RESUMEN Objetivo. El objetivo de este estudio fue determinar la precisión y el sesgo de predicción de valores genómicos directos (VGD) usando genotipos imputados a densidad media, en características productivas y reproductivas en ganado Holstein de Antioquia, Colombia. Materiales y métodos. Fueron genotipificados 31 animales con el chip Illumina BovineLD, 64 con el chip Illumina BovineSNP50v2 y 48 con el chip Illumina BovineHD. La imputación se realizó usando dos paneles de SNPs (6K y 40K) a una densidad 44K, usando el programa FINDHAP.f90 v4. Los efectos de los SNPs fueron estimados mediante el método bayes C, usando genotipos de baja densidad (6K) y genotipos imputados a una densidad media (44_imputado). La precisión y el sesgo de los VGDs fueron determinados mediante validación cruzada. Las características evaluadas fueron: producción de leche (PL), porcentaje de proteína (PRO), porcentaje de grasa (GRA), puntaje de células somáticas (SCS), intervalo entre partos (IEP) y días abiertos (DA). Resultados. Las precisiones de VGD (rpVGD.EBV) en todas las características evaluadas oscilaron entre 0.19 y 0.24 y el sesgo (bVGD.EBV) entre 0.03 y 0.16 cuando se usó el panel 6K y usando el panel 44K_imputado las precisiones fueron mayores, oscilado entre 0.24 y 0.33 y sesgo entre 0.03 y 0.26. Conclusiones. La precisión de predicción de los VGDs fue mayor cuando se usaron genotipos imputados a densidad media, en comparación con la precisión de predicción obtenida empleando genotipos de baja densidad. Por lo cual, en este estudio se concluye que la imputación de genotipos es muy útil dado que aumenta la confiabilidad de la evaluación genómica.

ABSTRACT Objective. The goal of this study was to determine the accuracy and bias of direct genomic values (DGV) using imputed genotypes at medium density in yield- and reproduction-related traits for Holstein cattle from Antioquia, Colombia. Materials and Methods. A total of 31 animals were genotyped with the Illumina BovineLD chip, 64 with Illumina BovineSNP50v2 and 48 with Illumina BovineHD. Two SNP panels (6K and 40K) were imputed to a density of 44K using the FINDHAP.f90 v4 program. The effects of the SNPs were estimated using the Bayes C method, using low-density (6K) genotypes as well as medium-density imputed genotypes (44_imputed). The accuracy and bias of the DGVs were determined by cross-validation. The evaluated traits were: milk yield (MY), percentage of protein (PP), percentage of fat (PF), somatic cell score (SCS), calving interval (CI) and open days (OD). Results. When using the 6K panel, the accuracy values for DGV (rpDGV.EBV) in all the studied traits ranged from 0.19 to 0.24, and the bias (bDGV.EBV) from 0.03 to 0.16. In contrast, using the 44K_imputed panel generated higher accuracy values ranging from 0.24 to 0.33 and a bias ranging from 0.03 to 0.26. Conclusions. The accuracy of prediction the DGV was higher with genotypes imputed to medium densities when compared to the accuracy of prediction obtained using low-density genotypes. Therefore, in this study it is concluded that the imputation of genotypes is very useful, because it improves the reliability of the genomic evaluation.

RESUMO. O Objetivo deste estudo foi determinar a associação genômica entre os marcadores do chip bovino LD (LD BeadChip) com características importantes na produção de leite. Foram utilizadas informações do programa de melhoramento genético da Universidade Nacional de Colômbia. BLUP-EBVs foram utilizados para a produção de leite (DY), porcentagem de gordura (FP), porcentagem de proteína (PP) e escore de células somáticas (SCS). 150 animais foram selecionados para extração de DNA do sangue ou sêmen e genotipados com o chip BovineLD (Illumina). A informação autossômica foi mantida e a edição da informação foi executada usando o programa Plink v1.07. Os efeitos dos SNPs foram determinados por Bayes C com o programa GS3. A frequência do alelo menor para a maioria dos marcadores no chip foi alta, o que aumenta a probabilidade de encontrar locos importantes segregando na população. As estimativas da fração de marcadores, com efeito, foram próximas de zero em quase todas as situações. Os marcadores mais importantes foram mapeados com ENSEMBL. Um total de 6510 SNPs autossômicos foram preservados, dos quais apenas uma proporção foi tomada com efeito a partir da função mista de Bayes C. Para cada característica foram encontrados genes importantes, como ANKS1B, CLCN1, NMBR e CTSD, para AL, FP, PP e SCS, respectivamente. Finalmente, a estimativa de Bayes-C permitiu a identificação de SNPs com possível associação com QTLs.

ABSTRACT. The objective of this study was to determine the genome association between markers of bovine LD BeadChip with dairy important traits. Information of breeding program of the Universidad Nacional de Colombia was used. BLUP-EBVs were used for dairy yield (DY), fat percentage (FP), protein percentage (PP) and somatic cell score (SCS). 150 animals were selected for blood or semen DNA extraction and genotyping with BovineLD BeadChip (Illumina). Autosomal information was retained and the editing information was performed using Plink v1.07 software. The effects of SNPs were determined by Bayes C with GS3 software. The minor allele frequency for most of the markers on the bead chip was high, which increases the probability of finding important loci segregating in the population. Estimations of fraction markers with an effect were close to zero in almost all cases. The most important markers were mapped by trait using ENSEMBL. A total of 6,510 autosomal SNPs were retained, out of which only a proportion with effect was taken from the mixed function of Bayes C. Important genes as ANKS1B, CLCN1, NMBR and CTSD, were found for each trait for AL, FP, PP and SCS respectively. Finally, Bayes C estimation allowed to identify specific SNPs possibly associated with QTLs.

Debido a que la FSH y su receptor cumplen un rol fundamental para la reproducción, el objetivo de este estudio fue determinar el efecto del polimorfismo A-320T en parámetros productivos y reproductivos en el ganado Holstein de Antioquia. Se utilizó la PCR-RFLP para amplificar un segmento de 970 pb del gen que codifica para el receptor de la hormona folículo estimulante (FSHR) que se digirió con la endonucleasa TaqI. El efecto de los genotipos de FSHR en los parámetros productivos y reproductivos se determinó mediante un Modelo Linear Mixto y se empleó la prueba de Tukey para establecer diferencias significativas entre las medias de los genotipos. El efecto de sustitución alélica se estudió mediante un modelo de regresión lineal donde los genotipos AA, AT y TT se transformaron a una escala de 0, 1 y 2 de acuerdo con el número de alelos T poseídos. Para el ganado Holstein de Antioquia el genotipo más común fue el AT (0,485) seguido por el TT (0,0417) y el AA (0,096). Las frecuencias alélicas fueron 0,339 y 0,660 para A y T. Los genotipos de FSHR no presentaron un efecto significativo en los parámetros productivos, excepto para el porcentaje de grasa (P<0.01) donde los individuos TT presentaron el mayor porcentaje. Los resultados mostraron que el alelo T parece mejorar el contenido de sólidos en leche, mientras que el alelo A mejora la producción de leche. Los parámetros reproductivos no se vieron afectados por este SNP pero los animales AT mostraron un mayor número de servicios por concepción. Se requieren más estudios para determinar si este SNP puede ser usado como marcador molecular.

Because FSH and its receptor play a fundamental role in reproduction, the objective of this research was determining the effect of the A-320T polymorphism in productive and reproductive traits in Antioquia Holstein cows. The PCR-RFLP was used to amplify a segment of 970 bp of the bovine follicle stimulating hormone receptor gene (FSHR) which was digested with the restriction enzyme TaqI. The effect of the FSHR genotypes on productive and reproductive traits was determinate by a Mixed Linear Model and Tukey Test was used to establish significant differences between means for the three genotypes. The effect of allelic substitution was studied through a linear regression model where the genotypes AA, AT and TT were transformed into a quantitative scale of 0, 1 and 2, respectively according to the number of possessed T alleles. In Antioquia Holstein cattle the most common genotype was the AT (0.485) followed by TT (0.417) and AA (0.096) genotypes. Allele frequencies were 0.339 for A and 0.660 for T, respectively. The FSHR genotypes did not exert a significant effect on the principal productive parameters, except for fat percentage (P<0.01) where the TT individuals presented the highest percent. Results showed that T allele seems to improve the solids in milk while A allele improves dairy yield. The reproductive parameters were not affected by this SNP but AT animals showed a higher number of services per conception. Further studies are required to determine whether this SNP may be used as a molecular marker.

Las tendencias mundiales en producción animal han llevado a disminuir el uso de compuestos antimicrobianos en la alimentación, generando la necesidad de implementar estrategias nutricionales que estimulen el crecimiento y promuevan la salud intestinal. Este estudio tuvo como objetivo determinar si la adición de E. faecium en el agua potable mejora parámetros morfométricos intestinal en cerdos de destete posteriores en comparación con las cepas de probióticos L. acidophilus y L. casei en los días 1 (21 días de edad), 15 y 30 posteriores destete. El intestino delgado se eliminó completamente para evaluar los parámetros morfométricos (longitud y anchura de las vellosidades y criptas) en los diferentes segmentos intestinales (duodeno, yeyuno, íleon). Los animales fueron alimentados con dos dietas: dieta comercial con y sin la adición de antibióticos. Los probióticos L. acidophillus, L. casei y E. faecium, se suministraron separadamente en el agua de bebida de los animales que consumieron la dieta comercial sin antibiótico. El diseño estadístico utilizado fue de bloques al azar en un arreglo de parcelas divididas. Se observó un aumento significativo (P<0.01) en ancho y altura de vellosidades, y una disminución (P<0.01) en los valores obtenidos para ancho y profundidad de criptas en los animales que consumieron E. faecium, frente a aquellos que consumieron la dieta con adición de antibiótico. El uso de probióticos, especialmente E. faecium se constituye en una estrategia terapéutica nutricional al uso de compuestos antimicrobianos, mejorando las características morfométricas intestinales de los animales.

Global trends for animal production have seen a decrease in the use of antimicrobial compounds in feed, generating the need to implement new nutritional strategies that stimulate growth and promote intestinal health. This study aimed to determine whether the addition of E. faecium in drinking water improves intestinal morphometric parameters in post- weaning pigs compared with the probiotics strains L. acidophilus and L. casei on days 1 (21 days of age), 15 and 30 postweaning. The small intestine was completely removed to evaluate the morphometric parameters (length and width of villi and crypts) in the different intestinal segments (duodenum, jejunum, and ileum). They were fed for 30 days with two diets: commercial diet with or without antibiotics. The different probiotics, L. acidophillus, L. casei and E. faecium, were administered in the drinking water of the animals that consumed the commercial diet without antibiotics. A randomized block design in split-plot arrangement was used. There was a significant increase (P<0.01) in the width and length of villi, and a decrease (P<0.01) in the values obtained for the width and depth of crypts in the animals that consumed E .faecium, as compared to those that consumed the diet with addition of antibiotics. The use of probiotics, especially E. faecium, is a nutritional treatment strategy when antimicrobial compound are used, improving the intestinal morphometric parameters and, at the same time, the digestive and productive parameters of the animals. Work is in progress to investigate the effects of probiotic supplementation on the mofication of gut microbiota of post-weaning piglets.