Estrógeno exógeno para indução do comportamento de estro no início do ciclo estral em vacas leiteiras

• Ano de defesa: 2008
• Autor(a) principal: Almeida Neto, José Rogério Moura de
• Orientador(a): Costa, Eduardo Paulino da
• Banca de defesa: Guimarães, José Domingos , Sá, Wanderlei Ferreira de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Medicina Veterinária
• Departamento: Biotecnologia, diagnóstico e controle de doenças; Epidemiologia e controle de qualidade de prod. de
• País: BR
• Palavras-chave em Português: Bovinos; Ciclo estral; Tratamento hormonal
• Palavras-chave em Inglês: Cattle; Estrous cycle; Hormonal treatment
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA
• Link de acesso: http://locus.ufv.br/handle/123456789/5067

The objective of this work was to check the exogenous estrogen, in early phase of estrous cycle, on the range of estrus reduction. The experiment was conducted in Campo Experimental Santa Mônica (CESM). Sixteen Holsteinzebu crossbred cows were used, distributed in two groups, according to the used hormone (estradiol). These animals had body score ≥ 3,0 (scale of 1 to 5), were non-lactating, with average live weight of 458 kg. Animals cycling regularly were selected by gynecological exam (rectal palpation and vaginoscopic examination). The animals without any clinical or reproductive alterations were used in the experiment. The cows were casually included in their treatments. Treatment 1: eight cows received 2,5 mL of estradiol cipionate at the first day of the estrous cycle (considering day 0 the estrus day), intramuscularly (IM) injected into the hip region, with a 25 X 0,7 mm needle. Treatment 2 (control): eight cows without treatment constituted the control group. The expression of estrus was monitored visually during one hour, three times a day. The ultrasound scans were conducted via transrectal. The measurements began at the estrus day and were done daily in the morning by a single operator. The diameters of the biggest and the second biggest follicles in each ovary were registered. The morphologic characteristics of the corpus luteum were evaluated daily during the estrous cycle, measuring the crosssectional area (cm2). The blood collections for the measurements of the levels of progesterone began at the estrus day (0 day) and were conducted once every three days until the next estrus day. All the animals that received estrogen at the first day after the estrus showed the estrus signals (psychics, turgid uterus and abundant mucus) the next day. It was observed that six animals showed these signals for two consecutive days. This reduction of the range of estrus for two days can promote the elimination of uterus bacteria (if present), enhancing, consequently, the reproductive capacity. It s known that some estrus alterations can promote the elimination of in-uterus infections (clinical or sub clinical), and the reduction of the range of estrus is indicated for the treatment of such diseases. Except for the day of the first follicular wave emergence, all the other studied variables (number and wave length, characteristics of dominant and subordinate follicles and the parameters related to the corpus luteum and progesterone production) weren t affected by the application of estrogen the day after the estrus. In this experiment, the follicular dynamic of the crossbred cows (Holstein X Zebu) showed a two or three follicular wave growth pattern, regardless of the treatment with estrogen and was the same to the treated and control groups (37,5% with two wave cycles and 62,5% with three wave cycles). The application of estradiol cipionate in crossbred cows (Holstein X Zebu) the day after the natural estrus promote the emergence of estrus sign (psychic, turgid uterus and abundant mucus) two days after the natural estrus, without affecting the next estrous cycle.