Resumen Los objetivos fueron analizar la estructura y variabilidad genética del bisonte americano con marcadores genéticos de tipo SNP. Se muestrearon 174 bisontes y se analizaron 42,366 SNP distribuidos en los 29 cromosomas. Se estimó la heterocigosis esperada (He) y observada (Ho), contenido de información polimórfica (CIP), índice de fijación (FIS), índice de Shannon (IS), desequilibrio de ligamiento y relación de parentesco (Rij; %), así como el tamaño efectivo de población (Ne). Se realizó un análisis de estructura genética para inferir cuántas líneas o genomas (k) definen la población. Se identificó y seleccionó un panel con 2,135 SNP polimórficos, con un promedio de 74 SNP por cromosoma. En el proceso de exclusión, 84.5 % fueron monomórficos, 8.5 % con porcentaje de usables menor a 90 %, 6.3 % con frecuencia del alelo menor inferior a 0.01 y 0.70 % por desequilibrio Hardy-Weinberg (P<0.05). Las estimaciones de IS, Ho, He, FIS y CIP fueron de 0.30, 0.187, 0.182, -0.029 y 0.152, respectivamente. Se generaron 15,051 estimaciones de Rij, el valor promedio de éstas fue 7.6 %, y el 45.1 % de ellas fue igual a cero. El Ne fue de 12.5, señalando un posible incremento de consanguinidad por generación de 4 %. Se identificaron tres líneas genéticas, con proporciones de 0.730, 0.157 y 0.113; dado el origen de la población, se asocian a selección natural o deriva genética. La variabilidad genética, así como los niveles de la Rij, se deben de considerar en esquemas de conservación.

Abstract Controlling for genetic variables to managing conservation populations. Single nucleotide polymorphism (SNP) genetic markers were used to analyze genetic structure and variability in an American bison population in the state of Chihuahua, Mexico. A total of 174 individuals were sampled and analysis done of 42,366 SNP distributed in 29 chromosomes. Estimates were done of expected (He) and observed (Ho) heterozygosity, polymorphic information content (PIC), the fixation index (FST), the Shannon index (SI), linkage disequilibrium (LD), kinship relationships (Rij; %), and effective population size (Ne). A genetic structure analysis was run to infer how many lines or genomes (k) define the studied population. A panel with 2,135 polymorphic SNPs was identified and selected, with an average of 74 SNP per chromosome. In the exclusion process, 84.5 % were monomorphic, 8.5 % had a usable percentage less than 90 %, 6.3 % had a minor allele frequency less than 0.01 and 0.70 % exhibited Hardy-Weinberg disequilibrium (P<0.05). Estimated values were 0.30 for the SI, 0.187 for Ho, 0.182 for He, -0.029 for the FST, and 0.152 for PIC. Of the 15,051 Rij estimates generated, the average value was 7.6 %, and 45.1 % were equal to zero. The Ne was 12.5, indicating a possible increase of 4 % in consanguinity per generation. Three genetic lines were identified (proportions = 0.730, 0.157 and 0.113), and, given the study population’s origin, are probably associated with natural selection or genetic drift. Genetic variability, as well as Rij levels, must be considered in conservation schemes.

RESUMO: Os objetivos deste estudo foram analisar o pedigree (41.521 registros de 1958 a 2019) da raça Sardo Negro para avaliar a estrutura, evolução e variabilidade genética (VG) da população. Os parâmetros genéticos populacionais utilizados foram: número efetivo de fundadores (fe) e ancestrais (fa); integridade do pedigree; relação genética aditiva (RGA); número de gerações completas (NGC), máximo plotado (NGT) e equivalentes (NGE); tamanho efetivo (Ne); consanguinidade (F); intervalo geracional (IG). O IG médio foi de 7,45 anos. Foram identificados 7.804 fundadores e 4.856 ancestrais, para fe 185 e 97 na fa. As médias e máximas para NGC, NGE e NGT foram 1,6 e 5,0, 2,5 e 6,5, 4,3 e 12, com estimativas de Ne 15,9, 25,9 e 69,0, respectivamente. O aumento de F, vinculado ao Ne, ficou na faixa de 0,72% a 3,1% por geração. A média para F 3,6% e 1,0% em RGA; a proporção de consanguíneos foi de 32,0%, com F na faixa de 0,01 a 62,2% e média de 11,3%. A taxa da população consanguínea foi de 1,3% ao ano. No RGA, a taxa ao ano era de 0,04%. Para a continuidade e projeção da raça, deve-se considerar a evolução de F em função de Ne e as possíveis implicações dos esquemas de seleção. A variabilidade genética sustentada ao longo do tempo resulta do Ne.

ABSTRACT: This study analyzed the Sardo Negro breed pedigree (41,521 animals registered from 1958 to 2019) to determine its structure, evolution, and genetic variability (GV). The population genetic parameters evaluated were effective number of founders (fe) and ancestors (fa), pedigree integrity, additive genetic relationship (AGR); number of complete generations (NCG), maximum generations traced (NMGT), and equivalent complete generations (NECG); effective population size (Ne), inbreeding coefficient (F), and generation interval (GI). The average GI was 7.45 years. A total of 7,804 founders and 4,856 ancestors were identified for a fe of 185 and a fa of 97. The average and maximum values of NCG, NECG, and NMGT were 1.6 and 5.0, 2.5 and 6.5, 4.3 and 12, with Ne estimates of 15.9, 25.9, and 69.0, respectively. The increase in F, linked to Ne, ranged from 0.72% to 3.1% per generation. The average values for F and AGR were 3.6% and 1.0%, respectively. The proportion of inbred individuals was 32.0%, with F values ranging from 0.01 to 62.2% and an average of 11.3%. The rate of inbred population was 1.3% per year. The annual rate of AGR was 0.04%. For the continuity and projection of the breed, the evolution of F as a function of Ne and the possible implications of the selection schemes must be considered. The genetic variability sustained over time results from the Ne.

ABSTRACT This study aimed to evaluate the lactation curve of female Murrah buffaloes, using mixed nonlinear models (NLM), across three lactation periods (180 d, 210 d, and 240 d). A total of 5334 data on daily milk production (kg) were analyzed. The data were collected every seven days in the interval of one to 250 days of lactation, corresponding to 221 lactations and 145 females, with calvings from 2017 to 2019. The data came from a herd located in the Centro municipality, Tabasco, Mexico. Five NLM were evaluated: Wood (WOD), Wiltmink (WIL), Cobby (COB), Brody (BRO), Sikka (SIK). The best fit model was selected based on the mean prediction error, mean absolute percentage error (MAPE), prediction error variance, coefficient of determination (R2), concordance correlation coefficient (CCC), Akaike (AIC) and Bayesian (BIC) information criteria. A regression analysis was performed between the observed and predicted values. All the NLM had a R2 above 0.91. They tend to underestimate the predictions, without residual autocorrelation. The MAPE showed an average value of 23.5%. The best fit model was WOD, followed by SIK and BRO. For WIL and COB, the mixed model did not improve the fitting. The shortest lactation period showed the best fit, followed by the 210 d and 240 d periods. The relationship between observed:predicted values fluctuated from 0.65 to 1.00, with an average value of 0.94. The use of NLM transcended in the AIC and BIC. The evaluated models showed goodness of fit, with good predictability, but low values in accuracy and precision of prediction.

Introduction:Water is esential for life and, for this reason, it is considered as the most important natural resource to earth. The objective of this research was to evaluate the quality of drinking water used for the Ascension's inhabitants in Chihuahua, Mexico, in terms of physical-chemical-metals and microbiological analysis.Method: Water samples were collected in 10 sites of the city of Ascension in four season; spring, summer, autumn and winter. In each season five samples from each well that supply water to the community and five samples in houses were obtained. The first sampling was conducted in July 2011 (Summer), the second in September 2011 (Autumn), the third in December 2011 (winter) and the fourth in May 2012 (Spring); therefore, a total of 40 samples were collected. In these aliquots were estimated the following variables; potential hydrogen (pH), electrical conductivity (EC), temperature (T), dissolved oxygen (DO), turbidity (Tur), total dissolved solids (TDS), total coliforms (TC) and fecal coliforms (FC). In addition, the following metals were quantified; Al, As, B, Cd, Ca, Cu, Cr, Fe, Mg, Mn, Ni, Ag, Pb, K, Na, Se, Si and Zn. An Analysis of Variance (ANOVA) looking for season differences (Factor A), water source differences (Factor B) and their interaction (AxB) was performed. For the variables total coliforms and fecal coliforms the non-parametric test of Kruskal-Wallis was applied. In all cases it was considered a level of significance of 0.05 (α=0.05).Results: The results showed that about 80% of the water samples were positive for TC and FC and the Kruskal-Wallis test detected season´s differences (P<0.05). The variables pH and T were different due to season (P<0.05), for water source (P<0.05) and for the interaction (P<0.05). The DO was different for seasons (P<0.05) and no differences were noted for TDS and EC while Tur was undetected. The metals Be, Cd and Co were not detected and no statistical differences were noted for the elements As, Cr, Cu, Fe, Li, Ni, Pb, Sb, Se and Zn; Nevertheless, some concentrations of As, Cr, Fe, Ni, Se and Zn are higher than the permitted values established in national and international norms. The metals Ca, Mg, Mn and Sr were statistically different due to one factor or the interaction.Discussion or Conclusion: It is concluded that drinking water that is being consumed for the community of Ascension is contaminated with coliforms and some metals that potentially represent a health risk to the community.

Introducción:El agua es una sustancia indispensable para la vida por lo que se considera como el recurso natural más apreciado en el planeta. En el norte de México existe el "Programa ambiental México-Estados Unidos: Frontera 2020"; en el cual participan instituciones mexicanas como la Junta Municipal de Aguas y Saneamiento (JMAS) mientras que por parte de los Estados Unidos de Norteamérica participan el Taskforce U.S., la Agencia Ambiental (USEPA) y la Universidad Estatal de Nuevo Mexico, entre otras (PAMEUF, 2013). En dicho programa ambiental el municipio de Ascensión está contemplado dentro de los planes de acción, por ser una región fronteriza, en especial en lo relacionado a la meta 2, la cual especifica el suministro de agua limpia y segura. Es importante mencionar que, a la fecha, no se conoce información que permita evaluar el nivel de calidad que aportan los cinco pozos que surten de agua a la cabecera municipal de Ascención, Chihuahua. El objetivo fue evaluar la calidad del agua potable que utiliza la comunidad de Ascensión, Chihuahua, mediante análisis físico-químico-metales y microbiológicos.Método:Las muestras de agua se obtuvieron de cinco pozos y de cinco hogares seleccionados al azar en cuatro temporadas. Se realizaron cuatro muestreos; julio de 2011, septiembre de 2011, diciembre de 2011 y mayo de 2012. Por lo tanto, se analizaron un total de 40 muestras a las que se les cuantificó el potencial de hidrógeno (pH), conductividad eléctrica (CE), temperatura (T), oxígeno disuelto (OD), turbidez (Tur), sólidos totales (SDT), coliformes totales (CT), coliformes fecales (CF) y los siguientes metales; Al, As, B, Cd, Ca, Cu, Cr, Fe, Mg, Mn, Ni, Ag, Pb, K, Na, Se, Si y Zn. Se aplicó un ANOVA para buscar diferencias por estación (Factor A), por fuente (Factor B) y su interacción (AxB). Para la variable de coliformes se aplicó la prueba no-paramétrica de Kruskal-Wallis. En todos los casos se consideró un nivel de significancia de 0.05 (α=0.05).Resultados:Alrededor del 80% de las muestras de agua dieron positivo para CT y CF y se encontraron diferencias por estación (P<0.05). El pH y T fueron diferentes por estación (P<0.05), por fuente (P<0.05) y en la interacción (P<0.05). El pH supera los valores establecidos en la norma mexicana NOM-127-SSA1-1994 (NOM, 1994) e internacional (EPA, 2013). La variable OD fue diferente por estación (P<0.05) y no se encontraron diferencias para SDT y CE. La variable Tur y los metales Be, Cd y Co no fueron detectados y no se encontraron diferencias para ningún factor o su interacción para los elementos As, Cr, Cu, Fe, Li, Ni, Pb, Sb, Se y Zn; sin embargo, algunas concentraciones de As, Cr, Fe, Ni, Se, y Zn superan lo establecido en alguna norma nacional (NOM, 1996) o internacional (EPA, 2013; OMS, 2014). Los metales Ca, Mg, Mn y Sr fueron estadísticamente diferentes para un factor o su interacción.Discusión o Conclusión: Se concluye que el agua potable de la comunidad de Ascensión está contaminada desde el punto de vista microbiológico (NOM, 1987), toda vez que se encontró la presencia de coliformes totales y fecales en todos los muestreos realizados. Además, la concentración de algunos metales como As, Cr, Fe, Ni, Se y Zn fueron detectados en diversos muestreos por encima de lo permitido en normas nacionales e internacionales.