Fatores que interferem na manutenção da gestação de receptoras submetidas a TETF in vitro
Data
2022-07-13
Autores
Munhoz, Susiandra Kloster
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os objetivos deste estudo foram avaliar fatores relacionados à categoria das doadoras de oócitos e efeito do touro na manutenção da gestação de receptoras Bos indicus x Bos taurus, submetidas a transferência de embrião em tempo fixo (TETF) de embriões Nelore produzidos in vitro. Foram utilizadas 463 doadoras Nelore e 6 touros Nelore para a produção in vitro de embriões. As doadoras foram divididas em 3 categorias: novilhas precoces (< 15 meses de idade; NP); novilhas regulares (entre 18 e 24 meses de idade; NR) e vacas multíparas paridas (VM). Os embriões (n = 4366) foram transferidos a fresco em receptoras Bos indicus x Bos taurus, sincronizadas através do seguinte protocolo: D-17: inserção do dispositivo intravaginal de 0,5g de P4 (ReproOne, Globalgen) e 2mg de benzoato de estradiol (Bioestrogen, Biogenesis); D-9: remoção do dispositivo de P4 + 1 mg de cipionato de estradiol (Cronicip, Biogenesis) + 300UI de eCG (Ecegon, Biogenesis) + 150 µg de D-cloprostenol (Croniben, Biogenesis). Foi administrado 10,5 mcg de acetato de buserelina, análogo do hormônio GnRH (Gonaxal, Biogenesis) em todas as receptoras no dia da TETF (D0). Os diagnósticos para verificação da prenhez foram realizados através da ultrassonografia aos 25 ± 1,5 dias (DG1) e 83 ± 18,1 dias (DG2) após a TE. As receptoras prenhas ao DG2 foram acompanhadas até o parto, sendo que aquelas que não pariram, foi considerado perda gestacional. Não houve efeito da recuperação oocitária/doadora nos índices de manutenção da gestação (P > 0,05). Embriões provenientes de doadoras NP tiveram menor índice ao DG1 (39%, [808/2072]) e DG2 (22,7%; [470/2072]), comparado a doadoras NR (DG1 42,6%; [349/819] e DG2 27,4%; [224/819]) e VM (DG1 26,8%; [396/1475] e DG2 26,8%; [396/1475]). Embriões de doadoras NR apresentaram a maior taxa de parição (18,9%; [155/819]) comparado às NP (14,5%; [301/2072]) e VM (15,9%; [234/1475]). As receptoras em diferentes manejos nutricionais no momento da TE, tiveram concepção semelhante ao DG1 (a pasto 41,4%; [1317/3182] vs. confinadas 41%; [485/1184]), no entanto, receptoras mantidas a pasto evidenciaram maior manutenção gestacional até o parto (a pasto 17,7% [564/3182] vs. confinadas 10,6% [126/1184]). Houve efeito do touro utilizado em todo o período gestacional avaliado: variações entre 39,3% a 47,6% ao DG1, 21,4% a 31,1% ao DG2 e 13,1% a 25% ao parto de acordo com o touro utilizado. Em resumo, os resultados demonstraram que a categoria da doadora utilizada pode impactar resultados de prenhez à TETF, sendo que doadoras NP exibiram menores taxas de concepção e parto; foram observadas maiores perdas gestacionais em receptoras submetidas a mudança de manejo após DG1 (do confinamento para pasto); e por fim, houve efeito do touro em todo o período gestacional avaliado, promovendo variações significativas na manutenção da gestação até o parto.
The objectives of this study were to evaluate factors related to the category of oocyte donors and the effect of the bull on the maintenance of pregnancy in Bos indicus x Bos taurus recipients, submitted to fixed-time embryo transfer (FTET) of Nellore embryos produced in vitro. A total of 463 Nellore donors and 6 Nellore bulls were used for the in vitro embryo production. Donors were divided into 3 categories: precocious heifers (< 15 months of age; NP); heifers (18-24 months of age; NR) and multiparous cows (VM). The embryos (n = 4366) were transferred fresh into Bos indicus x Bos taurus recipients, synchronized using the following protocol: D-17: insertion of 0.5g-P4 intravaginal device (ReproOne, Globalgen) + 2mg of estradiol benzoate (Bioestrogen, Biogenesis); D-9: P4 device removal + 1 mg of estradiol cypionate (Cronicip, Biogenesis) + 300IU of eCG (Ecegon, Biogenesis) + 150 µg of D-cloprostenol (Croniben, Biogenesis). On the day of FTET (D0), all recipients received 10.5mcg of buserelin acetate (GnRH hormone analogue; Gonaxal, Biogenesis). Pregnancy diagnosis were performed through ultrasound at 25 ± 1.5 days (DG1) and 83 ± 18.1 days (DG2) after FTET. The recipients that were pregnant at DG2 were separated until parturition; and the ones that did not delivered a calf, were considered to have gestational loss. There was no effect of oocyte per donor recovery on pregnancy maintenance rates (P > 0.05). Embryos from PH-donors had a lower rate at DG1 (39%, [808/2072]) and DG2 (22.7%; [470/2072]), compared to H-donors (DG1 42.6%; [349 /819] and DG2 27.4%; [224/819]) and MC-donors (DG1 26.8%; [396/1475] and DG2 26.8%; [396/1475]). Embryos from H-donors had the highest calving rate (18.9%; [155/819]) compared to PH-donors (14.5%; [301/2072]) and MC-donors (15.9%; [234/ 1475]). Recipients in different nutritional managements at the time of FTET had similar conception rate at DG1 (41.4% on pasture; [1317/3182] vs. confined 41%; [485/1184]); however, recipients maintained on pasture showed evidence of greater gestational maintenance until calving (pasture 17.7% [564/3182] vs. confined 10.6% [126/1184]). There was a bull effect throughout the evaluated gestational period: 39.3% to 47.6% at DG1; 21.4% to 31.1% at DG2; and 13.1% to 25% at parturition. In summary, the results showed that donors’ category can impact pregnancy results at FTET, with PH-donors resulting in decreased conception and parturition rates. In addition, higher gestational losses were observed in recipients submitted to managements changes after FTET (from confinement to pasture). Moreover, a bull effect was detected throughout the evaluated gestational period, promoting significant variations in pregnancy maintenance until calving.
The objectives of this study were to evaluate factors related to the category of oocyte donors and the effect of the bull on the maintenance of pregnancy in Bos indicus x Bos taurus recipients, submitted to fixed-time embryo transfer (FTET) of Nellore embryos produced in vitro. A total of 463 Nellore donors and 6 Nellore bulls were used for the in vitro embryo production. Donors were divided into 3 categories: precocious heifers (< 15 months of age; NP); heifers (18-24 months of age; NR) and multiparous cows (VM). The embryos (n = 4366) were transferred fresh into Bos indicus x Bos taurus recipients, synchronized using the following protocol: D-17: insertion of 0.5g-P4 intravaginal device (ReproOne, Globalgen) + 2mg of estradiol benzoate (Bioestrogen, Biogenesis); D-9: P4 device removal + 1 mg of estradiol cypionate (Cronicip, Biogenesis) + 300IU of eCG (Ecegon, Biogenesis) + 150 µg of D-cloprostenol (Croniben, Biogenesis). On the day of FTET (D0), all recipients received 10.5mcg of buserelin acetate (GnRH hormone analogue; Gonaxal, Biogenesis). Pregnancy diagnosis were performed through ultrasound at 25 ± 1.5 days (DG1) and 83 ± 18.1 days (DG2) after FTET. The recipients that were pregnant at DG2 were separated until parturition; and the ones that did not delivered a calf, were considered to have gestational loss. There was no effect of oocyte per donor recovery on pregnancy maintenance rates (P > 0.05). Embryos from PH-donors had a lower rate at DG1 (39%, [808/2072]) and DG2 (22.7%; [470/2072]), compared to H-donors (DG1 42.6%; [349 /819] and DG2 27.4%; [224/819]) and MC-donors (DG1 26.8%; [396/1475] and DG2 26.8%; [396/1475]). Embryos from H-donors had the highest calving rate (18.9%; [155/819]) compared to PH-donors (14.5%; [301/2072]) and MC-donors (15.9%; [234/ 1475]). Recipients in different nutritional managements at the time of FTET had similar conception rate at DG1 (41.4% on pasture; [1317/3182] vs. confined 41%; [485/1184]); however, recipients maintained on pasture showed evidence of greater gestational maintenance until calving (pasture 17.7% [564/3182] vs. confined 10.6% [126/1184]). There was a bull effect throughout the evaluated gestational period: 39.3% to 47.6% at DG1; 21.4% to 31.1% at DG2; and 13.1% to 25% at parturition. In summary, the results showed that donors’ category can impact pregnancy results at FTET, with PH-donors resulting in decreased conception and parturition rates. In addition, higher gestational losses were observed in recipients submitted to managements changes after FTET (from confinement to pasture). Moreover, a bull effect was detected throughout the evaluated gestational period, promoting significant variations in pregnancy maintenance until calving.
Descrição
Palavras-chave
Embrião, Perda gestacional, Touro, Bos indicus, Pregnancy loss, Sire, Bull, ETFT, TETF