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We evaluated the effects of nulliparous, primiparous, and multiparous conditions on the estrus and pregnancy rates in females that did not show estrus but were treated with gonadotropin-releasing hormone (GnRH) at the time of timed artificial insemination (TAI). Nelore females (n = 531) were allocated according to the following categories: nulliparous (n = 144), primiparous (n = 132), and multiparous (n = 255). The animals received a conventional TAI protocol, and estrus expression was identified by the absence of paint in the sacrococcygeal region on the day of TAI. Females that did not show estrus were treated with 10 µg of GnRH together with insemination. The rates of estrus and pregnancy were analyzed using a logistic regression model (P < 0.05). The estrus expression was lower (P = 0.006) in the primiparous (61.36%) group than in the nulliparous (76.39%) and multiparous (75.69%) groups. Similar pregnancy rates were observed in females that showed estrus (nulliparous 84.54%, primiparous 86.42%, and multiparous 80.31%; P = 0.39) and in females that did not show estrus and received GnRH (nulliparous 41.18%, primiparous 56.86%, and multiparous 58.06%; P = 0.24). The total pregnancy rates were also similar (P = 0.98) among the categories (nulliparous 74.3%, primiparous 75.0%, and multiparous 74.9%). The primiparous females had a lower rate of estrus, and the pregnancy rates were similar among the categories that received GnRH. O objetivo do trabalho foi avaliar o efeito das categorias nulíparas, primíparas e multíparas sobre a taxa de manifestação de estro e a taxa de prenhez de fêmeas que não manifestaram estro, mas foram tratadas com GnRH no momento da inseminação artificial em tempo-fixo (IATF). Foram utilizadas 531 matrizes, todas da raça Nelore, alocadas de acordo com a categoria: nulíparas (n = 144), primíparas (n = 132) e multíparas (n = 255). As matrizes foram submetidas a um protocolo reprodutivo para inseminação artificial em tempo-fixo (IATF) e tiveram a expressão do estro identificada pela ausência de tinta na região sacrococcígea no dia da inseminação. As fêmeas que não apresentaram estro receberam 10 µg de GnRH no momento que foram inseminadas. As taxas de estro e prenhez foram analisadas por meio de um modelo de regressão logística (P < 0,05). A expressão do estro foi menor (P = 0,006) no grupo de primíparas (61,36%) do que nos grupos de nulíparas (76,39%) e multíparas (75,69%). Taxas de prenhez semelhantes foram observadas em fêmeas que apresentaram estro (nulíparas 84,54%, primíparas 86,42% e multíparas 80,31%; P = 0,39) e em fêmeas que não apresentaram estro e receberam GnRH (nulíparas 41,18%, primíparas 56,86% e multíparas 58,06%; P = 0,24). As taxas de prenhez total também foram semelhantes (P = 0,98) entre as categorias (nulíparas 74,3%, primíparas 75,0% e multíparas 74,9%). As fêmeas primíparas apresentaram menor taxa de estro e as taxas de prenhez foram semelhantes entre as categorias que receberam GnRH.

We evaluated the effect of quercetin on the in vitro culture of bovine ovarian fragments in relation to morphology, development, and oxidative stress. Ovaries (n = 12) from Nelore heifers (n = 6) were used. Each pair of ovaries was divided into nine fragments, and one fragment from each animal was fixed in Bouin solution for 24 h (histology control) or frozen (− 80°C; control for oxidative stress). Other ovarian fragments (n = 8) were distributed into concentrations of 0, 10, 25, and 50 μg/mL of quercetin added to the culture medium for 5 or 10 d. Data were analyzed by chi-square test or ANOVA followed by Tukey’s test (P 0.1) was observed in the production of reactive oxygen species or in the oxidative degradation of lipids between treatments and non-cultivated controls. Treatment with 25 μg/mL quercetin preserved the morphological integrity of the developing follicles for 5 and 10 d of culture, in addition to promoting the best antioxidant potential after 10 d of culture in bovine ovarian fragments.

Melhorar o desempenho reprodutivo é importante para aumentar a lucratividade das propriedades. Assim, nós avaliamos a contagem de folículos antrais (CFA), o escore de condição corporal (ECC), o peso vivo e o comportamento animal sobre à taxa de concepção de vacas Brahman submetidas à inseminação artificial em tempo-fixo (IATF). Vacas (n=122) receberam um protocolo convencional de IATF de três manejos (D0, 8 e 10) a base de estrógeno e progesterona, além do monitoramento da expressão de estro antes da inseminação. O ECC e o comportamento animal foram avaliados em todos os dias do protocolo, o peso foi mensurado no D0 e no diagnóstico de gestação (D40) e a CFA no D0. Para análise, estabeleceu-se os grupos de CFA (baixa, intermediária e alta), do comportamento (calma, inquieta e agitada), do peso (ganhando, mantendo e perdendo) e do ECC (ganhando, mantendo e perdendo). A taxa de concepção geral foi de 50%, e não esteve associada (p>0,05) a classificação da CFA (baixa/52,6%, intermediária/50,9% e alta/45,4%), do peso (ganhando/43,0%, mantendo/54,7% e perdendo/47,1%), do ECC (ganhando/44,0%, mantendo/54,3% e perdendo/37,5%) e do comportamento (calma/43,0%, inquieta/54,7% e agitada/47,1%). No entanto, a baixa CFA apresentou maior (p=0,05) proporção de animais com alta intensidade de estro (94,7%) e foi observado maior escore de reatividade (p=0,001) no primeiro dia de manejo da IATF em relação aos outros dias. Vacas com baixa CFA resultaram em maior proporção de expressão de estro e o primeiro dia de manejo da IATF determinou uma maior reatividade animal em relação aos outros dias do protocolo. Palavras-chave: Condição Corporal. Inseminação Artificial. Performance Reprodutiva. Peso Vivo. Abstract Improving reproductive performance is important to increase farm profitability. The relationship of antral follicle count (AFC), body condition score (BCS), weight, and animal behavior on the conception rate in cows submitted to timed artificial insemination (TAI). Cows (n=122) received a conventional TAI protocol of three managements (D0, 8, and 10) based on estrogen and progesterone, in addition to monitoring estrus expression before insemination. The BCS and behavior score were assessed every day of the TAI protocol. Weight was measured at D0 and in the pregnancy diagnosis (D40), and AFC was determined at D0. For analysis, the groups were established according to AFC (low, intermediate, and high), behavior animal (calm, restless, and agitated), weight variation (gaining, maintaining, and losing), and BCS variation (gaining, maintaining, and losing). The overall conception rate was 50%, and it was not associated with (P>0.05) the AFC classification (low/52.6%, intermediate/50.9%, and high/45.4%), weight variations (gaining/43.0%, maintaining/54.7%, and losing/47.1%), BCS variations (gaining/44.0%, maintaining/54.3%, and losing/37.5%) and animal behavior (calm/43.0%, restless/54.7%, and agitated/47.1%). However, the low AFC showed a higher (P=0.05) proportion of animals with high intensity of estrus expression (94.7%). In addition, a higher score for animal reactivity (P=0.001) was noted on the first day of the management of TAI protocol than to the other days of the hormonal protocol. The low AFC resulted in a higher proportion of cows with high estrus expression and the management practices for TAI determined a greater animals reactivity at the beginning of the breeding program. Keywords: Body Condition. Artificial Insemination. Reproductive Performance. Live Weight.