RESUMEN
ABSTRACT Global advances in reproductive biotechnology have allowed for the transfer of embryos from donor females with high genetic merit to recipients using the cryopreservation technique, which preserves an embryo of excellent quality and viability, thereby achieving a feasible pregnancy rate. The objective of this study was to evaluate the quality and viability of Holstein embryos that have been cryopreserved for more than 40 years under glycerol freezing. The embryos were transferred to the recipient heifers using a non-surgical method. Two 17-month-old Holstein heifers (360 kg live weights) which were clinically healthy and reproductively active were used as the recipients. Two bovine embryos of Grade 1 quality were thawed and evaluated for their morphology. Of the two embryo transfers, one pregnancy was achieved, resulting in the birth of a calf. Therefore, embryos frozen in liquid nitrogen and glycerol as a cryopreservative for more than 40 years maintained their quality and viability to produce a live calf.
RESUMO Os avanços globais em biotecnologia reprodutiva permitiram a transferência de embriões de fêmeas doadoras com alto mérito genético para receptoras, usando-se a técnica de criopreservação, que preserva um embrião de excelente qualidade e viabilidade, alcançando, assim, uma taxa de gravidez viável. O objetivo deste estudo foi avaliar a qualidade e a viabilidade de embriões Holstein, criopreservados por mais de 40 anos, sob congelamento de glicerol. Os embriões foram transferidos para as novilhas receptoras, usando-se um método não cirúrgico. Duas novilhas Holstein de 17 meses de idade (360kg de peso vivo), que eram clinicamente saudáveis e reprodutivamente ativas, foram utilizadas como receptoras. Dois embriões bovinos de qualidade Grau 1 foram descongelados e avaliados quanto à sua morfologia. Das duas transferências embrionárias, uma gravidez foi obtida, resultando no nascimento de um bezerro. Portanto, os embriões congelados em nitrogênio líquido e glicerol como criopreservante por mais de 40 anos mantiveram sua qualidade e viabilidade para produzir um bezerro vivo.
RESUMEN
A total of 600 serum samples from five farms were collected and the geographic coordinates of each farm were georeferenced to establish two Köppen climate classes (wet tropical and tropical rainforest). Serum samples were examined by commercially available enzyme-linked immunosorbent assay (ELISA) kits to detect antibodies against N. caninum and T. gondii, while anti-B. abortus antibodies were analysed using the Rose Bengal test and ELISA kit. The overall estimated prevalence of N. caninum, T. gondii and B. abortus was 41.2%, 30.7% and 0.5%, respectively. The highest percentages of positive buffaloes with neosporosis and toxoplasmosis were found in the states of Tabasco (46.7%, wet tropical climate) and Veracruz (32.7%, tropical rainforest climate), respectively. Multivariate logistic regression showed that N. caninum seropositivity in buffalos was associated with the normalized difference vegetation index (NDVI) (OR: 1.068; 95% CI: 1.026-1.112; P = 0.001) and tropical climate regions (OR: 1.737; 95% CI: 1.112-2.712; P = 0.015). In addition, statistical analysis revealed that sex (OR: 1.737, 95% CI: 1.685-9.737; P = 0.002), NDVI (OR: 1.382; 95% CI: 1.095-1.746; P = 0.007) and rainfall (OR: 1.478; 95% CI: 1.110-1.967; P = 0.007) were significant risk factors for T. gondii infections. These results indicate that the potential impact of the risk factors was different for each disease in buffaloes, which may be useful for developing regionally adapted control strategies and preventive measures.