In vitro production of gas methane by tropical grasses / Produccion in vitro de gas metano por gramineas forrajeras tropicales

ABSTRACT Objective. Estimate the production of methane (CH4) by tropical grasses fermented in vitro. Materials and methods. A sample of 20 g dry matter of Cynodon nlemfuensis, Hyparrhenia rufa, Megathyrsus maximus and Digitaria swazilandensis plus 200 ml of culture medium were plated in triplicate flasks sterile stainless steel with CO2 flux, inoculated with 20 ml of ruminal fluid bovine, incubated at 38 °C for 24, 48, 72 and 96 h. Total production of gas, CH4, volatile fatty acids, and pH were evaluated in a completely randomized design with three replicates per treatment and comparison of means with Tukey; the concentration of total and cellulolytic bacteria were analyzed with the Kruskal-Wallis, and the GLM procedure independent data Wilcoxon rank. Results. H. rufa and D. swazilandensis both had the lowest total gas production (p<0.05), while D. swazilandensis had lower production of CH4, increased production of propionic acid (p<0.05) and lower pH 96 hours of incubation (p<0.05). D. swazilandensis showed greater efficiency in energy production due to reduced production of CH4 and increased propionate production. The concentration of total bacteria was similar between treatments (p>0.05), while the concentration of cellulolytic bacteria was lower in C. nlemfuensis y D. swazilandensis when 96 of incubation (p<0.05). Conclusions. The Digitaria swazilandensis, showed favorable conditions to have lower total methane and total gas production.

RESUMEN Objetivo. Estimar la producción de metano (CH4) por gramíneas tropicales fermentadas in vitro. Materiales y métodos. Una muestra de 20 g de materia seca de Cynodon nlemfuensis, Hyparrhenia rufa, Megathyrsus maximus y Digitaria swazilandensis más 200 ml de medio de cultivo se depositaron por triplicado en frascos de acero inoxidable estériles con flujo de CO2, se inocularon con 20 ml de líquido ruminal de bovino e incubaron a 38 °C por 24, 48, 72 y 96 h. Se evaluó producción total de gas, CH4, ácidos grasos volátiles, y pH en un diseño completamente al azar con tres repeticiones por tratamiento y la comparación de medias con Tukey; la concentración de bacterias totales y celulolíticas, se analizaron con la prueba de Kruskal-Wallis, y el procedimiento GLM con datos de rangos independientes de Wilcoxon. Resultados. H. rufa y D. swazilandensis tuvieron la menor producción total de gases (p<0.05), mientras que D. swazilandensis tuvo menor producción de CH4, mayor producción de ácido propónico (p<0.05) y menor pH a las 96 horas de incubación (p<0.05). D. swazilandensis mostró mayor eficiencia en la producción de energía por la menor producción de CH4 y mayor producción de propionato. La concentración de bacterias totales fue similar entre tratamientos (p>0.05), mientras que la concentración de bacterias celulolíticas fue menor en C. nlemfuensis y D. swazilandensis a la hora 96 de incubación (p<0.05). Conclusiones. La Digitaria swazilandensis, mostró condiciones favorables para tener menor producción total de metano y gases totales.

Effect of sugarcane silage on productive parameters of replacement Holstein-Friesian heifers / Efecto del ensilado de caña de azúcar en los parámetros productivos de vaquillas Holstein-Friesian para reemplazo

Objective. Measure the productive parameters of Holstein-Friesian females from weaning to 470 days old, comparing feeding through sugarcane silage (SCS) and corn silage (CS) in a concentrated fodder ratio of 70:30. Materials and methods. Twenty-eight post-weaning calves were used, with an average age of 80±16 days old and an initial weight of 79.5±12.9 kg. The T-Student test was used for the comparison of means, where calves were divided into two groups of 14, one for each treatment. The body weight BW (kg), wither height WH (cm), body condition BC (1 to 5 scale), daily weight gain DWG (kg) and feed conversion FC (kg) was measured every 30 days. Results. Differences were found between treatments, where heifers fed with SCS showed better BC (3.12), FC (7.4) as compared to the CS treatment. No significant differences were found in terms of DWG (0.666 and 0.743 kg/d). Conclusions. Feeding based on sugarcane silage allows for an improved body condition and feed conversion of animals having with this an acceptable and cost-effective production performance in the raising of dairy replacements.

Objetivo. Medir los parámetros productivos de hembras Holstein-Friesian desde el destete hasta los 470 días de edad, comparando la alimentación con ensilado de caña de azúcar (ECA) y ensilado de maíz (EM) en una proporción forraje concentrado de 70:30. Materiales y métodos. Se utilizaron 28 becerras, con una edad promedio de 80±16 días y un peso inicial de 79.5±12.9 kg. Se utilizó la prueba de comparación de medias T- Student, donde se dividieron las becerras en dos grupos de 14, uno para cada tratamiento. Cada 30 días se midió el peso corporal, PC (kg); altura a la cruz, AC (cm); condición corporal, CC (escala de 1 a 5); ganancia diaria de peso, GDP (kg); y conversión alimenticia, CA (kg). Resultados. Se encontraron diferencias entre los tratamientos, donde las vaquillas alimentadas con ECA mostraron mejor CC (3.12), CA (7.4) en comparación con el tratamiento EM. No se encontraron diferencias significativas en cuanto a la GDP (0.666 y 0.743 kg/d). Conclusiones. La alimentación basada en ensilaje de caña de azúcar permite una mejora en la condición corporal y en la conversión alimenticia de los animales teniendo con esto un comportamiento productivo aceptable y económicamente rentable en la crianza de reemplazos lecheros.

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

The values of biological parameters related to hatching, lifespan, the number of blood meals between moults, mortality, time lapse before the beginning of feeding, feeding time and defecation delay for each instar of three Mexican-American species of Triatominae, Triatoma recurva, Triatoma protracta (former subspecies protracta) and Triatoma rubida (former subspecies uhleri), were evaluated and compared. No significant (p > 0.05) differences were recorded among the three species with respect to the average time required to hatch. This time was approximately 19 days. The average egg-to-adult development time was significantly (p < 0.05) shorter for T. rubida. The number of blood meals at each nymphal instar varied from one-five for each species. The mortality rates were higher for the first-instar nymphs of the three species studied. The mean time lapse before the beginning of feeding was between 0.3-3 min for most nymphs of all instars of each species studied. The mean feeding time was the longest for T. recurva, followed by T. protracta. The defecation delay was less than 10 min for T. recurva and T. rubida. Given these results, only T. rubida should be considered an important potential vector of Trypanosoma cruzi transmission to humans in areas of Mexico where these species exist, whereas T. recurva and T. protracta would be of secondary importance.

Presencia de Meccus longipennis y Triatoma recurva en el estado de Durango, México / Presence of Meccus longipennis and Triatoma recurva in the state of Durango, Mexico

Se reporta por primera vez la recolecta de ejemplares de Meccus longipennis (Usinger) y de Triatoma recurva (Stål) en el estado de Durango. La búsqueda de triatominos se realizó durante 12 meses (septiembre 2010-agosto 2011) en cuatro comunidades de dos municipios (Pueblo Nuevo y Mezquital) del estado de Durango. Se recolectaron 71 ejemplares de M. longipennis y seis de T. recurva provenientes mayoritariamente del interior de las viviendas humanas (recámaras). La presencia de M. longipennis en el área abre la posibilidad de un riesgo potencial de transmisión de Trypanosoma cruzi Chagas a las poblaciones humanas del área estudiada.

The collection of Meccus longipennis (Usinger) and of Triatoma recurva (Stål) in the state of Durango is reported for the first time. Both species were collected during twelve months (from September 2010 to August 2011) in four localities of two municipalities (Pueblo Nuevo y Mezquital) in the state of Durango. Seventy one specimens of M. longipennis and six of T. recurva were collected mostly from indoors of human dwellings (bedrooms). Presence of M. longipennis means a potential risk of transmission of Trypanosoma cruzi Chagas to human populations in the study area.

Distribution and infection of triatomines (Hemiptera: Reduviidae) by Trypanosoma cruzi in the state of Michoacán, Mexico

An entomological study of triatomine species was carried out to assess their prevalence in 10 localities of the state of Michoacán, Mexico. Entomological indices were calculated to estimate the risk for vector-borne transmission of Trypanosoma cruzi to the human population in this area. Four triatomine species (Triatoma barberi, Triatoma dimidiata, Meccus pallidipennis and Meccus longipennis) were collected from the study area. This is the first report of M. longipennis and T. dimidiata in Michoacán. M. pallidipennis was significantly (p < 0.05) more abundant than any of the other species collected in the study area. Infection indices were greater than 50 percent for each of the four collected triatomine species. Significantly more triatomines were collected from intradomiciliary areas than from peridomiciliary or sylvatic areas. Infestation, crowding and density indices were low, whereas colonisation indices were high in five localities. The current vectorial conditions in the study area require continuous entomological and serological surveillance to diminish the risk of T. cruzi transmission to human populations.

Use of Pleurotus Pulmonarius to change the nutritional quality of wheat straw. I: Effect on chemical composition / Uso de Pleurotus Pulmonarius para cambiar la calidad nutritiva de la paja de trigo. I: Efecto en la composición química / Uso de Pleurotus Pulmonarius para mudar a qualidade nutritiva da palha de trigo. I: Efeito na composição química

The effect of Pleurotus pulmonarius on the chemical composition of wheat straw was evaluated. Wheat straw, treated and untreated with P. pulmonarius, was obtained from a commercial facility. Ten samples plastic bags of wheat straw used previously as substrate to culture edible fungus were collected at random. The negative control group consisted of the pasteurized wheat straw untreated with P. pulmonarius. All samples were analyzed to determine dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, cellulose and hemicellulose of each wheat straw. Data were analyzed by mean comparison using a t-Student test. No differences (P>0.05) between treatments were found for dry matter, crude protein and hemicellulose; however, straw treated with P. pulmonarius showed higher percentages (P<0.05) of organic matter, neutral and acid detergent fiber. It is concluded that growing P. pulmonarius in wheat straw improves the chemical composition of the straw by increasing its organic matter content and modifies the fiber structure, which increases the soluble carbohydrates content.

Se midió el efecto en la composición química de la paja de trigo usada como sustrato en la producción de Pleurotus pulmonarius. Las pajas de trigo, tanto tratadas con P. pulmonarius como no tratadas, fueron obtenidas de una empresa comercial. Para obtener muestras representativas para el análisis químico se tomaron al azar diez bolsas de la paja usada como sustrato para cultivar el hongo. El grupo testigo consistió en las pajas esterilizadas sin tratamiento con P. pulmonarius. A todas las muestras se les determinó materia seca, materia orgánica, proteína cruda, fibra detergente neutro, fibra ácido detergente, celulosa y hemicelulosa. Los datos obtenidos fueron analizados mediante una comparación de medias utilizando una prueba de t-Student. No se encontraron diferencias (P>0,05) para el porcentaje de materia seca, proteína cruda y hemicelulosa; sin embargo, se presentó un mayor (P<0,05) porcentaje de materia orgánica, fibra detergente neutro y ácido para la paja tratada en comparación con la no tratada. Se concluye que el crecimiento del P. pulmonarius en paja de trigo mejora la composición química de las pajas aumentando el contenido de materia orgánica y modifica la estructura de la fibra, con lo que se incrementa el contenido de carbohidratos solubles.

Mede-se o efeito na composição química da palha de trigo usada como substrato na produção de Pleurotus pulmonarius. As palhas de trigo, tanto tratadas com P. pulmonarius como não tratadas, foram obtidas de uma empresa comercial. Para obter amostras representativas para a análise química se tomaram aleatoriamente dez sacolas da palha usada como substrato para cultivar o fungo. O grupo testemunha consistiu em palhas esterilizadas sem tratamento com P. pulmonarius. Determinou-se, em todas as amostras, matéria seca, matéria orgânica, proteína crua, fibra detergente neutro, fibra ácido detergente, celulose e hemicelulose. Os dados obtidos foram analisados mediante uma comparação de médias utilizando uma prova de t. Não se encontraram diferenças (P>0,05) para a porcentagem de matéria seca, proteína crua e hemicelulose; no entanto, se apresentou uma maior (P<0,05) porcentagem de matéria orgânica, fibra detergente neutra e ácida para a palha tratada em comparação com a não tratada. Conclui-se que o crescimento do P. pulmonarius na palha de trigo melhora a composição química das palhas aumentando o conteúdo de matéria orgânica e modifica a estrutura da fibra, com o que se incrementa o conteúdo de carboidratos solúveis.

Efecto de la adición de vitaminas B en la digestibilidad in vitro de dietas con diferente fuente de carbohidratos / Effect of the supplementation of b vitamins on in vitro digestibility of diets with different source of carbohydrates

Se realizó un estudio con el fin de observar el efecto de la adición de vitaminas hidrosolubles en la digestibilidad in vitro de la materia seca (DIVMS) y materia orgánica (DIVMO) en dietas con distinta fuente de carbohidratos (sorgo y cebada en grano), adicionadas con cinco dosis de vitaminas B (VB; 0, 2, 4, 6 y 8 g kg-1 MS). Se encontraron diferencias significativas (P < 0,01), tanto para los efectos principales (fuente de carbohidratos y cantidad de VB), como para la interacción de éstos, en ambos casos (DIVMS y DIVMO). Al adicionar dietas con 8 g y como fuente de carbohidratos el sorgo, la DIVMS y DIVMO aumentó, pero no cambió cuando la fuente de carbohidratos fue la cebada. La adición de vitaminas hidrosolubles a dietas con sorgo mejora la DIVMS y DIVMO, observándose que la naturaleza y calidad de la dieta puede influir en la producción de vitaminas hidrosolubles por los microorganismos ruminales.

The objective of this study was to evaluate the effect of B vitamins on in vitro digestibility of dry matter (IVDMD) and organic matter (IVOMD) of diets with different source of carbohydrates (sorghum and barley grain), with five concentrations of B vitamins (BV; 0, 2, 4, 6 and 8 g kg-1 DM). There were differences (P < 0.01) for the principal effects (source of carbohydrates x concentration of BV), also for the interaction of them in both cases (IVDMD and IVOMD). At 8 g with sorghum increases the IVDMD and IVOMD, but did not change when the source of carbohydrates was the barley. The addition of B vitamins improves the IVDMD and IVOMD, also the nature and quality of the diet effect the microbial B vitamin production.