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.