State Of Chihuahua Research Articles

Aedes (Georgecraigius) epactius from Zacatecas and Chihuahua Mexico: New Geographical Distribution and Altitude Records

Adults and immatures of Aedes epactius were collected in July and December 2022 at sites of high elevation in the states of Chihuahua (2300 masl) and Zacatecas (2182 and 2595 masl), Mexico, respectively. Mosquitoes were identified morphologically and sequenced for a DNA barcode of the cytochrome c oxidase I (COX1). This is the first distributional record of Ae. epactius in Zacatecas and provides evidence of the highest altitude in the Americas, including Mexico. The geographical distribution of Ae. epactius in Mexico was reviewed, and the COX1 analysis, using phylogenetic Bayesian analysis to confirm species identification, was performed.

Emergence and development of Chihuahuan Desert grasses under simulated wet-dry sequences

We evaluated the response (emergence, speed of germination, survival) of nine grasses (six native, three introduced) commonly occurring in the State of Chihuahua, Mexico to four irrigation “wet-dry” sequences that simulate sequences of days with and without rainfall, under greenhouse conditions. The sequences provide a total of 120, 100, 80 and 60 mm (high, medium, low, and very low) of water for 40 days. The native species were Bouteloua curtipendula, B. dactyloides, B. eriopoda, B. gracilis, Digitaria californica, and Leptochloa dubia. The introduced grasses were Cynodon dactylon, Eragrostis curvula, and E. superba. A decrease in water, resulting from the drier sequences, delayed the emergence from 4 to 7 days in most species. The native B. dactyloides displayed the best potential for growth with high emergence (18%) and high survival (44%) under low or very low water sequences. In general, survival for native species was higher than for introduced species under water restrictions. The native species showed high survival and high root:shoot ratio (RSR) under drought, which was not observed in introduced species. As expected, we found that plant species responded differently to modeled rainfall sequences, providing insight into plant adaptations to drought and potential for survival under environmental variation.

PSX-2 Productive performance of Raramuri Criollo, Angus x Raramuri Criollo and Hereford x Angus cows in a low-input cow-calf system in northern Mexico

Abstract Raramuri Criollo cattle (RC), a local heritage breed in the Chihuahua state of Mexico, are highly rustic and well-adapted animals that can contribute to cow productivity in a low-input cow-calf production system. The aim was to evaluate traits related to productive performance of purebred RC, Angus x RC (AC) and Hereford x Angus (HA) cows. Each cow breed group was randomly assigned to one of three pastures within each of two mountains dominant exposures and evaluated during 2022 and 2023 at Rancho Teseachi (28◦48′ N, 107◦25′ W) belonging to Universidad Autonoma de Chihuahua. The six grazing pastures ranged from 263 to 400 ha, with similar slope, altitude and water sources characteristics. The stocking rate was moderate (forage utilization <50%). Forage biomass availability for the period of use was sampled in October, and stocking rate adjusted accordingly in March. RC cows were bred with RC bulls, and AC and HA with Angus bulls. The breeding season was from September to November, and pregnancy diagnosis at mid-January. Non-pregnant cows were replaced by pregnant cows from other pastures of the same farm. Feed supplementation was limited in 2022 and according to nutritional requirements in 2023. Evaluated variables included calf birth (BW) and weaning weight adjusted (WW) to the average age at weaning (190 d in 2022 and 165 d in 2023); body condition score (BCS 1 to 9), cow body weight (CBW) at the beginning of the breeding season, as well as body weight of calf weaned by unit of cow weight (WW/CBW), and pregnancy rate (PR). A general linear model with fixed effects of breed group, sex, dominant exposure of mountains, their interaction, cow age subclass (Young, 4 yr; Middle, 5 to 8 yr; Adult, > 9 yr) and Julian date at calving as a covariate was adjusted using PROC GLM of SAS for continuous, normally distributed variables, and PROC CATMOD for pregnancy rate, leaving out sex and interaction effects. Means of BW and WW on calves from AC and HA cows were greater (P < 0.5) than those from RC cows in both years (Table 1). In 2022, the mean CBW of HA was greater (P < 0.5) than for AC, and this greater (P < 0.5) than for RC cows; BCS was greater for AC than for HA and RC, and PR lower (P < 0.5) for HA than for AC and RC. In 2023, there was no difference in CBW between AC and HA; BCS was similar (P > 0.05) among the three groups; and PR was the lowest (P < 0.5) for HA. The AC cows had the greatest WW/CBW mean (P < 0.5) in both years. Overall, using AC cows resulted on a combination of traits that outperformed on general productivity in the evaluated production system.

Multitemporal Analysis of Land Cover Changes in Areas with Contrasted Forest Management and Conservation Policies in Northern Mexico

This study evaluates and contrasts changes in vegetation cover over three decades in two forest areas in the State of Chihuahua in northern Mexico with different management statuses: one with sustainable forest management and the other protected as a Flora and Fauna Protection Area. The hypothesis proposed that both areas would have maintained or increased their vegetation cover since 1995. Satellite images from the periods 1995–2008, 2008–2014, 2014–2022, and 1995–2022 were analyzed. The results showed that Ejido El Largo y Anexos significantly increased forest areas and reduced grasslands due to sustainable management practices, with a notable expansion of pine–oak and pine forests. In contrast, the Tutuaca Flora and Fauna Protection Area experienced a notable loss of oak and oak–pine forests, suggesting ineffectiveness in its conservation policies. However, there was less loss in Douglas Fir forests, indicating some effective protection efforts. The comparison reveals opposing dynamics: while Ejido El Largo y Anexos demonstrates success in sustainable management, the Tutuaca Flora and Fauna Protection Area faces conservation challenges. In conclusion, this study highlights the need for active management approaches to maintain ecosystem cover and functionality.

Mancera-Valencia, F.J. & Mayagoitia, E.A. (2023) Cultural Heritage and Education. Universidad Pedagógica del Estado de Chihuahua Editorial

Although the topics of the research articles that are compiled in this book focus on a wide range of themes, such as the connection between school and museums, the use of radio as a schooling device for indigenous population or the unique architecture of Mennonite schools in the north of Mexico; they all share the same objective: to foster a debate regarding the relevance of heritage education. Some of the texts are research articles, others document intervention experiences in different educational contexts, both formal and informal. Most of them narrate practices that were implemented in Mexican territory (specifically, the states of Chihuahua, Nuevo León, Mexico City and Baja California), except for one project that was conducted in Spain. The articles cover topics like the implications of educational heritage, its purpose, didactic orientations, devices, and places. The book coordinators, Federico Mancera-Valencia and Eva Mayagoitia, prestigious Mexican researchers, argue that patrimonial education is in its gestational state, and, since it is a research field that is constantly evolving, it has its own tensions and contradictions. The book is composed of 12 chapters, created by authors of different backgrounds and fields: professors, researchers, educators, an archeologist, an anthropologist and a geographer, all of them with extensive experience in educational heritage. These articles are organized in four sections: a) Educational heritage: tensions and debates, b) Academic Cultural Heritage, c) Cultural Heritage of Indigenous Education and d) Museums, libraries and cultural heritage management.

Trends in drug overdose deaths in Mexico (1999–2019). A national descriptive analysis and interstate comparison

BackgroundWe assess trends in overdose mortality rates in Mexico from 1999 to 2019 and identify the states with the highest overdose mortality rates over time. MethodsThe analysis using mortality statistics examined deaths related to drug use. We estimated general overdose mortality rates at the national and state levels and calculated specific mortality rates associated with opioid and stimulant use using central rate estimation. We used joinpoint regression to analyse national and state-specific trends in overdose mortality from 1999 to 2019. FindingsNationally, the general overdose mortality rate increased annually by 10.49 % (p < 0.01, CI=11.4–18.9) from 2015 to 2019. The northern states of Baja California and Chihuahua were the states with the higher annual increases (18.6 %, p < 0.01, CI=4.2–29.6; and 15.6 %, p < 0.01, CI=12.9–19.7, respectively). By substance type, the national opioid-related mortality rate increased by 29.82 % per year from 2014 to 2019 (p < 0.01; CI=20.1–40.3), compared with an annual decrease of 11.43 % in the previous period (2005–2014) (p < 0.01; CI=-14.7- 8.0). Baja California was the state with the highest rise in opioid-related mortality from 2013 to 2019, with an annual increase of 15.84 % (p < 0.01; CI=1.4–32.3). Stimulant-related mortality increased by 21.79 % per year since 2013 (p < 0.01; CI=16.9–26.9), but it was not possible to calculate state-level trends. ConclusionsDrug-related mortality rates have increased in Mexico since 2015, particularly in the northern states of Baja California, Chihuahua, Sonora and Sinaloa. Improving harm reduction programmes and local surveillance of fatal and non-fatal overdoses is essential to address the silent escalation of overdose mortality.

Clinical and histological profiling of triple-negative breast cancer at Chihuahua´s state cancer center: An observational study.

e22529 Background: Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by the absence of estrogen receptor, progesterone receptor, and HER2 expression. This subtype is associated with a poorer prognosis and higher recurrence rates compared to other breast cancer subtypes. Understanding the histopathological and clinical characteristics of TNBC is crucial for improving early detection, clinical management, and treatment outcomes. In this context, a descriptive analysis was conducted to explore the association between TNBC and histological grade, histopathological type, and clinical stage at the State Cancer Center. Methods: A retrospective, single-center study was conducted at Chihuahua's State Cancer Center, where medical records of patients aged ≥ 18 years old diagnosed with TNBC between January 2018 and December 2022 were retrospectively reviewed. Data related to weight, histological grade, histopathological type, and clinical stage at TNBC diagnosis were collected. Frequency analysis was performed to determine the distribution of these characteristics in the TNBC patient population. Additionally, the association between histological grade and clinical stage at diagnosis was examined using appropriate statistical tests. Results: During the study period, 753 patients were diagnosed with breast cancer. Of these, 84 (11%) were diagnosed with triple-negative breast cancer and were included in the study. The mean age was 49 ± 13 years, with a mean BMI of 28 ± 5. The most common histologic subtype in this group was invasive ductal carcinoma, accounting for 78 (93%) of the TNBC cases. At the time of diagnosis, 19 (23%) were diagnosed with stage IIA, 17 (20%) with stage IIIA, 9 (11%) with stage IV, and 4 (5%) were detected in situ. Overall, the majority were identified as grade 3 tumors (44; 52%). Finally, within the stage IIA group, the majority were grade 3 tumors (58%). Conclusions: As seen in other cohorts, we found a similar frequency of TNBC among patients with breast cancer in our facility in the northwest of Mexico. The distribution of clinical stages highlights the varying degrees of disease progression at the time of diagnosis, with a considerable portion presenting at advanced stages. Moreover, these insights underscore the urgent need for improved screening strategies and early detection methods.

Adherence to fertility preservation guidelines in young patients with breast cancer: A retrospective analysis.

e23255 Background: Breast cancer affects a considerable proportion of women of childbearing age making it important to provide options for fertility preservation. At Chihuahua's State Cancer Center, a state-federal-funded institution providing free oncological care, and ensuring access to fertility preservation measures is integral to the multidisciplinary approach for young cancer survivors. Recognizing chemotherapy's impact on fertility, implementing fertility preservation measures is key. Assessing adherence to these guidelines is essential for comprehensive care and holistic well-being in young breast cancer patients at our center. Methods: In this retrospective study at the Chihuahua´s State Cancer Center, we examined adherence to fertility preservation guidelines among breast cancer patients aged 18 to 40 years. The primary method used for fertility preservation was the administration of GnRH analogs, such as triptorelin and goserelin. Data on GnRH analog use, chemotherapy regimens, and patient demographics were collected from medical records. The study aimed to assess the integration of fertility preservation measures, particularly GnRH analogs, into treatment plans for young breast cancer patients. Additionally, we aimed to identify barriers to accessing fertility preservation services in this population. Results: The study findings revealed that out of the 749 registered breast cancer patients, 95 (12.6%) were 40 years old or younger. Among these, 75 (79%) received adjuvant and/or neoadjuvant chemotherapy, with 58 (77.3%) being in locally advanced clinical stages. Of the 75 patients who underwent chemotherapy, 20 (26.7%) also received GnRH analogs, while 55 (73.3%) did not. Among the 75 chemotherapy recipients, 16 (p = 0.046) were estrogen receptor-positive and received analogs. Furthermore, out of the 20 patients with triple-negative breast cancer, only 1 (1.3%) received an analog. Conclusions: The study indicates that GnRH analogs usage in breast cancer patients is significantly associated with estrogen receptor positivity. While estrogen receptor status is crucial for determining treatment suitability, GnRH analog utilization was notably low among triple-negative breast cancer patients. This suggests that triple-negative status alone should not preclude GnRH analog use. The findings underscore the need to raise awareness and improve adherence to ovarian suppression recommendations to enhance clinical outcomes and quality of life for breast cancer patients.

Seed morphometry and NaCl and sucrose effect on germination rates and phytochemicals in sotol (Dasylirion acrotrichum) from the Chihuahua state, Mexico

In Mexico, “sotoles” (Dasylirion spp.) are used to elaborate the “sotol” liquor, handicraft making, and construction materials. These activities have enhanced the probability that sotol populations could decline because plants are extracted directly from their native ecosystems, given no commercial sotol plant species exist. Furthermore, from an ecological point of view, this genus has also been little studied regarding its seed morphology and germination process. The objective of this study was to characterize the morphometry of the D. acrotrichum seeds and to evaluate the effect of different concentrations of NaCl (30, 60, and 90 mM) and sucrose (30, 60, and 90 mM) on seed germination rates, seedling morphology, and the phytochemical content in the seedling leaves under in vitro conditions from plants grown in the Chihuahua State. The exogenous NaCl and sucrose treatments influenced the germination speed index, mean germination time, and mean germination speed. The NaCl treatment impacted the total weight, root weight, and leaf length of seedlings, the content of chlorophyll a, sugar, and phenolics, and the antioxidant activity determined by FRAP. Besides, the sucrose treatment affected the seedling length, the content of chlorophyll a, chlorophyll b, total chlorophyll, and sugars, and the antioxidant activity determined by FRAP and DPPH. These results could provide the guidelines to generate better afforestation programs in the areas affected by the overexploitation of the Dasylirion spp. and new information about the capacity of these species for developing under these types of stress in the natural environment.

Administrative strategy for the management of drinking water in rural communities of the State of Chihuahua

La gestión del agua en las comunidades rurales es una de las acciones esenciales para una mayor eficiencia en la administración y operación de los sistemas de agua potable. Por lo que es necesario diseñar estrategias que apoyen al fortalecimiento de las diferentes actividades que llevan a cabo. El objetivo general de la presente investigación fue diseñar una estrategia administrativa para la gestión del agua en comunidades rurales del estado de Chihuahua. El enfoque fue mixto, el diseño fue no experimental y transeccional, el muestreo fue no probabilístico por conveniencia, se describió y analizó la situación de los comités, se propusieron 8 dimensiones con sus indicadores respectivos y se validaron por expertos. Los principales resultados arrojados fueron que la Junta Central de Agua y Saneamiento y los comités, no cuentan con una estrategia administrativa, que permita conocer el estado actual de eficiencia y sustentabilidad. Uno de los problemas esenciales en resolver a las comunidades rurales por parte del organismo normativo, es proporcionar el apoyo a los comités en el arreglo de su infraestructura, ya que no cuentan las comunidades con los recursos ni las destrezas y conocimientos técnicos para lograr resolver algún problema que se les presente en la operación. La validación por medio de correlaciones de Pearson, regresión lineal, k-medias y análisis de brechas, permitió concluir que es viable la aplicación de la estrategia diseñada.

Identification of the Causes that Hinder Innovation in Companies in Chihuahua, Mexico

Innovation is a fundamental activity for product diversification and market expansion through the improvement of production processes and product quality. Understanding the causes that hinder innovation within organizations will allow the establishment of mechanisms to reactivate this important activity. With the aim of identifying the causes that hinder innovation in commercial and industrial organizations, the survey identified as CIS-4 was applied to 169 organizations in the state of Chihuahua, with 101 corresponding to organizations in the industrial sector and the rest in the services sector. The results showed cost as the main obstacle, followed by the knowledge factor. By applying the standard instrument for measuring innovation CIS-4, a comparison was made with the application to 20,747 companies in the countries of France and Italy, similarly obtaining cost as the main determinant hindering innovation. The results help us understand how innovation can be stimulated and supported.

Estimating Water Use Efficiency for Major Crops in Chihuahua, Mexico: Crop Yield Function Models vs. Evapotranspiration

Water use in agriculture is a critical aspect of sustainable food production. Efficient water management is essential to address both yield optimization and environmental concerns. The current study evaluated the water diversions by the Irrigation District 05—Delicias (DR-05), in the State of Chihuahua, Mexico, for four major crops grown in the region including alfalfa, chile, pecans and peanuts. The amounts of water applied to raise these crops were compared to the amounts of water use estimated with the evapotranspiration (ET) method and with the crop yield function model, and respective water use efficiencies were estimated with both the methods. The water use efficiency measured using the ET estimation (WUE-ET) for alfalfa ranged from 60.9% to 70.4%, while the water use efficiency derived from the yield function data (WUE-YF) showed lower values and ranged from 43.6% to 59.7%. In the case of chile, the opposite trends were observed than in alfalfa, with the WUE-ET for chile ranging from 47.7% to 54.8%, and WUE-YF showing higher values that ranged from 49% to 70%. In the case of peanuts and pecans, only the WUE-ET was estimated and it ranged from 55.9% to 68.8% for peanuts and 90.9% to 116.9% pecans, respectively. Among the four crops studied, pecans were found to have the highest WUE-ET, with values of WUE-ET reaching higher than 100%. However, it is to be noted that these high values of water use efficiencies are more indicative that pecans are probably under irrigated.

Characteristics of the white-tailed deer hunting exploitation (Odocoileus virginianus) in Chihuahua, Mexico

Objective: To describe the characteristics of the number of hectares (located in the UMAs registered in the state of Chihuahua) used for the white-tailed deer free-range production, the level of exploitation of the species, and its economic value. Design/Methodology/Approach: This study determined the number of Units for the Conservation, Management, and Sustainable Use of Wildlife (UMAs) registered in the state of Chihuahua, where white tailed deer had been exploited since 2015. Forty-three municipalities in the state of Chihuahua, with a total of 159 UMAs, were analyzed. Twenty-three randomly selected UMAs were characterized, taking into account the hectares and the presence of white-tailed deer per municipality. Finally, the exploitation value of the species use per community was established in order to determine its exploitation and economic value. Results: The total area used for the exploitation of the white-tailed deer reaches 1,067,380 hectares. Thirty-two municipalities had potential for the exploitation of white-tailed deer. Thirty-three deer were hunted per season in the 23 UMAs under study, which accounts for a $990,000 Mexican pesos gross income for the state of Chihuahua per season; this exploitation generates a total of 115 temporary jobs for the communities surrounding the 23 UMAs studied. Chihuahua’s UMAs welcome a total of 33 white-tailed deer hunters per season. Hunters pay $30,000 to $34,000 Mexican pesos for each white-tailed deer specimen. Study Limitations/Implications: The study provides an overview of the current state of the UMAs in the state of Chihuahua that have a permit for the white-tailed deer hunting exploitation. Each of the UMAs under study has specific characteristics, including: the services offered, the associated hunting species, and the exploitation populations under an integrated sustainability arrangement. This study does not include the benefits of exploiting associated species, such as the collared peccary (Dicotyles tajacu) and the wild turkey (Meleagris gallopavo). Findings/Conclusions: Based on the number of registered UMAs, 32 out of 40 municipalities use 100% of their registered area for the exploitation of white-tailed deer. The white-tailed deer hunting exploitation increases the profitability and productivity of livestock ranches.

List of the flea species of the State of Chihuahua, Mexico, with new records and a new species of Strepsylla Traub, 1950 (Siphonaptera: Ctenophthalmidae: Neopsyllinae: Phalacropsyllini).

A total of 45 flea species, assigned to 22 genera, are documented for the state of Chihuahua, Mexico. Fourteen records are new for the state, five species are recorded for the first time for the country and the state, and the number of species of Mexico is increased to 177 species. Chihuahua now has 25.4% of the total flea species registered for the country. A new species of the genus Strepsylla is described from specimens from the Flora and Fauna Protection Area Cerro del Mohinora, in the northwestern part of the Sierra Madre Occidental. Strepsylla mohinora sp. nov. is included in a published taxonomic key for the species of Strepsylla.

Exploring Microbial Rhizosphere Communities in Asymptomatic and Symptomatic Apple Trees Using Amplicon Sequencing and Shotgun Metagenomics

The rhizosphere is a dynamic and highly interactive habitat where diverse microbial communities are established, and it plays crucial roles in plant health and disease dynamics. In this study, microbial communities and functional profiles in the rhizosphere of both asymptomatic and symptomatic apple trees were investigated through amplicon sequencing and shotgun metagenomics. The research was conducted at a location in the municipality of Cuauhtemoc, Chihuahua State, Mexico, and a total of 22 samples were collected, comprising 12 for amplicon sequencing and 10 for shotgun metagenomic sequencing. Symptomatic trees were identified based on reddish branches and internal necrosis in the trunk and root, while asymptomatic trees exhibited a healthy physiology. The findings showed that the dominant bacterial phyla included Proteobacteria, Actinobacteria, and Bacteroidetes, with prevalent genera such as Streptomyces, Pseudomonas, and Rhodanobacter. The fungal communities featured Ascomycota, Mortierellomycota, and Basidiomycota, which were dominated by Fusarium, Penicillium, and Mortierella. In the fungal communities, Mortierellomycota, notably abundant in asymptomatic trees, holds potential as a biocontrol agent, as seen in other studies on the suppression of Fusarium wilt disease. The application of shotgun metagenomic sequencing revealed significant differences in alpha and beta diversities in bacterial communities, suggesting a health-dependent change in species composition and abundance. Functional profile analysis highlighted enzymatic activities associated with lipid synthesis/degradation, amino acid biosynthesis, carbohydrate metabolism, and nucleotide synthesis, which have been documented to participate in symbiotic relationships between plants. These insights not only contribute to understanding the dynamics of rhizosphere microbial activity but also provide valuable perspectives on the potential application of microbial communities for tree health and implications for the management of apple orchards.

Spatial-temporal risk factors in the occurrence of rabies in Mexico.

Rabies is a zoonotic disease that affects livestock worldwide. The distribution of rabies is highly correlated with the distribution of the vampire bat Desmodus rotundus, the main vector of the disease. In this study, climatic, topographic, livestock population, vampire distribution and urban and rural zones were used to estimate the risk for presentation of cases of rabies in Mexico by co- Kriging interpolation. The highest risk for the presentation of cases is in the endemic areas of the disease, i.e. the States of Yucatán, Chiapas, Campeche, Quintana Roo, Tabasco, Veracruz, San Luis Potosí, Nayarit and Baja California Sur. A transition zone for cases was identified across northern Mexico, involving the States of Sonora, Sinaloa, Chihuahua, and Durango. The variables topography, vampire distribution, bovine population and rural zones are the most important to explain the risk of cases in livestock. This study provides robust estimates of risk and spread of rabies based on geostatistical methods. The information presented should be useful for authorities responsible of public and animal health when they plan and establish strategies preventing the spread of rabies into rabies-free regions of México.

Spatial Survival Model for COVID-19 in México

A spatial survival analysis was performed to identify some of the factors that influence the survival of patients with COVID-19 in the states of Guerrero, México, and Chihuahua. The data that we analyzed correspond to the period from 28 February 2020 to 24 November 2021. A Cox proportional hazards frailty model and a Cox proportional hazards model were fitted. For both models, the estimation of the parameters was carried out using the Bayesian approach. According to the DIC, WAIC, and LPML criteria, the spatial model was better. The analysis showed that the spatial effect influences the survival times of patients with COVID-19. The spatial survival analysis also revealed that age, gender, and the presence of comorbidities, which vary between states, and the development of pneumonia increase the risk of death from COVID-19.

Barriers to promoting breastfeeding in primary health care in Mexico: a qualitative perspective.

This article aimed to identify the main barriers related to promoting and counseling breastfeeding (BF) at the Primary Health Care (PHC) in Mexico. A qualitative study with a phenomenological approach was carried out in 88 health centers of the Ministry of Health in the states of Chihuahua, Oaxaca, Chiapas, Veracruz, Mexico, and Yucatan. From September to November 2021, we interviewed 88 key health professionals (HPs) (physicians, nurses, nutritionists, and others) from the PHC of the Ministry of Health in Mexico and 80 parents of children under 5 years old. In addition, nine focus groups were conducted with parents and caregivers. The data obtained were triangulated with information from focus groups and semi-structured interviews. Of the total interviews, 43.2% (n = 38) were nurses, 29.5% (n = 26) were physicians, 19.3% (n = 17) were nutritionists, and the rest were other health professionals. In the group of users, 97.6% (n = 121) were women. We identified contextual barriers, such as the lack of well-trained health professionals and the scarcest nutrition professionals, as material resources in the health units, without mentioning the low user attendance at their control consultations. Furthermore, we identified barriers related to the orientation and promotion of breastfeeding in health units, including a lack of specific strategies, ineffective communication, and the recommendations of commercial milk formulas. The results presented reflect the reality of Mexico in relation to BF, making it urgent to take immediate action to improve the quality of nutritional care related to the promotion and orientation of BF at the PHC.

Distribution of Pseudotsuga menziesii (Mirb.) Franco forest in Mexico

Pseudotsuga menziesii is a boreal species that is naturally distributed in North America. In Mexico it is listedin NOM-059-SEMARNAT-2010 in the category "subject to special protection", its populations are small anddiscontinuous, and its areas are considered of High Conservation Value. To determine its distribution andsurface area, we processed the Land Use and Vegetation Charts Series VI scale 1:250000 (nationalcontinuum), and that of the state of Chihuahua scale 1:50000 and considered maps and geographiccoordinates reported in various research works. In addition, information was obtained on the environmentalconditions where Pseudotsuga menziesii thrives; the results show that this species is distributed in 14 Stateswith approximately 57,000 ha and 98.5% of its populations are concentrated in the northern states ofChihuahua, Coahuila, Durango and Nuevo León; its communities develop in the high parts of the SierraMadre Oriental, Sierra Madre Occidental and Eje Neovolcanico in cold and humid climates with altitudesthat fluctuate from 2,200 to 3,400 m; it coexists mainly with species of the genus Pinus, Quercus, Abies,Populus, Picea, Arbutus and Cupressus; and its populations are being affected by natural and anthropogenicfactors. This study will allow a better management of these forests.

Characteristics Associated with Genetic Progress in Grain Yield in Wheat (Triticum aestivum L.)

Increasing the yield potential of cultivars can contribute to solving the problems of climate change and the increase in world population. The objectives of this study were to study the variation of 60 wheat (Triticum aestivum L.) genotypes and to estimate the genetic progress in agronomic characters of varieties released in Mexico in the period from 1966 to 2015. The hypothesis was that the increases in yield of the genotypes are the result of the increase in the number of grains per surface unit and biomass. The study was established in six experimental stations of the National Institute of Agricultural Forestry and Livestock Research in the states of Guanajuato, Sonora, Chihuahua, Jalisco, Sinaloa, and Baja California, Mexico. Phenology, yield, and its components were measured. The treatment design was alpha lattice with two replications. The location and genotype that showed the highest yield (P ≤ 0.01) were Baja California and COLIBRI/MONARCA, with 7309 and 5966 kg·ha−1. The average genetic gain in yield was 23.8 kg·ha−1·year−1. The grain weight increase rate was 0.21 g per year. During the period, there was no genetic progress in plant height, heading days, harvest index, grains per square meter, and ears per square meter. The increases in yield of the recent lines are due to increases in ears per square meter, grains per square meter, and biomass.