RESUMO Tanto a presença de cães com dono quanto de cães vadios permitem a disseminação de Toxocara, e o parasita está presente no solo, na água e nos alimentos. Animais, incluindo cavalos, apresentam-se como hospedeiros definitivos e paratênicos. No México, o consumo de carne de cavalo é comum, e Toxocara é um parasita zoonótico. ELISA foi escolhido para análise, já que hospedeiros paratênicos não jogam ovos de Toxocara em suas fezes. O objetivo deste estudo foi identificar a presença de anticorpos anti-Toxocara por ELISA, em cavalos de trabalho e em cavalos para o consumo humano. As amostras de sangue foram retiradas de 188 cavalos: 94 cavalos de trabalho e 94 cavalos de trabalho do matadouro. Soros dos animais foram analisados por ELISA e 44,6% dos equinos apresentaram anticorpos anti-Toxocara. Cavalos adultos para abate têm 61,7% mais elevada a presença de anticorpos anti-Toxocara (P = 0,006). Anticorpos IgG Toxocara foram encontrados em cavalos, confirmando cavalos paratênicos como hospedeiros e possíveis fontes de infecção para outros animais e pessoas.

ABSTRACT Both the presence of owned dogs and stray dogs allows the spread of Toxocara, a parasite whose eggs can be found in soil, water and food. Animals, including horses, serve as definitive and paratenic hosts. In México, where consumption of horse meat is common, Toxocara is a zoonotic parasite. The aim of this study was to identify the presence of anti-Toxocara antibodies in work horses and horses intended for human consumption by ELISA. ELISA was chosen for analysis as paratenic hosts do not shed Toxocara eggs in their feces. Blood samples were collected from a total of 188 horses, 94 of which were work horses and 94 horses from the slaughter house. Samples were analyzed by ELISA, and the general equine seroprevalence was found to be 44.6% (n = 188). Adult horses for slaughter had a 61.7% greater presence of anti-Toxocara antibodies (p = 0.006). Toxocara IgG antibodies were found in horses, confirming that horses are paratenic hosts and possible sources of infection for other animals and people.

The objective of this study was to evaluate the effects of natural zeolite on the performance and nitrogen metabolism of Rambouillet ewe lambs. Forty Rambouillet ewe lambs with an initial weight of 41.06 ± 3.9 kg were randomly assigned to one of four experimental diets, namely 0, 20, 40 and 60 g of natural zeolite (Comercializadora Omega® México) per kg dietary dry matter in a completely randomized design and sixteen ewe lambs were used in a 4 x 4 Latin square metabolism study. Performance was not modified by natural zeolite levels in the diet, and daily gain showed a quadratic response. Ammonia concentration at 8 and 12 hours increased linearly with zeolite. Zeolite increased ruminal pH linearly at 8 and 12 hours. Acetate and butyrate presented a quadratic response, and total ruminal volatile fatty acid concentration was linearly increased by zeolite. Nitrogen retention showed a linear and quadratic response to zeolite. The estimated fractions of protein digested in the small intestine, when rumen-fermentable energy was limiting (PDIE) and when rumen-fermentable nitrogen was limiting, showed a linear and quadratic response to zeolite. PDIE was positively correlated (r = 0.96) with average daily gain.

The new electricity industry is evolving in market activities. The first electricity market models considering only one traded commodity: energy. All the supportive services, ancillary services (SA), were imputed in the energy price. Currently, the supportive services are clearly defined. In some electricity markets concurrent spot markets exist for some of the supportive services. In an unbundled electricity market, Generation Companies (GenCos) may participate in the provision of different services. Two concurrent spot markets are considered in this paper: energy and spinning reserve. Optimal self-scheduling for a GenCo is formulated in a real options framework. In the context of electricity producing firms, real options approach (ROA) can be used as a method of identifying and quantifying the contingent decisions embedded in owning generation assets. It enhances the potential to improve greatly the effectiveness ofoperating decisions and to unlock hidden assets. The bidsfor reserve are submitted on a day-to-day basis. The bids consist of a capacity and energy price.

La nueva industria eléctrica está evolucionando en las actividades del mercado. Los primeros modelos de mercados solamente consideraban un producto negociable: energía. Todos los servicios auxiliares (SA), se agregaban o incluían en el precio de la energía. En la actualidad los SA están claramente definidos y en algunos mercados de electricidad, existen mercados simultáneos para algunos de los SA. En un mercado de electricidad desagregado, las compañías de generación (GenCos) podrán participar en la prestación de diferentes servicios. En este trabajo, se consideran dos mercados simultáneos: energía y reserva rodante. La asignación óptima de servicios ofertados por una GenCo es formulado en un marco de opciones reales (OR). En el contexto de electricidad, el enfoque de OR puede usarse como un método para identificar y cuantificar las decisiones ante contingencias embebidas en la posesión de activos de generación, lo cual permite mejorar considerablemente la eficacia de las decisiones operativas. Las ofertas para reserva se presentan sobre una base diaria. Las ofertas consisten en un precio por capacidad y uno por energía.

Two yeast products formulated with Saccharomyces cerevisiae were evaluated at the same colony-forming units (CFUs) per gram of substrate. Samples of maize, lucerne and oat hays were mixed (0.5 kg) to a proportion of 80% forage (lucerne or oat) with 20% maize (DM basis) and combined with each yeast to obtain 1.5 x 10(7) or 3.0 x 10(7) CFU/g DM. There was also a control without yeast. In vitro gas production was measured at 0, 2, 4, 6, 8, 10, 14, 18, 24, 30, 36, 42, 48, 60, and 72 h incubation. There was no forage/yeast interaction. Both yeast products tended to reduce the maximum volume produced quadratically and lag time linearly, while in vitro dry matter digestibility (IVDMD) increased linearly. Ruminal ammonia N and lactic acid were not affected, whereas methane and carbon dioxide tended to be reduced with the intermediate dose of yeast. When the mixture included oat hay, the total volume of gas increased, the lag time decreased, and there was higher IVDMD than in the lucerne-based mixtures, which were associated with lower methane production. Ammonia and lactic acid remained unchanged. The two yeast products showed the same effects on the dynamics of gas production and in vitro digestibility when dosed at the same number of viable cells or CFUs, and there was no interaction with forage quality.

The objective of this study was to evaluate the effects of slow-release a-amylase in ruminal in vitro digestion of maize and sorghum grains. Digestibility was measured using an in vitro procedure with 40 mL of buffer and 10 mL of ruminal fluid, flushed with CO2 and incubated at 39 °C. The digestibility of sorghum and maize grain was measured after 6 and 12 hours of fermentation with or without exogenous a-amylase in powder form or dispersed in a matrix system for slow release by a diffusional mechanism. Tablets were used as the drug release matrix system, and were formulated with barium sulphate and ethylcellulose as the core of the final tablet. Treatments consisted of incubation of sorghum or maize grains with four doses of enzyme, using a-amylase in powder or in the press-coated tablet (16 treatments). The results showed that with a higher dose of exogenous enzyme, the digestibility of the grains was improved. Sorghum and maize digestion with tablets were improved compared with a-amylase in powder form. Releasing a-amylase from matrix tablets represents a potential technology to improve grain digestion in ruminants.

Twenty four multiparous Holstein dairy cows were rotationally grazed on a mixed alfalfaorchard sward. Three treatments were evaluated: 0, 4, and 8 kg of DM of MFP cow-1 day-1. Each cow received 3.8 kg of concentrate (DM basis). The experimental design was a cross-over (3 treatments, 2 replicates with 4 animals each), with 3 periods lasting 19 days each (10 adaptation plus 9 sampling period). There were no differences on individual milk production nor on milk composition. Herbage dry matter intake decreased (p<0.0001) from 8.4 to 5.2 and 3.1 kg of DM when increasing MFP from 0 to 4 and 8 kg of DM, respectively; while total DM intake increased (p<0.0001) on those cows with the highest level of supplementation, averaging 12.2, 12.9, 14.8 kg of total DM at 0, 4, and 8 kg of DM of FCM, respectively. Substitution rate of pasture for MFP was 0.75 and 0.67 kg of pasture per kg of FCM with 4 and 8 kg of DM of MFP, respective. Consequently, stocking rate (STR) increased (p<0.0001) from 3.8, to 6.2, and 8.8 cows ha-1, with 0, 4, and 8 kg of DM of MFP, respectively; and milk production per hectare increased (p<0.0001) from 39.3 to 64.5 and 95.5 kg of milk with 0, 4, and 8 kg of DM of FCM, respectively. This means that STR increases 0.63 cows ha-1, and 0.75 kg of milk when MFP is increased in one kg of DM. It is suggested that offering MFP as supplement to grazing dairy cows in their final lactation stage had no benefits in individual milk production or milk composition; but on milk production per hectare.

A 24 vacas Holstein multíparas en pastoreo rotacional en una pradera mixta alfalfa-pasto ovillo, se suministraron: 0, 4 y 8 kg de MS de maíz fresco picado (MFP) animal-1día-1. Además, cada animal recibió 3,8 kg de MS de alimento concentrado. Se utilizó un diseño reversible simple (crossover) (tres tratamientos, dos repeticiones con cuatro animales cada uno), de 3 períodos, con una duración de 19 días cada uno (10d de adaptación y 9d de muestreo). No hubo diferencias significativas en producción individual ni en composición de la leche. El consumo de pradera disminuyó (p<0,0001) de 8,4 a 5,2 y 3,1 kg de MS de pradera al aumentar el nivel de MFP de 0 a 4 y 8 kg de MS, respectivamente; mientras que el consumo total de MS incrementó (p<0,0001) en aquellas vacas con un nivel de suplemento más alto, promediando 12,2, 12,9, y 14,8 kg de MS total con 0,4 y 8 kg de MS de MFP, respectivamente. La tasa de sustitución fue de 0,75 y 0,67 kg de MFP con 4 y 8 kg de MS de MFP respectivamente, consecuentemente incrementó (p<0,0001) la carga animal (CA), de 3,8 a 6,2, y 8,8 vacas ha-1 al aumentar de 0 a 4 y 8 kg de MS de MFP, respectivamente, mientras que la producción de leche por hectárea incrementó (p<0,0001) de 39,3 a 64,5 y 95,5 kg de leche, respectivamente. Esto indica que por cada kg de MS de MFP, la CA aumenta 0,63 vacas y 0,75 kg de leche ha-1. La suplementación con MFP a vacas en etapa final de lactancia no presentó beneficios en producción de leche individual, ni cambios en composición de la leche, pero sí incrementó la producción de leche por hectárea, como resultado de aumento en la CA.