ABSTRACT The sheep populations of the Colombian Caribbean Region are characterized by having a high phenotypic heterogeneity mainly due to the use of Creole animals in crossbreeding with exotic breeds. The aim of this study was to estimate the genetic diversity and the population structure of sheep in this region. In total, 459 sheep from 26 farms in 19 municipalities were selected. The DNA samples were genotyped with the ovine low-density chip (15K). Analyses of molecular variance, genetic diversity and population structure were performed. At the phenotypic level, 65.8% of the sampled animals were assigned to the Criollo population, while 15.7% showed signs of introgression with other commercial breeds (mestizos). The populations presented a high degree of genetic diversity within individuals (90.6%) and low levels of genetic variation between populations (FST = 0.075). This low differentiation, together with the low levels of genetic variation between populations, could be attributed to a lack of selection pressure and the existence of gene flow (crossbreeding) between populations.

RESUMEN Las poblaciones ovinas de la Región Caribe colombiana se caracterizan por tener una alta heterogeneidad fenotípica debido principalmente al uso de animales criollos en cruzamiento con razas exóticas. El presente estudio tuvo como objetivo estimar la diversidad genética y la estructura poblacional de ovinos de esta región. Se seleccionaron 459 animales ovinos de 26 granjas de 19 municipios. Las muestras de ADN fueron genotipadas con el chip ovino de baja densidad (15K). Se realizaron análisis de varianza molecular, diversidad genética y estructura poblacional. A nivel fenotípico, se asignó el 65.8% de los animales muestreados a la población Criollo mientras que 15.7% presentaron señales de introgresión con otras razas comerciales (mestizos). Las poblaciones presentaron un alto grado de diversidad genética dentro de los individuos (90.6%) y bajos niveles de variación genética entre poblaciones (FST = 0.075). Esta baja diferenciación, junto con los bajos niveles de variación genética entre poblaciones podría atribuirse a una falta de presión de selección y a la existencia de un flujo genético (mestizaje) entre las poblaciones.

ABSTRACT The aim of this study was to evaluate the effect of adding ascorbic acid (AA) to the vitrification medium of bovine preantral follicles (PFs) subjected previously to cooling at 4 °C for 4 h or 24 h. Ovaries were collected from Nelore heifers at 14 months of age. In the laboratory, ovarian fragments were removed from the cortical region and distributed to fragments as fresh control (C0h), and fragments to cooling at 4 ºC for 4 and 24 hours in TCM-199 plus HEPES and antibiotics. Of the cooled fragments, two were fixed as controls for each cooling time (C4h, C24h), and the remaining fragments were distributed in four vitrification treatments, using the TCM-199 medium associated with ethylene glycol and dimethyl sulfoxide (V), sucrose (VSUC) or ascorbic acid (VAA), and the treatment with ethylene glycol, dimethyl sulfoxide, sucrose and AA (VSUC+AA). After 72 h, fragments were warmed and fixed for histological analysis and mechanical follicular isolation. No difference (p>0.05) between C0h and C4h for morphologically normal PFs was detected (99.3 and 96.0%, respectively). Vitrification reduced the morphological integrity and follicular viability in all treatments compared to C0h; nevertheless, VAA treatment maintained the follicular viability like C24h (p>0.05). It is concluded that bovine PFs were conserved efficiently at 4 °C during 4 h, and the addition of ascorbic acid to the vitrification medium improved survival rates and kept the morphological integrity of the follicles.

RESUMEN El objetivo del estudio fue evaluar el efecto de la adición de ácido ascórbico (AA) al medio de vitrificación de folículos preantrales (FPs) bovinos previamente enfriados a 4 °C durante 4 o 24 h. Se recolectaron ovarios de novillas Nelore a los 14 meses de edad. En el laboratorio se extrajeron fragmentos de ovario de la región cortical y se distribuyeron a fragmentos para control fresco (C0h), y fragmentos para refrigeración a 4 ºC por 4 y 24 horas en TCM-199 más HEPES y antibióticos. De los fragmentos enfriados, dos se fijaron como controles para cada tiempo de enfriamiento (C4h, C24h), y los restantes se distribuyeron en cuatro tratamientos de vitrificación, utilizando el medio TCM-199 asociado con etilenglicol y dimetilsulfóxido (V), sacarosa (VSUC) o ácido ascórbico (VAA), y el tratamiento con etilenglicol, dimetilsulfóxido, sacarosa y AA (VSUC+AA). Después de72h, los fragmentos se calentaron y fijaron para el análisis histológico y el aislamiento folicular mecánico. No se detectó diferencia (p>0.05) entre C0h y C4h para FPs morfológicamente normales (99.3 y96.0%, respectivamente). La vitrificación redujo la integridad morfológica y la viabilidad folicular en todos los tratamientos en comparación con C0h; sin embargo, el tratamiento VAA mantuvo la viabilidad folicular similar a C24h (p>0.05). Se concluye que los FAs bovinos se conservaron eficientemente a 4 °C durante 4 h, y la adición de ácido ascórbico al medio de vitrificación mejoró las tasas de supervivencia y mantuvo la integridad morfológica folicular.

RESUMO: O Complexo de Doenças Respiratórias Bovinas causa perdas significativas aos produtores de gado. Sua apresentação envolve a interação entre múltiplos patógenos virais e bacterianos, dentre os agentes virais estão: vírus da diarreia viral bovina (BVDV), alphaherpesvírus bovino tipo 1 (BoHV-1), vírus da parainfluenza bovina 3 (bPI3v) e vírus sincicial respiratório bovino (BRSV); esses vírus têm sido pouco estudados em populações de búfalos. O objetivo deste estudo foi avaliar a presença destes vírus em populações de búfalos do departamento de Córdoba, Colômbia. Foi realizado um estudo transversal, avaliando 37 fazendas e 861 bubalinos. As soroprevalências em animais foram: 21.7% (BVDV), 51.5% (BoHV-1), 73.6% (bPI3v) e 58.9% (BSRV) e as soroprevalências em fazendas foram: 94.6% (BVDV), 100% (BoHV-1), 100% (bPI3v) e 100% (BSRV). Por outro lado, a soropositividade múltipla em búfalos ou infectividades acontecidas dos agentes virais foi de 23.3% para um único vírus, 31.8% para dois vírus, 29.4% para três vírus e 7.1% para os quatro vírus; apenas 8.4% dos búfalos foram soronegativos para os quatro vírus. Este é o primeiro estudo epidemiológico regional em populações de búfalos da Colômbia, os resultados evidenciam a circulação viral e múltiplas infecções em animais; além disso, as altas prevalências encontradas apresentam um cenário epidemiológico preocupante.

ABSTRACT: The bovine respiratory disease complex causes sizable losses for livestock producers. Its presentation involves the interaction among multiple viral and bacterial pathogens. Viral agents include: bovine viral diarrhea virus (BVDV), bovine alphaherpesvírus 1 (BoHV-1), bovine parainfluenza virus (bPI3v) and bovine respiratory syncytial virus (BRSV); so far, these viruses have been little studied in the buffalo population. This study is aimed to assess the presence of these viruses in buffalo populations of the department of Córdoba, Colombia. A transversal study was conducted upon assessment of 37 farms and 861 buffaloes. Seroprevalence in animals were as follows: 21.7% (BVDV), 51.5% (BoHV-1), 73.6% (bPI3v) and 58.9% (BSRV), while seroprevalence in farms stood at: 94.6% (BVDV), 100% (BoHV-1), 100% (bPI3v) and 100% (BSRV). Conversely, the multiple seropositivity in buffaloes or past coinfection of viral agents amounted to 23.3% for a single virus, 31.8% for two viruses, 29.4% for three viruses and 7.1% for four viruses; only 8.4% of buffaloes were seronegative for four viruses. This is the first regional epidemiological study in the buffalo populations of Colombia and the results showed viral circulation and multiple seropositivity in animals; in addition, the high prevalence found pose a concerning epidemiological threat.