Oscar Vergara G

Bio: Oscar Vergara G is an academic researcher from University of Córdoba (Spain). The author has contributed to research in topics: Heritability & Population. The author has an hindex of 4, co-authored 17 publications receiving 57 citations.

Evaluación química y organoléptica del ensilaje de maralfalfa (Pennisetum sp.) más yuca fresca (Manihot esculenta)

Abstract: Objective. To evaluate the chemical composition and the organoleptic traits of maralfalfa silage (Pennisetum sp.), containing different proportions of fresh cassava (Manihot esculenta). Materials and methods. Four treatment (T) groups of maralfalfa silage containing different percentage of fresh cassava were compared: 0% (Treatment 1, Control), Treatment 5% (Treatment 2), 10% (Treatment 3), and 15% (Treatment 4). Neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, fraction of dry matter (DM), ether extract (EE), ash, and crude protein (CP) were analyzed by an analysis of variance and orthogonal polynomials. In addition, consumption and organoleptic traits were also analyzed using descriptive statistics, in 20 heifers, that received 30 kg of silage per treatment. Results. Nutritional variables showed different types of polynomial trends. DM and EE were linear trends, lignin was quadratic, and CP, ash, NDF, ADF, and pH were cubic trends. Organoleptic traits for T3 and T4 were excellent. The average consumption for T1, T2, T3 and T4 was 4.66, 4.42, 4.58, and 4.74 kg, respectively. Conclusions. The inclusion of fresh cassava root contributed positively in the nutritional quality of maralfalfa silage and organoleptic traits.

Estimación de los parámetros genéticos para el peso al nacer y al destete en ganado bovino de la raza brahman

Abstract: Objective. To estimate the heritability and genetic environmental and phenotypic correlations of birth and weaning weight in Brahman bovines. Materials and methods. 612 values for birth weight (BW) and weaning weight (WW) were analyzed for Brahman Bovines born form 1996 to 2003. The data derived from "Pradera" and "Mundo Nuevo" farms in Sucre department (Colombia). Data were analyzed using the mixed SAS V 8.0 system. The proposed mathematical model included the fixed effects: year, time, sex, number of calves, and farm and suggested the random effect of bull for both characteristics. Results. It was found that the effects farm and bull were statistically significant for the (BW). For WW, the year was statistically significant (p≤0.05); sex, number of calves and bull effects were highly significant (p≤0.05) and time and farm effects were not significant (p≥0.05). The estimated heritability was 0.16 and 0.37 for BW and WW, respectively. Genetic, phenotypic and environmental correlation values were -0.2, 0.14 and 0.26 respectively. Conclusions. Values found for heritability indicate that the phenotype is not a good indicator of genotype, and that it is necessary to use tests of progeny or pedigree for selection. The value of the genetic correlations allows the affirmation that calves with better birth weight will not be those that reach higher weights at weaning.

Factores ambientales que afectan la edad al primer parto y primer intervalo de partos en vacas del sistema doble propósito

Abstract: Objetivo. Determinar los factores que influyen en la edad al primer parto (AFC) y primer intervalo de parto (PIDP) en hembras bovinas bajo el sistema de doble proposito, en la finca “El Rodeo”, municipio de Magangue, Bolivar - Colombia. Materiales y metodos. Se analizaron 379 datos provenientes de los registros productivos entre los anos 1993 hasta 2002, usando el programa estadistico GLM del Statistical Analysis System, donde se obtuvieron la media y el error estandar de cada fuente de variacion. En el analisis se consideraron los efectos de ano de parto, epoca de parto, edad al primer parto (no se considero para EPP), sexo de la cria, grupo racial y peso a los 24 meses. Resultados. La media para la EPP y PIDP fue de 38.9 ± 3.9 meses y 469.2 ± 9 dias, respectivamente, donde el efecto epoca de parto, fue significativo para la duracion del PIDP. Los efectos sexo de la cria, peso a los 24 meses y epoca, no fueron significativos sobre la EPP. Los efectos ano de parto, edad al primer parto, sexo de la cria, peso a los 24 meses no fueron significativos sobre el PIDP. Conclusiones. La EPP y PIDP fueron afectados por el ano y la epoca de parto, respectivamente.

Determinación de un índice de selección para el peso al nacer y al destete en ganado bovino de la raza brahman

Abstract: Objetivo. Estimar un indice de seleccion para el peso al nacer y al destete en ganado bovino de la raza Brahman en la “Hacienda Mundo Nuevo”, Costa Norte Colombiana. Materiales y metodos. Para el calculo de este indice fue necesario estimar los componentes de varianza entre y dentro de reproductor y las covarianzas geneticas y fenotipicas entre las caracteristicas en estudio utilizando el procedimiento MIXED de SAS. Resultados. El indice estimado fue: I=X1-0.4286X2 , obteniendo asi una maxima correlacion entre el fenotipo agregado y genotipo agregado, convirtiendose en una herramienta de mejoramiento genetico para hacer el proceso de seleccion mas tecnico y eficiente y lograr un mayor progreso genetico por unidad de tiempo. Conclusiones. Se recomienda la utilizacion de los animales de mejor indice, ya que existe correlacion entre el indice y el genotipo agregado.

Diferencia esperada de progenie como herramienta de selección para peso al destete en ganado Brahman

Abstract: Objetivo. Determinar la diferencia esperada de progenie (DEP�fs) para el peso al destete (PD) en ganado Brahman como criterio de seleccion de futuros reproductores. Materiales y metodos. Se utilizaron 552 registros (PD) recolectados entre 1997 y 2007 de la hacienda Mundo Nuevo (San Onofre, Sucre, Colombia), provenientes de 33 padres. El modelo estadistico utilizado incluyo los efectos fijos de ano y epoca de nacimiento, sexo del ternero, numero de partos de la vaca y el efecto aleatorio del padre. Para el analisis, se utilizo el metodo de los cuadrados minimos mediante el procedimiento PROC GLM, contenido en el statistical analysis system (SAS). La heredabilidad fue estimada con los componentes de varianza entre y dentro de toro, obtenidos por el procedimiento PROC VARCOMP. Las diferencias esperadas de progenies (DEP�fs), fueron calculadas a traves del metodo de mejor predictor lineal insesgado (BLUP). Resultados. La media del PD fue 238.5 �} 31.6 kg. Los efectos de padre, sexo, numero de partos y ano de nacimiento fueron significativos (p.0.05). La heredabilidad para PD fue 0.43 �} 0.15. Las DEP�fs variaron entre -16.9 y + 17 kg, con una exactitud (EXA) que oscilo entre 0.71 y 0.78. Conclusiones. La significancia de las diferentes fuentes de variacion de PD coincide con la mayoria de los reportes referenciados en la literatura. El valor estimado de la heredabilidad para PD, indica que se puede lograr progreso genetico para PD. Los resultados de las (DEP�fs) evidenciaron que el 52% de los toros aportan variaciones negativas para PD.

Effects of energy supplementation on productivity of dual-purpose cows grazing in a silvopastoral system in the tropics

Abstract: The aim of the present work was to evaluate milk yield, postpartum (pp) ovarian activity and pregnancy rate in dual-purpose cows grazing Cynodon nlemfuensis and browsing L. leucocephala, with or without energy supplementation. Twenty-four Bos taurus × B. indicus cows were divided in two groups from calving to 70 days post-calving: supplemented group (SG) with ground sorghum grain offered at 0.4% of live weight at calving and control group (CG) without supplement. There was a trend for milk yield (kg day−1) to be greater (p = 0.08) for SG (10.55 ± 0.51) compared to CG (9.53 ± 0.61), although without differences in fat (0.42 ± 0.02 vs. 0.38 ± 0.03 kg day−1), protein (0.29 ± 0.02 vs. 0.29 ± 0.02 kg day−1) or lactose (0.49 ± 0.02 vs. 0.49 ± 0.03 kg day−1) concentration. Populations of large, medium and small follicles were similar between treatments. Percentage of cows which showed corpus luteum tended to be greater in SG (50%), compared to CG (33%). Supplemented cows tended to have a shorter calving-first corpus luteum interval (40 ± 10 vs. 51 ± 10 days) and had a significantly higher (χ 2 = 0.03) pregnancy rate (42% vs. 0%). It is concluded that energy supplementation helped to improve ovarian activity and pregnancy rate. Since supplementation did not avoid loss of body condition, the higher pregnancy rate in SG suggests beneficial effects of supplementation probably mediated by metabolic hormones.

Donkey Fascioliasis Within a One Health Control Action: Transmission Capacity, Field Epidemiology, and Reservoir Role in a Human Hyperendemic Area.

Abstract: A One Health initiative has been implemented for fascioliasis control in a human hyperendemic area for the first time. The area selected for this multidisciplinary approach is the Northern Bolivian Altiplano, where the highest prevalences and intensities in humans have been reported. Within the strategic intervention axis of control activities concerning animal reservoirs, complete experimental studies, and field surveys have been performed to assess the fascioliasis transmission capacity and epidemiological role of the donkey for the first time. Laboratory studies with altiplanic donkey-infecting Fasciola hepatica and altiplanic Galba truncatula snail vector isolates demonstrate that the donkey assures the viability of the whole fasciolid life cycle. Several aspects indicate, however, that F. hepatica does not reach, in the donkey, the level of adaptation it shows in sheep and cattle in this high altitude hyperendemic area. This is illustrated by a few-day delay in egg embryonation, longer prepatent period despite similar miracidial infectivity and shorter patent period in the intramolluscan development, lower cercarial production per snail, different cercarial chronobiology, shorter snail survival after shedding end, shorter longevity of shedding snails, and lower metacercarial infectivity in Wistar rats. Thus, the role of the donkey in the disease transmission should be considered secondary. Field survey results proved that liver fluke prevalence and intensity in donkeys are similar to those of the main reservoirs sheep and cattle in this area. Fasciolid egg shedding by a donkey individual contributes to the environment contamination at a rate similar to sheep and cattle. In this endemic area, the pronounced lower number of donkeys when compared to sheep and cattle indicates that the epidemiological reservoir role of the donkey is also secondary. However, the donkey plays an important epidemiological role in the disease spread because of its use by Aymara inhabitants for good transport, movements, and travel from one locality/zone to another, a repercussion to be considered in the present geographical spread of fascioliasis in the Altiplano due to climate change. Donkey transport of parasite and vector, including movements inside the zone under control and potential introduction from outside that zone, poses a problem for the One Health initiative.

Genetic parameter estimation for pre- and post-weaning traits in Brahman cattle in Brazil.

Abstract: Beef cattle producers in Brazil use body weight traits as breeding program selection criteria due to their great economic importance. The objectives of this study were to evaluate different animal models, estimate genetic parameters, and define the most fitting model for Brahman cattle body weight standardized at 120 (BW120), 210 (BW210), 365 (BW365), 450 (BW450), and 550 (BW550) days of age. To estimate genetic parameters, single-, two-, and multi-trait analyses were performed using the animal model. The likelihood ratio test was verified between all models. For BW120 and BW210, additive direct genetic, maternal genetic, maternal permanent environment, and residual effects were considered, while for BW365 and BW450, additive direct genetic, maternal genetic, and residual effects were considered. Finally, for BW550, additive direct genetic and residual effects were considered. Estimates of direct heritability for BW120 were similar in all analyses; however, for the other traits, multi-trait analysis resulted in higher estimates. The maternal heritability and proportion of maternal permanent environmental variance to total variance were minimal in multi-trait analyses. Genetic, environmental, and phenotypic correlations were of high magnitude between all traits. Multi-trait analyses would aid in the parameter estimation for body weight at older ages because they are usually affected by a lower number of animals with phenotypic information due to culling and mortality.

Calidad bromatológica y organoléptica de ensilajes de residuos orgánicos del sistema de producción café - musáceas Bromatological and organoleptic quality of organic waste silages of coffee-musaceous production system

Abstract: This study was carried out in the Laboratory of Animal Ecophysiology, University of Tolima (Ibague, Colombia). The objective was to analyze the nutritional quality through bromatological and organoleptic characteristics of organic waste silages of coffee and musaceous agroecosystem. Silages were prepared with each of the organic wastes (coffee, banana leaves and banana stems) 5% molasses was added as an energy source. The units of analysis were represented by 5 kg microsilos packed in 6 gauge polyethylene bags. 4 fermentation times were evaluated (1, 7, 14 and 21 days). The following variables were evaluated weekly: pH, temperature, dry matter, ash. At the end of the process the percentage of protein, NDF, and lignin FDA were evaluated. The results show that the highest temperature recorded at the beginning was 26 ° C and stabilized at 23,3 °C over time, the lowest value reported was the silage pH of coffee (3,8), the banana leaf silage on fermentation time 4 presented the highest protein content (14,45 %), followed by coffee silages (11,65%) and banana stem (5,25%). The sensory evaluation was analyzed using descriptive statistics which showed that all silages showed characteristics within acceptable quality parameters on the characteristics of color, smell, humidity and texture.

Avaliação genética multirracial para ganho de peso pré-desmama em bovinos de uma população composta

Abstract: Three different models including or not the direct and maternal non-additive effects and the fixed effects of contemporary group, parity order, direct and maternal heterosis and the direct and maternal additive genetic random effects were compared for predicting breeding values for pre-weaning daily gain in a composite cattle population in tropical climate. The analyses were done in two stages: firstly, breed and individual and maternal heterosis effects were estimated and after variances and the heritability were obtained for prediction of breeding values of the animals. The breed additive effect seemed to be overestimated when the maternal effect was not included in the model. Estimates of additive and maternal breed effects and individual and maternal heterosis for pre-weaning daily gain were significantly different for the biological types. Direct and maternal heritability estimates from analyses using data adjusted for direct and maternal non-additive effects were respectively 0.22 and 0.20. The maternal breed effect and individual and maternal heterosis should be included in models used for genetic evaluation of pre-weaning daily gain in this composite cattle population.