918 resultados para VACAS HOLSTEIN - INSEMINACIÓN ARTIFICIAL
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The dairy sector has undergone considerable economic losses due to low fertility rates due to adverse effects of heat stress on reproduction of cows. Genetic selection for increased production, coupled with the expanding dairy to tropical areas of the planet, and global warming has further aggravated the problem of heat stress. The effects of heat stress are multifactorial and act directly or indirectly at various levels of reproductive tissues, resulting in low fertility of cows, which in practice, results in reduced reproductive efficiency in the property, reducing the producers’ profit. Some strategies related to breeding biotechnology such as fixed-time artificial insemination, embryo transfer and use of BST, can minimize these effects and improve the reproductive efficiency of the herd
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Current cattlemen must seek methods to maximum reproductive efficiency of their beef herds, making the business competitive and enhancing greater profitability. For the cow-calf producers, efficiency translates into more cows producing one calf every year. Fixed-time artificial insemination (TAI) is one of several technologies that producers utilize to reach this goal. Postpartum anestrus is one of the biggest obstacles to overcome in order to obtain suitable results at the end of the breeding season. The TAI protocols are efficient in re-establishing cyclicity in noncycling cows during the postpartum period, streamlining the use of labor on farms, allowing the use of artificial insemination (AI) on a large scale, and introducing superior genetics to the herd. The protocols that are most commonly used in Brazil are based on progesterone (P4) releasing devices that prevent premature estrus and ovulation; and estradiol (E2) to synchronize the initiation of a new follicular wave. In such protocols, administration of equine chorionic gonadotropin (eCG) helps the development of the follicle, increases ovulation rate, improves the endocrine and uterine environment during proestrus and diestrus, and improves fertility. The use of eCG in TAI protocols for suckled cows, non-lactating cows and heifers increases the pregnancy rate allowing more calves at the end of the breeding season and higher profitability to the cattlemen
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Climate change in tropical countries, like Brazil, causes major problems in dairy production due to an increase of heat stress effects. In recent years, milk production in Brazil increased 36.07%. The Southeast region remains a leader in production with herds of high producing Holstein cattle (mostly), which is more susceptible to heat stress. Thermal stress decreases fertility in direct and indirect ways. Conception rates are reduced of 40-60% during cooler months of the year and 10-20% in the warmer months. Negative effects of heat stress involve changes in reproductive hormones, follicular development, oocytes, and embryos, and decreased dry matter intake. Several studies discuss change in reproductive hormones, such as reduction in plasma concentration of GnRH, LH, and oestradiol, which lead to decreased detection of estrus and ovulation. Various methods are being studied to bypass these negative effects and increase the fertility of dairy cows under heat stress. Cooling systems are the most advantageous and can be associated with technologies such as ET and TAI
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Zootecnia - FCAV
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A bovinocultura é um dos principais destaques dentro do universo pecuário brasileiro e mundial, uma vez que o rebanho nacional é detentor do expressivo número de 200 milhões de cabeças entre as atividades de corte e leite, produzindo um valor bruto estimado em 67 bilhões de reais. Ainda assim, a pecuária de corte nacional apresenta baixos índices produtivos por continuar sendo conduzida, ao menos em considerável parcela do país, como uma atividade extrativista que emprega reduzido uso de insumos e biotecnologias, como inseminação artificial, transferência de embriões, fertilização in vitro e inseminação artificial em tempo fixo. No atual cenário mundial, essa característica da bovinocultura brasileira necessita ser alterada para que a atividade torne-se ainda mais rentável e competitiva. Neste caso, a pecuária de corte nacional terá que se apoiar no aumento de sua eficiência reprodutiva e produtiva, tendo como principais alternativas para atingir tal objetivo a elevação do número de vacas com estro no início da estação de monta, o aumento na taxa de concepção no primeiro serviço e a redução no intervalo entre partos, de improdutivos 21 meses para um ano, tempo considerado ideal e de máxima eficiência reprodutiva de um rebanho. Assim sendo, torna-se imprescindível elencar os principais fatores prolongadores do intervalo entre partos para, somente depois, instituir um ou mais métodos para se reduzir essa eficiência reprodutiva e finalmente impulsionar ainda mais a pecuária bovina brasileira
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Pós-graduação em Medicina Veterinária - FMVZ
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Ciência Animal - FMVA
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The aim of this study was to evaluate the serum protein concentration in newborns fed with colostrum derived from healthy cows (n = 10), cows with subclinical mastitis (n = 10) and cows with clinical mastitis (n = 10). 30 Holstein cows were assigned to their respective groups according to macroscopic examination of colostral secretion, somatic cell count, CMT and presence of bacteria in colostrum samples. Blood samples of the calves were collected immediately after birth, at 24 and 48 hours after ingestion of colostrum. The total protein was measured by the biuret method and the concentrations of immunoglobulin A (IgA), immunoglobulin G (IgG), transferrin, albumin and haptoglobin was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). No differences were obser- ved amongst groups in the concentrations of albumin, total protein and IgA. In animals from cows with subclinical and clinical mastitis haptoglobin concentrations were higher than those of healthy animals. The concentrations of IgG and transferrin were significantly lower in calves from cows with mastitis. We concluded that the ingestion of colostrum from infected and uninfected glands from cows with mastitis (GII e GIII) is unlikely to be an important contributor to the high rate of failure of passive transfer of immunoglobulins in calves.