Juan Carlos Vázquez Chagoyán

Effects of Saccharomyces Cerevisiae at Direct Addition or Pre-incubation on in Vitro Gas Production Kinetics and Degradability of Four Fibrous Feeds

The objective of this study was to evaluate the effects of Saccharomyces cerevisiae on in vitro gas production (GP) kinetics and degradability of corn stover, oat straw, sugarcane bagasse and sorghum straw. Feedstuffs were incubated with different doses of yeast [0, 4, 8 and 12 mg/g dry matter (DM)] at direct addition or 72 h pre-incubation. Rumen GP was recorded at 2, 4, 6, 8, 10, 12, 14, 24, 30, 48, 54 and 72 h of incubation. After 72 h, rumen pH and methane were determined and contents were filtrated for DM, neutral (NDF) and acid detergent fibre (ADF) degradability. Fibrous species×method of application×yeast interactions occurred (P< 0.001) for all measured ruminal GP parameters and degradability. The direct addition or 72 h pre-incubation of S. cerevisiae with corn stover improved (P< 0.05) GP and methane and decreased (P< 0.05) the lag time (L) and NDF degradability (NDFD). The direct addition of S. cerevisiae to oat straw increased (P< 0.05) rate of GP (c) and decreased (P< 0.05) asymptotic GP (b). However, 72 h pre-incubation increased (P< 0.05) c with linearly decreased b, DM degradability (DMD) and NDFD. Applying S. cerevisiae for 72 h pre-incubation decreased (P< 0.001) methane emission. The direct addition or 72 h pre-incubation of S. cerevisiae to sorghum straw increased (P< 0.05) b, c, L, DMD and NDFD. Overall, the effect of dose varied among different feedstuffs and different application methods. Results suggested that the direct addition of S. cerevisiae could support and improve ruminal fermentation of low-quality forages at 4 to 12 g/kg DM.

Direct-fed microbes: A tool for improving the utilization of low quality roughages in ruminants

Abstract For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency of different ruminant species. Removal and restriction of antibiotics sub-therapeutic uses from ruminant diets has amplified interest in improving nutrient utilization and animal performance and search for more safe alternatives. Some bacterial and fungal microorganisms as a direct-fed microbial (DFM) can be the most suitable solutions. Microorganisms that are commonly used in DFM for ruminants may be classified mainly as lactic acid producing bacteria (LAB), lactic acid utilizing bacteria (LUB), or other microorganisms species like Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus, Propionibacterium, Megasphaera elsdenii and Prevotellabryantii , in addition to some fungal species of yeast such as Saccharomyces and Aspergillus . A definitive mode of action for bacterial or fungal DFM has not been established; although a variety of mechanisms have been suggested. Bacterial DFM potentially moderate rumen conditions, and improve weight gain and feed efficiency. Fungal DFM may reduce harmful oxygen from the rumen, prevent excess lactate production, increase feed digestibility, and alter rumen fermentation patterns. DFM may also compete with and inhibit the growth of pathogens, immune system modulation, and modulate microbial balance in the gastrointestinal tract. Improved dry matter intake, milk yield, fat corrected milk yield and milk fat content were obtained with DFM administration. However, the response to DFM is not constant; depending on dosages, feeding times and frequencies, and strains of DFM. Nonetheless, recent studies have supported the positive effects of DFM on ruminant performance.

Prevalence of Trypanosoma cruzi in Dogs (Canis familiaris) and Triatomines During 2008 in a Sanitary Region of the State of Mexico, Mexico

American trypanosomiasis is a public health problem in Latin America and southern parts of the United States. Infection in triatomines (vector) and domestic dogs (reservoir host) is a good indicator of Trypanosoma cruzi circulation and human risk of infection. The State of Mexico, Mexico, has been considered free of T. cruzi, and no detailed epidemiologic study has been conducted to assess the intricacies of the transmission cycle of the parasite in the region. Such studies would enhance our understanding of the epidemiology of T. cruzi infection in this geographic region and provide regional sanitary authorities with stronger fundamental knowledge for making decisions and allocating funds for Chagas disease control programs in the State of Mexico. The objective of this study was to determine the prevalence of T. cruzi infection in dogs (seroprevalence) and triatomines (fecal parasites) in a previously identified, discrete endemic region of parasite circulation and to widen our studies in the Tejupilco Sanitary Region located in the southern part of the State of Mexico. Dog blood samples (n=102) were analyzed for the presence of anti-T. cruzi antibodies by two assays, namely indirect hemagglutination assay and enzyme-linked immunosorbent assay. Triatomines (n=88) were collected and fecal aliquots were analyzed for the presence of parasites by light microscopy. Average seroprevalence in dogs in the Tejupilco Sanitary region was 24.5%, and the overall triatomine infection rate was 34.01%. Triatoma pallidipennis was the only triatomine species found in this region. Our data demonstrate that T. cruzi is actively circulating in the Tejupilco Sanitary Region and emphasize the requirement for epidemiologic surveillance programs throughout the putative endemic areas of the State of Mexico.

Effects of cellulase and xylanase enzymes mixed with increasing doses of Salix babylonica extract on in vitro rumen gas production kinetics of a mixture of corn silage with concentrate

Abstract An in vitro gas production (GP) technique was used to investigate the effects of combining different doses of Salix babylonica extract (SB) with exogenous fibrolytic enzymes (EZ) based on xylanase (X) and cellulase (C), or their mixture (XC; 1:1 v/v) on in vitro fermentation characteristics of a total mixed ration of corn silage and concentrate mixture (50:50, w/w) as substrate. Four levels of SB (0, 0.6, 1.2 and 1.8 mL g −1 dry matter (DM)) and four supplemental styles of EZ (1 μL g −1 DM; control (no enzymes), X, C and XC (1:1, v/v) were used in a 4×4 factorial arrangement. In vitro GP (mL g −1 DM) were recorded at 2, 4, 6, 8, 10, 12, 24, 36, 48 and 72 h of incubation. After 72 h, the incubation process was stopped and supernatant pH was determined, and then filtered to determine dry matter degradability (DMD). Fermentation parameters, such as the 24 h gas yield (GY 24 ), in vitro organic matter digestibility (OMD), metabolizable energy (ME), short chain fatty acid concentrations (SCFA), and microbial crude protein production (MCP) were also estimated. Results indicated that there was a SB×EZ interaction ( P b ), the rate of gas production ( c ), GP from 6 to 72 h, GP 2 ( P =0.0095), and GP 4 ( P =0.02). The SB and different combination of enzymes supplementation influenced ( P in vitro GP parameters after 12 h of incubation; the highest doses of SB (i.e., 1.8 mL g −1 DM), in the absence of any EZ, quadratically increased ( P L ) and GP at different incubation times, with lowering b (quadratic effect, P c (quadratic effect, P P =0.0018). The GP was the lowest ( P P 72 ), GY 24 , SCFA, MCP ( P =0.0143), and pH ( P =0.0008). The OMD, ME, GY 24 and SCFA with supplementation of SB extract at 1.8 mL g −1 DM were higher ( P 72 was lower (quadratic effect, P =0.0194) than the other levels. Both C and X had no effect ( P >on OMD, pH, ME, GY 24 , SCFA and MP. The combination of SB with EZ increased ( P 72 and GP 24 , whereas there was no impact on pH. It could be concluded that addition of SB extract, C, and X effectively improved the in vitro rumen fermentation, and the combination of enzyme with SB extract at the level of 1.2 mL g −1 was more effective than the other treatments.

Detection of Quinolone Resistance in Salmonella typhimurium Pig Isolates Determined by gyrA Gene Mutation Using PCR- and Sequence-Based Techniques within the gyrA Gene

BACKGROUND The emergence of reduced susceptibility to fluoroquinolones among Salmonella enterica serotype Typhimurium isolates leading to clinical failure of treatment poses a great therapeutic challenge. METHODS The current study is focused on the evaluation of the minimum inhibitory concentration (MIC) of quinolones in 29 Salmonella typhimurium of 86 Salmonella spp. strains, obtained from pigs from the State of Mexico. The MIC was performed with the Kirby-Bauer method. On the other hand, the GyrA gene was sequenced. The present study was undertaken to describe the resistance profiles and fluoroquinolone resistance mechanism of Salmonella Typhimurium. RESULTS The DNA sequence of the gyrA genes from Salmonella enterica serovar typhimurium revealed strong similarity between gyrA and its counterpart in Escherichia coli. The sequencing of quinolone resistance-determining region (QRDR) of the gyrA gene showed the presence of mutation at either S83 or at D87 in almost all the Salmonella typhimurium isolates. CONCLUSION This mutation, although phenotypically expressed as decreased susceptibility to fluoroquinolones goes undetected by the disk diffusion method using the present method of Kirby-Bauer. Hence, it can increase morbidity and mortality due to delay in appropriate antibiotic treatment.

Natural infection of Trypanosoma cruzi in a dog with heart lesions: a case report from Malinalco, State of Mexico, Mexico

1Centro de Investigacion y estudios Avanzados en salud Animal, Facultad de Medicina Veterinaria y Zootecnia Universidad Autonoma del estado de Mexico, Toluca, Mexico; 2Laboratorio estatal de salud Publica del Instituto salud del estado de Mexico; 3Instituto de Diagnostico y Referencia epidemiologicos, ssA, Mexico; 4Departments of Pathology, 5Microbiology and Immunology, University of Texas Medical Branch, UsA; 6Universidad Autonoma de Chiapas, Tapachula, Chiapas, Mexico