Tropical Region Of Mexico Research Articles

ACTUALIZACIÓN SOBRE ASPECTOS EPIDEMIOLÓGICOS DE LA RICKETTSIOSIS EN EL TRÓPICO DE MÉXICO

<p><strong>Background:</strong> Rickettsioses are diseases caused by <em>Rickettsia</em> bacteria, transmitted through tick or mite bites, or through contact with feces from lice or fleas. In Mexico, these diseases are a major public health concern, particularly in the tropical states where they appear to be responsible for most cases and the highest mortality rates. In the epidemiology of rickettsiosis, domiciled dogs and rodents play a significant role in maintaining of biological vectors in the vicinity of dwellings and in domestic and companion animals that people live with. It has been determined that some characteristics of households in localities with some degree of social-economic marginalization increase the risk of occurrence of <em>Rickettsia</em> spp. in the occupants. <strong>Objective:</strong> To present a literature review on the epidemiology of rickettsiosis, delving into studies about the characteristics of the peridomiciliary space and the most common animals that live there involved in the occurrence of rickettsiosis in localities of the Mexican tropic<strong>. Methodology:</strong> Using keywords related to the objective, a search between November 2022 and April 2023 was carried out on digital sources of information from various types of scientific references. The search results were classified according to eligibility criteria. <strong>Results:</strong> The information generated in the Mexican tropic on the epidemiology of rickettsiosis involving synanthropic and domestic animals, as well as the characteristics of the peridomiciliary space, is more extensive and numerous than in other regions of the country. <strong>Implications:</strong> The present review includes part of the epidemiological panorama of endemic rickettsiosis in the Mexican tropics, which is not necessarily attributable to other regions where environmental and socioeconomic conditions can modify the behavior of these diseases. <strong>Conclusions:</strong> It has been documented that the transmission of zoonoses such as rickettsiosis is influenced by ecological or environmental conditions and the characteristics of anthropized environments such as the peridomicile, which represent factors related to the occurrence of these diseases in the households’ occupants of localities in the Mexican tropics. Several pathogenic species of Rickettsia are found in domesticated dogs and some species of wild and synanthropic rodents, indicating their significant epidemiological role in the tropical regions of Mexico.</p>

Physiological response of Katahdin ewes to the absence of shadows in tropical region of Mexico

This study evaluated the effect of environmental conditions on the physiological and body infrared temperature traits of Katahdin sheep. Ten recently reproductive-managed ewes were randomly segregated into two groups. The control group (CG) was under outdoor conditions with shadow access, and the experimental group (EG) was under outdoor conditions without shadow access. Traits were measured for 16 days, and the environmental traits confirmed significant differences between groups, with an average temperature-humidity index (THI) of 68.64±1.46 for the CG and 72.98±3.17 for the EG, with a breach of five units between groups. The THI was subsequently used to evaluate the heat load. Respiratory frequency was the physiological variable that responded the most to heat stress. The rectal temperature of the sheep was greater in the experimental group than in the control group, indicating an increase in heat stress. The EG also presented higher heat emissions from body regions, which was associated with changes in core body temperature and blood flow at the body surface. Differences in hematological parameters, such as the erythrocyte count, mean corpuscular volume, and total plasma protein concentration, were found between the groups. Infrared thermography was found to be efficient for estimating heat stress in sheep species, and head temperature was found to be a reliable indicator of physiological thermal stress.

Activity patterns and use of artificial water ponds by White-tailed deer (Odocoileus virginianus) in western Campeche

Artificial Water Ponds (AWP) are widely employed for preserving and managing white-tailed deer (Odocoileus virginianus) in arid, and tropical regions of Mexico. However, there is a significant knowledge gap concerning the impact of these AWP on white-tailed deer activity. To determine the effect of AWP on the ecological aspects of white-tailed deer, we assessed the visitation rates and activity patterns of this species in AWP and compared them with areas devoid of water such as Dirt Roads (DR) using camera traps during the dry season within the seasonal wetland region of Nicte Ha, situated in western Campeche, Mexico. The research was conducted in a highly seasonal tropical wetland area at the Nicte-Ha UMA in southwestern Campeche, México. We established set camera trap stations during the dry season of 2019, 2020, and 2021 in seven AWP and 12 DR that operated for at least 80 days and compared the white-tailed deer visitation rate (measured as the Relative Abundance Index, RAI) and activity patterns among both treatments and across the three studied years. We collected a total of 3,640 independent records of white-tailed deer (2,584 in AWP and 1,056 in DR) for three years, with a combined effort of 3,978 camera days (1,306 camera days in AWP and 2,672 in DR). Our analysis revealed that the Relative Abundance Index (RAI) was consistently higher in the AWP than the DR across the three study years. However, we examined RAI variations over the three years and observed differences in the AWP, while the DR exhibited a relatively stable pattern. In the case of the activity patterns, we observed that white-tailed deer were primarily diurnal, with a significant overlap in activity between the two treatment areas. Nonetheless, within the AWP, the species exhibited continuous daytime activity, whereas, in the PR, distinct activity peaks occurred during sunrise and sunset. The results show that the presence of AWP in Nicte Ha has important effects on the presence of white-tailed deer during the dry season since we observed that there is a higher RAI in the sites where there is AWP compared to the PR sites. In the case of activity patterns, the AWP sites maintain constant activity throughout the day compared to DR, where activity peaks associated with sunrise and sunset occur. Our results show the importance that this type of structure has for the management of the species during the dry season of the year in Nicte Ha and the potential benefits of these structures in tropical seasonal areas, especially under a scenario in which drought during the dry season may be more severe in the near future due to the global change.

PRODUCTIVE RESPONSE OF LACTATING DUAL-PURPOSE COWS GRAZING IN AN AGROSILVOPASTORAL SYSTEM DURING THE DRY SEASON SUPPLEMENTED WITH LOW LEVELS OF CRUDE PROTEIN

<p><strong>Background. </strong>Cattle production in tropical regions of Mexico is in dual-purpose farms (DP) on unintended agrosilvopastoral systems (ASPS) with pastures dominated by tropical grasses with scattered shrubs and trees. During the dry season due to the forage diminished nutritional value and availability most farmers supplement their cattle to sustain milk production and weight gains of calves, without taking into consideration the wide variety of forages available in grazing lands to decide the composition of supplements offered to their cattle. <strong>Objective/hypothesis. </strong>The objective of the study was to determine the effect of low levels of crude protein (CP) content in supplements (S10 = 100, S11 = 110 and S12 = 120 g CP/kg of DM) on the performance of lactating Brown Swiss (BS) cows on an ASPS during the dry season. We hypothesize that low levels of CP in supplements of lactating grazing cows on an agrosilvopastoral system during the dry season would not affect animal performance. <strong>Methodology. </strong>The study was carried out in the dry season (March to June of 2012), in a commercial DP in the State of Mexico. Eighteen multiparous BS cows and their calves were used in the study, randomly allocated to three groups (six cows/group), to receive one of three supplements (4.5 kg DM/cow/day), consisting of 100, 110 or 120 g/kg DM of crude protein (CP) S10, S11 and S12, respectively. Data were analysed as a complete random experimental design with a mixed model. <strong>Results. </strong>There were no significant differences in most of the animal performance variables (P > 0.05), except for fat protein corrected milk (FPCM) where S12 (6.4) was significantly higher than S10 and S11 (4.7 and 4.5 kg/day, respectively). Milk protein yields (kg/day) significantly increased as the CP level increased in supplements. High levels of milk urea nitrogen (MUN) were detected (mean 14.0 mg/dL). <strong>Implications. </strong>In similar DP farms where cattle have access to other sources of forages like shrubs and trees, it is possible to reduce the CP content of supplements and to increase the efficiency of utilization of those alternative forages as well as a reduction in supplementation costs. <strong>Conclusion. </strong>There were no significant differences in the performance of BS cows grazing on an ASPS during the dry season receiving supplements with low crude protein levels. When correcting to fat-protein milk yields a significant difference was found in favour of supplement with 120 g CP/kg of DM.<strong></strong></p>

Dragon fruit farming by-products as an important source of several glycosylated flavonoids

Plants are globally used as an alternative for conventional drugs in treatment of many diseases. A significant proportion of medicinal properties of plants is addressed to antioxidant constituents as flavonoids and phenolic acids. The genus Selenicereus, known as dragon fruit, has about 15 species of epiphytic or hemiepiphytic cactus with hotspots in the tropical region of Mexico. Recently, these plants have been the focus of pharmacological studies due to the antioxidant activity of its fruits. Although many studies have investigated the biological activities of fruits, few studies investigated the chemical constituents and biological activities of cladodes. Despite the little knowledge about cladodes, it has been already observed to have higher antioxidant activities and other biological activities than the fruits. Besides this, cladodes are by-products resulting from the year-round pruning. Another important point about studies involving dragon fruit is that none of them identify the variety that is being used. As it is a commercial plant, it has many varieties created by artificial selection and hybridization such as many other food plants. In this study we found that varieties from the same species showed quantitative and qualitative differences in the metabolite profile using LC-MS. Metabolite profile from Cerrado (Selenicereus setaceus) was closer to Branca (Selenicereus undatus) than Thick King (S. setaceus), as well as Golden (S. undatus) was closer to Thick King than Branca. These results show that it is essential to identify varieties that are being used in the studies, whereas studies that attempt to replicate the experiments or use these plants for phytopreparations are prone to mislead.

The relationships between dung beetles and monkeys in the Neotropical region

The relationship between dung beetles and arboreal mammals has been scarcely studied, and many of the reports refer to observations without a standardized methodology. The accelerated loss of tropical forests urges us to understand this mutualistic association. Using our studies on arboreal dung beetles in the Palenque Archaeological Zone-National Park, Mexico, as a baseline, we analyzed the information on arboreal dung beetles in Neotropical forests in Mexico and around the world. Canthon euryscelis Bates, 1867, Canthon angustatus Harold, 1867, Canthon subhyalinus Harold, 1867, and Canthon femoralis (Chevrolat, 1834) are the main species collected in trees of Palenque, Onthophagus maya Zunino, 1981 and other non-Scarabaeinae species were occasionally collected from trees in Palenque. The small Canthon species are skilled fliers strongly relationship with monkeys in Palenque and other tropical regions of Mexico and Central America. In South America, arboreal dung beetles are more diverse and include these and other dung beetle species associated with monkeys. Several dung beetle species of the genus Onthophagus have been reported in association with African monkeys. In India, several studies report a wide variety of dung beetle species associated with monkeys. In Australia and New Guinea, only some species of Macropocopris are described as being associated with arboreal marsupials, but in Borneo, several dung beetle species have been observed associated with arboreal marsupials, mostly in managed forests. In Madagascar, Arachnoides gandi is the only beetle species reported in trees. We need to formulate a systematic and comparative methodology to understand better how arboreal beetles search for food, where the food is located, and how brood balls are made, how male-female pairs meet and nest, and how they contribute to arboreal dung recycling.

Payment for environmental services: Forest conservation and poverty alleviation in a tropical region of Mexico

Payment for environmental services (PES) is a scheme that seeks to reduce human pressure on forest ecosystems by financially rewarding forest landowners for conserving their forests. However, in Mexico, the program is questioned because it prioritizes communities in the poorest regions over areas with a high risk of deforestation. This study evaluates the effectiveness of the PES program for forest cover conservation and poverty alleviation in a tropical region of Mexico. Deforestation and forest cover maintenance was determined by land use/cover change analysis using GIS. Effect on poverty alleviation was analyzed qualitatively in two communities. In the study area, 4738 ha of tropical and temperate forests were deforested during 2007–2017. The deforestation rate is similar in ejidos and private properties with and without PES. Most ejidos where deforestation occurred correspond to areas with higher economic development. Deforestation and the percentage of the population living in poverty are negatively correlated. Compared to other subsidies, the PES represents very low income, nevertheless, the social perception of the program is positive. Based on the lower percentage of deforestation avoided in the poorest areas and the minimal impact on livelihoods, the current PES approach is not highly effective.

Comparison of models for lactation curves of Holstein, Brown Swiss, and F1 crossbred cows under subtropical conditions.

Tropical and subtropical milk production herds in Mexico generally generate different types of milk-yield records as milk yield per month and mean production per month. Lactation curves generated by these types of records may contribute to understand milk production in the tropical regions of Mexico. The aim of this study was to compare five lactation-curve models fitted to two types of milk-yield records of Holstein, Brown Swiss, and F1 crossbred cows under subtropical conditions. The two types of records (n = 3756) used were: (1) milk yield per month (TR) and 2) mean production per months (MR). Goodness-of-fit statistics, including Akaike's information criterion (AIC) and root mean square error (RMSE), were applied to compare the models for each type of records. The Brody model provided the best goodness-of-fit when using monthly milk-yield records, while the Wilmink model provided the best goodness-of-fit for lactation milk-yield records. The RMSE and AIC values were similar between datasets. The final third of the lactation curve showed a little difference between model predictions in both datasets. The comparison of several models was useful to better describe the actual lactation curves of the herd. The Wood model may be adequate to compare information as a reference with other models for decision making process at milk production.

Babesiosis and Theileriosis in North America.

Babesia and Theileria are apicomplexan parasites that cause established and emerging diseases in humans, domestic and wild animals. These protozoans are transmitted by Ixodid ticks causing babesiosis or theileriosis, both characterized by fever, hemolytic anemia, jaundice, and splenomegaly. In North America (NA), the most common species affecting humans is B. microti, which is distributed in the Northeastern and Upper Midwestern United States (US), where the tick vector Ixodes scapularis is established. In livestock, B. bovis and B. bigemina are the most important pathogens causing bovine babesiosis in tropical regions of Mexico. Despite efforts toward eradication of their tick vector, Rhipicephalus microplus, B. bovis and B. bigemina present a constant threat of being reintroduced into the southern US and represent a continuous concern for the US cattle industry. Occasional outbreaks of T. equi, and T. orientalis have occurred in horses and cattle, respectively, in the US, with significant economic implications for livestock including quarantine, production loss, and euthanasia of infected animals. In addition, a new species, T. haneyi, has been recently discovered in horses from the Mexico-US border. Domestic dogs are hosts to at least four species of Babesia in NA that may result in clinical disease that ranges from subclinical to acute, severe anemia. Herein we review the pathogenesis, diagnosis, and epidemiology of the most important diseases caused by Babesia and Theileria to humans, domestic and wild animals in Canada, the US, and Mexico.

SAG3 Toxoplasma gondii cloning reveals unexpected fivefold infection in the blood of feral cats in the Mexican Caribbean

BackgroundCurrently, more than 300 genotypes of Toxoplasma gondii (T. gondii) have been described throughout the world, demonstrating its wide genetic diversity. The SAG3 locus is one of the genes included in the genotyping panel of this parasite. It is associated with its virulence since it participates during the invasion process of the host cells. Therefore, cloning, sequencing, and bioinformatic analysis were used to deepen the understanding of the SAG3 locus genetic diversity of T. gondii in blood samples from feral cats.ResultsSix different SAG3 sequences were detected, five of which were detected in one feline. Three sequences were first reported here; one of them was an intragenic recombinant. In the cladogram, four out of ten SAG3 sequences did not share nodes with others reported worldwide.ConclusionsCloning and sequencing of samples with more than one restriction pattern by PCR-RFLP were very helpful tools to demonstrate the presence of more than three genotypes of T. gondii in the blood of feral cats from southeastern Mexico. This suggests a potential mixed infection of multiple T. gondii strains and high genetic diversity of the parasites in felines in this tropical region of Mexico.

Physiological responses of two equine breeds to a tropical winter climate

In tropical regions of Mexico, breed horses introduced from European countries are used for recreational activities under hot and humid conditions without considering their well-being. In order to evaluate the effect of winter conditions on physiological responses of two equine breeds, twelve horses (six Spanish and six Friesian breeds) were evaluated in the western Pacific coast of Mexico. The winter season was divided in 3 periods so that the statistical model included the factors breed and period. The physiological responses evaluated were: heart rate (HR), respiratory rate (RR), capillary refill time (CRT), and rectal temperature (RT). The climatic variables ambient temperature (AT) and relative humidity (RH) were used to estimate the temperature-humidity index (THI). Averages for THI, AT and RH were 71.4 units, 24.3 °C, and 53.4%, respectively. The CRT was similar (P > 0.05) among breeds and periods. The interaction B X P was significant (P < 0.05) for HR, RR, and RT in the second and third periods, but not in the first one. As a result, Spanish horses experimented higher (P < 0.05) HR (38.1 vs 37.6 and 38.0 vs 37.0 beats/min), RR (18.8 vs 18.5 and 18.9 vs 17.4 bpm), and RT (38.1 vs 38.0 °C and 38.0 vs 37.8 °C) than Friesian horses during the second and third periods, respectively. Both breeds of horses were exposed to a mild to moderate heat stress during winter tropical conditions; however, Spanish breed horses showed better tolerance to heat stress than Friesian horses based on their physiological measures evaluated.

EFECTO MEDIOAMBIENTAL Y DEL DISEÑO DE CORRAL EN COMPORTAMIENTO AGONISTA DE BOVINOS EN FINALIZACIÓN INTENSIVA

<p><strong>Background.</strong> Environmental factors can affect the welfare of cattle in the feedlot and alter their behavior. <strong>Objective.</strong> The present study determine the effect of the feedlot environment on the agonist behavior of cattle during two seasons in a tropical region of Mexico. <strong>Methodology.</strong> A prospective observational study was conducted in pens identified as Type 1, Type 2 and Type 3. The agonist behaviour, environmental temperature, relative humidity and Temperature and Humidity Index (THI) were recorded at 8:00, 12:00 and 16:00 h. <strong>Results</strong>. In autumn, the variation in the threat rate (34 vs. 14; P <0.05) and bumps (20 vs. 12, P <0.01) is influenced by the THI value and the hour of day; at 8:00 the THI did not exceed 77 units, while at 12:00 and 16:00, it exceeded 82 units. In Flehmen's reaction, mounts and vocalizations influenced the hour and design of the pen (P <0.02). In winter, the mounts (18 vs. 10) occurred when the THI value was 69 units (P <0.01), and decreased when it increased to 74 units. The Flehmen´s reaction was higher in Type 3 (14 vs. 7) than in Type 1 (P <0.01). <strong>Implications. </strong>The agonist behavior of cattle, as measured in this work, should be considered as a measured of cattle welfare indicators in feedlots <strong>Conclusions</strong>. The increase of THI and design of the pen influence the manifestation of agonist behavior in beef cattle.</p>

Abstract P407: Role Of Cyclic AMP During The Intracellular Infection Cycle Of Trypanosoma Cruzi

Trypanosoma cruzi is the causative agent of Chagas disease, a vector-borne disease. In the 1990s the distribution of the vector, a hematophagous triatomine, and consequently the parasite, was from the southeast tropical regions of Mexico to South America. Now, global warming is causing this distribution to expand to northern territories in Mexico, reaching southern parts of US, in which up to 300,000 people are affected. Furthermore, an increase in chronically-infected immigrants to the US makes Chagas disease a matter of Pan-American public health that it should be addressed by all the America countries. Chagas disease manifests clinically as cardiovascular disease, characterized by hypertrophy of heart, esophagus and colon. Congestive heart failure is the main cause of death (58%) in Chagas patients, whereas cardiac arrhythmias and unexpected deaths add another 36%. A major cause of heart pathology in Chagas disease damage is caused by the host immune system, as it attacks chronically infected tissue. Therefore, pathology of the disease is a direct consequence of the ability of the parasite to invade host cells, so it can establish chronic infection. To achieve this, T. cruzi must sense and adapt to the host environment, but the underlying mechanisms are poorly understood. In particular, parasite signaling pathways used to sense and transduce signals from the host environment are most completely unknown. Our lab studies cAMP signaling in trypanosome parasites and several lines of evidence suggest T. cruzi cAMP signaling is important for host cell invasion, differentiation and persistent infection, which in turn underlies heart tissue pathology of Chagas disease. A transcriptome analysis revealed that mRNA of proteins involved in cAMP metabolism, i.e. adenylate cyclases and phosphodiesterases, are either upregulated or downregulated during the intracellular infection cycle. In fact, the phosphodiesterases have flagellar homologs with known cAMP signaling functions in a related parasite. This suggests that cAMP might fluctuate during as T. cruzi invades, differentiates, and multiplies inside the host cells. We have implemented a cAMP FRET sensor to monitor cAMP levels in trypanosomes to understand the role of cAMP in T. cruzi pathogenesis.

Tendencias minimalistas en la gestión de los bosques tropicales mexicanos: motivaciones y experiencias

Tropical timber regions across the world share common problems such as degradation and poor regeneration after timber harvesting. Traditional Mayan land management through slash and burn is now recognized as an effective way of renewing forest stands in multispecies tropical forests. The practice of slash and burn for forest management in Mexico has led to area regulation, which has made land value a convenient means of assessing alternative forest plans. The use of expected land value as a performance indicator shifts the manager's attention from managing a species mix to balancing financial tradeoffs between liquidation or retention of the standing biomass. Since the forest-wide residual stock is so large, land value overrides the importance of revenue from timber sales. Several forest management methods along these lines have appeared in tropical regions of Mexico over a thirty-year time span and represent a patrimonial system of forest management (PS). The gradual innovation generated by PS is described here, as well as examples of PS practices. PS methods today provide stewardship for a total of 155,814 ha in different parts of Mexico. PS performance will become evident in the long run; in the meantime, the embrace of PS by private landowners and regulatory institutions is equated with a positive, independent opinion about PS design. The Mexican experience suggests pathways for rational management of all types of forests. PS features that are worth replicating are, for instance, the inclusion of disturbance patterns as factors in decision making, as well as the use of specific silvicultural regimes for roads, woodlands, closed forests, hilltops, swamps, riparian zones, clearings and forest edges.

Reproductive and cost assessment of a seasonal breeding program with Bos indicus in tropical Mexico

Objective. To compare the reproductive performance of postpartum and open Bos indicus cows and to study the cost effectiveness of retaining non-pregnant animals after a short breeding season in tropical region of Mexico. Material and Methods. A total of 128 Bos indicus were included, 87 postpartum cows (PP) with ≤90 days after calving and 41 open cows (OC) with >90 days open. The study was divided into three phases: 1) Estrus synchronization followed by FTAI (day 0-10), 2) Estrus detection and AI (day 11-45) and 3) Natural mating (day 46-90). For the first phase, all animals were synchronized and AI at fixed time (day 10). Cows displaying overt signs of estrus (day 11-45) were AI. Open cows during the previous two phases were exposed to the bull. Results. Pregnancy in phase 1 was different (p<0.01) for PP and OC groups, 58.6% and 34.1%, respectively. Overall pregnancy percentage over the second service was 42.5% (p>0.05). No differences (p>0.05) were observed at phase 3, average 44.2%. By the end of the breeding season, the cost of OC, was 3 times more than PP cows. Conclusions. Pregnancy rate at first phase was higher in PP cows than OC cows. At the end of breeding season, a pregnancy rate of 80% was found. Incorporation of open cows from previous breeding season was more expensive than PP cows in all phases of the breeding program. Retaining an open cow for rebreeding one year or more could not be economically feasible.

Determinación de la calidad fisicoquímica de la miel de abeja Apis mellifera mellifera producida en el Municipio de Tepatlaxco, Ver., envasada en vidrio y PET apoyado en un estudio etnobiológico

La apicultura en las regiones tropicales de México tiene antecedentes de cientos de años. Las abejas sociales y productoras de miel son parte esencial de las costumbres religiosas, alimenticias y comerciales de muchos pueblos indígenas. La miel para consumo humano debe tener buenas condiciones higiénicas, comportamiento microbiológico característico como consecuencia de la composición del producto base elaborado por las abejas. El conocimiento ancestral no se pierde, sin embargo el proceso de elaboración y envasado ha ido cambiando de acuerdo a las necesidades de los productores y consumidores. Sin embargo no se tiene registro de la forma de elaboración, se desconoce si el proceso de envasado es el correcto y si las características que dicho envase proporciona a la miel diferentes características físicoquímicas. Por lo anterior en esta investigación se realizaron encuestas a apicultores del Municipio de Tepatlaxco, para registrar los conocimientos que poseen en cuanto a la producción de miel. Se determinaron variables fisicoquímicas (pH, grados Brix y acidez) de la miel envasada en plástico, vidrio nuevo y vidrio reutilizado a diferentes tiempos de anaquel. Algunos de los resultados encontrados fueron que el envase de vidrio, nuevo y reciclado son opciones viables para los apicultores del municipio de Tepatlaxco, Veracruz ya que preserva las características particulares de la miel.

Efecto de dos sistemas de alojamiento y del sexo sobre el comportamiento productivo de corderos durante el engorde

Los corrales elevados (RP) han sido promovidos en las regiones tropicales de México como un sistema de alojamiento que mejora el comportamiento productivo de los corderos en crecimiento y han mostrado una gran aceptación entre los productores, tanto para corderos machos como en hembras; sin embargo, han sido poco estudiados y se han usado sin enriquecimiento ambiental en los sistemas intensivos. Por lo tanto, el objetivo de este estudio fue comparar el comportamiento productivo de corderos en crecimiento tanto machos como hembras alojados en RP y a nivel del suelo (GL) usando viruta como material de cama. Se usaron 32 corderos, 15 machos y 17 hembras, con un promedio de peso vivo y edad inicial de 10,54 ± 1,89 kg y 66,54 ± 22,43 días, respectivamente. Los datos fueron analizados empleando análisis de varianza, incluyendo como efectos fijos el tipo de alojamiento (RP y GL) y el sexo (machos y hembras) y las variables dependiente ganancia diaria de peso (DWG), el consumo de alimento (DMI), la conversión alimenticia (FC) y el peso vivo final (FBW). El tipo de alojamiento no tuvo efecto sobre DWG, DMI, FC y FBW (P > 0,05). Los machos presentaron mejores valores en todos los indicadores productivos que las hembras (excepto en FC). Bajo las condiciones de este estudio, el comportamiento productivo de corderos en crecimiento alojados ya sea en RP o en GL fue similar.

Isolation of pure Trichostrongylus colubriformis strains from naturally infected sheep using two methodologies.

Two methodologies were tested to isolate pure Trichostrongylus colubriformis strains from naturally infected sheep. Also, the in vitro susceptibility status to commercial anthelmintic (AH) drugs was determined in these strains. These methods were performed in a tropical region of Mexico where naturally infected sheep and goats host Haemonchus contortus, T. colubriformis and Oesophagostomum columbianum. For the first strain, a group of 6 naturally infected lambs from the "Paraiso" farm were treated with closantel (subcutaneous (SC), 10mg/kg). On day 10 post-treatment, the eggs per gram (EPG) of faeces were determined with the McMaster technique. The faeces from the two lambs with the highest EPG were used for coprocultures (4days, 28°C). The L3 larvae were recovered and identified as T. colubriformis (69%) and O. columbianum (31%). The latter was removed by 10-day refrigeration (4-5°C) followed by sieving (25μm), resulting in 100% T. colubriformis (PARAISO strain). The second strain was isolated using repeated doses of levamisole (LEV, SC 7.5mg/kg) in an 8-year-old sheep. The sheep had 1700 EPG before the LEV treatments and maintained 1300 EPG after both LEV treatments (day 10). The coproculture (4days, 28°C) after the second treatment contained 100% T. colubriformis (FMVZ-UADY strain). The in vitro AH susceptibility was determined using the egg hatch test for benzimidazole (BZ), and the larval migration inhibition test for ivermectin (IVM) and LEV. The PARAISO strain was BZ- and LEV-susceptible, and IVM-resistant. Meanwhile, the FMVZ-UADY strain was BZ- and IVM-susceptible, and LEV-resistant. The conditions where these two protocols could be used in other parts of the world were discussed.

Cnidoscolus aconitifolius: usos terapéuticos y propiedades fitoquímicas. Revisión de la literatura

Introducción. El uso tradicional de plantas medicinales para tratar diferentes enfermedades, ya sean infecciosas o no, es ampliamente aceptado debido a su bajo costo y sus bajos índices de toxicidad. Estas plantas son frecuentemente usadas en casos que involucran irritaciones de la piel, heridas superficiales, picaduras de insectos y mordeduras de víboras.Objetivo. Recopilar la información disponible sobre los principales usos terapéuticos y los componentes fitoquímicos de Cnidoscolus aconitifolius, una planta conocida popularmente como chaya y que crece en regiones tropicales de México y Centroamérica.Materiales y métodos. Se realizó una revisión de la literatura sobre C. aconitifolius publicada hasta 2017 en las bases de datos BIREME, PubMed/Medline, Elsevier y SciELO. Para la búsqueda se emplearon los descriptores “Cnidoscolus” y “aconitifoloius”, y no se aplicaron filtros de idioma.Resultados. Se identificaron 82 artículos luego de completar la búsqueda inicial. Después de filtrar los estudios por título (presencia de descriptores de búsqueda en el título) y remover duplicados, se incluyeron 18 artículos en la revisión. De acuerdo a la información encontrada, fue posible confirmar que esta planta ofrece diversos beneficios para la salud.Conclusiones. El uso terapéutico tradicional de la chaya está sustentado por evidencia científica, por lo que se sugiere realizar más investigaciones centradas en la identificación de nuevas propiedades fitoquímicas de esta planta y, así, establecer alternativas terapéuticas para distintas afecciones.

Immune response related to Pelibuey sheep naturally infected with gastrointestinal nematodes in a tropical region of Mexico

We analysed the immune response involved in sheep naturally infected with gastrointestinal (GI) nematodes. Fifteen Pelibuey lambs were grazed in paddocks contaminated with GI nematodes for 13weeks. To assess the infection, the number of eggs per gram (epg) and the percentage of packed cell volume (pcv) were evaluated. Blood and abomasal tissue samples were collected at week 8 post-infection to analyse the expression levels of IL-4, IL-5, IL-6, IL-8, IL-13, TGF-β and FCεR1A genes. The nematode Haemonchus contortus was the main species identified. In addition, two groups of lambs were classified based on the x±SE of epg and pcv values: G-1, with 151 ± 28 and 29±0.33%, respectively, and G-2, with 475±59.5 and 26±0.38%, respectively. For G-1, upregulation of IL-4, IL-8, IL-13, TGF-β and FCεR1A genes from 2.42- to 14.99-fold was observed in blood and abomasal tissue samples (p>.05), and IL-5, IL-8 and TGF-β genes had significant gene expression levels in blood (p<.05). For G-2, moderate gene expression levels, ranging from 1.22- to 3.45-fold, were observed in abomasal tissue (p>.05), and the IL-5 gene presented significant gene expression in blood (p<.05). Strong positively correlated values (r) between pcv and IL-4, IL-8 and TGF-β genes were observed in G-1. In contrast, significant negative correlations between epg and IL-4, IL-5 and FCεR1A genes indicate acute infection for G-2. Our results suggest that IL-4, IL-5, IL-13, TGF-β and FCεR1A genes are important modulators of GI nematode infections of Pelibuey lambs.