular (im) on day -9 (D-9). After seven days (D-2), P4 implants were removed, and 150 µg of D-cloprostenol (PGF), i.m., and 1 mg of estradiol cypionate (EC), i.m., were administered. The TAI was performed between 48 and 54 h after removal of the P4 implant (D0). Twenty-four days after the first TAI (D24), heifers were randomly divided into the following experimental groups: Control (n = 167, no treatment), EB (n = 208, 1 mg of EB, i.m.), and hCG (n = 151, 1000 IU of hCG, i.m.). Heifers of EB and hCG groups received a new intravaginal device containing 750 mg of P4 on D24. On day 31 (D31), P4 implants were removed and pregnancy diagnosis were performed by ultrasound. Pregnancy rates from the first TAI on D31 were 58.7% (98/167), 53.4% (111/208) and 52.9% (80/151) respectively for groups Control, EB and hCG.[...]
Assuntos
Feminino , Animais , Gravidez , Bovinos , Benzoatos/uso terapêutico , Estradiol/uso terapêutico , Gonadotropina Coriônica/uso terapêutico , Sincronização do Estro/métodos , Inseminação Artificial/veterináriaResumo
Desde os primórdios da inseminação artificial (IA), houve uma corrida para o seu aprimoramento, multiplicação e desenvolvimento de novas biotécnicas da reprodução. Após longo tempo, a IA convencional foi robustecida pela adição da inseminação artificial em tempo fixo (IATF), técnica esta, que predomina atualmente na bovinocultura de corte no Brasil. As taxas da eficiência reprodutiva oriundas da IATF após a sincronização do estro (SE) e da ovulação, ainda constituem desafios, em função das relativamente pobres taxas de prenhez (TP). Para aumentar a performance reprodutiva de animais na IATF, buscou-se alternativas como a ressincronização do estro (RES), visando aumentar o número de bezerros provenientes de touros de elite. Deste modo, a RES veio adicionar maior número nos produtos da IA, pois em curto espaço de tempo chega-se a satisfatórias TP ao se computar as taxas acumuladas (1a + 2a IATF). O presente estudo foi delineado para avaliar as TC de vacas Bos taurus indicus submetidas a protocolos de SE e RES, utilizando implantes intravaginais de progesterona (P4) novos e usados (um uso), antes do diagnóstico de gestação (DG), e correlacionar o diâmetro do folículo pré-ovulatório (FPO) no momento das inseminações artificiais em tempo fixo (IATFs) com as TCs. Foram utilizadas 378 vacas Bos taurus indicus multíparas, lactantes, idade média de 6 anos e 55 dias abertos após o parto. As vacas eram criadas em sistema extensivo com suplementação mineral e água ad libitum. Os animais foram distribuídos em dois grupos: o GRN (Grupo Ressincronização Dispositivo Novo; n=185) e GRU (Grupo Ressincronização Dispositivo Usado; n=193), os quais receberam no d0 (dia zero = início da administração do protocolo) um implante intravaginal novo com P4 (1,0g) + benzoato de estradiol (BE, 2mg, IM); no d8 remoção da P4 + D-cloprostenol (500µg, IM) + gonadotrofina coriônica equina (eCG, 300UI) (IM) + cipionato de estradiol (CE, 0,5mg); em d10 foi executada a ultrassonografia (US) do FPO + IATF. No d32 (22 dias após a 1a IATF), as vacas foram mantidas nos grupos, distribuíndo-as em dois grupos com vistas à RES: GRN (n = 185) e GRU (n = 193). O GRN recebeu um implante de P4 intra-vaginal novo + 1mg de BE; o GRU recebeu um implante de P4 usado (um uso) + 1mg de BE. No D40, executou-se a remoção da P4 intravaginal e realizou-se o diagnóstico de gestação com US; as vacas diagnosticadas não-prenhes receberam 500µg de D-Cloprostenol + 300UI de eCG + 0,5mg de CE; no d42 foi feita a US do FPO + IATF. A TP dos GRN e GRU resultou em 56,2 e 57,0 (P=0,067) respectivamente, e a TP após a RES redundou em 58,0 % e 37,3% (P<0,001). A TP acumulada após as IATFs (SE + RES) resultou em 81,6 e 73,1% respectivamente (P=0,045). Não houve diferença (P=0,06) do diâmetro do FPO entre as vacas prenhes (13,1 mm) e vazias (12,6 mm) após a SE no GRN, no GRU foi observada diferença (P=0,003) (vacas prenhes = 13,2mm) e (vazias=11,1mm). Concluiu-se que a utilização de protocolos de RES otimizou as TP em ambos os grupos, sobretudo no GRN; os implantes intravaginais novos com P4 produziram resultados superiores nas TP na RES e na TP acumulada, quando comparados com o grupo que recebeu os usados; o diâmetro do FPO correlacionou-se com as TP entre as vacas gestantes e vazias.
Since the beginning of artificial insemination (AI), there has been a race to its improvement, developing new reproductive biotechnologies. After a long time, conventional AI was added the fixed time artificial insemination (FTAI), currently predominating in Brazilian beef cattle. The reproductive efficiency rates from FTAI after synchronization of estrus and ovulation are still challenges due to relatively poor pregnancy rates. In order to increase the reproductive performance in animals at FTAI, we searched for estrous resynchronization alternatives (RES), in order to increase the number of calves, coming from elite bulls. In this way, the RES can add a larger number to the AI calves, because in a short time, it can achieve satisfactory pregnancy rates (PR) in accumulated conception rate. The present study was designed to evaluate the conception rate (CR) in Bos taurus indicus cows submitted to estrus synchronization (ES) and estrus resynchronization (RES) protocols, using intravaginal (P4) new and used progesterone implants (one use), prior to the diagnosis of gestation (DG), and to correlate the preovulatory follicle (POF) diameter for fixed time artificial inseminations (FTAI) with CR. A total of 378 Bos taurus indicus cows, lactating, with a mean age of 6 years and open days of 55 days were used. Cows were raised in an extensive system with mineral supplementation and water ad libitum. The animals were divided into two groups: the GRN (Resynchronization Group Device New; n = 185) and GRU (Resynchronization Group Device Used; n = 193); who received a new intravaginal implant with P4 (1.0g) + estradiol benzoate (EB, 2 mg, IM) on d0 (day zero = begin of protocol administration); in d8 P4 removal + D-cloprostenol (500 g, IM) + 300 IU of equine chorionic gonadotrophin (eCG) + estradiol cypionate (EC) (0.5 mg); in d10 the ultrasonography (US) of the POF+ FTAI was performed. In d32 (22 days after 1st TAI), the cows were resynchronized and composed to two groups: GRN (n = 185) and GRU (n = 193). The GRN received a new intra-vaginal P4 implant + 1mg EB; the GRU received a used P4 implant + 1mg EB. In D40, P4 removal and the pregnancy diagnosis by US was performed; no pregnant cows received 500 g of D-Cloprostenol + 300 IU of eCG + 0.5 mg of EC; in D42 the US from POF + FTAI was done. The CR of the GRN and GRU resulted in 56.2 and 57.0 (P = 0.06) respectively, and the CR after the RES resulted in 58.0% and 37.3% (P <0.001). The CR accumulated after the FTAI (ES + RES) resulted in 81.6 and 73.1% respectively (P = 0.04). There was no difference (P = 0.06) in the POF diameter between the pregnant (13.1 mm) and no pregnant (12.6 mm) cows after ES in the GRN, except in the GRU difference (P = 0.003) was observed (Pregnant cows = 13.2mm) and (no pregnant = 11.1mm). It was concluded that the use of RES protocols optimized CR in both groups, especially in the GRN; the new intravaginal implants with P4 produced superior results in the CR in the RES and in the accumulated CR, when compared with the group that received the used ones; the diameter of the POF was correlated with the CR between the pregnant and no pregnant cows.
Resumo
O objetivo deste estudo foi avaliar o efeito da ressincronização da ovulação, iniciada 24 dias após a primeira IATF, sobre a área do corpo lúteo (CL), a concentração plasmática de progesterona (P4) e a taxa de prenhez. Exp.1 526 novilhas Brangus com idades entre 24 e 26 meses, foram submetidas a um programa de IATF no início da estação de acasalamento. O protocolo de sincronização para a primeira IATF começou com a inserção de um implante intra-vaginal contendo 750 mg de P4 e a administração de 2 mg de benzoato de estradiol (BE) intramuscular (i.m.) no dia -9 (D-9). Depois de sete dias (D-2), os implantes de P4 foram removidos, e 150 µg de D-cloprostenol (PGF), i.m., e 1 mg de cipionato de estradiol (CE), i.m., foram administrados. A IATF foi realizada entre 48 e 54 horas após a remoção do implante de P4 (D0). Vinte e quatro dias após a primeira IATF (D24), as novilhas foram divididas aleatoriamente nos seguintes grupos experimentais: controle (n = 167, sem tratamento), BE (n = 208, 1 mg de BE, i.m.) e hCG (n = 151, 1000 UI de hCG, i.m.). Novilhas dos grupos BE e hCG receberam um novo implante intra-vaginal contendo 750 mg de P4 na D24. No dia 31 (D31), os implantes de P4 foram removidos e o diagnóstico de prenhez foi realizado por ultrassonografia. As taxas de prenhez da primeira IATF no D31 foram 58,7% (98/167), 53,4% (111/208) e 52,9% (80/151), respectivamente, para os grupos controle, BE e hCG. Novilhas diagnosticadas como não gestantes receberam 150 µg de PGF, i.m., e 1 mg de CE, i.m., sendo a segunda IATF realizada 48 a 54 horas após a remoção do implante (D33). No D31, os subgrupos de novilhas prenhes de cada grupo experimental foram aleatoriamente divididos, sendo realizado exame por ultrassonografia para determinar a área do CL e coleta de uma amostra de sangue para determinar a concentração sérica de P4: Controle (n = 13), BE (n = 26), e hCG (n = 24). A área de CL foi significativamente maior (P<0,05) no grupo hCG (3,42±0,76 cm 2 ), em comparação aos grupos de BE (2,44±0,57 cm 2 ) e controle (2,61±0,61 cm 2 ). Da mesma forma, a concentração sérica de P4 foi significativamente maior (P<0,05) no grupo hCG (12,43±3,48 ng/ml) em comparação aos grupos BE (6,92±3,04 ng/ml) e controle (7,29±2,45 ng/ml). O uso do BE e do hCG em programas de ressincronização da ovulação 24 dias após a IATF não interferiu na taxa de prenhez da primeira IATF. É provável que o mecanismo de ação do BE não afete a atividade do CL, a produção de P4, e consequentemente, não tenha efeito negativo na manutenção da prenhez em protocolos de ressincronização da ovulação. O tratamento com hCG resultou no aumento da área de CL e da produção de P4, porém, este efeito não favoreceu a taxa de prenhez da primeira IATF. Exp.2 184 novilhas Brangus com idade entre 24 a 26 meses e peso corporal médio de 361±29,2 kg foram submetidas a dois programas de IATF. O protocolo de sincronização para a primeira IATF foi o mesmo utilizado no Exp.1. Vinte e quatro dias após a primeira IATF (D24), as novilhas foram aleatoriamente divididas conforme os hormônios utilizados para ressincronização, formando os seguintes grupos experimentais: BE (n = 83, 1 mg de BE, i.m.) e hCG (n = 101, 1000 UI de hCG, i.m.). Novilhas dos grupos BE e hCG receberam um novo dispositivo intravaginal contendo 750mg de progesterona no D24. No D31, os implantes foram removidos e o diagnóstico de gestação por ultrassonografia foi realizado. As taxas de prenhez da primeira IATF no D31 foram de 63,9% (53/83) e 64,9% (65/101), respectivamente, para os grupos BE e hCG. Novilhas diagnosticadas como não gestantes (n=66) receberam 150 µg de PGF, i.m., e 1 mg de CE, im; a segunda IATF foi realizada no D33. Trinta dias após a segunda IATF (D63), foi realizado o segundo diagnóstico de gestação. As perdas gestacionais entre o D31 e D63, das novilhas prenhes da primeira IATF foram 9,4% (5/53) e 6,2% (4/65) respectivamente para os grupos BE e hCG. As taxas de prenhez da segunda IATF foram 40,0% (12/30) e 22,2% (8/36), respectivamente, para os grupos BE e hCG. As taxas de prenhez acumulada para os grupos BE e hCG foram, respectivamente, 72,3% (60/83) e 68,3% (69/101). O uso do BE e hCG para ressincronização da ovulação 24 dias após a primeira inseminação não afetou a taxa de prenhez da primeira IATF. As taxas de prenhez obtidas na segunda IATF foram inferiores às expectativas, considerando a resposta da primeira IATF. Entretanto, as taxas de prenhez acumulada foram similares e satisfatórias para os primeiros 33 dias da estação de acasalamento.
The aim of this study was to evaluate the effect of resynchronization of ovulation, which began 24 days after the first TAI, on the corpus luteum area (CL), plasma progesterone production (P4) and pregnancy rates. Exp.1 526 Brangus heifers between 24 and 26 months of age were submitted to a TAI program at the beginning of the breeding season. The protocol synchronization for the first TAI started with the insertion of an intravaginal implant containing 750 mg progesterone (P4) and the administration of 2 mg of estradiol benzoate (EB) intramuscular (i.m.) on day -9 (D-9). After seven days (D-2), P4 implants were removed, and 150 µg D-cloprostenol (PGF), and 1 mg estradiol cypionate (EC), were administered, i.m. The TAI was carried out between 48 and 54 hours after removal of the P4 implant (D0). Twenty-four days after the first TAI (D24), heifers were divided randomly into the following groups: control (n = 167, untreated), EB (n = 208, 1 mg EB, i.m.) and hCG (n = 151, 1000 IU hCG, i.m.). Heifers of the EB and hCG groups received a new intravaginal implant containing 750 mg of P4 on D24. On day 31 (D31), P4 implants were removed and the pregnancy diagnosis was performed by ultrasonography. Pregnancy rates for the first TAI, on D31, were 58.7% (98/167), 53.4% (111/208) and 52.9% (80/151), respectively, for the control, EB and hCG groups. Non-pregnant heifers received 150 µg PGF, i.m., and 1 mg EC, i.m., and the second TAI was performed 48 to 54 hours after removal of the P4 implant (D33). On D31, subgroups of pregnant cows from each experimental groups were randomly divided to determine the surface area of the CL by ultrasound and blood samples were collected to determine P4 concentrations: control (n = 13), BE (n = 26), and hCG (n = 24). The surface area of the CL was significantly higher (P<0.05) in the hCG group (3.42±0.76 cm 2 ) compared to the EB (2.44±0.57 cm 2 ) and control (2.61±0.61 cm 2 ) groups. Also, P4 concentrations were significantly higher (P<0.05) in the hCG group (12.43±3.48 ng/mL) compared to the EB groups (6.92±3.04 ng/mL) and control (7.29±2.45 ng/mL). The use of EB and hCG in ovulation resynchronization programs 24 days after TAI did not affect the pregnancy rates of the first TAI. It is likely that EB mechanism of action does not affect the activity of the CL and P4 production, consequently having no negative effect on the maintenance of pregnancy. Nevertheless, the hCG treatment on D24 increased the area of CL and P4 plasma levels, but this effect neither improves nor compromised pregnancy rate of the first TAI. Exp.2 184 aged 24-26 months Brangus heifers old with mean body weight of 361±29.2 kg were submitted to two consecutive TAI programs. The synchronization protocol to the first TAI was the same as in Exp.1. Twenty-four days after the first TAI (D24), heifers were randomly divided according to the hormones used for resynchronization, according to the following groups: BE (n = 83, 1 mg EB, i.m.) and hCG (n = 101, hCG 1000 IU, i.m.). Heifers of the EB and hCG groups received a new intravaginal device containing 750 mg of progesterone on D24. On D31, P4 implants were removed and pregnancy diagnosis was performed by ultrasonography. The first TAI pregnancy rates on D31 were 63.9% (53/83) and 64.9% (65/101), respectively, for the EB and hCG groups. Heifers diagnosed as open received 150 µg PGF, i.m., and 1 mg EC, i.m.; the second TAI was performed on D33. Thirty days after the second TAI (D63), the second pregnancy diagnosis was performed. Pregnancy loss rates from D31 to D63 were 9.4% (5/53) and 6.2% (4/65) respectively for the EB and hCG groups. Pregnancy rates for the second TAI were 40.0% (12/30) and 22.2% (8/36), for the EB and hCG groups respectively. The cumulative pregnancy rates for EB and hCG groups were, respectively, 72.3% (60/83) and 68.3% (69/101). The use of hCG and EB for resynchronization of ovulation 24 days after the first insemination did not affect pregnancy rates of the first TAI. Pregnancy rates obtained in the second TAI were below expected values, considering the first TAI response. However, cumulative pregnancy rates were similar and satisfactory for the first 33 days of the breeding season.