Search

Progesterone (P4) is essential for embryonic development and maintenance of pregnancy when deficiency causes early embryonic loss. In this study, we investigated the ability of hormonal supplementation to improve the fertility of Nellore females subjected to fixed-time artificial insemination (IATF) protocols. Here, we evaluated the effect of long-acting injectable progesterone (iP4) supplementation in the D4 after IATF on pregnancy rate and pregnancy loss in Nellore females (Bos taurus indicus) from different reproductive categories in Western Amazonia. Materials, Methods & Results: Eight hundred thirteen Nellore females from 5 farms were selected and distributed into 2 groups: control [GC; administration of 0.5 mL of 0.9% saline solution, intramuscularly - IM] (n = 407) and a group that received injectable progesterone (iP4) that was long-acting [GiP4; administration of 0.5 mL of iP4, 300 mg, via IM four days after IATF] (n = 406). Each group contained 3 subgroups: heifers, primiparous cows, and multiparous cows. Of the 407 animals in the CG, 103 were heifers, 107 primiparous, and 197 multiparous. Of the 406 animals in the GiP4 group, there were 101 heifers, 107 primiparous, and 198 multiparous. On a random day of the estrous cycle (D0), an intravaginal device containing 1 g of P4 and 2 mg of estradiol benzoate (BE) was inserted by intramuscular injection. On D8, the P4 device was removed and 150 μg of D-cloprostenol (PGF2α), 300 IU eCG, and 1 mg BE were administered IM. Cows were inseminated at D10, 48-52 h after procedure on D8. Pregnancy diagnosis was made between 35 and 40 days after insemination through ultrasound examination. Between 80 and 90 days after insemination, a new ultrasound examination was performed to assess early pregnancy loss. The data were processed using the SAS 9.2. The conception rate, pregnancy loss, and final conception rate were analyzed using PROC GLIMMIX according to groups (CG and GiP4), categories (heifers, primiparous and multiparous), and their interactions as variables. The differences in the means of least squares were adjusted using the Tukey?Kramer method. Statistical significance was defined as P < 0.05. The general conception rate was 46% (375/816). Regardless of the animal class, GiP4 animals (51.97%) had higher conception rates (P < 0.05) than CG (40.29%). In the subgroups (heifers, primiparous and multiparous cows), there was a difference (P < 0.05) between animals treated with iP4 (52.48%, 57.94%, and 48.48%, respectively) and those who were not (39.81%, 41.12%, and 40.10%, respectively). Gestational losses, regardless of the animal class, were higher in females in the CG (7.93%) [P < 0.05] compared to those in the GiP4 group (2.84%). Regardless of treatment with iP4, the percentage of gestational loss in heifers was significantly higher (10.64%) than that in primiparous and multiparous cows (3.77% and 2.86%, respectively). The final conception rates were higher in animals that received long-acting iP4, which increased the final pregnancy in all parity categories. Discussion: In the present study, the use of iP4 increased the pregnancy rate in Nellore females, regardless of the category. Although there has been no consensus on the use of iP4, there is an agreement that increases in the pregnancy rate are related to the moment of exogenous P4 application. In addition to influencing the pregnancy rate, reduction in pregnancy losses is also attributed to iP4 treatment, a fact demonstrated in the present study, where animals treated with iP4 had a lower pregnancy loss rate than normally occurs in beef cattle. Supplementation with long-acting iP4 increased the pregnancy rate at D35-40, reduced pregnancy losses, and increased the conception rate on D80-90 days in Nellore females reared in the Western Amazon, regardless of the animal category. Made available in DSpace on 2022-01-31T16:01:19Z (GMT). No. of bitstreams: 1 27293.pdf: 183754 bytes, checksum: 1d786ec7c3578c46ab24e7859d5545d5 (MD5) Previous issue date: 2021

Os pecuaristas brasileiros têm utilizado o cruzamento industrial entre raças zebuínas e taurinas com o intuito de elevar o ganho de características positivas dos animais, visando à produção de carnes nobres em locais de criação mais rústicos. Dessa maneira, avaliou-se o desempenho zootécnico de dois grupos genéticos de bovinos em pastos puros de Brachiaria humidicola e consorciados com Arachis pintoi BRS Mandobi nas condições ambientais de Rio Branco, Acre. O experimento foi realizado no período de maio a setembro de 2017, utilizando-se de 36 animais, sendo 18 Nelores e 18 cruzados meio-sangue Alberdeen Angus x Nelore (1/2 AN), recém-desmamados, não-castrados com idade e peso iniciais de 10 meses e 230 kg. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2x2, sendo dois grupos genéticos e dois tipos de pasto (puro e consorciado) com três repetições para avaliação das variáveis relacionadas aos piquetes determinando, dessa forma, os índices zootécnicos dos animais da raça Nelore e dos produtos do cruzamento industrial 1/2 AN, além de avaliar o valor nutritivo dos pastos puros e consorciados. O manejo utilizado garantiu qu a DMST fosse suficiente para não restringir o consumo do animal em ambos os pastos, mantendo uma disponibilidade de matéria seca maior que 4.000 kg/ha. A presença do amendoim forrageiro reduziu para 45,07% o crescimento de plantas daninhas quando comparado ao pasto puro. Para a concentração de ureia no plasma, observou-se diferença significativa entre os pastos e raça, sendo que a maior delas foi encontrada em animais do pasto puro. O ganho médio diário (GMD) e produtividade animal dos pastos consorciados foram superiores aos pastos puros e, além disso, os animais 1/2 AN do pasto em consórcio obtiveram ganhos superiores aos demais tratamentos, representando acréscimo de cerca de 80% no GMD, quando comparados aos Nelores em pasto puro. O cruzamento industrial e o consórcio de pastagens apresentam-se como tecnologias que podem agregar ganhos aos pecuaristas, além de favorecer o uso inteligente do ambiente amazônico, uma vez que essa combinação expressa resultados superiores aos obtidos convencionalmente. Made available in DSpace on 2018-08-03T00:58:23Z (GMT). No. of bitstreams: 1 26668.pdf: 407471 bytes, checksum: c33b5dcf1012c0c4ae1c128526525c70 (MD5) Previous issue date: 2018-08-02 Dissertação (Mestrado em Ciência Animal) - Programa de Pós-graduação em Sanidade e Produção Animal Sustentável na Amazônia Ocidental, Universidade Federal do Acre, Rio Branco. Orientador: Maykel Franklin Lima Sales.