Evaluation of depression, anxiety, risky eating behaviors, eating habits and physical activity after the COVID-19 pandemic among adolescents in Mexico City.

Introduction: Introduction: during the pandemic, an increase in symptoms of depression and anxiety, as well as lifestyle changes in adolescents has been reported. Objectives: to evaluate anxiety and depression symptoms, risky eating behaviors (REB), eating habits and physical activity after the COVID-19 pandemic in Mexican adolescents; to associate the study variables with the development of REB. Methods: a study was performed with a sample of 2,710 adolescents. The Hospital Anxiety and Depression Scale (HADS) and the Questionnaire to measure Risky Eating Behaviors were applied; eating habits and physical activity were evaluated. A Multivariate Logistic Regression analysis was performed to evaluate an association between study variables and REB. Results: it was found that 34.4 % and 47.2 % of the adolescents presented symptoms of depression and anxiety, respectively. Furthermore, 10.6 % had REB and 18.1 % were at risk of REB. The combined prevalence of overweight and obesity was 46.5 %; only 13.1 % of the participants had healthy eating habits and 18.2 % adequate physical activity. Symptoms of depression (p < 0.0001), anxiety (p < 0.0001), higher BMI (p < 0.0001), female sex, excessive consumption of sugary drinks, eating outside the home (p < 0.0001), and lifestyle (p = 0.001) were associated with REB. Conclusions: confinement caused chaos on the lifestyle of adolescents as well as their psychological health. It is essential to develop educational programs that involve government authorities, parents and health agencies to reinforce the topics of healthy eating, physical activity and mental health in the country's secondary schools.

Introducción: Introducción: durante la pandemia se han reportado un incremento de síntomas de depresión y ansiedad, así como cambios en el estilo de vida de los adolescentes. Objetivos: evaluar los síntomas de ansiedad y depresión, conductas alimentarias de riesgo (CAR), los hábitos alimentarios y actividad física posterior a la pandemia de COVID-19 en adolescentes mexicanos; asociar las variables del estudio con el desarrollo de CAR. Métodos: se realizó un estudio con una muestra de 2710 adolescentes. Se aplicó la Escala Hospitalaria de Ansiedad y Depresión y el Cuestionario para medir Conductas Alimentarias de Riesgo; se evaluaron hábitos alimentarios y actividad física. Se realizó un análisis de Regresión Logística Multivariante para evaluar una asociación entre variables del estudio y CAR. Resultados: se encontró que el 34,4 % y 47,2 % de los adolescentes presentaron síntomas de depresión y ansiedad, respectivamente. Además, el 10,6 % tuvieron CAR y el 18,1 % riesgo de CAR. La prevalencia combinada de sobrepeso y obesidad fue del 46,5 %, solo el 13,1 % de los participantes tuvieron hábitos alimentarios saludables y un 18,2 % actividad física adecuada. Los síntomas de depresión (p < 0,0001), la ansiedad (p < 0,0001), el mayor IMC (p < 0,0001), el sexo femenino, consumir bebidas azucaradas en exceso, comer fuera de casa (p < 0,0001) y el estilo de vida (p = 0,001) se asociaron con CAR Conclusiones: el confinamiento causó estragos en el estilo de vida de los adolescentes y en su salud psicológica. Es indispensable elaborar programas educativos que involucren a las autoridades gubernamentales, padres de familia e instancias sanitarias para reforzar temas de alimentación saludable, actividad física y salud mental en la educación secundaria del país.

Inclusion of chia seeds (Salvia hispanica L.) and pumpkin seeds (Cucurbita moschata) in dairy sheep diets.

Chia (Salvia hispanica L.) seed (CS) and Pumpkin (Cucurbita moschata) seed (PS) are used in ruminant diets as energy sources. The current experiment studied the impact of dietary inclusion of CS and PS on nutrient intake and digestibility, milk yield, and milk composition of dairy sheep. Twelve primiparous Texel × Suffolk ewes [70 ± 5 days in milk (DIM); 0.320 ± 0.029 kg milk yield] were distributed in a 4 × 3 Latin square design and fed either a butter-based control diet [CON; 13 g/kg dry matter] or two diets with 61 g/kg DM of either CS or PS. Dietary inclusion of CS and PS did not alter live weight (p >0.1) and DM intake (p >0.1). However, compared to the CON, dietary inclusion of both CS and PS increased the digestibility of neutral detergent fiber (p <0.001) and acid detergent lignin (p < 0.001). Milk production (p = 0.001), fat-corrected milk (p < 0.001), and feed efficiency (p < 0.001) were enhanced with PS, while the highest milk protein yield (p < 0.05) and lactose yield (p < 0.001) were for CS-fed ewes. Compared to the CON diet, the ingestion of either CS and/or PS decreased (p < 0.001) the C16:0 in milk. Moreover, both CS and PS tended to enhance the content of C18:3n6 (p > 0.05) and C18:3n3 (p > 0.05). Overall short-term feeding of CS and/or PS (up to 6.1% DM of diet) not only maintains the production performance and digestibility of nutrients but also positively modifies the milk FA composition.

Epidemiological Overview of Overweight and Obesity Related to Eating Habits, Physical Activity and the Concurrent Presence of Depression and Anxiety in Adolescents from High Schools in Mexico City: A Cross-Sectional Study.

Overweight and obesity in adolescents has become a serious public health problem worldwide and Mexico City is no exception. Therefore, the objective of this study was to investigate the epidemiological panorama of overweight and obesity related to eating habits, physical activity and the concurrent presence of depression and anxiety in adolescents from high schools in Mexico City. Anthropometric measurements were taken from 2710 adolescents from 33 participating high schools. Likewise, a previously validated eating habit and physical activity questionnaire was administered, which consisted of four different sections, where each of the sections focused on key aspects of the participants' lifestyle: (1) eating habits, (2) intake of non-recommended foods, (3) food and company environment, and (4) physical activity. Moreover, the Hospital Anxiety and Depression Scale (HADS) for anxiety and depression was applied. In this study, a high prevalence of overweight and obesity (26.5% overweight and 20.0% obese) was found in adolescents from high schools in Mexico City. Only 13.14% of participants had adequate eating habits and 18.19% physical activity habits. An association was found between having inadequate eating habits and obesity in adolescent women (OR = 1.95; CI 1.009-3.76). Additionally, associations were observed between depression symptoms and obesity (OR = 5.68, CI 1.36-32.81; p = 0.01), while anxiety was associated with underweight and obesity adjusted by other dietary habits and psychological factors. Therefore, it is important to identify adolescents with overweight or obesity and establish prevention strategies for weight control in this age group, promoting healthy eating, physical activity and education in mental health.

Construct Validity of a Questionnaire on Eating and Physical Activity Habits for Adolescents in Mexico City.

The assessment of eating and physical activity habits is an important step in promoting healthy behaviors among the adolescent population and is key in the prevention and management of chronic non-communicable diseases, such as obesity, diabetes, and cardiovascular disease. For this purpose, reliable and valid measuring instruments are essential. In this context, the aim of this article is to present the validation of a self-report questionnaire on eating and physical activity habits among adolescents in Mexico City. In order to validate the questionnaire, a cross-sectional study was conducted with a sample of 2710 adolescents between 11 and 12 years of age, the piloting of the questionnaire was carried out in September 2022 with a focus group, and the programming of the anthropometric measurements was established with the Federal Educational Authority of CDMX, as well as the application of the questionnaire to 33 schools, with these activities being scheduled from 7 November 2022 to 3 February 2023 and having an application duration of 15-25 min for each of the groups to which it was applied; the questionnaire that was applied consists of 31 questions that refer to the frequencies, quantity, or performance of behaviors related to the frequency and type of food, type of physical activity and behaviors related to the act of eating referring to the place where it is carried out (home or away from home) and with whom it is carried out (alone or in company), and about the individual's lifestyle. Subsequently, the reliability of the instrument was evaluated using Cronbach's alpha coefficient, and an exploratory factor analysis was conducted to determine the structure of the questionnaire. The results obtained showed that the questionnaire was adequately reliable (α = 0.778) with an eight-factor structure: four questions on mealtime frequencies, four questions on physical activity and lifestyles, six questions on the consumption of high-calorie foods, four questions on company and food consumption, four questions on the consumption of vegetables and fruits, four questions on the place of food consumption, two questions on the consumption of alcoholic beverages, and three questions on the consumption of sugary drinks, plain water, and milk. In conclusion, the self-report questionnaire on eating and physical activity habits among adolescents in Mexico City is reliable, has adequate internal consistency, and can therefore be used as a useful tool for the evaluation of eating and physical activity habits in this population.

Composición proximal y perfil de ácidos grasos en larvas de Cotinis columbica Burmeister

RESUMEN Objetivo. Determinar la composición proximal y perfil de ácidos grasos (AG) en larva de Cotinis columbica Burmeister colectada en los municipios de Mogotes y Garzón, Bogotá, Colombia. Materiales y métodos. Se colectaron seis muestras de larva C. columbica Burmeister durante tres meses, proveniente de los municipios de Mogotes y Garzón, Bogotá, Colombia (3 meses x 2=6). Las muestras fueron sometidas a análisis químico proximal y análisis de AG por cromatografía de gases con detector de ionización de flama y columna capilar. Resultados. En mogotes se encontraron 21.2 y 23.3% de grasa y proteína respectivamente, mientras que en Garzón se tuvieron valores de 31.1 y 25.9%, no hubo diferencia estadística (p≥0.05). Los análisis cromatográficos determinaron 18 AG, desde el C4:0 hasta el C22:2, c13,16. La prueba t de Student arrojó significancia (p<0.05) sólo en C10:0; a través del tiempo (mayo, junio y julio) los valores fueron más altos en larvas de Garzón. Los contenidos de grupos de ÁG saturados, monoinsaturados y poliinsaturados estuvieron entre 30.20 y 36.92 (% p/p). Conclusiones. La composición proximal y el perfil de ácidos grasos fueron similares, excepto para C10:0, en la grasa de larvas Cotinis columbica Burmeister provenientes de Mogotes y Garzón, Colombia.

ABSTRACT Objetive. To determine the proximal composition and profile of fatty acids (FA) in Cotinis columbica Burmeister larva collected in the municipalities of Mogotes and Garzón, Bogotá, Colombia. Materials and methods. Six samples of C. columbica Burmeister larvae were collected during three months, from the municipalities of Mogotes and Garzón, Bogotá, Colombia (3 months x 2 = 6). The samples were subjected to proximal chemical analysis and AG analysis by gas chromatography with a flame ionization detector and capillary column. Results. In mogotes, 21.2 and 23.3% of fat and protein were found, respectively, while in Garzón values of 31.1 and 25.9% were found, there was no statistical difference (p≥0.05). Chromatographic analyzes determined 18 AG, from C4:0 to C22:2, c13.16. The t-student test showed significance (p<0.05) only in C10:0; through time (May, June and July) the values were higher in Garzón larvae. The contents of saturated, monounsaturated and polyunsaturated AG groups were between 30.20 and 36.92 (% w/w). Conclusions. The proximal composition and fatty acid profile were similar, except for C10:0, in the fat of Cotinis columbica Burmeister larvae from Mogotes and Garzón, Colombia.

Environmental Exposure of Arsenic in Groundwater Associated to Carcinogenic Risk in Underweight Children Exposed to Fluorides.

BACKGROUND: The purpose of this study was to determine the concentration of inorganic arsenic (As) in the potable water available to the population to be able to estimate the non-carcinogenic risks for underweight children and the carcinogenic risk for adults exposed to As intake who live in the Mezquital municipality, Durango, Mexico. METHODS: The As content was quantifed in the water supply sources for human use and its intake was estimated in Mezquital population, southern Durango. With the data obtained, the hazard quotient (HQ) was calculated to determine the non-carcinogenic risk to develop chronic systemic effects in underweight children. The Environmental Protection Agency (EPA) reference health values estimating As exposure risk are from 0.0003 mg/kg/day (non-carcinogenic) to 1.5 mg/kg/day (carcinogenic risk). RESULTS: The analyzed waters presented as concentrations that varied from 0.3 to 10.2 µg/L, with a mean of 7.35 µg/L (CI 95% 6.27-8.38). The exposure dose was 0.4 to 1.36, and the HQ was 1.90 to 6.48 mg/kg/day, the estimated carcinogenic risk from adults varied from 1.28 to 4.37E-4, with values of 3.74-4.37E-4 mg/kg/day in central area. CONCLUSIONS: The children are at risk to develop chronic systemic effects due to ingestion of As from water.

[Intervention for the promotion on the consumption of milk and dairy products as a strategy to reduce overweight in adolescents of México]. / Intervención para el fomento del consumo de leche y productos lácteos como parte de una estrategia para la disminución del exceso de peso en adolescentes de la Ciudad de México.

INTRODUCTION: Introduction: the consumption of milk and dairy products can play an important role in the maintenance of healthy body weight, since, under normal conditions of individuals, a negative association has been observed between daily intake of calcium contained in milk and dairy products and adiposity markers. Objective: to determine if the consumption of milk and dairy products affects the body weight reduction of adolescents in high school in Mexico City. Methods: community trial with 2,368 adolescents in three phases: description of the initial nutritional status, multidisciplinary educational intervention in the intervention group and evaluation of the changes observed. A food frequency and reminder questionnaire of 24 hours was applied to the participants, anthropometric measures were taken and the Who Anthro Plus® program was used to obtain the nutritional diagnosis. Results: it was found, in the intervention group, that adolescents who never consume whole milk, skimmed milk, fresh cow's cheese and natural yogurt have a higher prevalence of obesity (15.8%, 12.5%, 19.0% and 19.0%, respectively), compared to the adolescents who consume them daily (0.0%, 0.0%, 2.3% and 5.6%, respectively), there being a highly significant difference for the consumption of cheese fresh cow's milk and natural yogurt (p ≤ 0.01). It was possible to increase the frequency of dairy consumption and changes in nutritional status were observed in the intervention group, where the prevalence of obesity decreased from 13.8% to 6.1%. Conclusions: adolescents with higher milk consumption and its dairy products had a lower prevalence of obesity.

INTRODUCCIÓN: Introducción: el consumo de leche y productos lácteos puede jugar un papel importante en el mantenimiento del peso corporal saludable, ya que, en condiciones normales de los individuos, se ha observado una asociación negativa entre la ingesta diaria del calcio contenido en la leche y los productos lácteos con el incremento adipositario. Objetivo: determinar si el consumo de leche y productos lácteos repercute en la disminución del peso corporal de los adolescentes de escuelas secundarias de la Ciudad de México. Métodos: ensayo comunitario con 2.368 adolescentes en tres fases: descripción del estado de nutrición inicial, intervención educativa multidisciplinaria en el grupo intervención y evaluación de los cambios observados. Se aplicó a los participantes un cuestionario de frecuencia de consumo de alimentos y recordatorio de 24 horas, se tomaron medidas antropométricas y se utilizó el programa Who Anthro Plus® para obtener el diagnóstico nutricional. Resultados: se encontró, en el grupo de intervención, que los adolescentes que nunca consumen leche entera, leche descremada, queso fresco de vaca y yogur natural presentan mayor prevalencia de obesidad (15,8%, 12,5%, 19,0% y 19,0%, respectivamente), en comparación con los adolescentes que los consumen diariamente (0,0%, 0,0%, 2,3% y 5,6%, respectivamente), con una diferencia altamente significativa para el consumo de queso fresco de vaca y yogurt natural (p ≤ 0,01). Se logró aumentar la frecuencia de consumo de lácteos y se observaron cambios en el estado de nutrición en el grupo de intervención, donde la prevalencia de obesidad disminuyó del 13,8% al 6,1%. Conclusiones: los adolescentes con mayor consumo de leche y productos lácteos presentaron menor prevalencia de obesidad.

Contenido de ácidos grasos en semillas de chía (Salvia hispanica L.) cultivadas en cuatro estados de México / Fatty acid content in chia (Salvia hispanica L.) seeds grown in four Mexican states

Introducción: existe evidencia científica de que la chía (Salvia hispanica L.) es originaria de México y que formó parte, junto con el maíz, frijol y amaranto, de la dieta prehispánica. Con la llegada de los españoles, su uso fue suprimido en las tradiciones y costumbres de los aztecas y mayas, no es hasta finales del siglo pasado que las semillas de chía han cobrado gran interés por su alto contenido de ácido alfa-linolénico así como su relación con la salud y nutrición humana. Objetivo: determinar el perfil de ácidos grasos en semillas de chía cultivadas en diferentes zonas de México. Métodos: se obtuvieron cinco lotes de semillas de chía, a los cuales se les extrajo el aceite en equipo soxhlet con éter de petróleo. El perfil de ácidos grasos se determinó por cromatografía de gases con detector de ionización de flama. Resultados: los análisis cromatográficos permitieron identificar y cuantificar nueve ácidos grasos en las muestras de aceite de chía, palmítico (C16) y palmitoleico (C16:1), esteárico (C18), oleico cis-9 (C18:1 c9), oleico cis-11 (C18:1 c11), oleico cis-12 (C18:1 c12), linoleico (C18: 2 c9c12), araquídico (C20), linolénico (C18:3 c6c9c12) y alfa-linolénico (C18:3 c9c12c15). El ácidos graso alfa-linolénico presentó la mayor concentración (62,67 %). Conclusiones: el contenido de ácidos grasos saturados e insaturados en el aceite de semillas de chía, cultivadas en zonas diferentes de México, se encuentra dentro del intervalo informado para otros países.

Introduction: there is scientific evidence that chia (Salvia hispanica L.) is native to Mexico and was part of the prehispanic diet alongside maize, beans and amaranth. Upon arrival of the Spanish colonizers, its use was suppressed from Aztec and Mayan customs and traditions. It is not until the end of the twentieth century that chia seeds attracted great interest due to their high alpha-linoleic acid content and its relationship to human nutrition and health. Objective: determine the fatty acid profile in chia seeds grown in various regions of Mexico. Methods: five lots of chia seeds were obtained, from which the oil was extracted in a Soxhlet device with petroleum ether. The fatty acid profile was determined by gas chromatography with a flame ionization detector. Results: chromatographic analysis permitted identification and quantification of nine fatty acids in the chia oil samples: palmitic (C16) and palmitoleic (C16:1), stearic (C18), cis-9 oleic (C18:1 c9), cis-11 oleic (C18:1 c11), cis-12 oleic (C18:1 c12), linoleic (C18: 2 c9c12), arachidic (C20), linolenic (C18:3 c6c9c12) and alpha-linolenic (C18:3 c9c12c15). Alpha-linolenic acid had the greatest concentration (62.67 %). Conclusions: the content of saturated and unsaturated fatty acids in oil from chia seeds grown in various regions of Mexico is within the range reported by other countries.

Aplicación de tres métodos analíticos para la detección de suero de quesería en leche UHT comercializada en la ciudad de México / Application of three analytic methods for the detection of cheese serum in UHT milk commercialized in Mexico city / Aplicação de três métodos analíticos para a detecção de soro de queijo oriundo de queijaria em leite UHT comercializado na cidade do México

Se determinó la presencia de suero de quesería en leches ultrapasteurizadas (UHT) comercializadas en la Ciudad de México mediante electroforesis en gel de poliacrilamida-dodecilsulfato de sodio (PAGE-SDS), cromatografía líquida de alta resolución (HPLC) y la cuarta derivada del espectro de absorción (UV-4ªDS). Se analizaron un total de 30 muestras de leche UHT descremada durante los meses de septiembre, octubre y noviembre a razón de 10 muestras por mes, contrastando los valores encontrados por los tres métodos con los de leche cruda auténtica adicionada con suero de quesería en diferentes niveles. El porcentaje de muestras positivas a suero de quesería analizadas por electroforesis, HPLC y UV-4ªDS fue de 70, 50 y 90% respectivamente. Las técnicas utilizadas relacionadas con la detección y estimación del glicomacropéptido (GMP) por electroforesis o por HPLC y los resultados obtenidos indicaron que la cuantificación de la relación proteínas de suero/proteína total (PS/PT) por UV-4ªDS fue un indicador más sensible a adiciones de suero de quesería.

The presence of cheese serum was detected in ultra pasteurized milks (UHT) commercialized in Mexico City. This was achieved through sodium dodecyl sulphate poliacrylamide gel electrophoresis (SDS-PAGE), by high performance liquid chromatography (HPLC) and by the calculation of the fourth derivative of the absorption spectrum (UV-4thDS). Monthly, ten (10) skimmed UHT milk samples were analyzed during September, October and November, and the values obtained through the three methods were compared against those from authentic raw milk with addition of cheese serum in different amounts. The percentage of positive samples to cheese serum analyzed through electrophoresis, HPLC and UV-4thDS was 70.50 and 90%, respectively. The applied techniques related to the detection and estimation of the glycomacropeptide (GMP) by electrophoresis or by HPLC, and the results obtained indicated that the quantification of the serum protein/total protein (PS/PT) relationship by UV-4thDS was a more sensitive indicator of cheese serum additions.

Determinou-se a presença de soro de queijo proveniente de queijaria em leites ultrapasteurizados (UHT) comercializados na Cidade do México mediante electroforese em gel de poliacrilamida-dodecilsulfato de sódio (PAGE-SDS), cromatografia líquida de alta resolução (HPLC) e a quarta derivada do espectro de absorção (UV-4ªDS). Analizaram-se um total de 30 amostras de leite UHT descremado durante os meses de setembro, outubro e novembro, média de 10 amostras por mês, contrastando os valores encontrados pelos três métodos com os de leite cru auténtico adicionada com soro de queijaria em diferentes níveis. A porcentagem de amostras positivas a soro de queijaria analizadas por electroforese, HPLC e UV-4ªDS foi de 70, 50 e 90% respectivamente. As técnicas utilizadas relacionadas com a detecção e estimação do glicomacropeptídeo (GMP) por electroforese ou por HPLC e os resultados obtidos indicaram que a quantificação da relação proteínas de soro/proteína total (PS/PT) por UV-4ªDS foi um indicador mais sensível a adições de soro de queijaria.

Detección de suero de quesería en leches ultrapasteurizadas mexicanas mediante la cuarta derivada del espectro de absorción / Rennet whey solids detection in Mexican ultrapasteurized milk using fourth derivative absortion spectrum

Presence of rennet whey solids in ultrapasteurized milk (UHT) commercialized in Mexico City was determined using fourth derivative of absorption spectrum method, which allows to know the variation in whey protein/total protein ratio (WP/TP). The quantification of WP/TP ratio was used as an indicator of adulteration with rennet whey solids. The method was standardized to evaluate the accuracy, linearity and repeatability by rennet whey addition in concentrations between 0-15%, in raw milk. Thirty samples of skim ultrapasteurized milk were analyzed during September, October and November; found values were compared to the ones of raw milk added with rennet whey solids (0-15%, in levels of 2.5%). A marginal difference was found in the WP/TP ratio for the 0% concentration between the two types of milk, while the rest of the concentrations showed a high significance (P < 0.01). Values above 13.5% of WP/TP showed rennet whey solids addition; 36.7% of the UHT milk samples were between 5% and 12% positive to rennet whey solids addition. The results indicated that fourth derivative of the absorption spectrum of the WP/TP ratio was a sensitive indicator to rennet whey solids additions.

Se determinó la presencia de suero de quesería en leches ultrapasteurizadas (UHT) comercializadas en la Ciudad de México mediante el método de la cuarta derivada del espectro de absorción, el cual permite conocer la variación de la relación proteínas de suero/proteína total (PS/PT). La cuantificación de la relación PS/PT se utilizó como indicador de la adulteración con suero de quesería. El método fue estandarizado evaluando la exactitud, linealidad y repetibilidad mediante la adición de suero en concentraciones entre 0%-15% a leche cruda. Se analizaron 30 muestras de leche ultrapasteurizada descremada durante septiembre, octubre y noviembre; los valores encontrados se contrastaron con los de leche cruda adicionada con suero de quesería (0%-15%, en niveles de 2.5%. Se encontró una diferencia marginal en la relación PS/PT para la concentración 0% entre los dos tipos de leche, mientras que el resto de las concentraciones mostró una significancia alta (P < 0.01). Valores por encima de 13.5% de PS/PT expresaron adición de suero; 36.7% de las muestras de leche UHT fueron positivas a la adición de suero entre 5% y 12%. Los resultados indicaron que la cuarta derivada del espectro de absorción de la relación PS/PT fue un indicador sensible a adiciones de suero de quesería.

Determination of the presence of 10 antimicrobial residues in mexican pasteurized milk

Los residuos de 9 agentes antimicrobianos aprobados en México para su uso veterinario en el ganado lechero (sulfatiazol, sulfamerazina, sulfametazina, sulfacloropiridazina, sulfamonometoxina, sulfametoxazol, nitrofurazona, furaltadona y furazolidona), así como de cloranfenicol, cuyo uso está prohibido en la producción pecuaria, fueron determinados en leche entera pasteurizada y comercializada en la Ciudad de México. Cuatro industrias de leche (A, B, C y D) fueron estudiadas quincenalmente durante un año (n= 4 x 24= 96). Los residuos fueron analizados por cromatografía de líquidos de alta presión (HPLC) con detector UV. El porcentaje de muestras positivas a residuos de sulfonamidas, fueron 47,2 por ciento (leche A); 58,3 por ciento (leche B); 44,7 por ciento (leche C) y 50 por ciento (leche D). Los residuos de sulfonamidas estuvieron en el intervalo de 1,9 a 180µg/kg. Residuos de sulfatiazol y sulfamerazina fueron los más encontrados. Sólo tres muestras (leche B) excedieron los niveles de residuo máximo establecidos para sulfonamidas. No se detectaron residuos de nitrofuranos en ninguna de las muestras de leche analizadas. Residuos de cloranfenicol fueron detectados en una muestra de leche (leche A) con un nivel de 27,2µg/g