Indução da ovulação e funcionalidade do corpo lúteo em novilhas Nelore pré-púberes
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Data
2017-04-18
Autores
Vrisman, Dayane Priscila [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Devido a comum ocorrência de regressão prematura (RP) do corpo lúteo (CL) em novilhas após primeira ovulação (OV), os objetivos do estudo foram: 1) acompanhar a dinâmica lútea após indução da OV em novilhas Nelore pré-púberes e 2) determinar diferenças relacionáveis a funcionalidade dessa estrutura. Cinquenta e sete fêmeas (289,61±32,28 kg, ECC de 5,66±0,65 e 17,47±0,81 meses de idade) foram divididas em dois grupos de tratamento para indução da OV. No grupo GP4+GnRH foi utilizado dispositivo intravaginal de progesterona (P4) de 3º uso por 10 dias e, 48 horas após remoção, aplicado 0,02mg de acetato de buserelina (GnRH), e no grupo GGnRH foi utilizado somente o GnRH. Os CLs formados foram acompanhados pela ultrassonografia a cada dois dias até a sua regressão funcional (diminuição do sinal vascular do Doppler colorido e concentrações de P4 abaixo de 1 ng/mL), sendo determinado para cada dia o diâmetro, área, valores numéricos (VPN) e heterogeneidade dos pixels e percentual (%) de vascularização. A velocidade do pico sistólico, velocidade diastólica final, índice de resistência e o índice de pulsatilidade (IP) da artéria ovariana também foram determinados para cada avaliação, além da concentração sérica de P4. Essas características foram comparadas entre os tratamentos, funções dos CLs (duração normal ou regredido prematuramente), dias das avaliações e suas interações, utilizando o procedimento MIXED do programa SAS (p≤0,05). Três animais de cada tratamento não responderam ao indutor da OV (6/57=11%), o que determinou taxa de ovulação de 89%. No GP4+GnRH foi observado maior % de CLs com duração normal (81%), e no GGnRH de afuncionais (52%; concentração sérica de P4 inferior a 1 ng/mL em todas as avaliações). Os CLs de duração normal apresentaram maior área, % de vascularização e concentração de P4 quando comparado com as outras categorias estabelecidas. Menores valores para o diâmetro, área (31,89±11,46mm2), VPN (84,05±2,90) e concentração de P4 foram observados para os CLs afuncionais e, os regredidos prematuramente, além de não diferirem em relação ao % de vascularização com os afuncionais, apresentaram valores intermediários para a área e concentração de P4. A P4 foi efetiva no diagnóstico da RP e afuncionalidade dos CLs, apresentando correlação positiva com a área (r=0,62; p<0,001) e com o % de vascularização do CL (r=0,38; p<0,001). As características diâmetro do CL e IP foram importantes no diagnóstico precoce da afuncionalidade e RP, respectivamente. Maior relação da área do CL com a concentração de P4 foi observada (R2=0,53). Em conclusão, o primeiro CL formado após indução da OV de novilhas pré-púberes apresentou diferenças quanto a funcionalidade, podendo ser diferenciada por meio dos parâmetros ultrassonográficos diâmetro e área do CL, VPN, % de vascularização e IP.
Due to the common occurrence of premature regression (PR) of the corpus luteum (CL) in heifers after the first ovulation (OV), the aims of this study were to: 1) monitor the luteal dynamics after OV induction in prepubertal Nellore heifers, and 2) determine differences related to the functionality of this structure. Fifty-seven females (BW 289.61±32.28 kg, BCS 5.66±0.65 and 17.47±0.81 months old) were divided into two treatment groups for OV induction. In the group GP4+GnRH, an intravaginal progesterone (P4) device of 3rd use was used for 10 days and, 48 hours after its removal 0.02 mg of buserelin acetate (GnRH) was applied, and in the GGnRH group only GnRH was used. Formed CLs were monitored via ultrasonography every two days until functional regression (decrease of the vascular signal of color Doppler and serum P4 concentrations below 1 ng/mL), being determined for each day the diameter, area, numerical values (NV) and heterogeneity of the pixels, and vascularization percentage (%). The systolic and diastolic peak velocity, resistance and pulsatility index (PI) of the ovarian artery were also determined for each day in addition to the serum P4 concentration. These characteristics were compared between treatments, CLs functions (normal duration or prematurely regressed), days of evaluations and their interactions, using the MIXED procedure of SAS program (p≤0.05). Three animals from each treatment did not respond to the OV inductor (6/57=11%), which determined an ovulation rate of 89%. In GP4+GnRH, a higher percentage of CLs with normal duration was observed (81%), while in the GGnRH the percentage of nonfunctional CLs was higher (52%; serum P4 concentration of less than 1 ng/mL in all evaluations). The CLs of normal duration presented greater area, % of vascularization and concentration of P4 when compared with other categories. Lower values for the diameter, area (31.89±11.46mm2), NV (84.05±2.90) and concentration of P4 were observed for the nonfunctional CLs and, those that regressed prematurely, presented intermediate values for the area and serum P4 concentration and did not differ in relation to the % of vascularization with the nonfunctional. The P4 was effective in the diagnosis of regressed prematurely and nonfunctional of CLs, presenting a positive correlation with the area (r=0.62; p<0.001) and, with the % of CL vascularization (r=0.38; p<0.001). The diameter of CL and PI were important in the early diagnosis of the nonfunctionality and PR, respectively. Greater relation of the area of the CL with the concentration of P4 was observed (R2=0.53). In conclusion, the first CL formed after OV induction in prepubertal heifers showed differences in functionality that can be differentiated by ultrasonography parameters diameter and area of CL, NV, % of vascularization and PI.
Due to the common occurrence of premature regression (PR) of the corpus luteum (CL) in heifers after the first ovulation (OV), the aims of this study were to: 1) monitor the luteal dynamics after OV induction in prepubertal Nellore heifers, and 2) determine differences related to the functionality of this structure. Fifty-seven females (BW 289.61±32.28 kg, BCS 5.66±0.65 and 17.47±0.81 months old) were divided into two treatment groups for OV induction. In the group GP4+GnRH, an intravaginal progesterone (P4) device of 3rd use was used for 10 days and, 48 hours after its removal 0.02 mg of buserelin acetate (GnRH) was applied, and in the GGnRH group only GnRH was used. Formed CLs were monitored via ultrasonography every two days until functional regression (decrease of the vascular signal of color Doppler and serum P4 concentrations below 1 ng/mL), being determined for each day the diameter, area, numerical values (NV) and heterogeneity of the pixels, and vascularization percentage (%). The systolic and diastolic peak velocity, resistance and pulsatility index (PI) of the ovarian artery were also determined for each day in addition to the serum P4 concentration. These characteristics were compared between treatments, CLs functions (normal duration or prematurely regressed), days of evaluations and their interactions, using the MIXED procedure of SAS program (p≤0.05). Three animals from each treatment did not respond to the OV inductor (6/57=11%), which determined an ovulation rate of 89%. In GP4+GnRH, a higher percentage of CLs with normal duration was observed (81%), while in the GGnRH the percentage of nonfunctional CLs was higher (52%; serum P4 concentration of less than 1 ng/mL in all evaluations). The CLs of normal duration presented greater area, % of vascularization and concentration of P4 when compared with other categories. Lower values for the diameter, area (31.89±11.46mm2), NV (84.05±2.90) and concentration of P4 were observed for the nonfunctional CLs and, those that regressed prematurely, presented intermediate values for the area and serum P4 concentration and did not differ in relation to the % of vascularization with the nonfunctional. The P4 was effective in the diagnosis of regressed prematurely and nonfunctional of CLs, presenting a positive correlation with the area (r=0.62; p<0.001) and, with the % of CL vascularization (r=0.38; p<0.001). The diameter of CL and PI were important in the early diagnosis of the nonfunctionality and PR, respectively. Greater relation of the area of the CL with the concentration of P4 was observed (R2=0.53). In conclusion, the first CL formed after OV induction in prepubertal heifers showed differences in functionality that can be differentiated by ultrasonography parameters diameter and area of CL, NV, % of vascularization and PI.
Descrição
Palavras-chave
Ciclo estral curto, Dispositivo de progesterona, GnRH, Indução hormonal, Puberdade, Luteólise prematura