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Master's Dissertation
DOI
https://doi.org/10.11606/D.10.2020.tde-30042019-151828
Document
Author
Full name
Marcos Henrique Alcantara Colli
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Baruselli, Pietro Sampaio (President)
Macedo, Gustavo Guerino
Nogueira, Guilherme de Paula
Title in Portuguese
Resposta folicular e taxa de prenhez de novilhas Nelore pré-púberes tratadas com Kisspeptina ou GnRH no momento da IATF
Keywords in Portuguese
Bos indicus
Neuropeptídios
Novilha
Ovulação
Pré-Púbere
Abstract in Portuguese
Objetivou-se nesse estudo avaliar a sincronização da ovulação, taxa de ovulação, taxa de prenhez e perda gestacional após o tratamento com Kisspeptina (Kp) ou GnRH no momento da inseminação artificial em tempo fixo (IATF) em novilhas Nelore pré-púberes de 14 meses de idade. No Experimento 1, avaliou-se o momento, dispersão e taxa de ovulação. No Experimento 2, avaliou-se a taxa de ovulação, diâmetro do corpo lúteo (CL) pós ovulação, taxa de prenhez aos 30 e 60 dias após a IATF, bem como a perda gestacional. Em ambos os experimentos foram utilizadas somente novilhas pré-púberes (sem CL) avaliadas por dois exames ultrassonográficos com intervalo de 10 dias. As novilhas foram sincronizadas com um implante auricular contendo 3mg de Norgestomet associado ao tratamento intramuscular (i.m.) de 1mg de benzoato de estradiol (BE) no D0. Após 8 dias (D8), o implante foi removido e as novilhas receberam 200UI i.m. de gonadotrofina coriônica equina (eCG), 0,5mg i.m. de cipionato de estradiol (CE) e 0,265mg i.m. de cloprostenol sódico (PGF). Após 48 horas da remoção do implante auricular (D10), as novilhas foram distribuídas em um de três grupos experimentais. Controle: sem tratamento adicional; Kiss: tratamento i.m. com 3,0mg de Kisspeptina-10 e; GnRH: tratamento i.m. com 0,01mg de acetato de buserelina. No Experimento 1, foram utilizadas 30 novilhas (Controle, N=10, Kiss, N=10 e; GnRH, N=10) avaliadas por ultrassonografia no D8am (0h), D9am (24h), D10am (48h), D10pm (60h), D11am (72h), D11pm (84h) para mensurar o diâmetro do maior folículo (MF) e o momento da ovulação. No Experimento 2, 592 novilhas foram inseminadas em tempo fixo (Controle, N=200, Kiss, N=198 e; GnRH, N=194). Foram realizadas avaliações ultrassonográficas no D8 e D10 para mensuração do MF e no D17 para confirmar a ovulação e mensurar o CL, no D40 e D70 para avaliar a taxa de prenhez e perda gestacional. No Experimento 1 não se verificou efeito de tratamento para o tamanho do folículo ovulatório (P=0,51), momento (P=0,51), taxa (P=0,83) e dispersão da ovulação (P=0,62). No Experimento 2, não se verificou efeito de tratamento na taxa de ovulação (P=0,38), taxa de prenhez aos 30 (P=0,77) e 60 dias (P=0,50) e perda gestacional (P=0,17). Verificou-se efeito da expressão de estro na taxa de ovulação (P<0,0001) e de prenhez aos 30 (P=0,03) e 60 dias (P=0,003). Não se verificou efeito de estro na perda gestacional (P=0,98). Verificou-se interação tratamento*estro para taxa de ovulação (P=0,04). Novilhas tratadas com GnRH apresentaram taxa de ovulação semelhante, independentemente da manifestação de estro. Entretanto, esse resultado não foi verificado nas novilhas do grupo controle e Kiss. Não se verificou interação tratamento*estro na taxa de prenhez aos 30 (P=0,24) e 60 dias (P=0,63) e, perda gestacional (P=0,99). Conclui-se que o tratamento com Kiss ou GnRH não melhora a sincronização, taxa de ovulação, prenhez aos 30 e 60 dias e, perda gestacional. Entretanto, as novilhas que demonstraram estro apresentaram maior taxa de ovulação, prenhez aos 30 e 60 dias após a IATF.
Title in English
Follicular response and pregnancy rate of prepubertal Nellore heifers treated with Kisspeptin or GnRH at TAI
Keywords in English
Bos indicus
Heifer
Neuropeptides
Ovulation
Prepubertal
Abstract in English
The objective of this study was to evaluate the synchronization of ovulation, ovulation rate, pregnancy rate and pregnancy loss after treatment with Kisspeptin (Kiss) or GnRH at timed artificial insemination (TAI) in 14-month old prepubertal Nellore heifers. On Experiment 1, ovulation was evaluated regarding moment, dispersion and rate. On Experiment 2, ovulation rate, corpus luteum (CL) diameter post-ovulation, pregnancy rate 30 and 60 days after TAI and pregnancy loss were evaluated. Both experiments used only prepubertal heifers (without CL) evaluated by two ultrasound examinations with an interval of 10 days. The heifers were synchronized with an auricular implant containing 3mg of Norgestomet associated to an intramuscular (i.m.) treatment of 1mg of estradiol benzoate (EB) on D0. After 8 days (D8), the implant was removed and the heifers received 200IU i.m. of equine chorionic gonadotropin (eCG), 0.5mg i.m. of estradiol cipionate (EC) and 0.265mg i.m. of sodic cloprostenol (PGF). After 48 hours of the auricular implant removal (D10), heifers were distributed into three experimental groups. Control: without additional treatment; Kiss: i.m. treatment with 3.0mg of Kisspeptin-10 and; GnRH: i.m. treatment with 0.01mg of buserelin acetate. On Experiment 1, 30 heifers (Control, N=10; Kiss, N=10; GnRH, N=10), were evaluated using ultrasonography on D8am (0h), D9am (24h), D10am (48h), D10pm (60h), D11am (72h), D11pm (84h) to measure the diameter of the largest follicle (LF) and moment of ovulation. On Experiment 2, 592 heifers were submitted to timed artificial insemination (Control, N=200; Kiss, N=198 and; GnRH, N=194). Ultrasound evaluations were performed on D8 and D10 to measure the LF and on D17 to confirm ovulation and to measure the CL, on D40 and D70 to evaluate pregnancy rate and pregnancy loss. On Experiment 1 no treatment effect was verified for ovulatory follicle size (P=0.51), moment (P=0.51), rate (P=0.83) and dispersion of ovulation (P=0.62). On Experiment 2, no treatment effect was verified for ovulation rate (P=0.38), pregnancy rate at 30 (P=0.77) and 60 days (P=0.50) and pregnancy loss (P=0.17). Estrus expression effect was verified on ovulation (P<0.0001) and pregnancy rates at 30 (P=0.03) and 60 days (P=0.003). No estrus effect was observed on pregnancy loss (P=0.98). Treatment*estrus interaction was verified on ovulation rate (P=0.04). Heifers treated with GnRH presented similar ovulation rate, independently of estrus manifestation. However, this result was not verified for heifers of the control and Kiss groups. Treatment*estrus interaction was not verified on pregnancy rate at 30 (P=0.24) and 60 days (P=0.63) and, on pregnancy loss (P=0.99). It is concluded that treatment with Kiss or GnRH does not improve synchronization, ovulation rate, pregnancy at 30 and 60 days and pregnancy loss. However, heifers that demonstrate estrus presented higher ovulation rate and pregnancy 30 and 60 days after TAI.
 
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Publishing Date
2020-03-18
 
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