Cattle In Mexico Research Articles

Advances in the Characterization of Creole Cattle from Nayarit, Chihuahua, and Baja California Sur.

Objective. This manuscript aims to contribute to disseminating the research conducted on creole cattle from Nayarit, Chihuahua, and Baja California, as these regions have been the focus of numerous studies. These studies include identifying the areas of opportunity that need to be addressed for the conservation of this zoogenetic resource present in Mexico. Description. Cattle farming in Mexico began with the arrival of the first bovines from the Iberian Peninsula to New Spain over 500 years ago. These cattle established itself in various regions of the country, developing specific characteristics that have allowed it to adapt primarily to harsh environmental conditions. As a result, these bovines are considered a productive alternative in various agroecological environments to address the challenges of climate change and mitigate the negative effects on the ecosystem. Limitations. To date, research on the morphological, productive, and genetic characterization, as well as the production environment of Creole cattle in Mexico, remains limited. Therefore, it is necessary to develop studies in this area to contribute to the conservation of this resource and, above all, to identify mechanisms for its rational use that justify its existence in a modern economic and productive environment. Conclusions. The documentary review conducted to present the current state of research on creole cattle herds in Nayarit, Chihuahua, and Baja California Sur revealed that the studies have primarily focused on productive aspects in various environments. Therefore, it is necessary to encourage research directed towards other productive areas of cattle, such as reproduction, animal health, and adaptation, in order to develop strategies that contribute to the conservation of this zoogenetic resource.

Infestation of Cattle with the Tick Amblyomma mixtum in the States with the Highest Cattle Inventory in Mexico

A Objective: The Amblyomma mixtum tick is one of the main parasites affecting cattle in Mexico. Epidemiological records of A. mixtum in leading states in the national cattle industry, such as Jalisco, Chiapas, Michoacán, Tabasco, and Veracruz, are outdated since this tick species was previously classified as A. cajennense. The objective was to update the records of the A. mixtum tick in the states of Jalisco, Chiapas, Michoacán, Tabasco, and Veracruz, as well as the main ixodicide molecules used for its control. Methodology: From March 2022 to July 2023, ticks were collected from cattle in 46 bovine production units (BPUs) distributed in the states mentioned above. Identification was performed using standardized taxonomic keys. Scanning electron microscopy was performed on specimens corresponding to A. mixtum. Results: Out of a total of 619 specimens of the genus Amblyomma from 22 PBUs, it was confirmed that 100% correspond to the species A. mixtum. Amitraz, an ixodicide molecule belonging to the chemical class of amidines, was used in 63.2% of the BPUs where the presence of A. mixtum was also reported. Conclusions: This research confirms cattle infestation with A. mixtum in states with the highest cattle production in Mexico. Further studies with a focus on resistance and extension are required to prolong the usefulness of available tools, including ixodicides, for integrated control of A. mixtum infestations where this tick infests cattle in Mexico.

Comparative Transcriptome Analysis of Babesia bigemina Attenuated Vaccine and Virulent Strains of Mexican Origin.

Bovine babesiosis, caused by the protozoan Babesia bigemina, is one of the most important hemoparasite diseases of cattle in Mexico and the world. An attenuated B. bigemina strain maintained under in vitro culture conditions has been used as a live attenuated vaccine; however, the biological mechanisms involved in attenuation are unknown. The objective of this study was to identify, through a comparative transcriptomics approach, the components of the B. bigemina virulent parasites that are differentially expressed in vivo, as opposed to those expressed by B. bigemina attenuated vaccine parasites when inoculated into naïve cattle. The biological material under study was obtained by inoculating spleen-intact cattle with infected erythrocytes containing either the attenuated strain or a virulent field strain. After RNA extraction, transcriptomic analysis (RNA-seq) was performed, followed by bioinformatic Differential Expression (DE) analysis and Gene Ontology (GO) term enrichment. The high-throughput sequencing results obtained by analyzing three biological replicates for each parasite strain ranged from 9,504,000 to 9,656,000, and 13,400,000 to 15,750,000 reads for the B. bigemina attenuated and virulent strains, respectively. At least 519 differentially expressed genes were identified in the analyzed strains. In addition, GO analysis revealed both similarities and differences across the three categories: cellular components, biological processes, and molecular functions. The attenuated strain of B. bigemina derived from in vitro culture presents global transcriptomic changes when compared to the virulent strain. Moreover, the obtained data provide insights into the potential molecular mechanisms associated with the attenuation or pathogenicity of each analyzed strain, offering molecular markers that might be associated with virulence or potential vaccine candidates.

Genetic diversity of SNPs associated with candidate genes for heat stress in Coreño Creole cattle in Mexico.

Mexican Coreño Creole cattle are an important genetic resource adapted to local environmental conditions, so the study of their genetic diversity is essential to know their status and implement conservation programs and their use for crossbreeding. This study evaluated the genetic diversity of heat stress tolerance characteristics of Coreño Creole cattle, and a gene ontology enrichment was performed to know the biological processes in which candidate genes are involved. A total of 48 samples from three localities of Nayarit were genotyped using 777K Illumina BovineHD BeadChip and 34 single nucleotide polymorphisms associated with candidate genes were selected. Genetic diversity was analyzed using allelic frequencies, expected heterozygosity (He), and Wright's fixation index (FST) using PLINK v1.9 software. Candidate genes were uploaded to the open-source GOnet for pathway analysis and linkage to biological processes. Coreño Creole cattle showed low genetic diversity (He = 0.35), the average FST obtained was 0.044, and only eight markers had allele frequencies higher than 0.80 in the three locations. We found that the genes GOT1 and NCAD are related in the biological processes of stress response, cell differentiation, and homeostatic process. The results revealed that Coreño Creole cattle have low genetic diversity; this could be due to the isolation of these populations.

Estimation of the water footprint in the production of beef from Euro-pean cattle in Mexico

Objective: To determine the water footprint of beef from Charolais cattle subjected to stable production and an established diet. Design/Methodology/Approach: The water footprint was estimated using the methodology proposed by Hoekstra, in which the water footprints of the ingredients of the feed consumed are added to the total volume of water that the animal drank during its life. Results: The estimated water footprint for beef in this research was 2,972.4 liters per kg, including the blue and green water footprint. Study Limitations/Implications: The calculation of the gray water footprint is not included, although it is an indicator of the specific zone. Findings/Conclusions: There is a difference between the water footprint obtained in this study and the footprint reported in the references, perhaps as a result, among other reasons, of the differences in diet and breed of the animals studied.

Molecular detection of Coxiella burnetii in vaginal swabs from aborted cattle in Mexico

Molecular detection of Coxiella burnetii in vaginal swabs from aborted cattle in Mexico

Molecular detection of bovine leukosis virus in naturally infected dairy and dual-purpose cattle in Mexico.

The objective of this study was to determine the prevalence of bovine leukosis virus (BLV) in specialized and dual-purpose dairy cows located in the central zone of Veracruz state in Mexico, using endpoint polymerase chain reaction (PCR). The study population consisted of 307 specialized dairy cows and 95 dual-purpose cows from 13 municipalities located in the study area. All cows were apparently healthy and ≥ 3 years old. Cows were stratified by age (3 - 5, 6 - 8 and ≥ 9 years). The overall prevalence of infection was 6.96%; the calculated prevalence in dairy cows was 7.82% and in dual-purpose cows it was 4.21%. The municipality with the highest proportion was Acajete (14.28%), followed by Huatusco and Tomatlán (11.53%). The association analysis confirms the infection's independence to the cows' productive purpose. The results by age strata were 3 - 5 (4.60%), 6 - 8 (8.00%) and ≥ 9 (18.40%) with X2 = 9.96, with an odds ratio of 4.68 for the stratum ≥ 9 years with a significant difference. The present study determined the prevalence of proviral DNA of BLV in dairy and dual-purpose cows in six municipalities in the central zone of Veracruz state, Mexico, using endpoint PCR.

Does Gender Impact Technology Adoption in Dual-Purpose Cattle in Mexico?

This paper examines the role of women in the dual-purpose livestock system (DP) in Mexico through their technological adoption patterns and aims to evaluate whether there are significant differences between the technology adoption networks of men and women farmers. The sample was composed of 383 DP small farms with 20 or fewer cows and a high level of vulnerability. Social Network Analysis (SNA) was applied, and the centrality measures were calculated for the technological areas of management, feeding, genetics, reproduction, and animal health. Significant differences were found in reproduction levels between men and women farmers. Therefore, SNA was developed in this technological area where men mainly occupied central positions (brokers) while women were just close to the leaders in the network. The results have shown that farms run by women were smaller and presented higher levels of specialization and milk productivity (20% higher), and women prioritized those technologies linked to female reproductive efficiency. Moreover, women were deeply embedded in men's networks through numerous ties and were capable of building connections with groups of farmers outside of their own group.

Discovering of Genomic Variations Associated to Growth Traits by GWAS in Braunvieh Cattle.

A genome-wide association study (GWAS) was performed to elucidate genetic architecture of growth traits in Braunvieh cattle. Methods: The study included 300 genotyped animals by the GeneSeek® Genomic Profiler Bovine LDv.4 panel; after quality control, 22,734 SNP and 276 animals were maintained in the analysis. The examined phenotypic data considered birth (BW), weaning (WW), and yearling weights. The association analysis was performed using the principal components method via the egscore function of the GenABEL version 1.8-0 package in the R environment. The marker rs133262280 located in BTA 22 was associated with BW, and two SNPs were associated with WW, rs43668789 (BTA 11) and rs136155567 (BTA 27). New QTL associated with these liveweight traits and four positional and functional candidate genes potentially involved in variations of the analyzed traits were identified. The most important genes in these genomic regions were MCM2 (minichromosome maintenance complex component 2), TPRA1 (transmembrane protein adipocyte associated 1), GALM (galactose mutarotase), and NRG1 (neuregulin 1), related to embryonic cleavage, bone and tissue growth, cell adhesion, and organic development. This study is the first to present a GWAS conducted in Braunvieh cattle in Mexico providing evidence for genetic architecture of assessed growth traits. Further specific analysis of found associated genes and regions will clarify its contribution to the genetic basis of growth-related traits.

Supervivencia intracelular de cepas de Mycobacterium bovis de alta y baja frecuencia probado en un modelo de macrófagos bovinos

Bovine tuberculosis is a disease caused by Mycobacterium bovis that affects cattle and other species, including humans. Mycobacterium bovis resides mainly in macrophages, so bacilli survival within macrophages is related to virulence. Isolation and strain identification are important for disease control. However, little is known about virulence of the circulating strains in cattle populations. Therefore, the aim of this study was to compare the intracellular survival of Mycobacterium bovis strains with high and low frequency genotypes in cattle in Mexico. Four high frequency genotypes and four low frequency genotypes were identified and subjected to intracellular survival assays in bovine macrophages. Results showed that the phagocytosis proportion was approximately 63 % for all strains. There were no significant differences in the average Colony Forming Units (CFUs) in phagocytosis and survival between the high and low frequency groups; however, when the CFU average of phagocytosis was compared with the survival, significant differences were found in both groups. In intracellular growth, a significant difference was observed between low and high frequency strains, and between low frequency strains. Finally, the intracellular growth average of the groups was analyzed showing no significant difference. These results suggest that the frequency of the genotype in cattle population is not related to the intracellular survival and the virulence of the M. bovis strains.

The Importance of Network Position in the Diffusion of Agricultural Innovations in Smallholders of Dual-Purpose Cattle in Mexico

The dual-purpose bovine production system (DP) is the most widespread small-scale model in Latin American tropics, where it constitutes a key tool in terms of food security. Most DPs are subsistence farms oriented to self-consumption, with a very low technology adoption rate. Hence, the main challenge is how to improve the technological level without compromising the system sustainability by applying land-sharing practices. Thus, through networks methodology, this paper analysed how farmers adopt reproductive technologies. The sample consisted of 383 very small farms of dual-purpose cattle. Seven reproduction technologies oriented to improve reproductive efficiency were evaluated: Breeding soundness evaluation in bulls, semen fertility evaluation, evaluation of female body condition, oestrus detection, pregnancy diagnosis, seasonal or continuous mating, and breeding policy. Social Network Analysis (SNA) allowed identifying adoption patterns, as the joint adoption of semen fertility evaluation, estrus detection, and pregnancy diagnosis, which were consider complementary technologies. Similarly, breeding soundness evaluation in bulls was found to be the most widely adopted technology. The results showed that these farmers presented a very low level of reproduction technology adoption rate and suggested that farmer’s affiliation with organizations such as the Livestock Groups for Technological Validation and Transfer (GGAVATT), and its network position had a significant impact on the level of technological adoption. In the first stage of adoption, this work highlighted the importance of centralized models from the GGAVATT to the farmers, related to the knowledge and absorption dynamic capabilities. In a later stage, decentralized models through technological leaders are a priority, related to integration and innovation dynamic capabilities.

Genetic Background and Inbreeding Depression in Romosinuano Cattle Breed in Mexico.

Simple SummaryThe objective of this study was to evaluate the genetic background and inbreeding depression in the Mexican Romosinuano cattle using pedigree and genomic information. Inbreeding was estimated using pedigree () and genomic information based on the genomic relationship matrix () and runs of homozygosity (). Linkage disequilibrium () was evaluated using the correlation between pairs of loci, and the effective population size () was calculated based on and pedigree information. The pedigree file consisted of 4875 animals; 71 had genotypes. decreased with the increase in distance between markers, and estimated using genomic information decreased from 610 to 72 animals (from 109 to 1 generation ago), the estimated using pedigree information was 86.44. The number of runs of homozygosity per animal ranged between 18 and 102 segments with an average of 55. The average inbreeding was 2.98 ± 2.81, 2.98 ± 4.01, and 7.28 ± 3.68% for , , and , respectively. A 1% increase in inbreeding decreased birth weight by 0.103 kg and weaning weight by 0.685 kg. A strategy such as optimum genetic contributions to maximize selection response and manage the long-term genetic variability and inbreeding could lead to sustainable breeding programs for the Mexican Romosinuano cattle breed.The ultimate goal of genetic selection is to improve genetic progress by increasing favorable alleles in the population. However, with selection, homozygosity, and potentially harmful recessive alleles can accumulate, deteriorating genetic variability and hampering continued genetic progress. Such potential adverse side effects of selection are of particular interest in populations with a small effective population size like the Romosinuano beef cattle in Mexico. The objective of this study was to evaluate the genetic background and inbreeding depression in Mexican Romosinuano cattle using pedigree and genomic information. Inbreeding was estimated using pedigree () and genomic information based on the genomic relationship matrix () and runs of homozygosity () of different length classes. Linkage disequilibrium () was evaluated using the correlation between pairs of loci, and the effective population size () was calculated based on and pedigree information. The pedigree file consisted of 4875 animals born between 1950 and 2019, of which 71 had genotypes. decreased with the increase in distance between markers, and estimated using genomic information decreased from 610 to 72 animals (from 109 to 1 generation ago), the estimated using pedigree information was 86.44. The reduction in effective population size implies the existence of genetic bottlenecks and the decline of genetic diversity due to the intensive use of few individuals as parents of the next generations. The number of runs of homozygosity per animal ranged between 18 and 102 segments with an average of 55. The shortest and longest segments were 1.0 and 36.0 Mb long, respectively, reflecting ancient and recent inbreeding. The average inbreeding was 2.98 ± 2.81, 2.98 ± 4.01, and 7.28 ± 3.68% for , , and , respectively. The correlation between and was −0.25, and the correlations among and of different length classes were low (from 0.16 to 0.31). The correlations between and of different length classes were moderate (from 0.44 to 0.58), indicating better agreement. A 1% increase in population inbreeding decreased birth weight by 0.103 kg and weaning weight by 0.685 kg. A strategy such as optimum genetic contributions to maximize selection response and manage the long-term genetic variability and inbreeding could lead to more sustainable breeding programs for the Mexican Romosinuano beef cattle breed.

Structural and Technological Characterization of Tropical Smallholder Farms of Dual-Purpose Cattle in Mexico.

Dual-purpose cattle smallholder farms (DP) exhibit a critical economic situation. The objective of this research was building a typology for DP in tropical conditions and characterizing them technologically. This will help developing more effective public policies in DP farms located in tropical conditions. A sample of 1.475 farms located in the tropical area of Mexico was selected. The typology was built using multiple correspondence analysis (MCA). Subsequently, five groups were identified by a hierarchical cluster analysis with Ward's method. Groups 1 and 2, covered a 46.5% of the farms; these ones presented a small-scale productive model with low levels of technological adoption, improvements were mainly associated to the area of reproduction and genetics. Very small farms (Group 3) showed orientation to subsistence. They need to improve all the technological areas. Groups 4 and 5 (29.4% of the sample) were the biggest and more specialized farms. Group four farms were located in dry tropics and showed the highest levels of technological adoption in the areas of reproduction, management, and feeding. These farms require improvement in the areas of reproduction, animal health, and feeding. Group 5 farms were located in the wet tropics and showed specialization in reproduction, genetics, and animal health areas. In this last group, it is necessary to improve management and feeding areas.

Accuracies of direct genomic breeding values for birth and weaning weights of registered Charolais cattle in Mexico

Context Genomic prediction is now routinely used in many livestock species to rank individuals based on genomic breeding values (GEBV). Aims This study reports the first assessment aimed to evaluate the accuracy of direct GEBV for birth (BW) and weaning (WW) weights of registered Charolais cattle in Mexico. Methods The population assessed included 823 animals genotyped with an array of 77000 single nucleotide polymorphisms. Genomic prediction used genomic best linear unbiased prediction (GBLUP), Bayes C (BC), and single-step Bayesian regression (SSBR) methods in comparison with a pedigree-based BLUP method. Key results Our results show that the genomic prediction methods provided low and similar accuracies to BLUP. The prediction accuracy of GBLUP and BC were identical at 0.31 for BW and 0.29 for WW, similar to BLUP. Prediction accuracies of SSBR for BW and WW were up to 4% higher than those by BLUP. Conclusions Genomic prediction is feasible under current conditions, and provides a slight improvement using SSBR. Implications Some limitations on reference population size and structure were identified and need to be addressed to obtain more accurate predictions in liveweight traits under the prevalent cattle breeding conditions of Mexico.

Characterization of Antimicrobial Resistant (AMR) Salmonella Enterica Isolates Associated With Cattle at Harvest in Mexico

Despite being the target of control efforts for many decades, Salmonella enterica continues to be linked with a large amount of foodborne illnesses and outbreaks worldwide. Over the years, Salmonella isolated from meat products have exhibited a high level of antibiotic resistance. In this study, a total of 351 Salmonella isolates, recovered from cattle fecal samples (n = 31), hides (n = 105), and beef carcasses (n = 215) from 3 abattoirs in Mexico were analyzed for antimicrobial susceptibility. Resistance to at least one antimicrobial drug was found in 205 (58.4%) isolates and 20 different resistance phenotypes were observed among this Salmonella isolates set. Resistance to tetracycline (40.2%) and nalidixic acid (21.1%) was most commonly observed. Additionally, the most common multidrug-resistant (MDR) phenotypes shared resistance to chloramphenicol, streptomycin, tetracycline, and trimethopin/sulfamethoxazole (11.3%), resistance to ampicillin, tetracycline, and trimethopin/sulfamethoxazole (3.4%), and resistance to ampicillin, streptomycin, and tetracycline (2.5%). When it came to antimicrobial resistance phenotypes in each abattoir, we determined there was no statistical difference in the frequency of resistant vs. susceptible Salmonella isolates among the three abattoirs (P > 0.05). These data indicate that Salmonella isolates recovered from beef cattle in Mexico are commonly resistant to antimicrobials and often multiple antimicrobials. In Mexico, antimicrobial resistance, and in particular, multidrug-resistance, maybe of particular concern due to the much higher prevalence of Salmonella in retail beef. This may lead to the spread of resistance and to the reduction of antibiotic efficacy for the control of animal and human infections. Promoting control measures and inspection standards on imported animals and food products should be applied to avoid the spread of antibiotic resistance in various populations and among countries.

Genetic diversity and geographic distribution of Mycobacterium bovis from cattle in Mexico

Se obtuvieron patrones moleculares (espoligotipos) de 878 aislados de Mycobacterium bovis de ganado de diferentes regiones de México entre los años 2009 y 2010. Setenta y dos por ciento (72 %) de los espoligotipos cayeron en nueve grupos y 27 % de los aislados dentro de sólo dos espoligotipos; 149 fueron espoligotipos individuales. Los dos espoligotipos predominantes, arbitrariamente identificados como SP1 y SP2, se distribuyen en la mayor parte del territorio nacional, en especial en la zona centro de México en ganado especializado en producción de leche. A pesar de la amplia distribución geográfica de los espoligotipos de mayor frecuencia, algunos muestran cierta localización, en especial los encontrados en zonas geográficas distantes, como es el caso de Chihuahua y Baja California. Aunque pocos, algunos espoligotipos muestran patrones moleculares distintos a los mostrados por los espoligotipos de mayor frecuencia, sugiriendo fuentes de infección desconocida. La mayoría de los Estados con ganadería predominantemente lechera muestran espoligotipos comunes, lo que sugiere intercambio regional frecuente de ganado. Algunos espoligotipos son comunes en ganado para leche y ganado para carne, lo que sugiere transmisión entre estas dos poblaciones; se desconoce, sin embargo, si los animales de carne infectados provienen de explotaciones extensivas o si son de engordas ubicadas dentro de la explotación lechera. Se propone la tipificación rutinaria de aislados de M. bovis obtenidos en todos los laboratorios de diagnóstico y mejorar la captura de información epidemiológica de los casos, para hacer mejores conclusiones epidemiológicas de la distribución espacial de las cepas de este agente en el territorio nacional.

Non-inferiority trial of two commercial zilpaterol HCl brands in <em>Bos indicus</em> cattle under humid tropical conditions

Commercial availability of a generic zilpaterol HCl (ZH) premix preparation for beef cattle in Mexico motivated a non-inferiority trial vs the reference preparation. The trial was conducted on zebu-type cattle (Bos indicus) under humid tropical conditions. Meat production and basic meat quality were assessed for 810 zebu bulls, aged 18-22 months and weighing 430 to 490 kg. Bulls were randomly assigned into one of three groups: ZHg, treated with the generic ZH (Zipamix®) preparation; ZHr, treated with the reference ZH (Zilmax®) preparation, and Cg, the untreated control group. Housing, shade surface, feeding and water availability were highly homogeneous between the animals’ pens. Results for the measured productive and meat quality parameters showed that both ZH-treated groups had higher values than the Cg (P < 0.05), and differences between the ZHg and ZHr groups were not statistically significant, thus fulfilling the criteria of a non-inferior ZH preparation. In this assay, ZH supplementation did not modify the amounts of moisture, fat, protein or ash in the Longissimus dorsi muscle compared with the meat from non-supplemented animals, and the overall meat acceptability was unaffected (P > 0.05).

Seroprevalence to and influence of exposure to bovine reproductive disease causative agents on pregnancy and preweaning calf survival of elk (Artiodactyla: Cervidae)

Una parte del éxito de las reintroducciones de ciervo wapití (C. elaphus) en México depende de las interacciones y posibles conflictos con el ganado doméstico. Algunos agentes patógenos pueden impactar la reproducción del wapití y al ganado, pero es raro que se considere para los rumiantes silvestres cuando existe un declive en la productividad de la población. Se investigó la exposición a enfermedades de los wapití utilizando un perfil de aborto bovino (e.g. Brucelosis, leptospirosis, rinotraqueitis infecciosa bovina, (RIB), diarrea viral bovina, e infección por Neospora sp.), ya que estas enfermedades pueden afectar negativamente a la reproducción de los bovinos y rumiantes silvestres, y el wapití y el ganado frecuentemente co-ocurren. Utilizamos una regresión logística jerárquica para modelar la proporción de preñez de las hembras en periodo de lactancia (un sustituto para la supervivencia de la cría al destete) como una función de la población y la exposición de las enfermedades reproductivas. Se hicieron pruebas a poblaciones de wapití y fueron expuestos a 2-4 de los agentes patógenos evaluados, excepto para la brucelosis, que no estaba presente. La preñez de las hembras osciló entre 0.73-0.96 y la proporción de supervivencia al pre-destete desde 0.40-0.67 entre poblaciones. La época de preñez varió por población en todos los contrastes (P <0,016), pero no por la exposición a cualquier enfermedad (P> 0,213). La proporción de hembras lactantes en otoño no varió entre las poblaciones (P> 0,247), ni por la exposición a cualquier patógeno (P> 0,281). La exposición a patógenos no afectó la productividad del wapití, a pesar de los niveles de exposición que reflejan previos estudios en Estados Unidos de Norteamérica y la baja preñez y la sobrevivencia de crías entre algunas poblaciones. Debido a su presencia en todas las poblaciones de wapití en Estados Unidos de Norteamérica, si los productores de ganado adyacentes a los sitios de introducción de wapití en México están viendo menos crías que las esperadas, es posible que quieran vigilar su ganado para IBR para ver si BHV-1 puede ser un posible factor contribuyente, ya que el patógeno está relacionado con la reproducción y es probable que esté presente en los wapití.

Immunological control of ticks and tick-borne diseases that impact cattle health and production

The cattle industry is one of the most important agroeconomic activities in Mexico. The national herd is estimated to include approximately 33.5. million head of cattle. Ticks and tick-borne diseases are principal factors with a negative impact on cattle health and production. The most economically important tick species parasitizing cattle in Mexico are Rhipicephalus microplus, R. annulatus, and Amblyomma mixtum. Parasitism by ticks affects cattle health and production directly. Morbidity and mortality caused by tick-borne diseases augment the detrimental effect of tick infestation in cattle. Bovine babesiosis and anaplasmosis are the most important tick-borne diseases of cattle, which are caused by infectious agents transmitted by R. microplus and R. annulatus. However, there are no prophylactic therapies to control bovine babesiosis and anaplasmosis. Chemical control is the most common way to treat animals against ticks, and the use of acaricides can also help manage tick-borne diseases. However, the evolution of resistance to acaricides among cattle tick populations renders chemical control ineffective; which represents a challenge for sustainable ticks and tick-borne diseases control. The only anti-tick vaccine commercially available globally is based on the recombinant antigen Bm86. Because of its mode of immunity against R. microplus and R. annulatus, the Bm86-based vaccine also decreases the exposition of bovines to babesiosis and anaplasmosis. Research with Bm86-based vaccines documented high efficacy against R. annulatus, the efficacy levels against R. microplus varies according to the geographic origin of tick populations, and there is not effect against other ticks species such as Amblyomma spp. The impact of ticks and tick-borne diseases, the problem of chemical control due to acaricide resistance, and progress with anti-tick vaccine research efforts in Mexico are reviewed herein.

Design and construction of low-cost respiration chambers for ruminal methane measurements in ruminants

ABSTRACTRuminant animals contribute significantly to methane emissions in tropical regions. Nonetheless, there are few facilities available in those regions of the world for in vivo measurement of methane production in cattle. The aim of the present work was to describe the design, construction and operation of respiration chambers for in vivo measurement of methane production in cattle in Mexico. Locally available materials were used in the construction. Walls, roof and doors were constructed of thermic panels with two windows of acrylic at the front so the animal can be observed at all times. Chambers have an air volume of 9.97 m3. Air is drawn from the chamber at a rate of 500 L/min by the effect of mass action flow generators. Methane was measured in air samples with an infrared analyzer. Chambers operate under a slight negative pressure of around -500 Pa. Air temperature inside the chambers is kept at 23 °C with an air conditioner, while relative humidity is maintained at 55 % with a dehumidifier. Functioning of the chambers was evaluated in Bos indicus, Nelore cattle fed Taiwan grass (Pennisetum purpureum) and a concentrate (18 % crude protein), and measurements were made during runs of 23 h duration. Methane production was on average 173.2 L per day, while the emission factor was 17.48 L methane per kilogram o dry matter consumed. It concludes that this respiration facility is capable of measuring methane production accurately in cattle fed tropical rations.